/* __ _____ _____ _____ __| | __| | | | JSON for Modern C++ | | |__ | | | | | | version 3.9.1 |_____|_____|_____|_|___| https://github.com/nlohmann/json Licensed under the MIT License . SPDX-License-Identifier: MIT Copyright (c) 2013-2019 Niels Lohmann . Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #ifndef INCLUDE_NLOHMANN_JSON_HPP_ #define INCLUDE_NLOHMANN_JSON_HPP_ #define NLOHMANN_JSON_VERSION_MAJOR 3 #define NLOHMANN_JSON_VERSION_MINOR 9 #define NLOHMANN_JSON_VERSION_PATCH 1 #include // all_of, find, for_each #include // nullptr_t, ptrdiff_t, size_t #include // hash, less #include // initializer_list #include // istream, ostream #include // random_access_iterator_tag #include // unique_ptr #include // accumulate #include // string, stoi, to_string #include // declval, forward, move, pair, swap #include // vector #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #if defined(JSON_HAS_CPP_17) #include #endif /*! @brief namespace for Niels Lohmann @see https://github.com/nlohmann @since version 1.0.0 */ namespace nlohmann { /*! @brief a class to store JSON values @tparam ObjectType type for JSON objects (`std::map` by default; will be used in @ref object_t) @tparam ArrayType type for JSON arrays (`std::vector` by default; will be used in @ref array_t) @tparam StringType type for JSON strings and object keys (`std::string` by default; will be used in @ref string_t) @tparam BooleanType type for JSON booleans (`bool` by default; will be used in @ref boolean_t) @tparam NumberIntegerType type for JSON integer numbers (`int64_t` by default; will be used in @ref number_integer_t) @tparam NumberUnsignedType type for JSON unsigned integer numbers (@c `uint64_t` by default; will be used in @ref number_unsigned_t) @tparam NumberFloatType type for JSON floating-point numbers (`double` by default; will be used in @ref number_float_t) @tparam BinaryType type for packed binary data for compatibility with binary serialization formats (`std::vector` by default; will be used in @ref binary_t) @tparam AllocatorType type of the allocator to use (`std::allocator` by default) @tparam JSONSerializer the serializer to resolve internal calls to `to_json()` and `from_json()` (@ref adl_serializer by default) @requirement The class satisfies the following concept requirements: - Basic - [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible): JSON values can be default constructed. The result will be a JSON null value. - [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible): A JSON value can be constructed from an rvalue argument. - [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible): A JSON value can be copy-constructed from an lvalue expression. - [MoveAssignable](https://en.cppreference.com/w/cpp/named_req/MoveAssignable): A JSON value van be assigned from an rvalue argument. - [CopyAssignable](https://en.cppreference.com/w/cpp/named_req/CopyAssignable): A JSON value can be copy-assigned from an lvalue expression. - [Destructible](https://en.cppreference.com/w/cpp/named_req/Destructible): JSON values can be destructed. - Layout - [StandardLayoutType](https://en.cppreference.com/w/cpp/named_req/StandardLayoutType): JSON values have [standard layout](https://en.cppreference.com/w/cpp/language/data_members#Standard_layout): All non-static data members are private and standard layout types, the class has no virtual functions or (virtual) base classes. - Library-wide - [EqualityComparable](https://en.cppreference.com/w/cpp/named_req/EqualityComparable): JSON values can be compared with `==`, see @ref operator==(const_reference,const_reference). - [LessThanComparable](https://en.cppreference.com/w/cpp/named_req/LessThanComparable): JSON values can be compared with `<`, see @ref operator<(const_reference,const_reference). - [Swappable](https://en.cppreference.com/w/cpp/named_req/Swappable): Any JSON lvalue or rvalue of can be swapped with any lvalue or rvalue of other compatible types, using unqualified function call @ref swap(). - [NullablePointer](https://en.cppreference.com/w/cpp/named_req/NullablePointer): JSON values can be compared against `std::nullptr_t` objects which are used to model the `null` value. - Container - [Container](https://en.cppreference.com/w/cpp/named_req/Container): JSON values can be used like STL containers and provide iterator access. - [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer); JSON values can be used like STL containers and provide reverse iterator access. @invariant The member variables @a m_value and @a m_type have the following relationship: - If `m_type == value_t::object`, then `m_value.object != nullptr`. - If `m_type == value_t::array`, then `m_value.array != nullptr`. - If `m_type == value_t::string`, then `m_value.string != nullptr`. The invariants are checked by member function assert_invariant(). @internal @note ObjectType trick from https://stackoverflow.com/a/9860911 @endinternal @see [RFC 7159: The JavaScript Object Notation (JSON) Data Interchange Format](http://rfc7159.net/rfc7159) @since version 1.0.0 @nosubgrouping */ NLOHMANN_BASIC_JSON_TPL_DECLARATION class basic_json { private: template friend struct detail::external_constructor; friend ::nlohmann::json_pointer; template friend class ::nlohmann::detail::parser; friend ::nlohmann::detail::serializer; template friend class ::nlohmann::detail::iter_impl; template friend class ::nlohmann::detail::binary_writer; template friend class ::nlohmann::detail::binary_reader; template friend class ::nlohmann::detail::json_sax_dom_parser; template friend class ::nlohmann::detail::json_sax_dom_callback_parser; template friend class ::nlohmann::detail::diagnostics_t; /// workaround type for MSVC using basic_json_t = NLOHMANN_BASIC_JSON_TPL; /// shortcut using diagnostics_t = ::nlohmann::detail::diagnostics_t; JSON_PRIVATE_UNLESS_TESTED: // convenience aliases for types residing in namespace detail; using lexer = ::nlohmann::detail::lexer_base; template static ::nlohmann::detail::parser parser( InputAdapterType adapter, detail::parser_callback_tcb = nullptr, const bool allow_exceptions = true, const bool ignore_comments = false ) { return ::nlohmann::detail::parser(std::move(adapter), std::move(cb), allow_exceptions, ignore_comments); } private: using primitive_iterator_t = ::nlohmann::detail::primitive_iterator_t; template using internal_iterator = ::nlohmann::detail::internal_iterator; template using iter_impl = ::nlohmann::detail::iter_impl; template using iteration_proxy = ::nlohmann::detail::iteration_proxy; template using json_reverse_iterator = ::nlohmann::detail::json_reverse_iterator; template using output_adapter_t = ::nlohmann::detail::output_adapter_t; template using binary_reader = ::nlohmann::detail::binary_reader; template using binary_writer = ::nlohmann::detail::binary_writer; JSON_PRIVATE_UNLESS_TESTED: using serializer = ::nlohmann::detail::serializer; public: using value_t = detail::value_t; /// JSON Pointer, see @ref nlohmann::json_pointer using json_pointer = ::nlohmann::json_pointer; template using json_serializer = JSONSerializer; /// how to treat decoding errors using error_handler_t = detail::error_handler_t; /// how to treat CBOR tags using cbor_tag_handler_t = detail::cbor_tag_handler_t; /// helper type for initializer lists of basic_json values using initializer_list_t = std::initializer_list>; using input_format_t = detail::input_format_t; /// SAX interface type, see @ref nlohmann::json_sax using json_sax_t = json_sax; //////////////// // exceptions // //////////////// /// @name exceptions /// Classes to implement user-defined exceptions. /// @{ /// @copydoc detail::exception using exception = detail::exception; /// @copydoc detail::parse_error using parse_error = detail::parse_error; /// @copydoc detail::invalid_iterator using invalid_iterator = detail::invalid_iterator; /// @copydoc detail::type_error using type_error = detail::type_error; /// @copydoc detail::out_of_range using out_of_range = detail::out_of_range; /// @copydoc detail::other_error using other_error = detail::other_error; /// @} ///////////////////// // container types // ///////////////////// /// @name container types /// The canonic container types to use @ref basic_json like any other STL /// container. /// @{ /// the type of elements in a basic_json container using value_type = basic_json; /// the type of an element reference using reference = value_type&; /// the type of an element const reference using const_reference = const value_type&; /// a type to represent differences between iterators using difference_type = std::ptrdiff_t; /// a type to represent container sizes using size_type = std::size_t; /// the allocator type using allocator_type = AllocatorType; /// the type of an element pointer using pointer = typename std::allocator_traits::pointer; /// the type of an element const pointer using const_pointer = typename std::allocator_traits::const_pointer; /// an iterator for a basic_json container using iterator = iter_impl; /// a const iterator for a basic_json container using const_iterator = iter_impl; /// a reverse iterator for a basic_json container using reverse_iterator = json_reverse_iterator; /// a const reverse iterator for a basic_json container using const_reverse_iterator = json_reverse_iterator; /// @} /*! @brief returns the allocator associated with the container */ static allocator_type get_allocator() { return allocator_type(); } /*! @brief returns version information on the library This function returns a JSON object with information about the library, including the version number and information on the platform and compiler. @return JSON object holding version information key | description ----------- | --------------- `compiler` | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version). `copyright` | The copyright line for the library as string. `name` | The name of the library as string. `platform` | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`. `url` | The URL of the project as string. `version` | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string). @liveexample{The following code shows an example output of the `meta()` function.,meta} @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @complexity Constant. @since 2.1.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json meta() { basic_json result; result["copyright"] = "(C) 2013-2021 Niels Lohmann"; result["name"] = "JSON for Modern C++"; result["url"] = "https://github.com/nlohmann/json"; result["version"]["string"] = std::to_string(NLOHMANN_JSON_VERSION_MAJOR) + "." + std::to_string(NLOHMANN_JSON_VERSION_MINOR) + "." + std::to_string(NLOHMANN_JSON_VERSION_PATCH); result["version"]["major"] = NLOHMANN_JSON_VERSION_MAJOR; result["version"]["minor"] = NLOHMANN_JSON_VERSION_MINOR; result["version"]["patch"] = NLOHMANN_JSON_VERSION_PATCH; #ifdef _WIN32 result["platform"] = "win32"; #elif defined __linux__ result["platform"] = "linux"; #elif defined __APPLE__ result["platform"] = "apple"; #elif defined __unix__ result["platform"] = "unix"; #else result["platform"] = "unknown"; #endif #if defined(__ICC) || defined(__INTEL_COMPILER) result["compiler"] = {{"family", "icc"}, {"version", __INTEL_COMPILER}}; #elif defined(__clang__) result["compiler"] = {{"family", "clang"}, {"version", __clang_version__}}; #elif defined(__GNUC__) || defined(__GNUG__) result["compiler"] = {{"family", "gcc"}, {"version", std::to_string(__GNUC__) + "." + std::to_string(__GNUC_MINOR__) + "." + std::to_string(__GNUC_PATCHLEVEL__)}}; #elif defined(__HP_cc) || defined(__HP_aCC) result["compiler"] = "hp" #elif defined(__IBMCPP__) result["compiler"] = {{"family", "ilecpp"}, {"version", __IBMCPP__}}; #elif defined(_MSC_VER) result["compiler"] = {{"family", "msvc"}, {"version", _MSC_VER}}; #elif defined(__PGI) result["compiler"] = {{"family", "pgcpp"}, {"version", __PGI}}; #elif defined(__SUNPRO_CC) result["compiler"] = {{"family", "sunpro"}, {"version", __SUNPRO_CC}}; #else result["compiler"] = {{"family", "unknown"}, {"version", "unknown"}}; #endif #ifdef __cplusplus result["compiler"]["c++"] = std::to_string(__cplusplus); #else result["compiler"]["c++"] = "unknown"; #endif return result; } /////////////////////////// // JSON value data types // /////////////////////////// /// @name JSON value data types /// The data types to store a JSON value. These types are derived from /// the template arguments passed to class @ref basic_json. /// @{ #if defined(JSON_HAS_CPP_14) // Use transparent comparator if possible, combined with perfect forwarding // on find() and count() calls prevents unnecessary string construction. using object_comparator_t = std::less<>; #else using object_comparator_t = std::less; #endif /*! @brief a type for an object [RFC 7159](http://rfc7159.net/rfc7159) describes JSON objects as follows: > An object is an unordered collection of zero or more name/value pairs, > where a name is a string and a value is a string, number, boolean, null, > object, or array. To store objects in C++, a type is defined by the template parameters described below. @tparam ObjectType the container to store objects (e.g., `std::map` or `std::unordered_map`) @tparam StringType the type of the keys or names (e.g., `std::string`). The comparison function `std::less` is used to order elements inside the container. @tparam AllocatorType the allocator to use for objects (e.g., `std::allocator`) #### Default type With the default values for @a ObjectType (`std::map`), @a StringType (`std::string`), and @a AllocatorType (`std::allocator`), the default value for @a object_t is: @code {.cpp} std::map< std::string, // key_type basic_json, // value_type std::less, // key_compare std::allocator> // allocator_type > @endcode #### Behavior The choice of @a object_t influences the behavior of the JSON class. With the default type, objects have the following behavior: - When all names are unique, objects will be interoperable in the sense that all software implementations receiving that object will agree on the name-value mappings. - When the names within an object are not unique, it is unspecified which one of the values for a given key will be chosen. For instance, `{"key": 2, "key": 1}` could be equal to either `{"key": 1}` or `{"key": 2}`. - Internally, name/value pairs are stored in lexicographical order of the names. Objects will also be serialized (see @ref dump) in this order. For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be stored and serialized as `{"a": 2, "b": 1}`. - When comparing objects, the order of the name/value pairs is irrelevant. This makes objects interoperable in the sense that they will not be affected by these differences. For instance, `{"b": 1, "a": 2}` and `{"a": 2, "b": 1}` will be treated as equal. #### Limits [RFC 7159](http://rfc7159.net/rfc7159) specifies: > An implementation may set limits on the maximum depth of nesting. In this class, the object's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the @ref max_size function of a JSON object. #### Storage Objects are stored as pointers in a @ref basic_json type. That is, for any access to object values, a pointer of type `object_t*` must be dereferenced. @sa @ref array_t -- type for an array value @since version 1.0.0 @note The order name/value pairs are added to the object is *not* preserved by the library. Therefore, iterating an object may return name/value pairs in a different order than they were originally stored. In fact, keys will be traversed in alphabetical order as `std::map` with `std::less` is used by default. Please note this behavior conforms to [RFC 7159](http://rfc7159.net/rfc7159), because any order implements the specified "unordered" nature of JSON objects. */ using object_t = ObjectType>>; /*! @brief a type for an array [RFC 7159](http://rfc7159.net/rfc7159) describes JSON arrays as follows: > An array is an ordered sequence of zero or more values. To store objects in C++, a type is defined by the template parameters explained below. @tparam ArrayType container type to store arrays (e.g., `std::vector` or `std::list`) @tparam AllocatorType allocator to use for arrays (e.g., `std::allocator`) #### Default type With the default values for @a ArrayType (`std::vector`) and @a AllocatorType (`std::allocator`), the default value for @a array_t is: @code {.cpp} std::vector< basic_json, // value_type std::allocator // allocator_type > @endcode #### Limits [RFC 7159](http://rfc7159.net/rfc7159) specifies: > An implementation may set limits on the maximum depth of nesting. In this class, the array's limit of nesting is not explicitly constrained. However, a maximum depth of nesting may be introduced by the compiler or runtime environment. A theoretical limit can be queried by calling the @ref max_size function of a JSON array. #### Storage Arrays are stored as pointers in a @ref basic_json type. That is, for any access to array values, a pointer of type `array_t*` must be dereferenced. @sa @ref object_t -- type for an object value @since version 1.0.0 */ using array_t = ArrayType>; /*! @brief a type for a string [RFC 7159](http://rfc7159.net/rfc7159) describes JSON strings as follows: > A string is a sequence of zero or more Unicode characters. To store objects in C++, a type is defined by the template parameter described below. Unicode values are split by the JSON class into byte-sized characters during deserialization. @tparam StringType the container to store strings (e.g., `std::string`). Note this container is used for keys/names in objects, see @ref object_t. #### Default type With the default values for @a StringType (`std::string`), the default value for @a string_t is: @code {.cpp} std::string @endcode #### Encoding Strings are stored in UTF-8 encoding. Therefore, functions like `std::string::size()` or `std::string::length()` return the number of bytes in the string rather than the number of characters or glyphs. #### String comparison [RFC 7159](http://rfc7159.net/rfc7159) states: > Software implementations are typically required to test names of object > members for equality. Implementations that transform the textual > representation into sequences of Unicode code units and then perform the > comparison numerically, code unit by code unit, are interoperable in the > sense that implementations will agree in all cases on equality or > inequality of two strings. For example, implementations that compare > strings with escaped characters unconverted may incorrectly find that > `"a\\b"` and `"a\u005Cb"` are not equal. This implementation is interoperable as it does compare strings code unit by code unit. #### Storage String values are stored as pointers in a @ref basic_json type. That is, for any access to string values, a pointer of type `string_t*` must be dereferenced. @since version 1.0.0 */ using string_t = StringType; /*! @brief a type for a boolean [RFC 7159](http://rfc7159.net/rfc7159) implicitly describes a boolean as a type which differentiates the two literals `true` and `false`. To store objects in C++, a type is defined by the template parameter @a BooleanType which chooses the type to use. #### Default type With the default values for @a BooleanType (`bool`), the default value for @a boolean_t is: @code {.cpp} bool @endcode #### Storage Boolean values are stored directly inside a @ref basic_json type. @since version 1.0.0 */ using boolean_t = BooleanType; /*! @brief a type for a number (integer) [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: > The representation of numbers is similar to that used in most > programming languages. A number is represented in base 10 using decimal > digits. It contains an integer component that may be prefixed with an > optional minus sign, which may be followed by a fraction part and/or an > exponent part. Leading zeros are not allowed. (...) Numeric values that > cannot be represented in the grammar below (such as Infinity and NaN) > are not permitted. This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, @ref number_integer_t, @ref number_unsigned_t and @ref number_float_t are used. To store integer numbers in C++, a type is defined by the template parameter @a NumberIntegerType which chooses the type to use. #### Default type With the default values for @a NumberIntegerType (`int64_t`), the default value for @a number_integer_t is: @code {.cpp} int64_t @endcode #### Default behavior - The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal `010` will be serialized to `8`. During deserialization, leading zeros yield an error. - Not-a-number (NaN) values will be serialized to `null`. #### Limits [RFC 7159](http://rfc7159.net/rfc7159) specifies: > An implementation may set limits on the range and precision of numbers. When the default type is used, the maximal integer number that can be stored is `9223372036854775807` (INT64_MAX) and the minimal integer number that can be stored is `-9223372036854775808` (INT64_MIN). Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as @ref number_unsigned_t or @ref number_float_t. [RFC 7159](http://rfc7159.net/rfc7159) further states: > Note that when such software is used, numbers that are integers and are > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense > that implementations will agree exactly on their numeric values. As this range is a subrange of the exactly supported range [INT64_MIN, INT64_MAX], this class's integer type is interoperable. #### Storage Integer number values are stored directly inside a @ref basic_json type. @sa @ref number_float_t -- type for number values (floating-point) @sa @ref number_unsigned_t -- type for number values (unsigned integer) @since version 1.0.0 */ using number_integer_t = NumberIntegerType; /*! @brief a type for a number (unsigned) [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: > The representation of numbers is similar to that used in most > programming languages. A number is represented in base 10 using decimal > digits. It contains an integer component that may be prefixed with an > optional minus sign, which may be followed by a fraction part and/or an > exponent part. Leading zeros are not allowed. (...) Numeric values that > cannot be represented in the grammar below (such as Infinity and NaN) > are not permitted. This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, @ref number_integer_t, @ref number_unsigned_t and @ref number_float_t are used. To store unsigned integer numbers in C++, a type is defined by the template parameter @a NumberUnsignedType which chooses the type to use. #### Default type With the default values for @a NumberUnsignedType (`uint64_t`), the default value for @a number_unsigned_t is: @code {.cpp} uint64_t @endcode #### Default behavior - The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in integer literals lead to an interpretation as octal number. Internally, the value will be stored as decimal number. For instance, the C++ integer literal `010` will be serialized to `8`. During deserialization, leading zeros yield an error. - Not-a-number (NaN) values will be serialized to `null`. #### Limits [RFC 7159](http://rfc7159.net/rfc7159) specifies: > An implementation may set limits on the range and precision of numbers. When the default type is used, the maximal integer number that can be stored is `18446744073709551615` (UINT64_MAX) and the minimal integer number that can be stored is `0`. Integer numbers that are out of range will yield over/underflow when used in a constructor. During deserialization, too large or small integer numbers will be automatically be stored as @ref number_integer_t or @ref number_float_t. [RFC 7159](http://rfc7159.net/rfc7159) further states: > Note that when such software is used, numbers that are integers and are > in the range \f$[-2^{53}+1, 2^{53}-1]\f$ are interoperable in the sense > that implementations will agree exactly on their numeric values. As this range is a subrange (when considered in conjunction with the number_integer_t type) of the exactly supported range [0, UINT64_MAX], this class's integer type is interoperable. #### Storage Integer number values are stored directly inside a @ref basic_json type. @sa @ref number_float_t -- type for number values (floating-point) @sa @ref number_integer_t -- type for number values (integer) @since version 2.0.0 */ using number_unsigned_t = NumberUnsignedType; /*! @brief a type for a number (floating-point) [RFC 7159](http://rfc7159.net/rfc7159) describes numbers as follows: > The representation of numbers is similar to that used in most > programming languages. A number is represented in base 10 using decimal > digits. It contains an integer component that may be prefixed with an > optional minus sign, which may be followed by a fraction part and/or an > exponent part. Leading zeros are not allowed. (...) Numeric values that > cannot be represented in the grammar below (such as Infinity and NaN) > are not permitted. This description includes both integer and floating-point numbers. However, C++ allows more precise storage if it is known whether the number is a signed integer, an unsigned integer or a floating-point number. Therefore, three different types, @ref number_integer_t, @ref number_unsigned_t and @ref number_float_t are used. To store floating-point numbers in C++, a type is defined by the template parameter @a NumberFloatType which chooses the type to use. #### Default type With the default values for @a NumberFloatType (`double`), the default value for @a number_float_t is: @code {.cpp} double @endcode #### Default behavior - The restrictions about leading zeros is not enforced in C++. Instead, leading zeros in floating-point literals will be ignored. Internally, the value will be stored as decimal number. For instance, the C++ floating-point literal `01.2` will be serialized to `1.2`. During deserialization, leading zeros yield an error. - Not-a-number (NaN) values will be serialized to `null`. #### Limits [RFC 7159](http://rfc7159.net/rfc7159) states: > This specification allows implementations to set limits on the range and > precision of numbers accepted. Since software that implements IEEE > 754-2008 binary64 (double precision) numbers is generally available and > widely used, good interoperability can be achieved by implementations > that expect no more precision or range than these provide, in the sense > that implementations will approximate JSON numbers within the expected > precision. This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note values smaller than `-1.79769313486232e+308` and values greater than `1.79769313486232e+308` will be stored as NaN internally and be serialized to `null`. #### Storage Floating-point number values are stored directly inside a @ref basic_json type. @sa @ref number_integer_t -- type for number values (integer) @sa @ref number_unsigned_t -- type for number values (unsigned integer) @since version 1.0.0 */ using number_float_t = NumberFloatType; /*! @brief a type for a packed binary type This type is a type designed to carry binary data that appears in various serialized formats, such as CBOR's Major Type 2, MessagePack's bin, and BSON's generic binary subtype. This type is NOT a part of standard JSON and exists solely for compatibility with these binary types. As such, it is simply defined as an ordered sequence of zero or more byte values. Additionally, as an implementation detail, the subtype of the binary data is carried around as a `std::uint8_t`, which is compatible with both of the binary data formats that use binary subtyping, (though the specific numbering is incompatible with each other, and it is up to the user to translate between them). [CBOR's RFC 7049](https://tools.ietf.org/html/rfc7049) describes this type as: > Major type 2: a byte string. The string's length in bytes is represented > following the rules for positive integers (major type 0). [MessagePack's documentation on the bin type family](https://github.com/msgpack/msgpack/blob/master/spec.md#bin-format-family) describes this type as: > Bin format family stores an byte array in 2, 3, or 5 bytes of extra bytes > in addition to the size of the byte array. [BSON's specifications](http://bsonspec.org/spec.html) describe several binary types; however, this type is intended to represent the generic binary type which has the description: > Generic binary subtype - This is the most commonly used binary subtype and > should be the 'default' for drivers and tools. None of these impose any limitations on the internal representation other than the basic unit of storage be some type of array whose parts are decomposable into bytes. The default representation of this binary format is a `std::vector`, which is a very common way to represent a byte array in modern C++. #### Default type The default values for @a BinaryType is `std::vector` #### Storage Binary Arrays are stored as pointers in a @ref basic_json type. That is, for any access to array values, a pointer of the type `binary_t*` must be dereferenced. #### Notes on subtypes - CBOR - Binary values are represented as byte strings. No subtypes are supported and will be ignored when CBOR is written. - MessagePack - If a subtype is given and the binary array contains exactly 1, 2, 4, 8, or 16 elements, the fixext family (fixext1, fixext2, fixext4, fixext8) is used. For other sizes, the ext family (ext8, ext16, ext32) is used. The subtype is then added as singed 8-bit integer. - If no subtype is given, the bin family (bin8, bin16, bin32) is used. - BSON - If a subtype is given, it is used and added as unsigned 8-bit integer. - If no subtype is given, the generic binary subtype 0x00 is used. @sa @ref binary -- create a binary array @since version 3.8.0 */ using binary_t = nlohmann::byte_container_with_subtype; /// @} private: /// helper for exception-safe object creation template JSON_HEDLEY_RETURNS_NON_NULL static T* create(Args&& ... args) { AllocatorType alloc; using AllocatorTraits = std::allocator_traits>; auto deleter = [&](T * obj) { AllocatorTraits::deallocate(alloc, obj, 1); }; std::unique_ptr obj(AllocatorTraits::allocate(alloc, 1), deleter); AllocatorTraits::construct(alloc, obj.get(), std::forward(args)...); JSON_ASSERT(obj != nullptr); return obj.release(); } //////////////////////// // JSON value storage // //////////////////////// JSON_PRIVATE_UNLESS_TESTED: /*! @brief a JSON value The actual storage for a JSON value of the @ref basic_json class. This union combines the different storage types for the JSON value types defined in @ref value_t. JSON type | value_t type | used type --------- | --------------- | ------------------------ object | object | pointer to @ref object_t array | array | pointer to @ref array_t string | string | pointer to @ref string_t boolean | boolean | @ref boolean_t number | number_integer | @ref number_integer_t number | number_unsigned | @ref number_unsigned_t number | number_float | @ref number_float_t binary | binary | pointer to @ref binary_t null | null | *no value is stored* @note Variable-length types (objects, arrays, and strings) are stored as pointers. The size of the union should not exceed 64 bits if the default value types are used. @since version 1.0.0 */ union json_value { /// object (stored with pointer to save storage) object_t* object; /// array (stored with pointer to save storage) array_t* array; /// string (stored with pointer to save storage) string_t* string; /// binary (stored with pointer to save storage) binary_t* binary; /// boolean boolean_t boolean; /// number (integer) number_integer_t number_integer; /// number (unsigned integer) number_unsigned_t number_unsigned; /// number (floating-point) number_float_t number_float; /// default constructor (for null values) json_value() = default; /// constructor for booleans json_value(boolean_t v) noexcept : boolean(v) {} /// constructor for numbers (integer) json_value(number_integer_t v) noexcept : number_integer(v) {} /// constructor for numbers (unsigned) json_value(number_unsigned_t v) noexcept : number_unsigned(v) {} /// constructor for numbers (floating-point) json_value(number_float_t v) noexcept : number_float(v) {} /// constructor for empty values of a given type json_value(value_t t) { switch (t) { case value_t::object: { object = create(); break; } case value_t::array: { array = create(); break; } case value_t::string: { string = create(""); break; } case value_t::binary: { binary = create(); break; } case value_t::boolean: { boolean = boolean_t(false); break; } case value_t::number_integer: { number_integer = number_integer_t(0); break; } case value_t::number_unsigned: { number_unsigned = number_unsigned_t(0); break; } case value_t::number_float: { number_float = number_float_t(0.0); break; } case value_t::null: { object = nullptr; // silence warning, see #821 break; } default: { object = nullptr; // silence warning, see #821 if (JSON_HEDLEY_UNLIKELY(t == value_t::null)) { JSON_THROW(other_error::create(500, "961c151d2e87f2686a955a9be24d316f1362bf21 3.9.1", diagnostics_t())); // LCOV_EXCL_LINE } break; } } } /// constructor for strings json_value(const string_t& value) { string = create(value); } /// constructor for rvalue strings json_value(string_t&& value) { string = create(std::move(value)); } /// constructor for objects json_value(const object_t& value) { object = create(value); } /// constructor for rvalue objects json_value(object_t&& value) { object = create(std::move(value)); } /// constructor for arrays json_value(const array_t& value) { array = create(value); } /// constructor for rvalue arrays json_value(array_t&& value) { array = create(std::move(value)); } /// constructor for binary arrays json_value(const typename binary_t::container_type& value) { binary = create(value); } /// constructor for rvalue binary arrays json_value(typename binary_t::container_type&& value) { binary = create(std::move(value)); } /// constructor for binary arrays (internal type) json_value(const binary_t& value) { binary = create(value); } /// constructor for rvalue binary arrays (internal type) json_value(binary_t&& value) { binary = create(std::move(value)); } void destroy(value_t t) noexcept { // flatten the current json_value to a heap-allocated stack std::vector stack; // move the top-level items to stack if (t == value_t::array) { stack.reserve(array->size()); std::move(array->begin(), array->end(), std::back_inserter(stack)); } else if (t == value_t::object) { stack.reserve(object->size()); for (auto&& it : *object) { stack.push_back(std::move(it.second)); } } while (!stack.empty()) { // move the last item to local variable to be processed basic_json current_item(std::move(stack.back())); stack.pop_back(); // if current_item is array/object, move // its children to the stack to be processed later if (current_item.is_array()) { std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(), std::back_inserter(stack)); current_item.m_value.array->clear(); } else if (current_item.is_object()) { for (auto&& it : *current_item.m_value.object) { stack.push_back(std::move(it.second)); } current_item.m_value.object->clear(); } // it's now safe that current_item get destructed // since it doesn't have any children } switch (t) { case value_t::object: { AllocatorType alloc; std::allocator_traits::destroy(alloc, object); std::allocator_traits::deallocate(alloc, object, 1); break; } case value_t::array: { AllocatorType alloc; std::allocator_traits::destroy(alloc, array); std::allocator_traits::deallocate(alloc, array, 1); break; } case value_t::string: { AllocatorType alloc; std::allocator_traits::destroy(alloc, string); std::allocator_traits::deallocate(alloc, string, 1); break; } case value_t::binary: { AllocatorType alloc; std::allocator_traits::destroy(alloc, binary); std::allocator_traits::deallocate(alloc, binary, 1); break; } default: { break; } } } }; private: /*! @brief checks the class invariants This function asserts the class invariants. It needs to be called at the end of every constructor to make sure that created objects respect the invariant. Furthermore, it has to be called each time the type of a JSON value is changed, because the invariant expresses a relationship between @a m_type and @a m_value. Furthermore, the parent relation is checked for arrays and objects: If @a check_parents true and the value is an array or object, then the container's elements must have the current value as parent. @param[in] check_parents whether the parent relation should be checked. The value is true by default and should only be set to true during destruction of objects when the invariant does not need to hold. */ void assert_invariant(bool check_parents = true) const noexcept { JSON_ASSERT(m_type != value_t::object || m_value.object != nullptr); JSON_ASSERT(m_type != value_t::array || m_value.array != nullptr); JSON_ASSERT(m_type != value_t::string || m_value.string != nullptr); JSON_ASSERT(m_type != value_t::binary || m_value.binary != nullptr); #if JSON_DIAGNOSTICS JSON_ASSERT(!check_parents || !is_structured() || std::all_of(begin(), end(), [this](const basic_json & j) { return j.m_parent == this; })); #endif } reference set_parent(reference j, bool recursive) { #if JSON_DIAGNOSTICS if (recursive) { switch (m_type) { case value_t::array: { for (auto& element : *m_value.array) { element.m_parent = this; } break; } case value_t::object: { for (auto& element : *m_value.object) { element.second.m_parent = this; } break; } default: break; } } else { j.m_parent = this; } #else static_cast(j); static_cast(recursive); #endif return j; } public: ////////////////////////// // JSON parser callback // ////////////////////////// /*! @brief parser event types The parser callback distinguishes the following events: - `object_start`: the parser read `{` and started to process a JSON object - `key`: the parser read a key of a value in an object - `object_end`: the parser read `}` and finished processing a JSON object - `array_start`: the parser read `[` and started to process a JSON array - `array_end`: the parser read `]` and finished processing a JSON array - `value`: the parser finished reading a JSON value @image html callback_events.png "Example when certain parse events are triggered" @sa @ref parser_callback_t for more information and examples */ using parse_event_t = detail::parse_event_t; /*! @brief per-element parser callback type With a parser callback function, the result of parsing a JSON text can be influenced. When passed to @ref parse, it is called on certain events (passed as @ref parse_event_t via parameter @a event) with a set recursion depth @a depth and context JSON value @a parsed. The return value of the callback function is a boolean indicating whether the element that emitted the callback shall be kept or not. We distinguish six scenarios (determined by the event type) in which the callback function can be called. The following table describes the values of the parameters @a depth, @a event, and @a parsed. parameter @a event | description | parameter @a depth | parameter @a parsed ------------------ | ----------- | ------------------ | ------------------- parse_event_t::object_start | the parser read `{` and started to process a JSON object | depth of the parent of the JSON object | a JSON value with type discarded parse_event_t::key | the parser read a key of a value in an object | depth of the currently parsed JSON object | a JSON string containing the key parse_event_t::object_end | the parser read `}` and finished processing a JSON object | depth of the parent of the JSON object | the parsed JSON object parse_event_t::array_start | the parser read `[` and started to process a JSON array | depth of the parent of the JSON array | a JSON value with type discarded parse_event_t::array_end | the parser read `]` and finished processing a JSON array | depth of the parent of the JSON array | the parsed JSON array parse_event_t::value | the parser finished reading a JSON value | depth of the value | the parsed JSON value @image html callback_events.png "Example when certain parse events are triggered" Discarding a value (i.e., returning `false`) has different effects depending on the context in which function was called: - Discarded values in structured types are skipped. That is, the parser will behave as if the discarded value was never read. - In case a value outside a structured type is skipped, it is replaced with `null`. This case happens if the top-level element is skipped. @param[in] depth the depth of the recursion during parsing @param[in] event an event of type parse_event_t indicating the context in the callback function has been called @param[in,out] parsed the current intermediate parse result; note that writing to this value has no effect for parse_event_t::key events @return Whether the JSON value which called the function during parsing should be kept (`true`) or not (`false`). In the latter case, it is either skipped completely or replaced by an empty discarded object. @sa @ref parse for examples @since version 1.0.0 */ using parser_callback_t = detail::parser_callback_t; ////////////////// // constructors // ////////////////// /// @name constructors and destructors /// Constructors of class @ref basic_json, copy/move constructor, copy /// assignment, static functions creating objects, and the destructor. /// @{ /*! @brief create an empty value with a given type Create an empty JSON value with a given type. The value will be default initialized with an empty value which depends on the type: Value type | initial value ----------- | ------------- null | `null` boolean | `false` string | `""` number | `0` object | `{}` array | `[]` binary | empty array @param[in] v the type of the value to create @complexity Constant. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The following code shows the constructor for different @ref value_t values,basic_json__value_t} @sa @ref clear() -- restores the postcondition of this constructor @since version 1.0.0 */ basic_json(const value_t v) : m_type(v), m_value(v) { assert_invariant(); } /*! @brief create a null object Create a `null` JSON value. It either takes a null pointer as parameter (explicitly creating `null`) or no parameter (implicitly creating `null`). The passed null pointer itself is not read -- it is only used to choose the right constructor. @complexity Constant. @exceptionsafety No-throw guarantee: this constructor never throws exceptions. @liveexample{The following code shows the constructor with and without a null pointer parameter.,basic_json__nullptr_t} @since version 1.0.0 */ basic_json(std::nullptr_t = nullptr) noexcept : basic_json(value_t::null) { assert_invariant(); } /*! @brief create a JSON value This is a "catch all" constructor for all compatible JSON types; that is, types for which a `to_json()` method exists. The constructor forwards the parameter @a val to that method (to `json_serializer::to_json` method with `U = uncvref_t`, to be exact). Template type @a CompatibleType includes, but is not limited to, the following types: - **arrays**: @ref array_t and all kinds of compatible containers such as `std::vector`, `std::deque`, `std::list`, `std::forward_list`, `std::array`, `std::valarray`, `std::set`, `std::unordered_set`, `std::multiset`, and `std::unordered_multiset` with a `value_type` from which a @ref basic_json value can be constructed. - **objects**: @ref object_t and all kinds of compatible associative containers such as `std::map`, `std::unordered_map`, `std::multimap`, and `std::unordered_multimap` with a `key_type` compatible to @ref string_t and a `value_type` from which a @ref basic_json value can be constructed. - **strings**: @ref string_t, string literals, and all compatible string containers can be used. - **numbers**: @ref number_integer_t, @ref number_unsigned_t, @ref number_float_t, and all convertible number types such as `int`, `size_t`, `int64_t`, `float` or `double` can be used. - **boolean**: @ref boolean_t / `bool` can be used. - **binary**: @ref binary_t / `std::vector` may be used, unfortunately because string literals cannot be distinguished from binary character arrays by the C++ type system, all types compatible with `const char*` will be directed to the string constructor instead. This is both for backwards compatibility, and due to the fact that a binary type is not a standard JSON type. See the examples below. @tparam CompatibleType a type such that: - @a CompatibleType is not derived from `std::istream`, - @a CompatibleType is not @ref basic_json (to avoid hijacking copy/move constructors), - @a CompatibleType is not a different @ref basic_json type (i.e. with different template arguments) - @a CompatibleType is not a @ref basic_json nested type (e.g., @ref json_pointer, @ref iterator, etc ...) - @ref @ref json_serializer has a `to_json(basic_json_t&, CompatibleType&&)` method @tparam U = `uncvref_t` @param[in] val the value to be forwarded to the respective constructor @complexity Usually linear in the size of the passed @a val, also depending on the implementation of the called `to_json()` method. @exceptionsafety Depends on the called constructor. For types directly supported by the library (i.e., all types for which no `to_json()` function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value. @liveexample{The following code shows the constructor with several compatible types.,basic_json__CompatibleType} @since version 2.1.0 */ template < typename CompatibleType, typename U = detail::uncvref_t, detail::enable_if_t < !detail::is_basic_json::value && detail::is_compatible_type::value, int > = 0 > basic_json(CompatibleType && val) noexcept(noexcept( JSONSerializer::to_json(std::declval(), std::forward(val)))) { JSONSerializer::to_json(*this, std::forward(val)); set_parent(*this, true); assert_invariant(); } /*! @brief create a JSON value from an existing one This is a constructor for existing @ref basic_json types. It does not hijack copy/move constructors, since the parameter has different template arguments than the current ones. The constructor tries to convert the internal @ref m_value of the parameter. @tparam BasicJsonType a type such that: - @a BasicJsonType is a @ref basic_json type. - @a BasicJsonType has different template arguments than @ref basic_json_t. @param[in] val the @ref basic_json value to be converted. @complexity Usually linear in the size of the passed @a val, also depending on the implementation of the called `to_json()` method. @exceptionsafety Depends on the called constructor. For types directly supported by the library (i.e., all types for which no `to_json()` function was provided), strong guarantee holds: if an exception is thrown, there are no changes to any JSON value. @since version 3.2.0 */ template < typename BasicJsonType, detail::enable_if_t < detail::is_basic_json::value&& !std::is_same::value, int > = 0 > basic_json(const BasicJsonType& val) { using other_boolean_t = typename BasicJsonType::boolean_t; using other_number_float_t = typename BasicJsonType::number_float_t; using other_number_integer_t = typename BasicJsonType::number_integer_t; using other_number_unsigned_t = typename BasicJsonType::number_unsigned_t; using other_string_t = typename BasicJsonType::string_t; using other_object_t = typename BasicJsonType::object_t; using other_array_t = typename BasicJsonType::array_t; using other_binary_t = typename BasicJsonType::binary_t; switch (val.type()) { case value_t::boolean: JSONSerializer::to_json(*this, val.template get()); break; case value_t::number_float: JSONSerializer::to_json(*this, val.template get()); break; case value_t::number_integer: JSONSerializer::to_json(*this, val.template get()); break; case value_t::number_unsigned: JSONSerializer::to_json(*this, val.template get()); break; case value_t::string: JSONSerializer::to_json(*this, val.template get_ref()); break; case value_t::object: JSONSerializer::to_json(*this, val.template get_ref()); break; case value_t::array: JSONSerializer::to_json(*this, val.template get_ref()); break; case value_t::binary: JSONSerializer::to_json(*this, val.template get_ref()); break; case value_t::null: *this = nullptr; break; case value_t::discarded: m_type = value_t::discarded; break; default: // LCOV_EXCL_LINE JSON_ASSERT(false); // LCOV_EXCL_LINE } set_parent(*this, true); assert_invariant(); } /*! @brief create a container (array or object) from an initializer list Creates a JSON value of type array or object from the passed initializer list @a init. In case @a type_deduction is `true` (default), the type of the JSON value to be created is deducted from the initializer list @a init according to the following rules: 1. If the list is empty, an empty JSON object value `{}` is created. 2. If the list consists of pairs whose first element is a string, a JSON object value is created where the first elements of the pairs are treated as keys and the second elements are as values. 3. In all other cases, an array is created. The rules aim to create the best fit between a C++ initializer list and JSON values. The rationale is as follows: 1. The empty initializer list is written as `{}` which is exactly an empty JSON object. 2. C++ has no way of describing mapped types other than to list a list of pairs. As JSON requires that keys must be of type string, rule 2 is the weakest constraint one can pose on initializer lists to interpret them as an object. 3. In all other cases, the initializer list could not be interpreted as JSON object type, so interpreting it as JSON array type is safe. With the rules described above, the following JSON values cannot be expressed by an initializer list: - the empty array (`[]`): use @ref array(initializer_list_t) with an empty initializer list in this case - arrays whose elements satisfy rule 2: use @ref array(initializer_list_t) with the same initializer list in this case @note When used without parentheses around an empty initializer list, @ref basic_json() is called instead of this function, yielding the JSON null value. @param[in] init initializer list with JSON values @param[in] type_deduction internal parameter; when set to `true`, the type of the JSON value is deducted from the initializer list @a init; when set to `false`, the type provided via @a manual_type is forced. This mode is used by the functions @ref array(initializer_list_t) and @ref object(initializer_list_t). @param[in] manual_type internal parameter; when @a type_deduction is set to `false`, the created JSON value will use the provided type (only @ref value_t::array and @ref value_t::object are valid); when @a type_deduction is set to `true`, this parameter has no effect @throw type_error.301 if @a type_deduction is `false`, @a manual_type is `value_t::object`, but @a init contains an element which is not a pair whose first element is a string. In this case, the constructor could not create an object. If @a type_deduction would have be `true`, an array would have been created. See @ref object(initializer_list_t) for an example. @complexity Linear in the size of the initializer list @a init. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The example below shows how JSON values are created from initializer lists.,basic_json__list_init_t} @sa @ref array(initializer_list_t) -- create a JSON array value from an initializer list @sa @ref object(initializer_list_t) -- create a JSON object value from an initializer list @since version 1.0.0 */ basic_json(initializer_list_t init, bool type_deduction = true, value_t manual_type = value_t::array) { // check if each element is an array with two elements whose first // element is a string bool is_an_object = std::all_of(init.begin(), init.end(), [](const detail::json_ref& element_ref) { return element_ref->is_array() && element_ref->size() == 2 && (*element_ref)[0].is_string(); }); // adjust type if type deduction is not wanted if (!type_deduction) { // if array is wanted, do not create an object though possible if (manual_type == value_t::array) { is_an_object = false; } // if object is wanted but impossible, throw an exception if (JSON_HEDLEY_UNLIKELY(manual_type == value_t::object && !is_an_object)) { JSON_THROW(type_error::create(301, "cannot create object from initializer list", diagnostics_t())); } } if (is_an_object) { // the initializer list is a list of pairs -> create object m_type = value_t::object; m_value = value_t::object; for (auto& element_ref : init) { auto element = element_ref.moved_or_copied(); m_value.object->emplace( std::move(*((*element.m_value.array)[0].m_value.string)), std::move((*element.m_value.array)[1])); } } else { // the initializer list describes an array -> create array m_type = value_t::array; m_value.array = create(init.begin(), init.end()); } set_parent(*this, true); assert_invariant(); } /*! @brief explicitly create a binary array (without subtype) Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats. @note Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident. @param[in] init container containing bytes to use as binary type @return JSON binary array value @complexity Linear in the size of @a init. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @since version 3.8.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json binary(const typename binary_t::container_type& init) { auto res = basic_json(); res.m_type = value_t::binary; res.m_value = init; return res; } /*! @brief explicitly create a binary array (with subtype) Creates a JSON binary array value from a given binary container. Binary values are part of various binary formats, such as CBOR, MessagePack, and BSON. This constructor is used to create a value for serialization to those formats. @note Note, this function exists because of the difficulty in correctly specifying the correct template overload in the standard value ctor, as both JSON arrays and JSON binary arrays are backed with some form of a `std::vector`. Because JSON binary arrays are a non-standard extension it was decided that it would be best to prevent automatic initialization of a binary array type, for backwards compatibility and so it does not happen on accident. @param[in] init container containing bytes to use as binary type @param[in] subtype subtype to use in MessagePack and BSON @return JSON binary array value @complexity Linear in the size of @a init. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @since version 3.8.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json binary(const typename binary_t::container_type& init, std::uint8_t subtype) { auto res = basic_json(); res.m_type = value_t::binary; res.m_value = binary_t(init, subtype); return res; } /// @copydoc binary(const typename binary_t::container_type&) JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json binary(typename binary_t::container_type&& init) { auto res = basic_json(); res.m_type = value_t::binary; res.m_value = std::move(init); return res; } /// @copydoc binary(const typename binary_t::container_type&, std::uint8_t) JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json binary(typename binary_t::container_type&& init, std::uint8_t subtype) { auto res = basic_json(); res.m_type = value_t::binary; res.m_value = binary_t(std::move(init), subtype); return res; } /*! @brief explicitly create an array from an initializer list Creates a JSON array value from a given initializer list. That is, given a list of values `a, b, c`, creates the JSON value `[a, b, c]`. If the initializer list is empty, the empty array `[]` is created. @note This function is only needed to express two edge cases that cannot be realized with the initializer list constructor (@ref basic_json(initializer_list_t, bool, value_t)). These cases are: 1. creating an array whose elements are all pairs whose first element is a string -- in this case, the initializer list constructor would create an object, taking the first elements as keys 2. creating an empty array -- passing the empty initializer list to the initializer list constructor yields an empty object @param[in] init initializer list with JSON values to create an array from (optional) @return JSON array value @complexity Linear in the size of @a init. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The following code shows an example for the `array` function.,array} @sa @ref basic_json(initializer_list_t, bool, value_t) -- create a JSON value from an initializer list @sa @ref object(initializer_list_t) -- create a JSON object value from an initializer list @since version 1.0.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json array(initializer_list_t init = {}) { return basic_json(init, false, value_t::array); } /*! @brief explicitly create an object from an initializer list Creates a JSON object value from a given initializer list. The initializer lists elements must be pairs, and their first elements must be strings. If the initializer list is empty, the empty object `{}` is created. @note This function is only added for symmetry reasons. In contrast to the related function @ref array(initializer_list_t), there are no cases which can only be expressed by this function. That is, any initializer list @a init can also be passed to the initializer list constructor @ref basic_json(initializer_list_t, bool, value_t). @param[in] init initializer list to create an object from (optional) @return JSON object value @throw type_error.301 if @a init is not a list of pairs whose first elements are strings. In this case, no object can be created. When such a value is passed to @ref basic_json(initializer_list_t, bool, value_t), an array would have been created from the passed initializer list @a init. See example below. @complexity Linear in the size of @a init. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The following code shows an example for the `object` function.,object} @sa @ref basic_json(initializer_list_t, bool, value_t) -- create a JSON value from an initializer list @sa @ref array(initializer_list_t) -- create a JSON array value from an initializer list @since version 1.0.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json object(initializer_list_t init = {}) { return basic_json(init, false, value_t::object); } /*! @brief construct an array with count copies of given value Constructs a JSON array value by creating @a cnt copies of a passed value. In case @a cnt is `0`, an empty array is created. @param[in] cnt the number of JSON copies of @a val to create @param[in] val the JSON value to copy @post `std::distance(begin(),end()) == cnt` holds. @complexity Linear in @a cnt. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The following code shows examples for the @ref basic_json(size_type\, const basic_json&) constructor.,basic_json__size_type_basic_json} @since version 1.0.0 */ basic_json(size_type cnt, const basic_json& val) : m_type(value_t::array) { m_value.array = create(cnt, val); set_parent(*this, true); assert_invariant(); } /*! @brief construct a JSON container given an iterator range Constructs the JSON value with the contents of the range `[first, last)`. The semantics depends on the different types a JSON value can have: - In case of a null type, invalid_iterator.206 is thrown. - In case of other primitive types (number, boolean, or string), @a first must be `begin()` and @a last must be `end()`. In this case, the value is copied. Otherwise, invalid_iterator.204 is thrown. - In case of structured types (array, object), the constructor behaves as similar versions for `std::vector` or `std::map`; that is, a JSON array or object is constructed from the values in the range. @tparam InputIT an input iterator type (@ref iterator or @ref const_iterator) @param[in] first begin of the range to copy from (included) @param[in] last end of the range to copy from (excluded) @pre Iterators @a first and @a last must be initialized. **This precondition is enforced with an assertion (see warning).** If assertions are switched off, a violation of this precondition yields undefined behavior. @pre Range `[first, last)` is valid. Usually, this precondition cannot be checked efficiently. Only certain edge cases are detected; see the description of the exceptions below. A violation of this precondition yields undefined behavior. @warning A precondition is enforced with a runtime assertion that will result in calling `std::abort` if this precondition is not met. Assertions can be disabled by defining `NDEBUG` at compile time. See https://en.cppreference.com/w/cpp/error/assert for more information. @throw invalid_iterator.201 if iterators @a first and @a last are not compatible (i.e., do not belong to the same JSON value). In this case, the range `[first, last)` is undefined. @throw invalid_iterator.204 if iterators @a first and @a last belong to a primitive type (number, boolean, or string), but @a first does not point to the first element any more. In this case, the range `[first, last)` is undefined. See example code below. @throw invalid_iterator.206 if iterators @a first and @a last belong to a null value. In this case, the range `[first, last)` is undefined. @complexity Linear in distance between @a first and @a last. