mirror of
https://github.com/nlohmann/json
synced 2024-11-26 22:00:07 +00:00
82 lines
3.0 KiB
C++
82 lines
3.0 KiB
C++
#pragma once
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#include <array> // array
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#include <cstddef> // size_t
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#include <cstdint> // uint8_t
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#include <string> // string
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namespace nlohmann
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{
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namespace detail
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{
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///////////////////////////
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// JSON type enumeration //
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///////////////////////////
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/*!
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@brief the JSON type enumeration
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This enumeration collects the different JSON types. It is internally used to
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distinguish the stored values, and the functions @ref basic_json::is_null(),
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@ref basic_json::is_object(), @ref basic_json::is_array(),
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@ref basic_json::is_string(), @ref basic_json::is_boolean(),
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@ref basic_json::is_number() (with @ref basic_json::is_number_integer(),
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@ref basic_json::is_number_unsigned(), and @ref basic_json::is_number_float()),
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@ref basic_json::is_discarded(), @ref basic_json::is_primitive(), and
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@ref basic_json::is_structured() rely on it.
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@note There are three enumeration entries (number_integer, number_unsigned, and
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number_float), because the library distinguishes these three types for numbers:
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@ref basic_json::number_unsigned_t is used for unsigned integers,
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@ref basic_json::number_integer_t is used for signed integers, and
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@ref basic_json::number_float_t is used for floating-point numbers or to
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approximate integers which do not fit in the limits of their respective type.
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@sa see @ref basic_json::basic_json(const value_t value_type) -- create a JSON
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value with the default value for a given type
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@since version 1.0.0
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*/
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enum class value_t : std::uint8_t
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{
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null, ///< null value
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object, ///< object (unordered set of name/value pairs)
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array, ///< array (ordered collection of values)
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string, ///< string value
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boolean, ///< boolean value
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number_integer, ///< number value (signed integer)
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number_unsigned, ///< number value (unsigned integer)
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number_float, ///< number value (floating-point)
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binary, ///< binary array (ordered collection of bytes)
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discarded ///< discarded by the parser callback function
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};
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/*!
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@brief comparison operator for JSON types
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Returns an ordering that is similar to Python:
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- order: null < boolean < number < object < array < string < binary
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- furthermore, each type is not smaller than itself
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- discarded values are not comparable
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- binary is represented as a b"" string in python and directly comparable to a
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string; however, making a binary array directly comparable with a string would
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be surprising behavior in a JSON file.
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@since version 1.0.0
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*/
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inline bool operator<(const value_t lhs, const value_t rhs) noexcept
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{
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static constexpr std::array<std::uint8_t, 9> order = {{
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0 /* null */, 3 /* object */, 4 /* array */, 5 /* string */,
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1 /* boolean */, 2 /* integer */, 2 /* unsigned */, 2 /* float */,
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6 /* binary */
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}
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};
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const auto l_index = static_cast<std::size_t>(lhs);
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const auto r_index