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @liveexample{The example below shows several ways to create JSON values by specifying a subrange with iterators.,basic_json__InputIt_InputIt} @since version 1.0.0 */ template < class InputIT, typename std::enable_if < std::is_same::value || std::is_same::value, int >::type = 0 > basic_json(InputIT first, InputIT last) { JSON_ASSERT(first.m_object != nullptr); JSON_ASSERT(last.m_object != nullptr); // make sure iterator fits the current value if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object)) { JSON_THROW(invalid_iterator::create(201, "iterators are not compatible", diagnostics_t())); } // copy type from first iterator m_type = first.m_object->m_type; // check if iterator range is complete for primitive values switch (m_type) { case value_t::boolean: case value_t::number_float: case value_t::number_integer: case value_t::number_unsigned: case value_t::string: { if (JSON_HEDLEY_UNLIKELY(!first.m_it.primitive_iterator.is_begin() || !last.m_it.primitive_iterator.is_end())) { JSON_THROW(invalid_iterator::create(204, "iterators out of range", diagnostics_t())); } break; } default: break; } switch (m_type) { case value_t::number_integer: { m_value.number_integer = first.m_object->m_value.number_integer; break; } case value_t::number_unsigned: { m_value.number_unsigned = first.m_object->m_value.number_unsigned; break; } case value_t::number_float: { m_value.number_float = first.m_object->m_value.number_float; break; } case value_t::boolean: { m_value.boolean = first.m_object->m_value.boolean; break; } case value_t::string: { m_value = *first.m_object->m_value.string; break; } case value_t::object: { m_value.object = create(first.m_it.object_iterator, last.m_it.object_iterator); break; } case value_t::array: { m_value.array = create(first.m_it.array_iterator, last.m_it.array_iterator); break; } case value_t::binary: { m_value = *first.m_object->m_value.binary; break; } default: JSON_THROW(invalid_iterator::create(206, "cannot construct with iterators from " + std::string(first.m_object->type_name()), diagnostics_t())); } set_parent(*this, true); assert_invariant(); } /////////////////////////////////////// // other constructors and destructor // /////////////////////////////////////// template, std::is_same>::value, int> = 0 > basic_json(const JsonRef& ref) : basic_json(ref.moved_or_copied()) {} /*! @brief copy constructor Creates a copy of a given JSON value. @param[in] other the JSON value to copy @post `*this == other` @complexity Linear in the size of @a other. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes to any JSON value. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is linear. - As postcondition, it holds: `other == basic_json(other)`. @liveexample{The following code shows an example for the copy constructor.,basic_json__basic_json} @since version 1.0.0 */ basic_json(const basic_json& other) : m_type(other.m_type) { // check of passed value is valid other.assert_invariant(); switch (m_type) { case value_t::object: { m_value = *other.m_value.object; break; } case value_t::array: { m_value = *other.m_value.array; break; } case value_t::string: { m_value = *other.m_value.string; break; } case value_t::boolean: { m_value = other.m_value.boolean; break; } case value_t::number_integer: { m_value = other.m_value.number_integer; break; } case value_t::number_unsigned: { m_value = other.m_value.number_unsigned; break; } case value_t::number_float: { m_value = other.m_value.number_float; break; } case value_t::binary: { m_value = *other.m_value.binary; break; } default: break; } set_parent(*this, true); assert_invariant(); } /*! @brief move constructor Move constructor. Constructs a JSON value with the contents of the given value @a other using move semantics. It "steals" the resources from @a other and leaves it as JSON null value. @param[in,out] other value to move to this object @post `*this` has the same value as @a other before the call. @post @a other is a JSON null value. @complexity Constant. @exceptionsafety No-throw guarantee: this constructor never throws exceptions. @requirement This function helps `basic_json` satisfying the [MoveConstructible](https://en.cppreference.com/w/cpp/named_req/MoveConstructible) requirements. @liveexample{The code below shows the move constructor explicitly called via std::move.,basic_json__moveconstructor} @since version 1.0.0 */ basic_json(basic_json&& other) noexcept : m_type(std::move(other.m_type)), m_value(std::move(other.m_value)) { // check that passed value is valid other.assert_invariant(false); // invalidate payload other.m_type = value_t::null; other.m_value = {}; set_parent(*this, true); assert_invariant(); } /*! @brief copy assignment Copy assignment operator. Copies a JSON value via the "copy and swap" strategy: It is expressed in terms of the copy constructor, destructor, and the `swap()` member function. @param[in] other value to copy from @complexity Linear. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is linear. @liveexample{The code below shows and example for the copy assignment. It creates a copy of value `a` which is then swapped with `b`. Finally\, the copy of `a` (which is the null value after the swap) is destroyed.,basic_json__copyassignment} @since version 1.0.0 */ basic_json& operator=(basic_json other) noexcept ( std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value&& std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value ) { // check that passed value is valid other.assert_invariant(); using std::swap; swap(m_type, other.m_type); swap(m_value, other.m_value); set_parent(*this, true); assert_invariant(); return *this; } /*! @brief destructor Destroys the JSON value and frees all allocated memory. @complexity Linear. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is linear. - All stored elements are destroyed and all memory is freed. @since version 1.0.0 */ ~basic_json() noexcept { assert_invariant(false); m_value.destroy(m_type); } /// @} public: /////////////////////// // object inspection // /////////////////////// /// @name object inspection /// Functions to inspect the type of a JSON value. /// @{ /*! @brief serialization Serialization function for JSON values. The function tries to mimic Python's `json.dumps()` function, and currently supports its @a indent and @a ensure_ascii parameters. @param[in] indent If indent is nonnegative, then array elements and object members will be pretty-printed with that indent level. An indent level of `0` will only insert newlines. `-1` (the default) selects the most compact representation. @param[in] indent_char The character to use for indentation if @a indent is greater than `0`. The default is ` ` (space). @param[in] ensure_ascii If @a ensure_ascii is true, all non-ASCII characters in the output are escaped with `\uXXXX` sequences, and the result consists of ASCII characters only. @param[in] error_handler how to react on decoding errors; there are three possible values: `strict` (throws and exception in case a decoding error occurs; default), `replace` (replace invalid UTF-8 sequences with U+FFFD), and `ignore` (ignore invalid UTF-8 sequences during serialization; all bytes are copied to the output unchanged). @return string containing the serialization of the JSON value @throw type_error.316 if a string stored inside the JSON value is not UTF-8 encoded and @a error_handler is set to strict @note Binary values are serialized as object containing two keys: - "bytes": an array of bytes as integers - "subtype": the subtype as integer or "null" if the binary has no subtype @complexity Linear. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @liveexample{The following example shows the effect of different @a indent\, @a indent_char\, and @a ensure_ascii parameters to the result of the serialization.,dump} @see https://docs.python.org/2/library/json.html#json.dump @since version 1.0.0; indentation character @a indent_char, option @a ensure_ascii and exceptions added in version 3.0.0; error handlers added in version 3.4.0; serialization of binary values added in version 3.8.0. */ string_t dump(const int indent = -1, const char indent_char = ' ', const bool ensure_ascii = false, const error_handler_t error_handler = error_handler_t::strict) const { string_t result; serializer s(detail::output_adapter(result), indent_char, error_handler); if (indent >= 0) { s.dump(*this, true, ensure_ascii, static_cast(indent)); } else { s.dump(*this, false, ensure_ascii, 0); } return result; } /*! @brief return the type of the JSON value (explicit) Return the type of the JSON value as a value from the @ref value_t enumeration. @return the type of the JSON value Value type | return value ------------------------- | ------------------------- null | value_t::null boolean | value_t::boolean string | value_t::string number (integer) | value_t::number_integer number (unsigned integer) | value_t::number_unsigned number (floating-point) | value_t::number_float object | value_t::object array | value_t::array binary | value_t::binary discarded | value_t::discarded @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `type()` for all JSON types.,type} @sa @ref operator value_t() -- return the type of the JSON value (implicit) @sa @ref type_name() -- return the type as string @since version 1.0.0 */ constexpr value_t type() const noexcept { return m_type; } /*! @brief return whether type is primitive This function returns true if and only if the JSON type is primitive (string, number, boolean, or null). @return `true` if type is primitive (string, number, boolean, or null), `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_primitive()` for all JSON types.,is_primitive} @sa @ref is_structured() -- returns whether JSON value is structured @sa @ref is_null() -- returns whether JSON value is `null` @sa @ref is_string() -- returns whether JSON value is a string @sa @ref is_boolean() -- returns whether JSON value is a boolean @sa @ref is_number() -- returns whether JSON value is a number @sa @ref is_binary() -- returns whether JSON value is a binary array @since version 1.0.0 */ constexpr bool is_primitive() const noexcept { return is_null() || is_string() || is_boolean() || is_number() || is_binary(); } /*! @brief return whether type is structured This function returns true if and only if the JSON type is structured (array or object). @return `true` if type is structured (array or object), `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_structured()` for all JSON types.,is_structured} @sa @ref is_primitive() -- returns whether value is primitive @sa @ref is_array() -- returns whether value is an array @sa @ref is_object() -- returns whether value is an object @since version 1.0.0 */ constexpr bool is_structured() const noexcept { return is_array() || is_object(); } /*! @brief return whether value is null This function returns true if and only if the JSON value is null. @return `true` if type is null, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_null()` for all JSON types.,is_null} @since version 1.0.0 */ constexpr bool is_null() const noexcept { return m_type == value_t::null; } /*! @brief return whether value is a boolean This function returns true if and only if the JSON value is a boolean. @return `true` if type is boolean, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_boolean()` for all JSON types.,is_boolean} @since version 1.0.0 */ constexpr bool is_boolean() const noexcept { return m_type == value_t::boolean; } /*! @brief return whether value is a number This function returns true if and only if the JSON value is a number. This includes both integer (signed and unsigned) and floating-point values. @return `true` if type is number (regardless whether integer, unsigned integer or floating-type), `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_number()` for all JSON types.,is_number} @sa @ref is_number_integer() -- check if value is an integer or unsigned integer number @sa @ref is_number_unsigned() -- check if value is an unsigned integer number @sa @ref is_number_float() -- check if value is a floating-point number @since version 1.0.0 */ constexpr bool is_number() const noexcept { return is_number_integer() || is_number_float(); } /*! @brief return whether value is an integer number This function returns true if and only if the JSON value is a signed or unsigned integer number. This excludes floating-point values. @return `true` if type is an integer or unsigned integer number, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_number_integer()` for all JSON types.,is_number_integer} @sa @ref is_number() -- check if value is a number @sa @ref is_number_unsigned() -- check if value is an unsigned integer number @sa @ref is_number_float() -- check if value is a floating-point number @since version 1.0.0 */ constexpr bool is_number_integer() const noexcept { return m_type == value_t::number_integer || m_type == value_t::number_unsigned; } /*! @brief return whether value is an unsigned integer number This function returns true if and only if the JSON value is an unsigned integer number. This excludes floating-point and signed integer values. @return `true` if type is an unsigned integer number, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_number_unsigned()` for all JSON types.,is_number_unsigned} @sa @ref is_number() -- check if value is a number @sa @ref is_number_integer() -- check if value is an integer or unsigned integer number @sa @ref is_number_float() -- check if value is a floating-point number @since version 2.0.0 */ constexpr bool is_number_unsigned() const noexcept { return m_type == value_t::number_unsigned; } /*! @brief return whether value is a floating-point number This function returns true if and only if the JSON value is a floating-point number. This excludes signed and unsigned integer values. @return `true` if type is a floating-point number, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_number_float()` for all JSON types.,is_number_float} @sa @ref is_number() -- check if value is number @sa @ref is_number_integer() -- check if value is an integer number @sa @ref is_number_unsigned() -- check if value is an unsigned integer number @since version 1.0.0 */ constexpr bool is_number_float() const noexcept { return m_type == value_t::number_float; } /*! @brief return whether value is an object This function returns true if and only if the JSON value is an object. @return `true` if type is object, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_object()` for all JSON types.,is_object} @since version 1.0.0 */ constexpr bool is_object() const noexcept { return m_type == value_t::object; } /*! @brief return whether value is an array This function returns true if and only if the JSON value is an array. @return `true` if type is array, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_array()` for all JSON types.,is_array} @since version 1.0.0 */ constexpr bool is_array() const noexcept { return m_type == value_t::array; } /*! @brief return whether value is a string This function returns true if and only if the JSON value is a string. @return `true` if type is string, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_string()` for all JSON types.,is_string} @since version 1.0.0 */ constexpr bool is_string() const noexcept { return m_type == value_t::string; } /*! @brief return whether value is a binary array This function returns true if and only if the JSON value is a binary array. @return `true` if type is binary array, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_binary()` for all JSON types.,is_binary} @since version 3.8.0 */ constexpr bool is_binary() const noexcept { return m_type == value_t::binary; } /*! @brief return whether value is discarded This function returns true if and only if the JSON value was discarded during parsing with a callback function (see @ref parser_callback_t). @note This function will always be `false` for JSON values after parsing. That is, discarded values can only occur during parsing, but will be removed when inside a structured value or replaced by null in other cases. @return `true` if type is discarded, `false` otherwise. @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies `is_discarded()` for all JSON types.,is_discarded} @since version 1.0.0 */ constexpr bool is_discarded() const noexcept { return m_type == value_t::discarded; } /*! @brief return the type of the JSON value (implicit) Implicitly return the type of the JSON value as a value from the @ref value_t enumeration. @return the type of the JSON value @complexity Constant. @exceptionsafety No-throw guarantee: this member function never throws exceptions. @liveexample{The following code exemplifies the @ref value_t operator for all JSON types.,operator__value_t} @sa @ref type() -- return the type of the JSON value (explicit) @sa @ref type_name() -- return the type as string @since version 1.0.0 */ constexpr operator value_t() const noexcept { return m_type; } /// @} private: ////////////////// // value access // ////////////////// /// get a boolean (explicit) boolean_t get_impl(boolean_t* /*unused*/) const { if (JSON_HEDLEY_LIKELY(is_boolean())) { return m_value.boolean; } JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(type_name()), diagnostics_t(*this))); } /// get a pointer to the value (object) object_t* get_impl_ptr(object_t* /*unused*/) noexcept { return is_object() ? m_value.object : nullptr; } /// get a pointer to the value (object) constexpr const object_t* get_impl_ptr(const object_t* /*unused*/) const noexcept { return is_object() ? m_value.object : nullptr; } /// get a pointer to the value (array) array_t* get_impl_ptr(array_t* /*unused*/) noexcept { return is_array() ? m_value.array : nullptr; } /// get a pointer to the value (array) constexpr const array_t* get_impl_ptr(const array_t* /*unused*/) const noexcept { return is_array() ? m_value.array : nullptr; } /// get a pointer to the value (string) string_t* get_impl_ptr(string_t* /*unused*/) noexcept { return is_string() ? m_value.string : nullptr; } /// get a pointer to the value (string) constexpr const string_t* get_impl_ptr(const string_t* /*unused*/) const noexcept { return is_string() ? m_value.string : nullptr; } /// get a pointer to the value (boolean) boolean_t* get_impl_ptr(boolean_t* /*unused*/) noexcept { return is_boolean() ? &m_value.boolean : nullptr; } /// get a pointer to the value (boolean) constexpr const boolean_t* get_impl_ptr(const boolean_t* /*unused*/) const noexcept { return is_boolean() ? &m_value.boolean : nullptr; } /// get a pointer to the value (integer number) number_integer_t* get_impl_ptr(number_integer_t* /*unused*/) noexcept { return is_number_integer() ? &m_value.number_integer : nullptr; } /// get a pointer to the value (integer number) constexpr const number_integer_t* get_impl_ptr(const number_integer_t* /*unused*/) const noexcept { return is_number_integer() ? &m_value.number_integer : nullptr; } /// get a pointer to the value (unsigned number) number_unsigned_t* get_impl_ptr(number_unsigned_t* /*unused*/) noexcept { return is_number_unsigned() ? &m_value.number_unsigned : nullptr; } /// get a pointer to the value (unsigned number) constexpr const number_unsigned_t* get_impl_ptr(const number_unsigned_t* /*unused*/) const noexcept { return is_number_unsigned() ? &m_value.number_unsigned : nullptr; } /// get a pointer to the value (floating-point number) number_float_t* get_impl_ptr(number_float_t* /*unused*/) noexcept { return is_number_float() ? &m_value.number_float : nullptr; } /// get a pointer to the value (floating-point number) constexpr const number_float_t* get_impl_ptr(const number_float_t* /*unused*/) const noexcept { return is_number_float() ? &m_value.number_float : nullptr; } /// get a pointer to the value (binary) binary_t* get_impl_ptr(binary_t* /*unused*/) noexcept { return is_binary() ? m_value.binary : nullptr; } /// get a pointer to the value (binary) constexpr const binary_t* get_impl_ptr(const binary_t* /*unused*/) const noexcept { return is_binary() ? m_value.binary : nullptr; } /*! @brief helper function to implement get_ref() This function helps to implement get_ref() without code duplication for const and non-const overloads @tparam ThisType will be deduced as `basic_json` or `const basic_json` @throw type_error.303 if ReferenceType does not match underlying value type of the current JSON */ template static ReferenceType get_ref_impl(ThisType& obj) { // delegate the call to get_ptr<>() auto ptr = obj.template get_ptr::type>(); if (JSON_HEDLEY_LIKELY(ptr != nullptr)) { return *ptr; } JSON_THROW(type_error::create(303, "incompatible ReferenceType for get_ref, actual type is " + std::string(obj.type_name()), diagnostics_t(obj))); } public: /// @name value access /// Direct access to the stored value of a JSON value. /// @{ /*! @brief get special-case overload This overloads avoids a lot of template boilerplate, it can be seen as the identity method @tparam BasicJsonType == @ref basic_json @return a copy of *this @complexity Constant. @since version 2.1.0 */ template::type, basic_json_t>::value, int> = 0> basic_json get() const { return *this; } /*! @brief get special-case overload This overloads converts the current @ref basic_json in a different @ref basic_json type @tparam BasicJsonType == @ref basic_json @return a copy of *this, converted into @tparam BasicJsonType @complexity Depending on the implementation of the called `from_json()` method. @since version 3.2.0 */ template < typename BasicJsonType, detail::enable_if_t < !std::is_same::value&& detail::is_basic_json::value, int > = 0 > BasicJsonType get() const { return *this; } /*! @brief get a value (explicit) Explicit type conversion between the JSON value and a compatible value which is [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) and [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). The value is converted by calling the @ref json_serializer `from_json()` method. The function is equivalent to executing @code {.cpp} ValueType ret; JSONSerializer::from_json(*this, ret); return ret; @endcode This overloads is chosen if: - @a ValueType is not @ref basic_json, - @ref json_serializer has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`, and - @ref json_serializer does not have a `from_json()` method of the form `ValueType from_json(const basic_json&)` @tparam ValueTypeCV the provided value type @tparam ValueType the returned value type @return copy of the JSON value, converted to @a ValueType @throw what @ref json_serializer `from_json()` method throws @liveexample{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map`.,get__ValueType_const} @since version 2.1.0 */ template < typename ValueTypeCV, typename ValueType = detail::uncvref_t, detail::enable_if_t < !detail::is_basic_json::value && detail::has_from_json::value && !detail::has_non_default_from_json::value, int > = 0 > ValueType get() const noexcept(noexcept( JSONSerializer::from_json(std::declval(), std::declval()))) { // we cannot static_assert on ValueTypeCV being non-const, because // there is support for get(), which is why we // still need the uncvref static_assert(!std::is_reference::value, "get() cannot be used with reference types, you might want to use get_ref()"); static_assert(std::is_default_constructible::value, "types must be DefaultConstructible when used with get()"); ValueType ret; JSONSerializer::from_json(*this, ret); return ret; } /*! @brief get a value (explicit); special case Explicit type conversion between the JSON value and a compatible value which is **not** [CopyConstructible](https://en.cppreference.com/w/cpp/named_req/CopyConstructible) and **not** [DefaultConstructible](https://en.cppreference.com/w/cpp/named_req/DefaultConstructible). The value is converted by calling the @ref json_serializer `from_json()` method. The function is equivalent to executing @code {.cpp} return JSONSerializer::from_json(*this); @endcode This overloads is chosen if: - @a ValueType is not @ref basic_json and - @ref json_serializer has a `from_json()` method of the form `ValueType from_json(const basic_json&)` @note If @ref json_serializer has both overloads of `from_json()`, this one is chosen. @tparam ValueTypeCV the provided value type @tparam ValueType the returned value type @return copy of the JSON value, converted to @a ValueType @throw what @ref json_serializer `from_json()` method throws @since version 2.1.0 */ template < typename ValueTypeCV, typename ValueType = detail::uncvref_t, detail::enable_if_t < !std::is_same::value && detail::has_non_default_from_json::value, int > = 0 > ValueType get() const noexcept(noexcept( JSONSerializer::from_json(std::declval()))) { static_assert(!std::is_reference::value, "get() cannot be used with reference types, you might want to use get_ref()"); return JSONSerializer::from_json(*this); } /*! @brief get a value (explicit) Explicit type conversion between the JSON value and a compatible value. The value is filled into the input parameter by calling the @ref json_serializer `from_json()` method. The function is equivalent to executing @code {.cpp} ValueType v; JSONSerializer::from_json(*this, v); @endcode This overloads is chosen if: - @a ValueType is not @ref basic_json, - @ref json_serializer has a `from_json()` method of the form `void from_json(const basic_json&, ValueType&)`, and @tparam ValueType the input parameter type. @return the input parameter, allowing chaining calls. @throw what @ref json_serializer `from_json()` method throws @liveexample{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map`.,get_to} @since version 3.3.0 */ template < typename ValueType, detail::enable_if_t < !detail::is_basic_json::value&& detail::has_from_json::value, int > = 0 > ValueType & get_to(ValueType& v) const noexcept(noexcept( JSONSerializer::from_json(std::declval(), v))) { JSONSerializer::from_json(*this, v); return v; } // specialization to allow to call get_to with a basic_json value // see https://github.com/nlohmann/json/issues/2175 template::value, int> = 0> ValueType & get_to(ValueType& v) const { v = *this; return v; } template < typename T, std::size_t N, typename Array = T (&)[N], detail::enable_if_t < detail::has_from_json::value, int > = 0 > Array get_to(T (&v)[N]) const noexcept(noexcept(JSONSerializer::from_json( std::declval(), v))) { JSONSerializer::from_json(*this, v); return v; } /*! @brief get a pointer value (implicit) Implicit pointer access to the internally stored JSON value. No copies are made. @warning Writing data to the pointee of the result yields an undefined state. @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, @ref number_unsigned_t, or @ref number_float_t. Enforced by a static assertion. @return pointer to the internally stored JSON value if the requested pointer type @a PointerType fits to the JSON value; `nullptr` otherwise @complexity Constant. @liveexample{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get_ptr} @since version 1.0.0 */ template::value, int>::type = 0> auto get_ptr() noexcept -> decltype(std::declval().get_impl_ptr(std::declval())) { // delegate the call to get_impl_ptr<>() return get_impl_ptr(static_cast(nullptr)); } /*! @brief get a pointer value (implicit) @copydoc get_ptr() */ template < typename PointerType, typename std::enable_if < std::is_pointer::value&& std::is_const::type>::value, int >::type = 0 > constexpr auto get_ptr() const noexcept -> decltype(std::declval().get_impl_ptr(std::declval())) { // delegate the call to get_impl_ptr<>() const return get_impl_ptr(static_cast(nullptr)); } /*! @brief get a pointer value (explicit) Explicit pointer access to the internally stored JSON value. No copies are made. @warning The pointer becomes invalid if the underlying JSON object changes. @tparam PointerType pointer type; must be a pointer to @ref array_t, @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, @ref number_unsigned_t, or @ref number_float_t. @return pointer to the internally stored JSON value if the requested pointer type @a PointerType fits to the JSON value; `nullptr` otherwise @complexity Constant. @liveexample{The example below shows how pointers to internal values of a JSON value can be requested. Note that no type conversions are made and a `nullptr` is returned if the value and the requested pointer type does not match.,get__PointerType} @sa @ref get_ptr() for explicit pointer-member access @since version 1.0.0 */ template::value, int>::type = 0> auto get() noexcept -> decltype(std::declval().template get_ptr()) { // delegate the call to get_ptr return get_ptr(); } /*! @brief get a pointer value (explicit) @copydoc get() */ template::value, int>::type = 0> constexpr auto get() const noexcept -> decltype(std::declval().template get_ptr()) { // delegate the call to get_ptr return get_ptr(); } /*! @brief get a reference value (implicit) Implicit reference access to the internally stored JSON value. No copies are made. @warning Writing data to the referee of the result yields an undefined state. @tparam ReferenceType reference type; must be a reference to @ref array_t, @ref object_t, @ref string_t, @ref boolean_t, @ref number_integer_t, or @ref number_float_t. Enforced by static assertion. @return reference to the internally stored JSON value if the requested reference type @a ReferenceType fits to the JSON value; throws type_error.303 otherwise @throw type_error.303 in case passed type @a ReferenceType is incompatible with the stored JSON value; see example below @complexity Constant. @liveexample{The example shows several calls to `get_ref()`.,get_ref} @since version 1.1.0 */ template::value, int>::type = 0> ReferenceType get_ref() { // delegate call to get_ref_impl return get_ref_impl(*this); } /*! @brief get a reference value (implicit) @copydoc get_ref() */ template < typename ReferenceType, typename std::enable_if < std::is_reference::value&& std::is_const::type>::value, int >::type = 0 > ReferenceType get_ref() const { // delegate call to get_ref_impl return get_ref_impl(*this); } /*! @brief get a value (implicit) Implicit type conversion between the JSON value and a compatible value. The call is realized by calling @ref get() const. @tparam ValueType non-pointer type compatible to the JSON value, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. The character type of @ref string_t as well as an initializer list of this type is excluded to avoid ambiguities as these types implicitly convert to `std::string`. @return copy of the JSON value, converted to type @a ValueType @throw type_error.302 in case passed type @a ValueType is incompatible to the JSON value type (e.g., the JSON value is of type boolean, but a string is requested); see example below @complexity Linear in the size of the JSON value. @liveexample{The example below shows several conversions from JSON values to other types. There a few things to note: (1) Floating-point numbers can be converted to integers\, (2) A JSON array can be converted to a standard `std::vector`\, (3) A JSON object can be converted to C++ associative containers such as `std::unordered_map`.,operator__ValueType} @since version 1.0.0 */ template < typename ValueType, typename std::enable_if < !std::is_pointer::value&& !std::is_same>::value&& !std::is_same::value&& !detail::is_basic_json::value && !std::is_same>::value #if defined(JSON_HAS_CPP_17) && (defined(__GNUC__) || (defined(_MSC_VER) && _MSC_VER >= 1910 && _MSC_VER <= 1914)) && !std::is_same::value #endif && detail::is_detected::value , int >::type = 0 > JSON_EXPLICIT operator ValueType() const { // delegate the call to get<>() const return get(); } /*! @return reference to the binary value @throw type_error.302 if the value is not binary @sa @ref is_binary() to check if the value is binary @since version 3.8.0 */ binary_t& get_binary() { if (!is_binary()) { JSON_THROW(type_error::create(302, "type must be binary, but is " + std::string(type_name()), diagnostics_t(*this))); } return *get_ptr(); } /// @copydoc get_binary() const binary_t& get_binary() const { if (!is_binary()) { JSON_THROW(type_error::create(302, "type must be binary, but is " + std::string(type_name()), diagnostics_t(*this))); } return *get_ptr(); } /// @} //////////////////// // element access // //////////////////// /// @name element access /// Access to the JSON value. /// @{ /*! @brief access specified array element with bounds checking Returns a reference to the element at specified location @a idx, with bounds checking. @param[in] idx index of the element to access @return reference to the element at index @a idx @throw type_error.304 if the JSON value is not an array; in this case, calling `at` with an index makes no sense. See example below. @throw out_of_range.401 if the index @a idx is out of range of the array; that is, `idx >= size()`. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @since version 1.0.0 @liveexample{The example below shows how array elements can be read and written using `at()`. It also demonstrates the different exceptions that can be thrown.,at__size_type} */ reference at(size_type idx) { // at only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { JSON_TRY { return set_parent(m_value.array->at(idx), false); } JSON_CATCH (std::out_of_range&) { // create better exception explanation JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range", diagnostics_t(*this))); } } else { JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief access specified array element with bounds checking Returns a const reference to the element at specified location @a idx, with bounds checking. @param[in] idx index of the element to access @return const reference to the element at index @a idx @throw type_error.304 if the JSON value is not an array; in this case, calling `at` with an index makes no sense. See example below. @throw out_of_range.401 if the index @a idx is out of range of the array; that is, `idx >= size()`. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @since version 1.0.0 @liveexample{The example below shows how array elements can be read using `at()`. It also demonstrates the different exceptions that can be thrown., at__size_type_const} */ const_reference at(size_type idx) const { // at only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { JSON_TRY { return m_value.array->at(idx); } JSON_CATCH (std::out_of_range&) { // create better exception explanation JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range", diagnostics_t(*this))); } } else { JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief access specified object element with bounds checking Returns a reference to the element at with specified key @a key, with bounds checking. @param[in] key key of the element to access @return reference to the element at key @a key @throw type_error.304 if the JSON value is not an object; in this case, calling `at` with a key makes no sense. See example below. @throw out_of_range.403 if the key @a key is is not stored in the object; that is, `find(key) == end()`. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Logarithmic in the size of the container. @sa @ref operator[](const typename object_t::key_type&) for unchecked access by reference @sa @ref value() for access by value with a default value @since version 1.0.0 @liveexample{The example below shows how object elements can be read and written using `at()`. It also demonstrates the different exceptions that can be thrown.,at__object_t_key_type} */ reference at(const typename object_t::key_type& key) { // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { JSON_TRY { return set_parent(m_value.object->at(key), false); } JSON_CATCH (std::out_of_range&) { // create better exception explanation JSON_THROW(out_of_range::create(403, "key '" + key + "' not found", diagnostics_t(*this))); } } else { JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief access specified object element with bounds checking Returns a const reference to the element at with specified key @a key, with bounds checking. @param[in] key key of the element to access @return const reference to the element at key @a key @throw type_error.304 if the JSON value is not an object; in this case, calling `at` with a key makes no sense. See example below. @throw out_of_range.403 if the key @a key is is not stored in the object; that is, `find(key) == end()`. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Logarithmic in the size of the container. @sa @ref operator[](const typename object_t::key_type&) for unchecked access by reference @sa @ref value() for access by value with a default value @since version 1.0.0 @liveexample{The example below shows how object elements can be read using `at()`. It also demonstrates the different exceptions that can be thrown., at__object_t_key_type_const} */ const_reference at(const typename object_t::key_type& key) const { // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { JSON_TRY { return m_value.object->at(key); } JSON_CATCH (std::out_of_range&) { // create better exception explanation JSON_THROW(out_of_range::create(403, "key '" + key + "' not found", diagnostics_t(*this))); } } else { JSON_THROW(type_error::create(304, "cannot use at() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief access specified array element Returns a reference to the element at specified location @a idx. @note If @a idx is beyond the range of the array (i.e., `idx >= size()`), then the array is silently filled up with `null` values to make `idx` a valid reference to the last stored element. @param[in] idx index of the element to access @return reference to the element at index @a idx @throw type_error.305 if the JSON value is not an array or null; in that cases, using the [] operator with an index makes no sense. @complexity Constant if @a idx is in the range of the array. Otherwise linear in `idx - size()`. @liveexample{The example below shows how array elements can be read and written using `[]` operator. Note the addition of `null` values.,operatorarray__size_type} @since version 1.0.0 */ reference operator[](size_type idx) { // implicitly convert null value to an empty array if (is_null()) { m_type = value_t::array; m_value.array = create(); assert_invariant(); } // operator[] only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { // fill up array with null values if given idx is outside range if (idx >= m_value.array->size()) { #if JSON_DIAGNOSTICS // remember array size before resizing const auto previous_size = m_value.array->size(); #endif m_value.array->resize(idx + 1); #if JSON_DIAGNOSTICS // set parent for values added above for (auto i = previous_size; i <= idx; ++i) { m_value.array->operator[](i).m_parent = this; } #endif } return m_value.array->operator[](idx); } JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief access specified array element Returns a const reference to the element at specified location @a idx. @param[in] idx index of the element to access @return const reference to the element at index @a idx @throw type_error.305 if the JSON value is not an array; in that case, using the [] operator with an index makes no sense. @complexity Constant. @liveexample{The example below shows how array elements can be read using the `[]` operator.,operatorarray__size_type_const} @since version 1.0.0 */ const_reference operator[](size_type idx) const { // const operator[] only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { return m_value.array->operator[](idx); } JSON_THROW(type_error::create(305, "cannot use operator[] with a numeric argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief access specified object element Returns a reference to the element at with specified key @a key. @note If @a key is not found in the object, then it is silently added to the object and filled with a `null` value to make `key` a valid reference. In case the value was `null` before, it is converted to an object. @param[in] key key of the element to access @return reference to the element at key @a key @throw type_error.305 if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be read and written using the `[]` operator.,operatorarray__key_type} @sa @ref at(const typename object_t::key_type&) for access by reference with range checking @sa @ref value() for access by value with a default value @since version 1.0.0 */ reference operator[](const typename object_t::key_type& key) { // implicitly convert null value to an empty object if (is_null()) { m_type = value_t::object; m_value.object = create(); assert_invariant(); } // operator[] only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { return set_parent(m_value.object->operator[](key), false); } JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief read-only access specified object element Returns a const reference to the element at with specified key @a key. No bounds checking is performed. @warning If the element with key @a key does not exist, the behavior is undefined. @param[in] key key of the element to access @return const reference to the element at key @a key @pre The element with key @a key must exist. **This precondition is enforced with an assertion.** @throw type_error.305 if the JSON value is not an object; in that case, using the [] operator with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be read using the `[]` operator.,operatorarray__key_type_const} @sa @ref at(const typename object_t::key_type&) for access by reference with range checking @sa @ref value() for access by value with a default value @since version 1.0.0 */ const_reference operator[](const typename object_t::key_type& key) const { // const operator[] only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { JSON_ASSERT(m_value.object->find(key) != m_value.object->end()); return m_value.object->find(key)->second; } JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief access specified object element Returns a reference to the element at with specified key @a key. @note If @a key is not found in the object, then it is silently added to the object and filled with a `null` value to make `key` a valid reference. In case the value was `null` before, it is converted to an object. @param[in] key key of the element to access @return reference to the element at key @a key @throw type_error.305 if the JSON value is not an object or null; in that cases, using the [] operator with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be read and written using the `[]` operator.,operatorarray__key_type} @sa @ref at(const typename object_t::key_type&) for access by reference with range checking @sa @ref value() for access by value with a default value @since version 1.1.0 */ template JSON_HEDLEY_NON_NULL(2) reference operator[](T* key) { // implicitly convert null to object if (is_null()) { m_type = value_t::object; m_value = value_t::object; assert_invariant(); } // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { return set_parent(m_value.object->operator[](key), false); } JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief read-only access specified object element Returns a const reference to the element at with specified key @a key. No bounds checking is performed. @warning If the element with key @a key does not exist, the behavior is undefined. @param[in] key key of the element to access @return const reference to the element at key @a key @pre The element with key @a key must exist. **This precondition is enforced with an assertion.** @throw type_error.305 if the JSON value is not an object; in that case, using the [] operator with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be read using the `[]` operator.,operatorarray__key_type_const} @sa @ref at(const typename object_t::key_type&) for access by reference with range checking @sa @ref value() for access by value with a default value @since version 1.1.0 */ template JSON_HEDLEY_NON_NULL(2) const_reference operator[](T* key) const { // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { JSON_ASSERT(m_value.object->find(key) != m_value.object->end()); return m_value.object->find(key)->second; } JSON_THROW(type_error::create(305, "cannot use operator[] with a string argument with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief access specified object element with default value Returns either a copy of an object's element at the specified key @a key or a given default value if no element with key @a key exists. The function is basically equivalent to executing @code {.cpp} try { return at(key); } catch(out_of_range) { return default_value; } @endcode @note Unlike @ref at(const typename object_t::key_type&), this function does not throw if the given key @a key was not found. @note Unlike @ref operator[](const typename object_t::key_type& key), this function does not implicitly add an element to the position defined by @a key. This function is furthermore also applicable to const objects. @param[in] key key of the element to access @param[in] default_value the value to return if @a key is not found @tparam ValueType type compatible to JSON values, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. Note the type of the expected value at @a key and the default value @a default_value must be compatible. @return copy of the element at key @a key or @a default_value if @a key is not found @throw type_error.302 if @a default_value does not match the type of the value at @a key @throw type_error.306 if the JSON value is not an object; in that case, using `value()` with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be queried with a default value.,basic_json__value} @sa @ref at(const typename object_t::key_type&) for access by reference with range checking @sa @ref operator[](const typename object_t::key_type&) for unchecked access by reference @since version 1.0.0 */ // using std::is_convertible in a std::enable_if will fail when using explicit conversions template < class ValueType, typename std::enable_if < detail::is_getable::value && !std::is_same::value, int >::type = 0 > ValueType value(const typename object_t::key_type& key, const ValueType& default_value) const { // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { // if key is found, return value and given default value otherwise const auto it = find(key); if (it != end()) { return it->template get(); } return default_value; } JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief overload for a default value of type const char* @copydoc basic_json::value(const typename object_t::key_type&, const ValueType&) const */ string_t value(const typename object_t::key_type& key, const char* default_value) const { return value(key, string_t(default_value)); } /*! @brief access specified object element via JSON Pointer with default value Returns either a copy of an object's element at the specified key @a key or a given default value if no element with key @a key exists. The function is basically equivalent to executing @code {.cpp} try { return at(ptr); } catch(out_of_range) { return default_value; } @endcode @note Unlike @ref at(const json_pointer&), this function does not throw if the given key @a key was not found. @param[in] ptr a JSON pointer to the element to access @param[in] default_value the value to return if @a ptr found no value @tparam ValueType type compatible to JSON values, for instance `int` for JSON integer numbers, `bool` for JSON booleans, or `std::vector` types for JSON arrays. Note the type of the expected value at @a key and the default value @a default_value must be compatible. @return copy of the element at key @a key or @a default_value if @a key is not found @throw type_error.302 if @a default_value does not match the type of the value at @a ptr @throw type_error.306 if the JSON value is not an object; in that case, using `value()` with a key makes no sense. @complexity Logarithmic in the size of the container. @liveexample{The example below shows how object elements can be queried with a default value.,basic_json__value_ptr} @sa @ref operator[](const json_pointer&) for unchecked access by reference @since version 2.0.2 */ template::value, int>::type = 0> ValueType value(const json_pointer& ptr, const ValueType& default_value) const { // at only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { // if pointer resolves a value, return it or use default value JSON_TRY { return ptr.get_checked(this).template get(); } JSON_INTERNAL_CATCH (out_of_range&) { return default_value; } } JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief overload for a default value of type const char* @copydoc basic_json::value(const json_pointer&, ValueType) const */ JSON_HEDLEY_NON_NULL(3) string_t value(const json_pointer& ptr, const char* default_value) const { return value(ptr, string_t(default_value)); } /*! @brief access the first element Returns a reference to the first element in the container. For a JSON container `c`, the expression `c.front()` is equivalent to `*c.begin()`. @return In case of a structured type (array or object), a reference to the first element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned. @complexity Constant. @pre The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, **guarded by assertions**). @post The JSON value remains unchanged. @throw invalid_iterator.214 when called on `null` value @liveexample{The following code shows an example for `front()`.,front} @sa @ref back() -- access the last element @since version 1.0.0 */ reference front() { return *begin(); } /*! @copydoc basic_json::front() */ const_reference front() const { return *cbegin(); } /*! @brief access the last element Returns a reference to the last element in the container. For a JSON container `c`, the expression `c.back()` is equivalent to @code {.cpp} auto tmp = c.end(); --tmp; return *tmp; @endcode @return In case of a structured type (array or object), a reference to the last element is returned. In case of number, string, boolean, or binary values, a reference to the value is returned. @complexity Constant. @pre The JSON value must not be `null` (would throw `std::out_of_range`) or an empty array or object (undefined behavior, **guarded by assertions**). @post The JSON value remains unchanged. @throw invalid_iterator.214 when called on a `null` value. See example below. @liveexample{The following code shows an example for `back()`.,back} @sa @ref front() -- access the first element @since version 1.0.0 */ reference back() { auto tmp = end(); --tmp; return *tmp; } /*! @copydoc basic_json::back() */ const_reference back() const { auto tmp = cend(); --tmp; return *tmp; } /*! @brief remove element given an iterator Removes the element specified by iterator @a pos. The iterator @a pos must be valid and dereferenceable. Thus the `end()` iterator (which is valid, but is not dereferenceable) cannot be used as a value for @a pos. If called on a primitive type other than `null`, the resulting JSON value will be `null`. @param[in] pos iterator to the element to remove @return Iterator following the last removed element. If the iterator @a pos refers to the last element, the `end()` iterator is returned. @tparam IteratorType an @ref iterator or @ref const_iterator @post Invalidates iterators and references at or after the point of the erase, including the `end()` iterator. @throw type_error.307 if called on a `null` value; example: `"cannot use erase() with null"` @throw invalid_iterator.202 if called on an iterator which does not belong to the current JSON value; example: `"iterator does not fit current value"` @throw invalid_iterator.205 if called on a primitive type with invalid iterator (i.e., any iterator which is not `begin()`); example: `"iterator out of range"` @complexity The complexity depends on the type: - objects: amortized constant - arrays: linear in distance between @a pos and the end of the container - strings and binary: linear in the length of the member - other types: constant @liveexample{The example shows the result of `erase()` for different JSON types.,erase__IteratorType} @sa @ref erase(IteratorType, IteratorType) -- removes the elements in the given range @sa @ref erase(const typename object_t::key_type&) -- removes the element from an object at the given key @sa @ref erase(const size_type) -- removes the element from an array at the given index @since version 1.0.0 */ template < class IteratorType, typename std::enable_if < std::is_same::value || std::is_same::value, int >::type = 0 > IteratorType erase(IteratorType pos) { // make sure iterator fits the current value if (JSON_HEDLEY_UNLIKELY(this != pos.m_object)) { JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", diagnostics_t(*this))); } IteratorType result = end(); switch (m_type) { case value_t::boolean: case value_t::number_float: case value_t::number_integer: case value_t::number_unsigned: case value_t::string: case value_t::binary: { if (JSON_HEDLEY_UNLIKELY(!pos.m_it.primitive_iterator.is_begin())) { JSON_THROW(invalid_iterator::create(205, "iterator out of range", diagnostics_t(*this))); } if (is_string()) { AllocatorType alloc; std::allocator_traits::destroy(alloc, m_value.string); std::allocator_traits::deallocate(alloc, m_value.string, 1); m_value.string = nullptr; } else if (is_binary()) { AllocatorType alloc; std::allocator_traits::destroy(alloc, m_value.binary); std::allocator_traits::deallocate(alloc, m_value.binary, 1); m_value.binary = nullptr; } m_type = value_t::null; assert_invariant(); break; } case value_t::object: { result.m_it.object_iterator = m_value.object->erase(pos.m_it.object_iterator); break; } case value_t::array: { result.m_it.array_iterator = m_value.array->erase(pos.m_it.array_iterator); break; } default: JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()), diagnostics_t(*this))); } return result; } /*! @brief remove elements given an iterator range Removes the element specified by the range `[first; last)`. The iterator @a first does not need to be dereferenceable if `first == last`: erasing an empty range is a no-op. If called on a primitive type other than `null`, the resulting JSON value will be `null`. @param[in] first iterator to the beginning of the range to remove @param[in] last iterator past the end of the range to remove @return Iterator following the last removed element. If the iterator @a second refers to the last element, the `end()` iterator is returned. @tparam IteratorType an @ref iterator or @ref const_iterator @post Invalidates iterators and references at or after the point of the erase, including the `end()` iterator. @throw type_error.307 if called on a `null` value; example: `"cannot use erase() with null"` @throw invalid_iterator.203 if called on iterators which does not belong to the current JSON value; example: `"iterators do not fit current value"` @throw invalid_iterator.204 if called on a primitive type with invalid iterators (i.e., if `first != begin()` and `last != end()`); example: `"iterators out of range"` @complexity The complexity depends on the type: - objects: `log(size()) + std::distance(first, last)` - arrays: linear in the distance between @a first and @a last, plus linear in the distance between @a last and end of the container - strings and binary: linear in the length of the member - other types: constant @liveexample{The example shows the result of `erase()` for different JSON types.,erase__IteratorType_IteratorType} @sa @ref erase(IteratorType) -- removes the element at a given position @sa @ref erase(const typename object_t::key_type&) -- removes the element from an object at the given key @sa @ref erase(const size_type) -- removes the element from an array at the given index @since version 1.0.0 */ template < class IteratorType, typename std::enable_if < std::is_same::value || std::is_same::value, int >::type = 0 > IteratorType erase(IteratorType first, IteratorType last) { // make sure iterator fits the current value if (JSON_HEDLEY_UNLIKELY(this != first.m_object || this != last.m_object)) { JSON_THROW(invalid_iterator::create(203, "iterators do not fit current value", diagnostics_t(*this))); } IteratorType result = end(); switch (m_type) { case value_t::boolean: case value_t::number_float: case value_t::number_integer: case value_t::number_unsigned: case value_t::string: case value_t::binary: { if (JSON_HEDLEY_LIKELY(!first.m_it.primitive_iterator.is_begin() || !last.m_it.primitive_iterator.is_end())) { JSON_THROW(invalid_iterator::create(204, "iterators out of range", diagnostics_t(*this))); } if (is_string()) { AllocatorType alloc; std::allocator_traits::destroy(alloc, m_value.string); std::allocator_traits::deallocate(alloc, m_value.string, 1); m_value.string = nullptr; } else if (is_binary()) { AllocatorType alloc; std::allocator_traits::destroy(alloc, m_value.binary); std::allocator_traits::deallocate(alloc, m_value.binary, 1); m_value.binary = nullptr; } m_type = value_t::null; assert_invariant(); break; } case value_t::object: { result.m_it.object_iterator = m_value.object->erase(first.m_it.object_iterator, last.m_it.object_iterator); break; } case value_t::array: { result.m_it.array_iterator = m_value.array->erase(first.m_it.array_iterator, last.m_it.array_iterator); break; } default: JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()), diagnostics_t(*this))); } return result; } /*! @brief remove element from a JSON object given a key Removes elements from a JSON object with the key value @a key. @param[in] key value of the elements to remove @return Number of elements removed. If @a ObjectType is the default `std::map` type, the return value will always be `0` (@a key was not found) or `1` (@a key was found). @post References and iterators to the erased elements are invalidated. Other references and iterators are not affected. @throw type_error.307 when called on a type other than JSON object; example: `"cannot use erase() with null"` @complexity `log(size()) + count(key)` @liveexample{The example shows the effect of `erase()`.,erase__key_type} @sa @ref erase(IteratorType) -- removes the element at a given position @sa @ref erase(IteratorType, IteratorType) -- removes the elements in the given range @sa @ref erase(const size_type) -- removes the element from an array at the given index @since version 1.0.0 */ size_type erase(const typename object_t::key_type& key) { // this erase only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { return m_value.object->erase(key); } JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief remove element from a JSON array given an index Removes element from a JSON array at the index @a idx. @param[in] idx index of the element to remove @throw type_error.307 when called on a type other than JSON object; example: `"cannot use erase() with null"` @throw out_of_range.401 when `idx >= size()`; example: `"array index 17 is out of range"` @complexity Linear in distance between @a idx and the end of the container. @liveexample{The example shows the effect of `erase()`.,erase__size_type} @sa @ref erase(IteratorType) -- removes the element at a given position @sa @ref erase(IteratorType, IteratorType) -- removes the elements in the given range @sa @ref erase(const typename object_t::key_type&) -- removes the element from an object at the given key @since version 1.0.0 */ void erase(const size_type idx) { // this erase only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { if (JSON_HEDLEY_UNLIKELY(idx >= size())) { JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range", diagnostics_t(*this))); } m_value.array->erase(m_value.array->begin() + static_cast(idx)); } else { JSON_THROW(type_error::create(307, "cannot use erase() with " + std::string(type_name()), diagnostics_t(*this))); } } /// @} //////////// // lookup // //////////// /// @name lookup /// @{ /*! @brief find an element in a JSON object Finds an element in a JSON object with key equivalent to @a key. If the element is not found or the JSON value is not an object, end() is returned. @note This method always returns @ref end() when executed on a JSON type that is not an object. @param[in] key key value of the element to search for. @return Iterator to an element with key equivalent to @a key. If no such element is found or the JSON value is not an object, past-the-end (see @ref end()) iterator is returned. @complexity Logarithmic in the size of the JSON object. @liveexample{The example shows how `find()` is used.,find__key_type} @sa @ref contains(KeyT&&) const -- checks whether a key exists @since version 1.0.0 */ template iterator find(KeyT&& key) { auto result = end(); if (is_object()) { result.m_it.object_iterator = m_value.object->find(std::forward(key)); } return result; } /*! @brief find an element in a JSON object @copydoc find(KeyT&&) */ template const_iterator find(KeyT&& key) const { auto result = cend(); if (is_object()) { result.m_it.object_iterator = m_value.object->find(std::forward(key)); } return result; } /*! @brief returns the number of occurrences of a key in a JSON object Returns the number of elements with key @a key. If ObjectType is the default `std::map` type, the return value will always be `0` (@a key was not found) or `1` (@a key was found). @note This method always returns `0` when executed on a JSON type that is not an object. @param[in] key key value of the element to count @return Number of elements with key @a key. If the JSON value is not an object, the return value will be `0`. @complexity Logarithmic in the size of the JSON object. @liveexample{The example shows how `count()` is used.,count} @since version 1.0.0 */ template size_type count(KeyT&& key) const { // return 0 for all nonobject types return is_object() ? m_value.object->count(std::forward(key)) : 0; } /*! @brief check the existence of an element in a JSON object Check whether an element exists in a JSON object with key equivalent to @a key. If the element is not found or the JSON value is not an object, false is returned. @note This method always returns false when executed on a JSON type that is not an object. @param[in] key key value to check its existence. @return true if an element with specified @a key exists. If no such element with such key is found or the JSON value is not an object, false is returned. @complexity Logarithmic in the size of the JSON object. @liveexample{The following code shows an example for `contains()`.,contains} @sa @ref find(KeyT&&) -- returns an iterator to an object element @sa @ref contains(const json_pointer&) const -- checks the existence for a JSON pointer @since version 3.6.0 */ template < typename KeyT, typename std::enable_if < !std::is_same::type, json_pointer>::value, int >::type = 0 > bool contains(KeyT && key) const { return is_object() && m_value.object->find(std::forward(key)) != m_value.object->end(); } /*! @brief check the existence of an element in a JSON object given a JSON pointer Check whether the given JSON pointer @a ptr can be resolved in the current JSON value. @note This method can be executed on any JSON value type. @param[in] ptr JSON pointer to check its existence. @return true if the JSON pointer can be resolved to a stored value, false otherwise. @post If `j.contains(ptr)` returns true, it is safe to call `j[ptr]`. @throw parse_error.106 if an array index begins with '0' @throw parse_error.109 if an array index was not a number @complexity Logarithmic in the size of the JSON object. @liveexample{The following code shows an example for `contains()`.,contains_json_pointer} @sa @ref contains(KeyT &&) const -- checks the existence of a key @since version 3.7.0 */ bool contains(const json_pointer& ptr) const { return ptr.contains(this); } /// @} /////////////// // iterators // /////////////// /// @name iterators /// @{ /*! @brief returns an iterator to the first element Returns an iterator to the first element. @image html range-begin-end.svg "Illustration from cppreference.com" @return iterator to the first element @complexity Constant. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. @liveexample{The following code shows an example for `begin()`.,begin} @sa @ref cbegin() -- returns a const iterator to the beginning @sa @ref end() -- returns an iterator to the end @sa @ref cend() -- returns a const iterator to the end @since version 1.0.0 */ iterator begin() noexcept { iterator result(this); result.set_begin(); return result; } /*! @copydoc basic_json::cbegin() */ const_iterator begin() const noexcept { return cbegin(); } /*! @brief returns a const iterator to the first element Returns a const iterator to the first element. @image html range-begin-end.svg "Illustration from cppreference.com" @return const iterator to the first element @complexity Constant. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. - Has the semantics of `const_cast(*this).begin()`. @liveexample{The following code shows an example for `cbegin()`.,cbegin} @sa @ref begin() -- returns an iterator to the beginning @sa @ref end() -- returns an iterator to the end @sa @ref cend() -- returns a const iterator to the end @since version 1.0.0 */ const_iterator cbegin() const noexcept { const_iterator result(this); result.set_begin(); return result; } /*! @brief returns an iterator to one past the last element Returns an iterator to one past the last element. @image html range-begin-end.svg "Illustration from cppreference.com" @return iterator one past the last element @complexity Constant. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. @liveexample{The following code shows an example for `end()`.,end} @sa @ref cend() -- returns a const iterator to the end @sa @ref begin() -- returns an iterator to the beginning @sa @ref cbegin() -- returns a const iterator to the beginning @since version 1.0.0 */ iterator end() noexcept { iterator result(this); result.set_end(); return result; } /*! @copydoc basic_json::cend() */ const_iterator end() const noexcept { return cend(); } /*! @brief returns a const iterator to one past the last element Returns a const iterator to one past the last element. @image html range-begin-end.svg "Illustration from cppreference.com" @return const iterator one past the last element @complexity Constant. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. - Has the semantics of `const_cast(*this).end()`. @liveexample{The following code shows an example for `cend()`.,cend} @sa @ref end() -- returns an iterator to the end @sa @ref begin() -- returns an iterator to the beginning @sa @ref cbegin() -- returns a const iterator to the beginning @since version 1.0.0 */ const_iterator cend() const noexcept { const_iterator result(this); result.set_end(); return result; } /*! @brief returns an iterator to the reverse-beginning Returns an iterator to the reverse-beginning; that is, the last element. @image html range-rbegin-rend.svg "Illustration from cppreference.com" @complexity Constant. @requirement This function helps `basic_json` satisfying the [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) requirements: - The complexity is constant. - Has the semantics of `reverse_iterator(end())`. @liveexample{The following code shows an example for `rbegin()`.,rbegin} @sa @ref crbegin() -- returns a const reverse iterator to the beginning @sa @ref rend() -- returns a reverse iterator to the end @sa @ref crend() -- returns a const reverse iterator to the end @since version 1.0.0 */ reverse_iterator rbegin() noexcept { return reverse_iterator(end()); } /*! @copydoc basic_json::crbegin() */ const_reverse_iterator rbegin() const noexcept { return crbegin(); } /*! @brief returns an iterator to the reverse-end Returns an iterator to the reverse-end; that is, one before the first element. @image html range-rbegin-rend.svg "Illustration from cppreference.com" @complexity Constant. @requirement This function helps `basic_json` satisfying the [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) requirements: - The complexity is constant. - Has the semantics of `reverse_iterator(begin())`. @liveexample{The following code shows an example for `rend()`.,rend} @sa @ref crend() -- returns a const reverse iterator to the end @sa @ref rbegin() -- returns a reverse iterator to the beginning @sa @ref crbegin() -- returns a const reverse iterator to the beginning @since version 1.0.0 */ reverse_iterator rend() noexcept { return reverse_iterator(begin()); } /*! @copydoc basic_json::crend() */ const_reverse_iterator rend() const noexcept { return crend(); } /*! @brief returns a const reverse iterator to the last element Returns a const iterator to the reverse-beginning; that is, the last element. @image html range-rbegin-rend.svg "Illustration from cppreference.com" @complexity Constant. @requirement This function helps `basic_json` satisfying the [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) requirements: - The complexity is constant. - Has the semantics of `const_cast(*this).rbegin()`. @liveexample{The following code shows an example for `crbegin()`.,crbegin} @sa @ref rbegin() -- returns a reverse iterator to the beginning @sa @ref rend() -- returns a reverse iterator to the end @sa @ref crend() -- returns a const reverse iterator to the end @since version 1.0.0 */ const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(cend()); } /*! @brief returns a const reverse iterator to one before the first Returns a const reverse iterator to the reverse-end; that is, one before the first element. @image html range-rbegin-rend.svg "Illustration from cppreference.com" @complexity Constant. @requirement This function helps `basic_json` satisfying the [ReversibleContainer](https://en.cppreference.com/w/cpp/named_req/ReversibleContainer) requirements: - The complexity is constant. - Has the semantics of `const_cast(*this).rend()`. @liveexample{The following code shows an example for `crend()`.,crend} @sa @ref rend() -- returns a reverse iterator to the end @sa @ref rbegin() -- returns a reverse iterator to the beginning @sa @ref crbegin() -- returns a const reverse iterator to the beginning @since version 1.0.0 */ const_reverse_iterator crend() const noexcept { return const_reverse_iterator(cbegin()); } public: /*! @brief wrapper to access iterator member functions in range-based for This function allows to access @ref iterator::key() and @ref iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator. For loop without iterator_wrapper: @code{cpp} for (auto it = j_object.begin(); it != j_object.end(); ++it) { std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; } @endcode Range-based for loop without iterator proxy: @code{cpp} for (auto it : j_object) { // "it" is of type json::reference and has no key() member std::cout << "value: " << it << '\n'; } @endcode Range-based for loop with iterator proxy: @code{cpp} for (auto it : json::iterator_wrapper(j_object)) { std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; } @endcode @note When iterating over an array, `key()` will return the index of the element as string (see example). @param[in] ref reference to a JSON value @return iteration proxy object wrapping @a ref with an interface to use in range-based for loops @liveexample{The following code shows how the wrapper is used,iterator_wrapper} @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @note The name of this function is not yet final and may change in the future. @deprecated This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use @ref items() instead; that is, replace `json::iterator_wrapper(j)` with `j.items()`. */ JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items()) static iteration_proxy iterator_wrapper(reference ref) noexcept { return ref.items(); } /*! @copydoc iterator_wrapper(reference) */ JSON_HEDLEY_DEPRECATED_FOR(3.1.0, items()) static iteration_proxy iterator_wrapper(const_reference ref) noexcept { return ref.items(); } /*! @brief helper to access iterator member functions in range-based for This function allows to access @ref iterator::key() and @ref iterator::value() during range-based for loops. In these loops, a reference to the JSON values is returned, so there is no access to the underlying iterator. For loop without `items()` function: @code{cpp} for (auto it = j_object.begin(); it != j_object.end(); ++it) { std::cout << "key: " << it.key() << ", value:" << it.value() << '\n'; } @endcode Range-based for loop without `items()` function: @code{cpp} for (auto it : j_object) { // "it" is of type json::reference and has no key() member std::cout << "value: " << it << '\n'; } @endcode Range-based for loop with `items()` function: @code{cpp} for (auto& el : j_object.items()) { std::cout << "key: " << el.key() << ", value:" << el.value() << '\n'; } @endcode The `items()` function also allows to use [structured bindings](https://en.cppreference.com/w/cpp/language/structured_binding) (C++17): @code{cpp} for (auto& [key, val] : j_object.items()) { std::cout << "key: " << key << ", value:" << val << '\n'; } @endcode @note When iterating over an array, `key()` will return the index of the element as string (see example). For primitive types (e.g., numbers), `key()` returns an empty string. @warning Using `items()` on temporary objects is dangerous. Make sure the object's lifetime exeeds the iteration. See for more information. @return iteration proxy object wrapping @a ref with an interface to use in range-based for loops @liveexample{The following code shows how the function is used.,items} @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @since version 3.1.0, structured bindings support since 3.5.0. */ iteration_proxy items() noexcept { return iteration_proxy(*this); } /*! @copydoc items() */ iteration_proxy items() const noexcept { return iteration_proxy(*this); } /// @} ////////////// // capacity // ////////////// /// @name capacity /// @{ /*! @brief checks whether the container is empty. Checks if a JSON value has no elements (i.e. whether its @ref size is `0`). @return The return value depends on the different types and is defined as follows: Value type | return value ----------- | ------------- null | `true` boolean | `false` string | `false` number | `false` binary | `false` object | result of function `object_t::empty()` array | result of function `array_t::empty()` @liveexample{The following code uses `empty()` to check if a JSON object contains any elements.,empty} @complexity Constant, as long as @ref array_t and @ref object_t satisfy the Container concept; that is, their `empty()` functions have constant complexity. @iterators No changes. @exceptionsafety No-throw guarantee: this function never throws exceptions. @note This function does not return whether a string stored as JSON value is empty - it returns whether the JSON container itself is empty which is false in the case of a string. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. - Has the semantics of `begin() == end()`. @sa @ref size() -- returns the number of elements @since version 1.0.0 */ bool empty() const noexcept { switch (m_type) { case value_t::null: { // null values are empty return true; } case value_t::array: { // delegate call to array_t::empty() return m_value.array->empty(); } case value_t::object: { // delegate call to object_t::empty() return m_value.object->empty(); } default: { // all other types are nonempty return false; } } } /*! @brief returns the number of elements Returns the number of elements in a JSON value. @return The return value depends on the different types and is defined as follows: Value type | return value ----------- | ------------- null | `0` boolean | `1` string | `1` number | `1` binary | `1` object | result of function object_t::size() array | result of function array_t::size() @liveexample{The following code calls `size()` on the different value types.,size} @complexity Constant, as long as @ref array_t and @ref object_t satisfy the Container concept; that is, their size() functions have constant complexity. @iterators No changes. @exceptionsafety No-throw guarantee: this function never throws exceptions. @note This function does not return the length of a string stored as JSON value - it returns the number of elements in the JSON value which is 1 in the case of a string. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. - Has the semantics of `std::distance(begin(), end())`. @sa @ref empty() -- checks whether the container is empty @sa @ref max_size() -- returns the maximal number of elements @since version 1.0.0 */ size_type size() const noexcept { switch (m_type) { case value_t::null: { // null values are empty return 0; } case value_t::array: { // delegate call to array_t::size() return m_value.array->size(); } case value_t::object: { // delegate call to object_t::size() return m_value.object->size(); } default: { // all other types have size 1 return 1; } } } /*! @brief returns the maximum possible number of elements Returns the maximum number of elements a JSON value is able to hold due to system or library implementation limitations, i.e. `std::distance(begin(), end())` for the JSON value. @return The return value depends on the different types and is defined as follows: Value type | return value ----------- | ------------- null | `0` (same as `size()`) boolean | `1` (same as `size()`) string | `1` (same as `size()`) number | `1` (same as `size()`) binary | `1` (same as `size()`) object | result of function `object_t::max_size()` array | result of function `array_t::max_size()` @liveexample{The following code calls `max_size()` on the different value types. Note the output is implementation specific.,max_size} @complexity Constant, as long as @ref array_t and @ref object_t satisfy the Container concept; that is, their `max_size()` functions have constant complexity. @iterators No changes. @exceptionsafety No-throw guarantee: this function never throws exceptions. @requirement This function helps `basic_json` satisfying the [Container](https://en.cppreference.com/w/cpp/named_req/Container) requirements: - The complexity is constant. - Has the semantics of returning `b.size()` where `b` is the largest possible JSON value. @sa @ref size() -- returns the number of elements @since version 1.0.0 */ size_type max_size() const noexcept { switch (m_type) { case value_t::array: { // delegate call to array_t::max_size() return m_value.array->max_size(); } case value_t::object: { // delegate call to object_t::max_size() return m_value.object->max_size(); } default: { // all other types have max_size() == size() return size(); } } } /// @} /////////////// // modifiers // /////////////// /// @name modifiers /// @{ /*! @brief clears the contents Clears the content of a JSON value and resets it to the default value as if @ref basic_json(value_t) would have been called with the current value type from @ref type(): Value type | initial value ----------- | ------------- null | `null` boolean | `false` string | `""` number | `0` binary | An empty byte vector object | `{}` array | `[]` @post Has the same effect as calling @code {.cpp} *this = basic_json(type()); @endcode @liveexample{The example below shows the effect of `clear()` to different JSON types.,clear} @complexity Linear in the size of the JSON value. @iterators All iterators, pointers and references related to this container are invalidated. @exceptionsafety No-throw guarantee: this function never throws exceptions. @sa @ref basic_json(value_t) -- constructor that creates an object with the same value than calling `clear()` @since version 1.0.0 */ void clear() noexcept { switch (m_type) { case value_t::number_integer: { m_value.number_integer = 0; break; } case value_t::number_unsigned: { m_value.number_unsigned = 0; break; } case value_t::number_float: { m_value.number_float = 0.0; break; } case value_t::boolean: { m_value.boolean = false; break; } case value_t::string: { m_value.string->clear(); break; } case value_t::binary: { m_value.binary->clear(); break; } case value_t::array: { m_value.array->clear(); break; } case value_t::object: { m_value.object->clear(); break; } default: break; } } /*! @brief add an object to an array Appends the given element @a val to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending @a val. @param[in] val the value to add to the JSON array @throw type_error.308 when called on a type other than JSON array or null; example: `"cannot use push_back() with number"` @complexity Amortized constant. @liveexample{The example shows how `push_back()` and `+=` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,push_back} @since version 1.0.0 */ void push_back(basic_json&& val) { // push_back only works for null objects or arrays if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array()))) { JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()), diagnostics_t(*this))); } // transform null object into an array if (is_null()) { m_type = value_t::array; m_value = value_t::array; assert_invariant(); } // add element to array (move semantics) m_value.array->push_back(std::move(val)); set_parent(m_value.array->back(), false); // if val is moved from, basic_json move constructor marks it null so we do not call the destructor } /*! @brief add an object to an array @copydoc push_back(basic_json&&) */ reference operator+=(basic_json&& val) { push_back(std::move(val)); return *this; } /*! @brief add an object to an array @copydoc push_back(basic_json&&) */ void push_back(const basic_json& val) { // push_back only works for null objects or arrays if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array()))) { JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()), diagnostics_t(*this))); } // transform null object into an array if (is_null()) { m_type = value_t::array; m_value = value_t::array; assert_invariant(); } // add element to array m_value.array->push_back(val); set_parent(m_value.array->back(), false); } /*! @brief add an object to an array @copydoc push_back(basic_json&&) */ reference operator+=(const basic_json& val) { push_back(val); return *this; } /*! @brief add an object to an object Inserts the given element @a val to the JSON object. If the function is called on a JSON null value, an empty object is created before inserting @a val. @param[in] val the value to add to the JSON object @throw type_error.308 when called on a type other than JSON object or null; example: `"cannot use push_back() with number"` @complexity Logarithmic in the size of the container, O(log(`size()`)). @liveexample{The example shows how `push_back()` and `+=` can be used to add elements to a JSON object. Note how the `null` value was silently converted to a JSON object.,push_back__object_t__value} @since version 1.0.0 */ void push_back(const typename object_t::value_type& val) { // push_back only works for null objects or objects if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object()))) { JSON_THROW(type_error::create(308, "cannot use push_back() with " + std::string(type_name()), diagnostics_t(*this))); } // transform null object into an object if (is_null()) { m_type = value_t::object; m_value = value_t::object; assert_invariant(); } // add element to object auto res = m_value.object->insert(val); set_parent(res.first->second, false); } /*! @brief add an object to an object @copydoc push_back(const typename object_t::value_type&) */ reference operator+=(const typename object_t::value_type& val) { push_back(val); return *this; } /*! @brief add an object to an object This function allows to use `push_back` with an initializer list. In case 1. the current value is an object, 2. the initializer list @a init contains only two elements, and 3. the first element of @a init is a string, @a init is converted into an object element and added using @ref push_back(const typename object_t::value_type&). Otherwise, @a init is converted to a JSON value and added using @ref push_back(basic_json&&). @param[in] init an initializer list @complexity Linear in the size of the initializer list @a init. @note This function is required to resolve an ambiguous overload error, because pairs like `{"key", "value"}` can be both interpreted as `object_t::value_type` or `std::initializer_list`, see https://github.com/nlohmann/json/issues/235 for more information. @liveexample{The example shows how initializer lists are treated as objects when possible.,push_back__initializer_list} */ void push_back(initializer_list_t init) { if (is_object() && init.size() == 2 && (*init.begin())->is_string()) { basic_json&& key = init.begin()->moved_or_copied(); push_back(typename object_t::value_type( std::move(key.get_ref()), (init.begin() + 1)->moved_or_copied())); } else { push_back(basic_json(init)); } } /*! @brief add an object to an object @copydoc push_back(initializer_list_t) */ reference operator+=(initializer_list_t init) { push_back(init); return *this; } /*! @brief add an object to an array Creates a JSON value from the passed parameters @a args to the end of the JSON value. If the function is called on a JSON null value, an empty array is created before appending the value created from @a args. @param[in] args arguments to forward to a constructor of @ref basic_json @tparam Args compatible types to create a @ref basic_json object @return reference to the inserted element @throw type_error.311 when called on a type other than JSON array or null; example: `"cannot use emplace_back() with number"` @complexity Amortized constant. @liveexample{The example shows how `push_back()` can be used to add elements to a JSON array. Note how the `null` value was silently converted to a JSON array.,emplace_back} @since version 2.0.8, returns reference since 3.7.0 */ template reference emplace_back(Args&& ... args) { // emplace_back only works for null objects or arrays if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array()))) { JSON_THROW(type_error::create(311, "cannot use emplace_back() with " + std::string(type_name()), diagnostics_t(*this))); } // transform null object into an array if (is_null()) { m_type = value_t::array; m_value = value_t::array; assert_invariant(); } // add element to array (perfect forwarding) #ifdef JSON_HAS_CPP_17 return set_parent(m_value.array->emplace_back(std::forward(args)...), false); #else m_value.array->emplace_back(std::forward(args)...); return set_parent(m_value.array->back(), false); #endif } /*! @brief add an object to an object if key does not exist Inserts a new element into a JSON object constructed in-place with the given @a args if there is no element with the key in the container. If the function is called on a JSON null value, an empty object is created before appending the value created from @a args. @param[in] args arguments to forward to a constructor of @ref basic_json @tparam Args compatible types to create a @ref basic_json object @return a pair consisting of an iterator to the inserted element, or the already-existing element if no insertion happened, and a bool denoting whether the insertion took place. @throw type_error.311 when called on a type other than JSON object or null; example: `"cannot use emplace() with number"` @complexity Logarithmic in the size of the container, O(log(`size()`)). @liveexample{The example shows how `emplace()` can be used to add elements to a JSON object. Note how the `null` value was silently converted to a JSON object. Further note how no value is added if there was already one value stored with the same key.,emplace} @since version 2.0.8 */ template std::pair emplace(Args&& ... args) { // emplace only works for null objects or arrays if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_object()))) { JSON_THROW(type_error::create(311, "cannot use emplace() with " + std::string(type_name()), diagnostics_t(*this))); } // transform null object into an object if (is_null()) { m_type = value_t::object; m_value = value_t::object; assert_invariant(); } // add element to array (perfect forwarding) auto res = m_value.object->emplace(std::forward(args)...); set_parent(res.first->second, false); // create result iterator and set iterator to the result of emplace auto it = begin(); it.m_it.object_iterator = res.first; // return pair of iterator and boolean return {it, res.second}; } /// Helper for insertion of an iterator /// @note: This uses std::distance to support GCC 4.8, /// see https://github.com/nlohmann/json/pull/1257 template iterator insert_iterator(const_iterator pos, Args&& ... args) { iterator result(this); JSON_ASSERT(m_value.array != nullptr); auto insert_pos = std::distance(m_value.array->begin(), pos.m_it.array_iterator); m_value.array->insert(pos.m_it.array_iterator, std::forward(args)...); result.m_it.array_iterator = m_value.array->begin() + insert_pos; // This could have been written as: // result.m_it.array_iterator = m_value.array->insert(pos.m_it.array_iterator, cnt, val); // but the return value of insert is missing in GCC 4.8, so it is written this way instead. return result; } /*! @brief inserts element Inserts element @a val before iterator @a pos. @param[in] pos iterator before which the content will be inserted; may be the end() iterator @param[in] val element to insert @return iterator pointing to the inserted @a val. @throw type_error.309 if called on JSON values other than arrays; example: `"cannot use insert() with string"` @throw invalid_iterator.202 if @a pos is not an iterator of *this; example: `"iterator does not fit current value"` @complexity Constant plus linear in the distance between @a pos and end of the container. @liveexample{The example shows how `insert()` is used.,insert} @since version 1.0.0 */ iterator insert(const_iterator pos, const basic_json& val) { // insert only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { // check if iterator pos fits to this JSON value if (JSON_HEDLEY_UNLIKELY(pos.m_object != this)) { JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", diagnostics_t(*this))); } // insert to array and return iterator #if JSON_DIAGNOSTICS iterator result = insert_iterator(pos, val); result->m_parent = this; return result; #else return insert_iterator(pos, val); #endif } JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief inserts element @copydoc insert(const_iterator, const basic_json&) */ iterator insert(const_iterator pos, basic_json&& val) { return insert(pos, val); } /*! @brief inserts elements Inserts @a cnt copies of @a val before iterator @a pos. @param[in] pos iterator before which the content will be inserted; may be the end() iterator @param[in] cnt number of copies of @a val to insert @param[in] val element to insert @return iterator pointing to the first element inserted, or @a pos if `cnt==0` @throw type_error.309 if called on JSON values other than arrays; example: `"cannot use insert() with string"` @throw invalid_iterator.202 if @a pos is not an iterator of *this; example: `"iterator does not fit current value"` @complexity Linear in @a cnt plus linear in the distance between @a pos and end of the container. @liveexample{The example shows how `insert()` is used.,insert__count} @since version 1.0.0 */ iterator insert(const_iterator pos, size_type cnt, const basic_json& val) { // insert only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { // check if iterator pos fits to this JSON value if (JSON_HEDLEY_UNLIKELY(pos.m_object != this)) { JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", diagnostics_t(*this))); } // insert to array and return iterator #if JSON_DIAGNOSTICS iterator result = insert_iterator(pos, cnt, val); for (size_type i = 0; i < cnt; ++i) { (result + static_cast(i))->m_parent = this; } return result; #else return insert_iterator(pos, cnt, val); #endif } JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()), diagnostics_t(*this))); } /*! @brief inserts elements Inserts elements from range `[first, last)` before iterator @a pos. @param[in] pos iterator before which the content will be inserted; may be the end() iterator @param[in] first begin of the range of elements to insert @param[in] last end of the range of elements to insert @throw type_error.309 if called on JSON values other than arrays; example: `"cannot use insert() with string"` @throw invalid_iterator.202 if @a pos is not an iterator of *this; example: `"iterator does not fit current value"` @throw invalid_iterator.210 if @a first and @a last do not belong to the same JSON value; example: `"iterators do not fit"` @throw invalid_iterator.211 if @a first or @a last are iterators into container for which insert is called; example: `"passed iterators may not belong to container"` @return iterator pointing to the first element inserted, or @a pos if `first==last` @complexity Linear in `std::distance(first, last)` plus linear in the distance between @a pos and end of the container. @liveexample{The example shows how `insert()` is used.,insert__range} @since version 1.0.0 */ iterator insert(const_iterator pos, const_iterator first, const_iterator last) { // insert only works for arrays if (JSON_HEDLEY_UNLIKELY(!is_array())) { JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()), diagnostics_t(*this))); } // check if iterator pos fits to this JSON value if (JSON_HEDLEY_UNLIKELY(pos.m_object != this)) { JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", diagnostics_t(*this))); } // check if range iterators belong to the same JSON object if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object)) { JSON_THROW(invalid_iterator::create(210, "iterators do not fit", diagnostics_t(*this))); } if (JSON_HEDLEY_UNLIKELY(first.m_object == this)) { JSON_THROW(invalid_iterator::create(211, "passed iterators may not belong to container", diagnostics_t(*this))); } // insert to array and return iterator #if JSON_DIAGNOSTICS iterator result = insert_iterator(pos, first.m_it.array_iterator, last.m_it.array_iterator); for (typename iterator::difference_type i = 0; i < std::distance(first, last); ++i) { (result + i)->m_parent = this; } return result; #else return insert_iterator(pos, first.m_it.array_iterator, last.m_it.array_iterator); #endif } /*! @brief inserts elements Inserts elements from initializer list @a ilist before iterator @a pos. @param[in] pos iterator before which the content will be inserted; may be the end() iterator @param[in] ilist initializer list to insert the values from @throw type_error.309 if called on JSON values other than arrays; example: `"cannot use insert() with string"` @throw invalid_iterator.202 if @a pos is not an iterator of *this; example: `"iterator does not fit current value"` @return iterator pointing to the first element inserted, or @a pos if `ilist` is empty @complexity Linear in `ilist.size()` plus linear in the distance between @a pos and end of the container. @liveexample{The example shows how `insert()` is used.,insert__ilist} @since version 1.0.0 */ iterator insert(const_iterator pos, initializer_list_t ilist) { // insert only works for arrays if (JSON_HEDLEY_UNLIKELY(!is_array())) { JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()), diagnostics_t(*this))); } // check if iterator pos fits to this JSON value if (JSON_HEDLEY_UNLIKELY(pos.m_object != this)) { JSON_THROW(invalid_iterator::create(202, "iterator does not fit current value", diagnostics_t(*this))); } // insert to array and return iterator #if JSON_DIAGNOSTICS const auto size = ilist.size(); iterator result = insert_iterator(pos, ilist.begin(), ilist.end()); for (std::size_t i = 0; i < size; ++i) { (result + static_cast(i))->m_parent = this; } return result; #else return insert_iterator(pos, ilist.begin(), ilist.end()); #endif } /*! @brief inserts elements Inserts elements from range `[first, last)`. @param[in] first begin of the range of elements to insert @param[in] last end of the range of elements to insert @throw type_error.309 if called on JSON values other than objects; example: `"cannot use insert() with string"` @throw invalid_iterator.202 if iterator @a first or @a last does does not point to an object; example: `"iterators first and last must point to objects"` @throw invalid_iterator.210 if @a first and @a last do not belong to the same JSON value; example: `"iterators do not fit"` @complexity Logarithmic: `O(N*log(size() + N))`, where `N` is the number of elements to insert. @liveexample{The example shows how `insert()` is used.,insert__range_object} @since version 3.0.0 */ void insert(const_iterator first, const_iterator last) { // insert only works for objects if (JSON_HEDLEY_UNLIKELY(!is_object())) { JSON_THROW(type_error::create(309, "cannot use insert() with " + std::string(type_name()), diagnostics_t(*this))); } // check if range iterators belong to the same JSON object if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object)) { JSON_THROW(invalid_iterator::create(210, "iterators do not fit", diagnostics_t(*this))); } // passed iterators must belong to objects if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object())) { JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects", diagnostics_t(*this))); } m_value.object->insert(first.m_it.object_iterator, last.m_it.object_iterator); } /*! @brief updates a JSON object from another object, overwriting existing keys Inserts all values from JSON object @a j and overwrites existing keys. @param[in] j JSON object to read values from @throw type_error.312 if called on JSON values other than objects; example: `"cannot use update() with string"` @complexity O(N*log(size() + N)), where N is the number of elements to insert. @liveexample{The example shows how `update()` is used.,update} @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update @since version 3.0.0 */ void update(const_reference j) { // implicitly convert null value to an empty object if (is_null()) { m_type = value_t::object; m_value.object = create(); assert_invariant(); } if (JSON_HEDLEY_UNLIKELY(!is_object())) { JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()), diagnostics_t(*this))); } if (JSON_HEDLEY_UNLIKELY(!j.is_object())) { JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(j.type_name()), diagnostics_t(*this))); } for (auto it = j.cbegin(); it != j.cend(); ++it) { m_value.object->operator[](it.key()) = it.value(); } } /*! @brief updates a JSON object from another object, overwriting existing keys Inserts all values from from range `[first, last)` and overwrites existing keys. @param[in] first begin of the range of elements to insert @param[in] last end of the range of elements to insert @throw type_error.312 if called on JSON values other than objects; example: `"cannot use update() with string"` @throw invalid_iterator.202 if iterator @a first or @a last does does not point to an object; example: `"iterators first and last must point to objects"` @throw invalid_iterator.210 if @a first and @a last do not belong to the same JSON value; example: `"iterators do not fit"` @complexity O(N*log(size() + N)), where N is the number of elements to insert. @liveexample{The example shows how `update()` is used__range.,update} @sa https://docs.python.org/3.6/library/stdtypes.html#dict.update @since version 3.0.0 */ void update(const_iterator first, const_iterator last) { // implicitly convert null value to an empty object if (is_null()) { m_type = value_t::object; m_value.object = create(); assert_invariant(); } if (JSON_HEDLEY_UNLIKELY(!is_object())) { JSON_THROW(type_error::create(312, "cannot use update() with " + std::string(type_name()), diagnostics_t(*this))); } // check if range iterators belong to the same JSON object if (JSON_HEDLEY_UNLIKELY(first.m_object != last.m_object)) { JSON_THROW(invalid_iterator::create(210, "iterators do not fit", diagnostics_t(*this))); } // passed iterators must belong to objects if (JSON_HEDLEY_UNLIKELY(!first.m_object->is_object() || !last.m_object->is_object())) { JSON_THROW(invalid_iterator::create(202, "iterators first and last must point to objects", diagnostics_t(*this))); } for (auto it = first; it != last; ++it) { m_value.object->operator[](it.key()) = it.value(); } } /*! @brief exchanges the values Exchanges the contents of the JSON value with those of @a other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. @param[in,out] other JSON value to exchange the contents with @complexity Constant. @liveexample{The example below shows how JSON values can be swapped with `swap()`.,swap__reference} @since version 1.0.0 */ void swap(reference other) noexcept ( std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value&& std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value ) { std::swap(m_type, other.m_type); std::swap(m_value, other.m_value); set_parent(*this, true); assert_invariant(); } /*! @brief exchanges the values Exchanges the contents of the JSON value from @a left with those of @a right. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. implemented as a friend function callable via ADL. @param[in,out] left JSON value to exchange the contents with @param[in,out] right JSON value to exchange the contents with @complexity Constant. @liveexample{The example below shows how JSON values can be swapped with `swap()`.,swap__reference} @since version 1.0.0 */ friend void swap(reference left, reference right) noexcept ( std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value&& std::is_nothrow_move_constructible::value&& std::is_nothrow_move_assignable::value ) { left.swap(right); } /*! @brief exchanges the values Exchanges the contents of a JSON array with those of @a other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. @param[in,out] other array to exchange the contents with @throw type_error.310 when JSON value is not an array; example: `"cannot use swap() with string"` @complexity Constant. @liveexample{The example below shows how arrays can be swapped with `swap()`.,swap__array_t} @since version 1.0.0 */ void swap(array_t& other) { // swap only works for arrays if (JSON_HEDLEY_LIKELY(is_array())) { std::swap(*(m_value.array), other); } else { JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief exchanges the values Exchanges the contents of a JSON object with those of @a other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. @param[in,out] other object to exchange the contents with @throw type_error.310 when JSON value is not an object; example: `"cannot use swap() with string"` @complexity Constant. @liveexample{The example below shows how objects can be swapped with `swap()`.,swap__object_t} @since version 1.0.0 */ void swap(object_t& other) { // swap only works for objects if (JSON_HEDLEY_LIKELY(is_object())) { std::swap(*(m_value.object), other); } else { JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief exchanges the values Exchanges the contents of a JSON string with those of @a other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. @param[in,out] other string to exchange the contents with @throw type_error.310 when JSON value is not a string; example: `"cannot use swap() with boolean"` @complexity Constant. @liveexample{The example below shows how strings can be swapped with `swap()`.,swap__string_t} @since version 1.0.0 */ void swap(string_t& other) { // swap only works for strings if (JSON_HEDLEY_LIKELY(is_string())) { std::swap(*(m_value.string), other); } else { JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()), diagnostics_t(*this))); } } /*! @brief exchanges the values Exchanges the contents of a JSON string with those of @a other. Does not invoke any move, copy, or swap operations on individual elements. All iterators and references remain valid. The past-the-end iterator is invalidated. @param[in,out] other binary to exchange the contents with @throw type_error.310 when JSON value is not a string; example: `"cannot use swap() with boolean"` @complexity Constant. @liveexample{The example below shows how strings can be swapped with `swap()`.,swap__binary_t} @since version 3.8.0 */ void swap(binary_t& other) { // swap only works for strings if (JSON_HEDLEY_LIKELY(is_binary())) { std::swap(*(m_value.binary), other); } else { JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()), diagnostics_t(*this))); } } /// @copydoc swap(binary_t) void swap(typename binary_t::container_type& other) { // swap only works for strings if (JSON_HEDLEY_LIKELY(is_binary())) { std::swap(*(m_value.binary), other); } else { JSON_THROW(type_error::create(310, "cannot use swap() with " + std::string(type_name()), diagnostics_t(*this))); } } /// @} public: ////////////////////////////////////////// // lexicographical comparison operators // ////////////////////////////////////////// /// @name lexicographical comparison operators /// @{ /*! @brief comparison: equal Compares two JSON values for equality according to the following rules: - Two JSON values are equal if (1) they are from the same type and (2) their stored values are the same according to their respective `operator==`. - Integer and floating-point numbers are automatically converted before comparison. Note that two NaN values are always treated as unequal. - Two JSON null values are equal. @note Floating-point inside JSON values numbers are compared with `json::number_float_t::operator==` which is `double::operator==` by default. To compare floating-point while respecting an epsilon, an alternative [comparison function](https://github.com/mariokonrad/marnav/blob/master/include/marnav/math/floatingpoint.hpp#L34-#L39) could be used, for instance @code {.cpp} template::value, T>::type> inline bool is_same(T a, T b, T epsilon = std::numeric_limits::epsilon()) noexcept { return std::abs(a - b) <= epsilon; } @endcode Or you can self-defined operator equal function like this: @code {.cpp} bool my_equal(const_reference lhs, const_reference rhs) { const auto lhs_type lhs.type(); const auto rhs_type rhs.type(); if (lhs_type == rhs_type) { switch(lhs_type) // self_defined case case value_t::number_float: return std::abs(lhs - rhs) <= std::numeric_limits::epsilon(); // other cases remain the same with the original ... } ... } @endcode @note NaN values never compare equal to themselves or to other NaN values. @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether the values @a lhs and @a rhs are equal @exceptionsafety No-throw guarantee: this function never throws exceptions. @complexity Linear. @liveexample{The example demonstrates comparing several JSON types.,operator__equal} @since version 1.0.0 */ friend bool operator==(const_reference lhs, const_reference rhs) noexcept { const auto lhs_type = lhs.type(); const auto rhs_type = rhs.type(); if (lhs_type == rhs_type) { switch (lhs_type) { case value_t::array: return *lhs.m_value.array == *rhs.m_value.array; case value_t::object: return *lhs.m_value.object == *rhs.m_value.object; case value_t::null: return true; case value_t::string: return *lhs.m_value.string == *rhs.m_value.string; case value_t::boolean: return lhs.m_value.boolean == rhs.m_value.boolean; case value_t::number_integer: return lhs.m_value.number_integer == rhs.m_value.number_integer; case value_t::number_unsigned: return lhs.m_value.number_unsigned == rhs.m_value.number_unsigned; case value_t::number_float: return lhs.m_value.number_float == rhs.m_value.number_float; case value_t::binary: return *lhs.m_value.binary == *rhs.m_value.binary; default: return false; } } else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_float) { return static_cast(lhs.m_value.number_integer) == rhs.m_value.number_float; } else if (lhs_type == value_t::number_float && rhs_type == value_t::number_integer) { return lhs.m_value.number_float == static_cast(rhs.m_value.number_integer); } else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_float) { return static_cast(lhs.m_value.number_unsigned) == rhs.m_value.number_float; } else if (lhs_type == value_t::number_float && rhs_type == value_t::number_unsigned) { return lhs.m_value.number_float == static_cast(rhs.m_value.number_unsigned); } else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer) { return static_cast(lhs.m_value.number_unsigned) == rhs.m_value.number_integer; } else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned) { return lhs.m_value.number_integer == static_cast(rhs.m_value.number_unsigned); } return false; } /*! @brief comparison: equal @copydoc operator==(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept { return lhs == basic_json(rhs); } /*! @brief comparison: equal @copydoc operator==(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) == rhs; } /*! @brief comparison: not equal Compares two JSON values for inequality by calculating `not (lhs == rhs)`. @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether the values @a lhs and @a rhs are not equal @complexity Linear. @exceptionsafety No-throw guarantee: this function never throws exceptions. @liveexample{The example demonstrates comparing several JSON types.,operator__notequal} @since version 1.0.0 */ friend bool operator!=(const_reference lhs, const_reference rhs) noexcept { return !(lhs == rhs); } /*! @brief comparison: not equal @copydoc operator!=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator!=(const_reference lhs, const ScalarType rhs) noexcept { return lhs != basic_json(rhs); } /*! @brief comparison: not equal @copydoc operator!=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator!=(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) != rhs; } /*! @brief comparison: less than Compares whether one JSON value @a lhs is less than another JSON value @a rhs according to the following rules: - If @a lhs and @a rhs have the same type, the values are compared using the default `<` operator. - Integer and floating-point numbers are automatically converted before comparison - In case @a lhs and @a rhs have different types, the values are ignored and the order of the types is considered, see @ref operator<(const value_t, const value_t). @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether @a lhs is less than @a rhs @complexity Linear. @exceptionsafety No-throw guarantee: this function never throws exceptions. @liveexample{The example demonstrates comparing several JSON types.,operator__less} @since version 1.0.0 */ friend bool operator<(const_reference lhs, const_reference rhs) noexcept { const auto lhs_type = lhs.type(); const auto rhs_type = rhs.type(); if (lhs_type == rhs_type) { switch (lhs_type) { case value_t::array: // note parentheses are necessary, see // https://github.com/nlohmann/json/issues/1530 return (*lhs.m_value.array) < (*rhs.m_value.array); case value_t::object: return (*lhs.m_value.object) < (*rhs.m_value.object); case value_t::null: return false; case value_t::string: return (*lhs.m_value.string) < (*rhs.m_value.string); case value_t::boolean: return (lhs.m_value.boolean) < (rhs.m_value.boolean); case value_t::number_integer: return (lhs.m_value.number_integer) < (rhs.m_value.number_integer); case value_t::number_unsigned: return (lhs.m_value.number_unsigned) < (rhs.m_value.number_unsigned); case value_t::number_float: return (lhs.m_value.number_float) < (rhs.m_value.number_float); case value_t::binary: return (*lhs.m_value.binary) < (*rhs.m_value.binary); default: return false; } } else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_float) { return static_cast(lhs.m_value.number_integer) < rhs.m_value.number_float; } else if (lhs_type == value_t::number_float && rhs_type == value_t::number_integer) { return lhs.m_value.number_float < static_cast(rhs.m_value.number_integer); } else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_float) { return static_cast(lhs.m_value.number_unsigned) < rhs.m_value.number_float; } else if (lhs_type == value_t::number_float && rhs_type == value_t::number_unsigned) { return lhs.m_value.number_float < static_cast(rhs.m_value.number_unsigned); } else if (lhs_type == value_t::number_integer && rhs_type == value_t::number_unsigned) { return lhs.m_value.number_integer < static_cast(rhs.m_value.number_unsigned); } else if (lhs_type == value_t::number_unsigned && rhs_type == value_t::number_integer) { return static_cast(lhs.m_value.number_unsigned) < rhs.m_value.number_integer; } // We only reach this line if we cannot compare values. In that case, // we compare types. Note we have to call the operator explicitly, // because MSVC has problems otherwise. return operator<(lhs_type, rhs_type); } /*! @brief comparison: less than @copydoc operator<(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator<(const_reference lhs, const ScalarType rhs) noexcept { return lhs < basic_json(rhs); } /*! @brief comparison: less than @copydoc operator<(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator<(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) < rhs; } /*! @brief comparison: less than or equal Compares whether one JSON value @a lhs is less than or equal to another JSON value by calculating `not (rhs < lhs)`. @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether @a lhs is less than or equal to @a rhs @complexity Linear. @exceptionsafety No-throw guarantee: this function never throws exceptions. @liveexample{The example demonstrates comparing several JSON types.,operator__greater} @since version 1.0.0 */ friend bool operator<=(const_reference lhs, const_reference rhs) noexcept { return !(rhs < lhs); } /*! @brief comparison: less than or equal @copydoc operator<=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator<=(const_reference lhs, const ScalarType rhs) noexcept { return lhs <= basic_json(rhs); } /*! @brief comparison: less than or equal @copydoc operator<=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator<=(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) <= rhs; } /*! @brief comparison: greater than Compares whether one JSON value @a lhs is greater than another JSON value by calculating `not (lhs <= rhs)`. @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether @a lhs is greater than to @a rhs @complexity Linear. @exceptionsafety No-throw guarantee: this function never throws exceptions. @liveexample{The example demonstrates comparing several JSON types.,operator__lessequal} @since version 1.0.0 */ friend bool operator>(const_reference lhs, const_reference rhs) noexcept { return !(lhs <= rhs); } /*! @brief comparison: greater than @copydoc operator>(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator>(const_reference lhs, const ScalarType rhs) noexcept { return lhs > basic_json(rhs); } /*! @brief comparison: greater than @copydoc operator>(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator>(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) > rhs; } /*! @brief comparison: greater than or equal Compares whether one JSON value @a lhs is greater than or equal to another JSON value by calculating `not (lhs < rhs)`. @param[in] lhs first JSON value to consider @param[in] rhs second JSON value to consider @return whether @a lhs is greater than or equal to @a rhs @complexity Linear. @exceptionsafety No-throw guarantee: this function never throws exceptions. @liveexample{The example demonstrates comparing several JSON types.,operator__greaterequal} @since version 1.0.0 */ friend bool operator>=(const_reference lhs, const_reference rhs) noexcept { return !(lhs < rhs); } /*! @brief comparison: greater than or equal @copydoc operator>=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator>=(const_reference lhs, const ScalarType rhs) noexcept { return lhs >= basic_json(rhs); } /*! @brief comparison: greater than or equal @copydoc operator>=(const_reference, const_reference) */ template::value, int>::type = 0> friend bool operator>=(const ScalarType lhs, const_reference rhs) noexcept { return basic_json(lhs) >= rhs; } /// @} /////////////////// // serialization // /////////////////// /// @name serialization /// @{ /*! @brief serialize to stream Serialize the given JSON value @a j to the output stream @a o. The JSON value will be serialized using the @ref dump member function. - The indentation of the output can be controlled with the member variable `width` of the output stream @a o. For instance, using the manipulator `std::setw(4)` on @a o sets the indentation level to `4` and the serialization result is the same as calling `dump(4)`. - The indentation character can be controlled with the member variable `fill` of the output stream @a o. For instance, the manipulator `std::setfill('\\t')` sets indentation to use a tab character rather than the default space character. @param[in,out] o stream to serialize to @param[in] j JSON value to serialize @return the stream @a o @throw type_error.316 if a string stored inside the JSON value is not UTF-8 encoded @complexity Linear. @liveexample{The example below shows the serialization with different parameters to `width` to adjust the indentation level.,operator_serialize} @since version 1.0.0; indentation character added in version 3.0.0 */ friend std::ostream& operator<<(std::ostream& o, const basic_json& j) { // read width member and use it as indentation parameter if nonzero const bool pretty_print = o.width() > 0; const auto indentation = pretty_print ? o.width() : 0; // reset width to 0 for subsequent calls to this stream o.width(0); // do the actual serialization serializer s(detail::output_adapter(o), o.fill()); s.dump(j, pretty_print, false, static_cast(indentation)); return o; } /*! @brief serialize to stream @deprecated This stream operator is deprecated and will be removed in future 4.0.0 of the library. Please use @ref operator<<(std::ostream&, const basic_json&) instead; that is, replace calls like `j >> o;` with `o << j;`. @since version 1.0.0; deprecated since version 3.0.0 */ JSON_HEDLEY_DEPRECATED_FOR(3.0.0, operator<<(std::ostream&, const basic_json&)) friend std::ostream& operator>>(const basic_json& j, std::ostream& o) { return o << j; } /// @} ///////////////////// // deserialization // ///////////////////// /// @name deserialization /// @{ /*! @brief deserialize from a compatible input @tparam InputType A compatible input, for instance - an std::istream object - a FILE pointer - a C-style array of characters - a pointer to a null-terminated string of single byte characters - an object obj for which begin(obj) and end(obj) produces a valid pair of iterators. @param[in] i input to read from @param[in] cb a parser callback function of type @ref parser_callback_t which is used to control the deserialization by filtering unwanted values (optional) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @param[in] ignore_comments whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.101 if a parse error occurs; example: `""unexpected end of input; expected string literal""` @throw parse_error.102 if to_unicode fails or surrogate error @throw parse_error.103 if to_unicode fails @complexity Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the parser callback function @a cb or reading from the input @a i has a super-linear complexity. @note A UTF-8 byte order mark is silently ignored. @liveexample{The example below demonstrates the `parse()` function reading from an array.,parse__array__parser_callback_t} @liveexample{The example below demonstrates the `parse()` function with and without callback function.,parse__string__parser_callback_t} @liveexample{The example below demonstrates the `parse()` function with and without callback function.,parse__istream__parser_callback_t} @liveexample{The example below demonstrates the `parse()` function reading from a contiguous container.,parse__contiguouscontainer__parser_callback_t} @since version 2.0.3 (contiguous containers); version 3.9.0 allowed to ignore comments. */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json parse(InputType&& i, const parser_callback_t cb = nullptr, const bool allow_exceptions = true, const bool ignore_comments = false) { basic_json result; parser(detail::input_adapter(std::forward(i)), cb, allow_exceptions, ignore_comments).parse(true, result); return result; } /*! @brief deserialize from a pair of character iterators The value_type of the iterator must be a integral type with size of 1, 2 or 4 bytes, which will be interpreted respectively as UTF-8, UTF-16 and UTF-32. @param[in] first iterator to start of character range @param[in] last iterator to end of character range @param[in] cb a parser callback function of type @ref parser_callback_t which is used to control the deserialization by filtering unwanted values (optional) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @param[in] ignore_comments whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.101 if a parse error occurs; example: `""unexpected end of input; expected string literal""` @throw parse_error.102 if to_unicode fails or surrogate error @throw parse_error.103 if to_unicode fails */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json parse(IteratorType first, IteratorType last, const parser_callback_t cb = nullptr, const bool allow_exceptions = true, const bool ignore_comments = false) { basic_json result; parser(detail::input_adapter(std::move(first), std::move(last)), cb, allow_exceptions, ignore_comments).parse(true, result); return result; } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, parse(ptr, ptr + len)) static basic_json parse(detail::span_input_adapter&& i, const parser_callback_t cb = nullptr, const bool allow_exceptions = true, const bool ignore_comments = false) { basic_json result; parser(i.get(), cb, allow_exceptions, ignore_comments).parse(true, result); return result; } /*! @brief check if the input is valid JSON Unlike the @ref parse(InputType&&, const parser_callback_t,const bool) function, this function neither throws an exception in case of invalid JSON input (i.e., a parse error) nor creates diagnostic information. @tparam InputType A compatible input, for instance - an std::istream object - a FILE pointer - a C-style array of characters - a pointer to a null-terminated string of single byte characters - an object obj for which begin(obj) and end(obj) produces a valid pair of iterators. @param[in] i input to read from @param[in] ignore_comments whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default) @return Whether the input read from @a i is valid JSON. @complexity Linear in the length of the input. The parser is a predictive LL(1) parser. @note A UTF-8 byte order mark is silently ignored. @liveexample{The example below demonstrates the `accept()` function reading from a string.,accept__string} */ template static bool accept(InputType&& i, const bool ignore_comments = false) { return parser(detail::input_adapter(std::forward(i)), nullptr, false, ignore_comments).accept(true); } template static bool accept(IteratorType first, IteratorType last, const bool ignore_comments = false) { return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments).accept(true); } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, accept(ptr, ptr + len)) static bool accept(detail::span_input_adapter&& i, const bool ignore_comments = false) { return parser(i.get(), nullptr, false, ignore_comments).accept(true); } /*! @brief generate SAX events The SAX event lister must follow the interface of @ref json_sax. This function reads from a compatible input. Examples are: - an std::istream object - a FILE pointer - a C-style array of characters - a pointer to a null-terminated string of single byte characters - an object obj for which begin(obj) and end(obj) produces a valid pair of iterators. @param[in] i input to read from @param[in,out] sax SAX event listener @param[in] format the format to parse (JSON, CBOR, MessagePack, or UBJSON) @param[in] strict whether the input has to be consumed completely @param[in] ignore_comments whether comments should be ignored and treated like whitespace (true) or yield a parse error (true); (optional, false by default); only applies to the JSON file format. @return return value of the last processed SAX event @throw parse_error.101 if a parse error occurs; example: `""unexpected end of input; expected string literal""` @throw parse_error.102 if to_unicode fails or surrogate error @throw parse_error.103 if to_unicode fails @complexity Linear in the length of the input. The parser is a predictive LL(1) parser. The complexity can be higher if the SAX consumer @a sax has a super-linear complexity. @note A UTF-8 byte order mark is silently ignored. @liveexample{The example below demonstrates the `sax_parse()` function reading from string and processing the events with a user-defined SAX event consumer.,sax_parse} @since version 3.2.0 */ template JSON_HEDLEY_NON_NULL(2) static bool sax_parse(InputType&& i, SAX* sax, input_format_t format = input_format_t::json, const bool strict = true, const bool ignore_comments = false) { auto ia = detail::input_adapter(std::forward(i)); return format == input_format_t::json ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict) : detail::binary_reader(std::move(ia)).sax_parse(format, sax, strict); } template JSON_HEDLEY_NON_NULL(3) static bool sax_parse(IteratorType first, IteratorType last, SAX* sax, input_format_t format = input_format_t::json, const bool strict = true, const bool ignore_comments = false) { auto ia = detail::input_adapter(std::move(first), std::move(last)); return format == input_format_t::json ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict) : detail::binary_reader(std::move(ia)).sax_parse(format, sax, strict); } template JSON_HEDLEY_DEPRECATED_FOR(3.8.0, sax_parse(ptr, ptr + len, ...)) JSON_HEDLEY_NON_NULL(2) static bool sax_parse(detail::span_input_adapter&& i, SAX* sax, input_format_t format = input_format_t::json, const bool strict = true, const bool ignore_comments = false) { auto ia = i.get(); return format == input_format_t::json ? parser(std::move(ia), nullptr, true, ignore_comments).sax_parse(sax, strict) : detail::binary_reader(std::move(ia)).sax_parse(format, sax, strict); } /*! @brief deserialize from stream @deprecated This stream operator is deprecated and will be removed in version 4.0.0 of the library. Please use @ref operator>>(std::istream&, basic_json&) instead; that is, replace calls like `j << i;` with `i >> j;`. @since version 1.0.0; deprecated since version 3.0.0 */ JSON_HEDLEY_DEPRECATED_FOR(3.0.0, operator>>(std::istream&, basic_json&)) friend std::istream& operator<<(basic_json& j, std::istream& i) { return operator>>(i, j); } /*! @brief deserialize from stream Deserializes an input stream to a JSON value. @param[in,out] i input stream to read a serialized JSON value from @param[in,out] j JSON value to write the deserialized input to @throw parse_error.101 in case of an unexpected token @throw parse_error.102 if to_unicode fails or surrogate error @throw parse_error.103 if to_unicode fails @complexity Linear in the length of the input. The parser is a predictive LL(1) parser. @note A UTF-8 byte order mark is silently ignored. @liveexample{The example below shows how a JSON value is constructed by reading a serialization from a stream.,operator_deserialize} @sa parse(std::istream&, const parser_callback_t) for a variant with a parser callback function to filter values while parsing @since version 1.0.0 */ friend std::istream& operator>>(std::istream& i, basic_json& j) { parser(detail::input_adapter(i)).parse(false, j); return i; } /// @} /////////////////////////// // convenience functions // /////////////////////////// /*! @brief return the type as string Returns the type name as string to be used in error messages - usually to indicate that a function was called on a wrong JSON type. @return a string representation of a the @a m_type member: Value type | return value ----------- | ------------- null | `"null"` boolean | `"boolean"` string | `"string"` number | `"number"` (for all number types) object | `"object"` array | `"array"` binary | `"binary"` discarded | `"discarded"` @exceptionsafety No-throw guarantee: this function never throws exceptions. @complexity Constant. @liveexample{The following code exemplifies `type_name()` for all JSON types.,type_name} @sa @ref type() -- return the type of the JSON value @sa @ref operator value_t() -- return the type of the JSON value (implicit) @since version 1.0.0, public since 2.1.0, `const char*` and `noexcept` since 3.0.0 */ JSON_HEDLEY_RETURNS_NON_NULL const char* type_name() const noexcept { { switch (m_type) { case value_t::null: return "null"; case value_t::object: return "object"; case value_t::array: return "array"; case value_t::string: return "string"; case value_t::boolean: return "boolean"; case value_t::binary: return "binary"; case value_t::discarded: return "discarded"; default: return "number"; } } } JSON_PRIVATE_UNLESS_TESTED: ////////////////////// // member variables // ////////////////////// /// the type of the current element value_t m_type = value_t::null; /// the value of the current element json_value m_value = {}; #if JSON_DIAGNOSTICS /// a pointer to a parent value (for debugging purposes) basic_json* m_parent = nullptr; #endif ////////////////////////////////////////// // binary serialization/deserialization // ////////////////////////////////////////// /// @name binary serialization/deserialization support /// @{ public: /*! @brief create a CBOR serialization of a given JSON value Serializes a given JSON value @a j to a byte vector using the CBOR (Concise Binary Object Representation) serialization format. CBOR is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse. The library uses the following mapping from JSON values types to CBOR types according to the CBOR specification (RFC 7049): JSON value type | value/range | CBOR type | first byte --------------- | ------------------------------------------ | ---------------------------------- | --------------- null | `null` | Null | 0xF6 boolean | `true` | True | 0xF5 boolean | `false` | False | 0xF4 number_integer | -9223372036854775808..-2147483649 | Negative integer (8 bytes follow) | 0x3B number_integer | -2147483648..-32769 | Negative integer (4 bytes follow) | 0x3A number_integer | -32768..-129 | Negative integer (2 bytes follow) | 0x39 number_integer | -128..-25 | Negative integer (1 byte follow) | 0x38 number_integer | -24..-1 | Negative integer | 0x20..0x37 number_integer | 0..23 | Integer | 0x00..0x17 number_integer | 24..255 | Unsigned integer (1 byte follow) | 0x18 number_integer | 256..65535 | Unsigned integer (2 bytes follow) | 0x19 number_integer | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A number_integer | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B number_unsigned | 0..23 | Integer | 0x00..0x17 number_unsigned | 24..255 | Unsigned integer (1 byte follow) | 0x18 number_unsigned | 256..65535 | Unsigned integer (2 bytes follow) | 0x19 number_unsigned | 65536..4294967295 | Unsigned integer (4 bytes follow) | 0x1A number_unsigned | 4294967296..18446744073709551615 | Unsigned integer (8 bytes follow) | 0x1B number_float | *any value representable by a float* | Single-Precision Float | 0xFA number_float | *any value NOT representable by a float* | Double-Precision Float | 0xFB string | *length*: 0..23 | UTF-8 string | 0x60..0x77 string | *length*: 23..255 | UTF-8 string (1 byte follow) | 0x78 string | *length*: 256..65535 | UTF-8 string (2 bytes follow) | 0x79 string | *length*: 65536..4294967295 | UTF-8 string (4 bytes follow) | 0x7A string | *length*: 4294967296..18446744073709551615 | UTF-8 string (8 bytes follow) | 0x7B array | *size*: 0..23 | array | 0x80..0x97 array | *size*: 23..255 | array (1 byte follow) | 0x98 array | *size*: 256..65535 | array (2 bytes follow) | 0x99 array | *size*: 65536..4294967295 | array (4 bytes follow) | 0x9A array | *size*: 4294967296..18446744073709551615 | array (8 bytes follow) | 0x9B object | *size*: 0..23 | map | 0xA0..0xB7 object | *size*: 23..255 | map (1 byte follow) | 0xB8 object | *size*: 256..65535 | map (2 bytes follow) | 0xB9 object | *size*: 65536..4294967295 | map (4 bytes follow) | 0xBA object | *size*: 4294967296..18446744073709551615 | map (8 bytes follow) | 0xBB binary | *size*: 0..23 | byte string | 0x40..0x57 binary | *size*: 23..255 | byte string (1 byte follow) | 0x58 binary | *size*: 256..65535 | byte string (2 bytes follow) | 0x59 binary | *size*: 65536..4294967295 | byte string (4 bytes follow) | 0x5A binary | *size*: 4294967296..18446744073709551615 | byte string (8 bytes follow) | 0x5B @note The mapping is **complete** in the sense that any JSON value type can be converted to a CBOR value. @note If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the @ref dump() function which serializes NaN or Infinity to `null`. @note The following CBOR types are not used in the conversion: - UTF-8 strings terminated by "break" (0x7F) - arrays terminated by "break" (0x9F) - maps terminated by "break" (0xBF) - byte strings terminated by "break" (0x5F) - date/time (0xC0..0xC1) - bignum (0xC2..0xC3) - decimal fraction (0xC4) - bigfloat (0xC5) - expected conversions (0xD5..0xD7) - simple values (0xE0..0xF3, 0xF8) - undefined (0xF7) - half-precision floats (0xF9) - break (0xFF) @param[in] j JSON value to serialize @return CBOR serialization as byte vector @complexity Linear in the size of the JSON value @a j. @liveexample{The example shows the serialization of a JSON value to a byte vector in CBOR format.,to_cbor} @sa http://cbor.io @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the analogous deserialization @sa @ref to_msgpack(const basic_json&) for the related MessagePack format @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format @since version 2.0.9; compact representation of floating-point numbers since version 3.8.0 */ static std::vector to_cbor(const basic_json& j) { std::vector result; to_cbor(j, result); return result; } static void to_cbor(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_cbor(j); } static void to_cbor(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_cbor(j); } /*! @brief create a MessagePack serialization of a given JSON value Serializes a given JSON value @a j to a byte vector using the MessagePack serialization format. MessagePack is a binary serialization format which aims to be more compact than JSON itself, yet more efficient to parse. The library uses the following mapping from JSON values types to MessagePack types according to the MessagePack specification: JSON value type | value/range | MessagePack type | first byte --------------- | --------------------------------- | ---------------- | ---------- null | `null` | nil | 0xC0 boolean | `true` | true | 0xC3 boolean | `false` | false | 0xC2 number_integer | -9223372036854775808..-2147483649 | int64 | 0xD3 number_integer | -2147483648..-32769 | int32 | 0xD2 number_integer | -32768..-129 | int16 | 0xD1 number_integer | -128..-33 | int8 | 0xD0 number_integer | -32..-1 | negative fixint | 0xE0..0xFF number_integer | 0..127 | positive fixint | 0x00..0x7F number_integer | 128..255 | uint 8 | 0xCC number_integer | 256..65535 | uint 16 | 0xCD number_integer | 65536..4294967295 | uint 32 | 0xCE number_integer | 4294967296..18446744073709551615 | uint 64 | 0xCF number_unsigned | 0..127 | positive fixint | 0x00..0x7F number_unsigned | 128..255 | uint 8 | 0xCC number_unsigned | 256..65535 | uint 16 | 0xCD number_unsigned | 65536..4294967295 | uint 32 | 0xCE number_unsigned | 4294967296..18446744073709551615 | uint 64 | 0xCF number_float | *any value representable by a float* | float 32 | 0xCA number_float | *any value NOT representable by a float* | float 64 | 0xCB string | *length*: 0..31 | fixstr | 0xA0..0xBF string | *length*: 32..255 | str 8 | 0xD9 string | *length*: 256..65535 | str 16 | 0xDA string | *length*: 65536..4294967295 | str 32 | 0xDB array | *size*: 0..15 | fixarray | 0x90..0x9F array | *size*: 16..65535 | array 16 | 0xDC array | *size*: 65536..4294967295 | array 32 | 0xDD object | *size*: 0..15 | fix map | 0x80..0x8F object | *size*: 16..65535 | map 16 | 0xDE object | *size*: 65536..4294967295 | map 32 | 0xDF binary | *size*: 0..255 | bin 8 | 0xC4 binary | *size*: 256..65535 | bin 16 | 0xC5 binary | *size*: 65536..4294967295 | bin 32 | 0xC6 @note The mapping is **complete** in the sense that any JSON value type can be converted to a MessagePack value. @note The following values can **not** be converted to a MessagePack value: - strings with more than 4294967295 bytes - byte strings with more than 4294967295 bytes - arrays with more than 4294967295 elements - objects with more than 4294967295 elements @note Any MessagePack output created @ref to_msgpack can be successfully parsed by @ref from_msgpack. @note If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the @ref dump() function which serializes NaN or Infinity to `null`. @param[in] j JSON value to serialize @return MessagePack serialization as byte vector @complexity Linear in the size of the JSON value @a j. @liveexample{The example shows the serialization of a JSON value to a byte vector in MessagePack format.,to_msgpack} @sa http://msgpack.org @sa @ref from_msgpack for the analogous deserialization @sa @ref to_cbor(const basic_json& for the related CBOR format @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format @since version 2.0.9 */ static std::vector to_msgpack(const basic_json& j) { std::vector result; to_msgpack(j, result); return result; } static void to_msgpack(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_msgpack(j); } static void to_msgpack(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_msgpack(j); } /*! @brief create a UBJSON serialization of a given JSON value Serializes a given JSON value @a j to a byte vector using the UBJSON (Universal Binary JSON) serialization format. UBJSON aims to be more compact than JSON itself, yet more efficient to parse. The library uses the following mapping from JSON values types to UBJSON types according to the UBJSON specification: JSON value type | value/range | UBJSON type | marker --------------- | --------------------------------- | ----------- | ------ null | `null` | null | `Z` boolean | `true` | true | `T` boolean | `false` | false | `F` number_integer | -9223372036854775808..-2147483649 | int64 | `L` number_integer | -2147483648..-32769 | int32 | `l` number_integer | -32768..-129 | int16 | `I` number_integer | -128..127 | int8 | `i` number_integer | 128..255 | uint8 | `U` number_integer | 256..32767 | int16 | `I` number_integer | 32768..2147483647 | int32 | `l` number_integer | 2147483648..9223372036854775807 | int64 | `L` number_unsigned | 0..127 | int8 | `i` number_unsigned | 128..255 | uint8 | `U` number_unsigned | 256..32767 | int16 | `I` number_unsigned | 32768..2147483647 | int32 | `l` number_unsigned | 2147483648..9223372036854775807 | int64 | `L` number_unsigned | 2147483649..18446744073709551615 | high-precision | `H` number_float | *any value* | float64 | `D` string | *with shortest length indicator* | string | `S` array | *see notes on optimized format* | array | `[` object | *see notes on optimized format* | map | `{` @note The mapping is **complete** in the sense that any JSON value type can be converted to a UBJSON value. @note The following values can **not** be converted to a UBJSON value: - strings with more than 9223372036854775807 bytes (theoretical) @note The following markers are not used in the conversion: - `Z`: no-op values are not created. - `C`: single-byte strings are serialized with `S` markers. @note Any UBJSON output created @ref to_ubjson can be successfully parsed by @ref from_ubjson. @note If NaN or Infinity are stored inside a JSON number, they are serialized properly. This behavior differs from the @ref dump() function which serializes NaN or Infinity to `null`. @note The optimized formats for containers are supported: Parameter @a use_size adds size information to the beginning of a container and removes the closing marker. Parameter @a use_type further checks whether all elements of a container have the same type and adds the type marker to the beginning of the container. The @a use_type parameter must only be used together with @a use_size = true. Note that @a use_size = true alone may result in larger representations - the benefit of this parameter is that the receiving side is immediately informed on the number of elements of the container. @note If the JSON data contains the binary type, the value stored is a list of integers, as suggested by the UBJSON documentation. In particular, this means that serialization and the deserialization of a JSON containing binary values into UBJSON and back will result in a different JSON object. @param[in] j JSON value to serialize @param[in] use_size whether to add size annotations to container types @param[in] use_type whether to add type annotations to container types (must be combined with @a use_size = true) @return UBJSON serialization as byte vector @complexity Linear in the size of the JSON value @a j. @liveexample{The example shows the serialization of a JSON value to a byte vector in UBJSON format.,to_ubjson} @sa http://ubjson.org @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the analogous deserialization @sa @ref to_cbor(const basic_json& for the related CBOR format @sa @ref to_msgpack(const basic_json&) for the related MessagePack format @since version 3.1.0 */ static std::vector to_ubjson(const basic_json& j, const bool use_size = false, const bool use_type = false) { std::vector result; to_ubjson(j, result, use_size, use_type); return result; } static void to_ubjson(const basic_json& j, detail::output_adapter o, const bool use_size = false, const bool use_type = false) { binary_writer(o).write_ubjson(j, use_size, use_type); } static void to_ubjson(const basic_json& j, detail::output_adapter o, const bool use_size = false, const bool use_type = false) { binary_writer(o).write_ubjson(j, use_size, use_type); } /*! @brief Serializes the given JSON object `j` to BSON and returns a vector containing the corresponding BSON-representation. BSON (Binary JSON) is a binary format in which zero or more ordered key/value pairs are stored as a single entity (a so-called document). The library uses the following mapping from JSON values types to BSON types: JSON value type | value/range | BSON type | marker --------------- | --------------------------------- | ----------- | ------ null | `null` | null | 0x0A boolean | `true`, `false` | boolean | 0x08 number_integer | -9223372036854775808..-2147483649 | int64 | 0x12 number_integer | -2147483648..2147483647 | int32 | 0x10 number_integer | 2147483648..9223372036854775807 | int64 | 0x12 number_unsigned | 0..2147483647 | int32 | 0x10 number_unsigned | 2147483648..9223372036854775807 | int64 | 0x12 number_unsigned | 9223372036854775808..18446744073709551615| -- | -- number_float | *any value* | double | 0x01 string | *any value* | string | 0x02 array | *any value* | document | 0x04 object | *any value* | document | 0x03 binary | *any value* | binary | 0x05 @warning The mapping is **incomplete**, since only JSON-objects (and things contained therein) can be serialized to BSON. Also, integers larger than 9223372036854775807 cannot be serialized to BSON, and the keys may not contain U+0000, since they are serialized a zero-terminated c-strings. @throw out_of_range.407 if `j.is_number_unsigned() && j.get() > 9223372036854775807` @throw out_of_range.409 if a key in `j` contains a NULL (U+0000) @throw type_error.317 if `!j.is_object()` @pre The input `j` is required to be an object: `j.is_object() == true`. @note Any BSON output created via @ref to_bson can be successfully parsed by @ref from_bson. @param[in] j JSON value to serialize @return BSON serialization as byte vector @complexity Linear in the size of the JSON value @a j. @liveexample{The example shows the serialization of a JSON value to a byte vector in BSON format.,to_bson} @sa http://bsonspec.org/spec.html @sa @ref from_bson(detail::input_adapter&&, const bool strict) for the analogous deserialization @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the related UBJSON format @sa @ref to_cbor(const basic_json&) for the related CBOR format @sa @ref to_msgpack(const basic_json&) for the related MessagePack format */ static std::vector to_bson(const basic_json& j) { std::vector result; to_bson(j, result); return result; } /*! @brief Serializes the given JSON object `j` to BSON and forwards the corresponding BSON-representation to the given output_adapter `o`. @param j The JSON object to convert to BSON. @param o The output adapter that receives the binary BSON representation. @pre The input `j` shall be an object: `j.is_object() == true` @sa @ref to_bson(const basic_json&) */ static void to_bson(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_bson(j); } /*! @copydoc to_bson(const basic_json&, detail::output_adapter) */ static void to_bson(const basic_json& j, detail::output_adapter o) { binary_writer(o).write_bson(j); } /*! @brief create a JSON value from an input in CBOR format Deserializes a given input @a i to a JSON value using the CBOR (Concise Binary Object Representation) serialization format. The library maps CBOR types to JSON value types as follows: CBOR type | JSON value type | first byte ---------------------- | --------------- | ---------- Integer | number_unsigned | 0x00..0x17 Unsigned integer | number_unsigned | 0x18 Unsigned integer | number_unsigned | 0x19 Unsigned integer | number_unsigned | 0x1A Unsigned integer | number_unsigned | 0x1B Negative integer | number_integer | 0x20..0x37 Negative integer | number_integer | 0x38 Negative integer | number_integer | 0x39 Negative integer | number_integer | 0x3A Negative integer | number_integer | 0x3B Byte string | binary | 0x40..0x57 Byte string | binary | 0x58 Byte string | binary | 0x59 Byte string | binary | 0x5A Byte string | binary | 0x5B UTF-8 string | string | 0x60..0x77 UTF-8 string | string | 0x78 UTF-8 string | string | 0x79 UTF-8 string | string | 0x7A UTF-8 string | string | 0x7B UTF-8 string | string | 0x7F array | array | 0x80..0x97 array | array | 0x98 array | array | 0x99 array | array | 0x9A array | array | 0x9B array | array | 0x9F map | object | 0xA0..0xB7 map | object | 0xB8 map | object | 0xB9 map | object | 0xBA map | object | 0xBB map | object | 0xBF False | `false` | 0xF4 True | `true` | 0xF5 Null | `null` | 0xF6 Half-Precision Float | number_float | 0xF9 Single-Precision Float | number_float | 0xFA Double-Precision Float | number_float | 0xFB @warning The mapping is **incomplete** in the sense that not all CBOR types can be converted to a JSON value. The following CBOR types are not supported and will yield parse errors (parse_error.112): - date/time (0xC0..0xC1) - bignum (0xC2..0xC3) - decimal fraction (0xC4) - bigfloat (0xC5) - expected conversions (0xD5..0xD7) - simple values (0xE0..0xF3, 0xF8) - undefined (0xF7) @warning CBOR allows map keys of any type, whereas JSON only allows strings as keys in object values. Therefore, CBOR maps with keys other than UTF-8 strings are rejected (parse_error.113). @note Any CBOR output created @ref to_cbor can be successfully parsed by @ref from_cbor. @param[in] i an input in CBOR format convertible to an input adapter @param[in] strict whether to expect the input to be consumed until EOF (true by default) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @param[in] tag_handler how to treat CBOR tags (optional, error by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.110 if the given input ends prematurely or the end of file was not reached when @a strict was set to true @throw parse_error.112 if unsupported features from CBOR were used in the given input @a v or if the input is not valid CBOR @throw parse_error.113 if a string was expected as map key, but not found @complexity Linear in the size of the input @a i. @liveexample{The example shows the deserialization of a byte vector in CBOR format to a JSON value.,from_cbor} @sa http://cbor.io @sa @ref to_cbor(const basic_json&) for the analogous serialization @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for the related MessagePack format @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the related UBJSON format @since version 2.0.9; parameter @a start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added @a strict parameter since 3.0.0; added @a allow_exceptions parameter since 3.2.0; added @a tag_handler parameter since 3.9.0. */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_cbor(InputType&& i, const bool strict = true, const bool allow_exceptions = true, const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::forward(i)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler); return res ? result : basic_json(value_t::discarded); } /*! @copydoc from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_cbor(IteratorType first, IteratorType last, const bool strict = true, const bool allow_exceptions = true, const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::move(first), std::move(last)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler); return res ? result : basic_json(value_t::discarded); } template JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len)) static basic_json from_cbor(const T* ptr, std::size_t len, const bool strict = true, const bool allow_exceptions = true, const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error) { return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler); } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len)) static basic_json from_cbor(detail::span_input_adapter&& i, const bool strict = true, const bool allow_exceptions = true, const cbor_tag_handler_t tag_handler = cbor_tag_handler_t::error) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = i.get(); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::cbor, &sdp, strict, tag_handler); return res ? result : basic_json(value_t::discarded); } /*! @brief create a JSON value from an input in MessagePack format Deserializes a given input @a i to a JSON value using the MessagePack serialization format. The library maps MessagePack types to JSON value types as follows: MessagePack type | JSON value type | first byte ---------------- | --------------- | ---------- positive fixint | number_unsigned | 0x00..0x7F fixmap | object | 0x80..0x8F fixarray | array | 0x90..0x9F fixstr | string | 0xA0..0xBF nil | `null` | 0xC0 false | `false` | 0xC2 true | `true` | 0xC3 float 32 | number_float | 0xCA float 64 | number_float | 0xCB uint 8 | number_unsigned | 0xCC uint 16 | number_unsigned | 0xCD uint 32 | number_unsigned | 0xCE uint 64 | number_unsigned | 0xCF int 8 | number_integer | 0xD0 int 16 | number_integer | 0xD1 int 32 | number_integer | 0xD2 int 64 | number_integer | 0xD3 str 8 | string | 0xD9 str 16 | string | 0xDA str 32 | string | 0xDB array 16 | array | 0xDC array 32 | array | 0xDD map 16 | object | 0xDE map 32 | object | 0xDF bin 8 | binary | 0xC4 bin 16 | binary | 0xC5 bin 32 | binary | 0xC6 ext 8 | binary | 0xC7 ext 16 | binary | 0xC8 ext 32 | binary | 0xC9 fixext 1 | binary | 0xD4 fixext 2 | binary | 0xD5 fixext 4 | binary | 0xD6 fixext 8 | binary | 0xD7 fixext 16 | binary | 0xD8 negative fixint | number_integer | 0xE0-0xFF @note Any MessagePack output created @ref to_msgpack can be successfully parsed by @ref from_msgpack. @param[in] i an input in MessagePack format convertible to an input adapter @param[in] strict whether to expect the input to be consumed until EOF (true by default) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.110 if the given input ends prematurely or the end of file was not reached when @a strict was set to true @throw parse_error.112 if unsupported features from MessagePack were used in the given input @a i or if the input is not valid MessagePack @throw parse_error.113 if a string was expected as map key, but not found @complexity Linear in the size of the input @a i. @liveexample{The example shows the deserialization of a byte vector in MessagePack format to a JSON value.,from_msgpack} @sa http://msgpack.org @sa @ref to_msgpack(const basic_json&) for the analogous serialization @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the related UBJSON format @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for the related BSON format @since version 2.0.9; parameter @a start_index since 2.1.1; changed to consume input adapters, removed start_index parameter, and added @a strict parameter since 3.0.0; added @a allow_exceptions parameter since 3.2.0 */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_msgpack(InputType&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::forward(i)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /*! @copydoc from_msgpack(detail::input_adapter&&, const bool, const bool) */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_msgpack(IteratorType first, IteratorType last, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::move(first), std::move(last)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict); return res ? result : basic_json(value_t::discarded); } template JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len)) static basic_json from_msgpack(const T* ptr, std::size_t len, const bool strict = true, const bool allow_exceptions = true) { return from_msgpack(ptr, ptr + len, strict, allow_exceptions); } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len)) static basic_json from_msgpack(detail::span_input_adapter&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = i.get(); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::msgpack, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /*! @brief create a JSON value from an input in UBJSON format Deserializes a given input @a i to a JSON value using the UBJSON (Universal Binary JSON) serialization format. The library maps UBJSON types to JSON value types as follows: UBJSON type | JSON value type | marker ----------- | --------------------------------------- | ------ no-op | *no value, next value is read* | `N` null | `null` | `Z` false | `false` | `F` true | `true` | `T` float32 | number_float | `d` float64 | number_float | `D` uint8 | number_unsigned | `U` int8 | number_integer | `i` int16 | number_integer | `I` int32 | number_integer | `l` int64 | number_integer | `L` high-precision number | number_integer, number_unsigned, or number_float - depends on number string | 'H' string | string | `S` char | string | `C` array | array (optimized values are supported) | `[` object | object (optimized values are supported) | `{` @note The mapping is **complete** in the sense that any UBJSON value can be converted to a JSON value. @param[in] i an input in UBJSON format convertible to an input adapter @param[in] strict whether to expect the input to be consumed until EOF (true by default) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.110 if the given input ends prematurely or the end of file was not reached when @a strict was set to true @throw parse_error.112 if a parse error occurs @throw parse_error.113 if a string could not be parsed successfully @complexity Linear in the size of the input @a i. @liveexample{The example shows the deserialization of a byte vector in UBJSON format to a JSON value.,from_ubjson} @sa http://ubjson.org @sa @ref to_ubjson(const basic_json&, const bool, const bool) for the analogous serialization @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for the related MessagePack format @sa @ref from_bson(detail::input_adapter&&, const bool, const bool) for the related BSON format @since version 3.1.0; added @a allow_exceptions parameter since 3.2.0 */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_ubjson(InputType&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::forward(i)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /*! @copydoc from_ubjson(detail::input_adapter&&, const bool, const bool) */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_ubjson(IteratorType first, IteratorType last, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::move(first), std::move(last)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } template JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len)) static basic_json from_ubjson(const T* ptr, std::size_t len, const bool strict = true, const bool allow_exceptions = true) { return from_ubjson(ptr, ptr + len, strict, allow_exceptions); } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len)) static basic_json from_ubjson(detail::span_input_adapter&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = i.get(); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::ubjson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /*! @brief Create a JSON value from an input in BSON format Deserializes a given input @a i to a JSON value using the BSON (Binary JSON) serialization format. The library maps BSON record types to JSON value types as follows: BSON type | BSON marker byte | JSON value type --------------- | ---------------- | --------------------------- double | 0x01 | number_float string | 0x02 | string document | 0x03 | object array | 0x04 | array binary | 0x05 | binary undefined | 0x06 | still unsupported ObjectId | 0x07 | still unsupported boolean | 0x08 | boolean UTC Date-Time | 0x09 | still unsupported null | 0x0A | null Regular Expr. | 0x0B | still unsupported DB Pointer | 0x0C | still unsupported JavaScript Code | 0x0D | still unsupported Symbol | 0x0E | still unsupported JavaScript Code | 0x0F | still unsupported int32 | 0x10 | number_integer Timestamp | 0x11 | still unsupported 128-bit decimal float | 0x13 | still unsupported Max Key | 0x7F | still unsupported Min Key | 0xFF | still unsupported @warning The mapping is **incomplete**. The unsupported mappings are indicated in the table above. @param[in] i an input in BSON format convertible to an input adapter @param[in] strict whether to expect the input to be consumed until EOF (true by default) @param[in] allow_exceptions whether to throw exceptions in case of a parse error (optional, true by default) @return deserialized JSON value; in case of a parse error and @a allow_exceptions set to `false`, the return value will be value_t::discarded. @throw parse_error.114 if an unsupported BSON record type is encountered @complexity Linear in the size of the input @a i. @liveexample{The example shows the deserialization of a byte vector in BSON format to a JSON value.,from_bson} @sa http://bsonspec.org/spec.html @sa @ref to_bson(const basic_json&) for the analogous serialization @sa @ref from_cbor(detail::input_adapter&&, const bool, const bool, const cbor_tag_handler_t) for the related CBOR format @sa @ref from_msgpack(detail::input_adapter&&, const bool, const bool) for the related MessagePack format @sa @ref from_ubjson(detail::input_adapter&&, const bool, const bool) for the related UBJSON format */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_bson(InputType&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::forward(i)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /*! @copydoc from_bson(detail::input_adapter&&, const bool, const bool) */ template JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json from_bson(IteratorType first, IteratorType last, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = detail::input_adapter(std::move(first), std::move(last)); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } template JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len)) static basic_json from_bson(const T* ptr, std::size_t len, const bool strict = true, const bool allow_exceptions = true) { return from_bson(ptr, ptr + len, strict, allow_exceptions); } JSON_HEDLEY_WARN_UNUSED_RESULT JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len)) static basic_json from_bson(detail::span_input_adapter&& i, const bool strict = true, const bool allow_exceptions = true) { basic_json result; detail::json_sax_dom_parser sdp(result, allow_exceptions); auto ia = i.get(); const bool res = binary_reader(std::move(ia)).sax_parse(input_format_t::bson, &sdp, strict); return res ? result : basic_json(value_t::discarded); } /// @} ////////////////////////// // JSON Pointer support // ////////////////////////// /// @name JSON Pointer functions /// @{ /*! @brief access specified element via JSON Pointer Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. Similar to @ref operator[](const typename object_t::key_type&), `null` values are created in arrays and objects if necessary. In particular: - If the JSON pointer points to an object key that does not exist, it is created an filled with a `null` value before a reference to it is returned. - If the JSON pointer points to an array index that does not exist, it is created an filled with a `null` value before a reference to it is returned. All indices between the current maximum and the given index are also filled with `null`. - The special value `-` is treated as a synonym for the index past the end. @param[in] ptr a JSON pointer @return reference to the element pointed to by @a ptr @complexity Constant. @throw parse_error.106 if an array index begins with '0' @throw parse_error.109 if an array index was not a number @throw out_of_range.404 if the JSON pointer can not be resolved @liveexample{The behavior is shown in the example.,operatorjson_pointer} @since version 2.0.0 */ reference operator[](const json_pointer& ptr) { return ptr.get_unchecked(this); } /*! @brief access specified element via JSON Pointer Uses a JSON pointer to retrieve a reference to the respective JSON value. No bound checking is performed. The function does not change the JSON value; no `null` values are created. In particular, the special value `-` yields an exception. @param[in] ptr JSON pointer to the desired element @return const reference to the element pointed to by @a ptr @complexity Constant. @throw parse_error.106 if an array index begins with '0' @throw parse_error.109 if an array index was not a number @throw out_of_range.402 if the array index '-' is used @throw out_of_range.404 if the JSON pointer can not be resolved @liveexample{The behavior is shown in the example.,operatorjson_pointer_const} @since version 2.0.0 */ const_reference operator[](const json_pointer& ptr) const { return ptr.get_unchecked(this); } /*! @brief access specified element via JSON Pointer Returns a reference to the element at with specified JSON pointer @a ptr, with bounds checking. @param[in] ptr JSON pointer to the desired element @return reference to the element pointed to by @a ptr @throw parse_error.106 if an array index in the passed JSON pointer @a ptr begins with '0'. See example below. @throw parse_error.109 if an array index in the passed JSON pointer @a ptr is not a number. See example below. @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr is out of range. See example below. @throw out_of_range.402 if the array index '-' is used in the passed JSON pointer @a ptr. As `at` provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below. @throw out_of_range.403 if the JSON pointer describes a key of an object which cannot be found. See example below. @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @since version 2.0.0 @liveexample{The behavior is shown in the example.,at_json_pointer} */ reference at(const json_pointer& ptr) { return ptr.get_checked(this); } /*! @brief access specified element via JSON Pointer Returns a const reference to the element at with specified JSON pointer @a ptr, with bounds checking. @param[in] ptr JSON pointer to the desired element @return reference to the element pointed to by @a ptr @throw parse_error.106 if an array index in the passed JSON pointer @a ptr begins with '0'. See example below. @throw parse_error.109 if an array index in the passed JSON pointer @a ptr is not a number. See example below. @throw out_of_range.401 if an array index in the passed JSON pointer @a ptr is out of range. See example below. @throw out_of_range.402 if the array index '-' is used in the passed JSON pointer @a ptr. As `at` provides checked access (and no elements are implicitly inserted), the index '-' is always invalid. See example below. @throw out_of_range.403 if the JSON pointer describes a key of an object which cannot be found. See example below. @throw out_of_range.404 if the JSON pointer @a ptr can not be resolved. See example below. @exceptionsafety Strong guarantee: if an exception is thrown, there are no changes in the JSON value. @complexity Constant. @since version 2.0.0 @liveexample{The behavior is shown in the example.,at_json_pointer_const} */ const_reference at(const json_pointer& ptr) const { return ptr.get_checked(this); } /*! @brief return flattened JSON value The function creates a JSON object whose keys are JSON pointers (see [RFC 6901](https://tools.ietf.org/html/rfc6901)) and whose values are all primitive. The original JSON value can be restored using the @ref unflatten() function. @return an object that maps JSON pointers to primitive values @note Empty objects and arrays are flattened to `null` and will not be reconstructed correctly by the @ref unflatten() function. @complexity Linear in the size the JSON value. @liveexample{The following code shows how a JSON object is flattened to an object whose keys consist of JSON pointers.,flatten} @sa @ref unflatten() for the reverse function @since version 2.0.0 */ basic_json flatten() const { basic_json result(value_t::object); json_pointer::flatten("", *this, result); return result; } /*! @brief unflatten a previously flattened JSON value The function restores the arbitrary nesting of a JSON value that has been flattened before using the @ref flatten() function. The JSON value must meet certain constraints: 1. The value must be an object. 2. The keys must be JSON pointers (see [RFC 6901](https://tools.ietf.org/html/rfc6901)) 3. The mapped values must be primitive JSON types. @return the original JSON from a flattened version @note Empty objects and arrays are flattened by @ref flatten() to `null` values and can not unflattened to their original type. Apart from this example, for a JSON value `j`, the following is always true: `j == j.flatten().unflatten()`. @complexity Linear in the size the JSON value. @throw type_error.314 if value is not an object @throw type_error.315 if object values are not primitive @liveexample{The following code shows how a flattened JSON object is unflattened into the original nested JSON object.,unflatten} @sa @ref flatten() for the reverse function @since version 2.0.0 */ basic_json unflatten() const { return json_pointer::unflatten(*this); } /// @} ////////////////////////// // JSON Patch functions // ////////////////////////// /// @name JSON Patch functions /// @{ /*! @brief applies a JSON patch [JSON Patch](http://jsonpatch.com) defines a JSON document structure for expressing a sequence of operations to apply to a JSON) document. With this function, a JSON Patch is applied to the current JSON value by executing all operations from the patch. @param[in] json_patch JSON patch document @return patched document @note The application of a patch is atomic: Either all operations succeed and the patched document is returned or an exception is thrown. In any case, the original value is not changed: the patch is applied to a copy of the value. @throw parse_error.104 if the JSON patch does not consist of an array of objects @throw parse_error.105 if the JSON patch is malformed (e.g., mandatory attributes are missing); example: `"operation add must have member path"` @throw out_of_range.401 if an array index is out of range. @throw out_of_range.403 if a JSON pointer inside the patch could not be resolved successfully in the current JSON value; example: `"key baz not found"` @throw out_of_range.405 if JSON pointer has no parent ("add", "remove", "move") @throw other_error.501 if "test" operation was unsuccessful @complexity Linear in the size of the JSON value and the length of the JSON patch. As usually only a fraction of the JSON value is affected by the patch, the complexity can usually be neglected. @liveexample{The following code shows how a JSON patch is applied to a value.,patch} @sa @ref diff -- create a JSON patch by comparing two JSON values @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902) @sa [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901) @since version 2.0.0 */ basic_json patch(const basic_json& json_patch) const { // make a working copy to apply the patch to basic_json result = *this; // the valid JSON Patch operations enum class patch_operations {add, remove, replace, move, copy, test, invalid}; const auto get_op = [](const std::string & op) { if (op == "add") { return patch_operations::add; } if (op == "remove") { return patch_operations::remove; } if (op == "replace") { return patch_operations::replace; } if (op == "move") { return patch_operations::move; } if (op == "copy") { return patch_operations::copy; } if (op == "test") { return patch_operations::test; } return patch_operations::invalid; }; // wrapper for "add" operation; add value at ptr const auto operation_add = [&result](json_pointer & ptr, basic_json val) { // adding to the root of the target document means replacing it if (ptr.empty()) { result = val; return; } // make sure the top element of the pointer exists json_pointer top_pointer = ptr.top(); if (top_pointer != ptr) { result.at(top_pointer); } // get reference to parent of JSON pointer ptr const auto last_path = ptr.back(); ptr.pop_back(); basic_json& parent = result[ptr]; switch (parent.m_type) { case value_t::null: case value_t::object: { // use operator[] to add value parent[last_path] = val; break; } case value_t::array: { if (last_path == "-") { // special case: append to back parent.push_back(val); } else { const auto idx = json_pointer::array_index(last_path); if (JSON_HEDLEY_UNLIKELY(idx > parent.size())) { // avoid undefined behavior JSON_THROW(out_of_range::create(401, "array index " + std::to_string(idx) + " is out of range", diagnostics_t(parent))); } // default case: insert add offset parent.insert(parent.begin() + static_cast(idx), val); } break; } // if there exists a parent it cannot be primitive default: // LCOV_EXCL_LINE JSON_ASSERT(false); // LCOV_EXCL_LINE } }; // wrapper for "remove" operation; remove value at ptr const auto operation_remove = [this, &result](json_pointer & ptr) { // get reference to parent of JSON pointer ptr const auto last_path = ptr.back(); ptr.pop_back(); basic_json& parent = result.at(ptr); // remove child if (parent.is_object()) { // perform range check auto it = parent.find(last_path); if (JSON_HEDLEY_LIKELY(it != parent.end())) { parent.erase(it); } else { JSON_THROW(out_of_range::create(403, "key '" + last_path + "' not found", diagnostics_t(*this))); } } else if (parent.is_array()) { // note erase performs range check parent.erase(json_pointer::array_index(last_path)); } }; // type check: top level value must be an array if (JSON_HEDLEY_UNLIKELY(!json_patch.is_array())) { JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects", diagnostics_t(json_patch))); } // iterate and apply the operations for (const auto& val : json_patch) { // wrapper to get a value for an operation const auto get_value = [&val](const std::string & op, const std::string & member, bool string_type) -> basic_json & { // find value auto it = val.m_value.object->find(member); // context-sensitive error message const auto error_msg = (op == "op") ? "operation" : "operation '" + op + "'"; // check if desired value is present if (JSON_HEDLEY_UNLIKELY(it == val.m_value.object->end())) { JSON_THROW(parse_error::create(105, 0, error_msg + " must have member '" + member + "'", diagnostics_t(val))); } // check if result is of type string if (JSON_HEDLEY_UNLIKELY(string_type && !it->second.is_string())) { JSON_THROW(parse_error::create(105, 0, error_msg + " must have string member '" + member + "'", diagnostics_t(val))); } // no error: return value return it->second; }; // type check: every element of the array must be an object if (JSON_HEDLEY_UNLIKELY(!val.is_object())) { JSON_THROW(parse_error::create(104, 0, "JSON patch must be an array of objects", diagnostics_t(val))); } // collect mandatory members const auto op = get_value("op", "op", true).template get(); const auto path = get_value(op, "path", true).template get(); json_pointer ptr(path); switch (get_op(op)) { case patch_operations::add: { operation_add(ptr, get_value("add", "value", false)); break; } case patch_operations::remove: { operation_remove(ptr); break; } case patch_operations::replace: { // the "path" location must exist - use at() result.at(ptr) = get_value("replace", "value", false); break; } case patch_operations::move: { const auto from_path = get_value("move", "from", true).template get(); json_pointer from_ptr(from_path); // the "from" location must exist - use at() basic_json v = result.at(from_ptr); // The move operation is functionally identical to a // "remove" operation on the "from" location, followed // immediately by an "add" operation at the target // location with the value that was just removed. operation_remove(from_ptr); operation_add(ptr, v); break; } case patch_operations::copy: { const auto from_path = get_value("copy", "from", true).template get(); const json_pointer from_ptr(from_path); // the "from" location must exist - use at() basic_json v = result.at(from_ptr); // The copy is functionally identical to an "add" // operation at the target location using the value // specified in the "from" member. operation_add(ptr, v); break; } case patch_operations::test: { bool success = false; JSON_TRY { // check if "value" matches the one at "path" // the "path" location must exist - use at() success = (result.at(ptr) == get_value("test", "value", false)); } JSON_INTERNAL_CATCH (out_of_range&) { // ignore out of range errors: success remains false } // throw an exception if test fails if (JSON_HEDLEY_UNLIKELY(!success)) { JSON_THROW(other_error::create(501, "unsuccessful: " + val.dump(), diagnostics_t(val))); } break; } default: { // op must be "add", "remove", "replace", "move", "copy", or // "test" JSON_THROW(parse_error::create(105, 0, "operation value '" + op + "' is invalid", diagnostics_t(val))); } } } return result; } /*! @brief creates a diff as a JSON patch Creates a [JSON Patch](http://jsonpatch.com) so that value @a source can be changed into the value @a target by calling @ref patch function. @invariant For two JSON values @a source and @a target, the following code yields always `true`: @code {.cpp} source.patch(diff(source, target)) == target; @endcode @note Currently, only `remove`, `add`, and `replace` operations are generated. @param[in] source JSON value to compare from @param[in] target JSON value to compare against @param[in] path helper value to create JSON pointers @return a JSON patch to convert the @a source to @a target @complexity Linear in the lengths of @a source and @a target. @liveexample{The following code shows how a JSON patch is created as a diff for two JSON values.,diff} @sa @ref patch -- apply a JSON patch @sa @ref merge_patch -- apply a JSON Merge Patch @sa [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902) @since version 2.0.0 */ JSON_HEDLEY_WARN_UNUSED_RESULT static basic_json diff(const basic_json& source, const basic_json& target, const std::string& path = "") { // the patch basic_json result(value_t::array); // if the values are the same, return empty patch if (source == target) { return result; } if (source.type() != target.type()) { // different types: replace value result.push_back( { {"op", "replace"}, {"path", path}, {"value", target} }); return result; } switch (source.type()) { case value_t::array: { // first pass: traverse common elements std::size_t i = 0; while (i < source.size() && i < target.size()) { // recursive call to compare array values at index i auto temp_diff = diff(source[i], target[i], path + "/" + std::to_string(i)); result.insert(result.end(), temp_diff.begin(), temp_diff.end()); ++i; } // i now reached the end of at least one array // in a second pass, traverse the remaining elements // remove my remaining elements const auto end_index = static_cast(result.size()); while (i < source.size()) { // add operations in reverse order to avoid invalid // indices result.insert(result.begin() + end_index, object( { {"op", "remove"}, {"path", path + "/" + std::to_string(i)} })); ++i; } // add other remaining elements while (i < target.size()) { result.push_back( { {"op", "add"}, {"path", path + "/-"}, {"value", target[i]} }); ++i; } break; } case value_t::object: { // first pass: traverse this object's elements for (auto it = source.cbegin(); it != source.cend(); ++it) { // escape the key name to be used in a JSON patch const auto key = json_pointer::escape(it.key()); if (target.find(it.key()) != target.end()) { // recursive call to compare object values at key it auto temp_diff = diff(it.value(), target[it.key()], path + "/" + key); result.insert(result.end(), temp_diff.begin(), temp_diff.end()); } else { // found a key that is not in o -> remove it result.push_back(object( { {"op", "remove"}, {"path", path + "/" + key} })); } } // second pass: traverse other object's elements for (auto it = target.cbegin(); it != target.cend(); ++it) { if (source.find(it.key()) == source.end()) { // found a key that is not in this -> add it const auto key = json_pointer::escape(it.key()); result.push_back( { {"op", "add"}, {"path", path + "/" + key}, {"value", it.value()} }); } } break; } default: { // both primitive type: replace value result.push_back( { {"op", "replace"}, {"path", path}, {"value", target} }); break; } } return result; } /// @} //////////////////////////////// // JSON Merge Patch functions // //////////////////////////////// /// @name JSON Merge Patch functions /// @{ /*! @brief applies a JSON Merge Patch The merge patch format is primarily intended for use with the HTTP PATCH method as a means of describing a set of modifications to a target resource's content. This function applies a merge patch to the current JSON value. The function implements the following algorithm from Section 2 of [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396): ``` define MergePatch(Target, Patch): if Patch is an Object: if Target is not an Object: Target = {} // Ignore the contents and set it to an empty Object for each Name/Value pair in Patch: if Value is null: if Name exists in Target: remove the Name/Value pair from Target else: Target[Name] = MergePatch(Target[Name], Value) return Target else: return Patch ``` Thereby, `Target` is the current object; that is, the patch is applied to the current value. @param[in] apply_patch the patch to apply @complexity Linear in the lengths of @a patch. @liveexample{The following code shows how a JSON Merge Patch is applied to a JSON document.,merge_patch} @sa @ref patch -- apply a JSON patch @sa [RFC 7396 (JSON Merge Patch)](https://tools.ietf.org/html/rfc7396) @since version 3.0.0 */ void merge_patch(const basic_json& apply_patch) { if (apply_patch.is_object()) { if (!is_object()) { *this = object(); } for (auto it = apply_patch.begin(); it != apply_patch.end(); ++it) { if (it.value().is_null()) { erase(it.key()); } else { operator[](it.key()).merge_patch(it.value()); } } } else { *this = apply_patch; } } /// @} }; /*! @brief user-defined to_string function for JSON values This function implements a user-defined to_string for JSON objects. @param[in] j a JSON object @return a std::string object */ NLOHMANN_BASIC_JSON_TPL_DECLARATION std::string to_string(const NLOHMANN_BASIC_JSON_TPL& j) { return j.dump(); } } // namespace nlohmann /////////////////////// // nonmember support // /////////////////////// // specialization of std::swap, and std::hash namespace std { /// hash value for JSON objects template<> struct hash { /*! @brief return a hash value for a JSON object @since version 1.0.0 */ std::size_t operator()(const nlohmann::json& j) const { return nlohmann::detail::hash(j); } }; /// specialization for std::less /// @note: do not remove the space after '<', /// see https://github.com/nlohmann/json/pull/679 template<> struct less<::nlohmann::detail::value_t> { /*! @brief compare two value_t enum values @since version 3.0.0 */ bool operator()(nlohmann::detail::value_t lhs, nlohmann::detail::value_t rhs) const noexcept { return nlohmann::detail::operator<(lhs, rhs); } }; // C++20 prohibit function specialization in the std namespace. #ifndef JSON_HAS_CPP_20 /*! @brief exchanges the values of two JSON objects @since version 1.0.0 */ template<> inline void swap(nlohmann::json& j1, nlohmann::json& j2) noexcept( is_nothrow_move_constructible::value&& is_nothrow_move_assignable::value ) { j1.swap(j2); } #endif } // namespace std /*! @brief user-defined string literal for JSON values This operator implements a user-defined string literal for JSON objects. It can be used by adding `"_json"` to a string literal and returns a JSON object if no parse error occurred. @param[in] s a string representation of a JSON object @param[in] n the length of string @a s @return a JSON object @since version 1.0.0 */ JSON_HEDLEY_NON_NULL(1) inline nlohmann::json operator "" _json(const char* s, std::size_t n) { return nlohmann::json::parse(s, s + n); } /*! @brief user-defined string literal for JSON pointer This operator implements a user-defined string literal for JSON Pointers. It can be used by adding `"_json_pointer"` to a string literal and returns a JSON pointer object if no parse error occurred. @param[in] s a string representation of a JSON Pointer @param[in] n the length of string @a s @return a JSON pointer object @since version 2.0.0 */ JSON_HEDLEY_NON_NULL(1) inline nlohmann::json::json_pointer operator "" _json_pointer(const char* s, std::size_t n) { return nlohmann::json::json_pointer(std::string(s, n)); } #include #endif // INCLUDE_NLOHMANN_JSON_HPP_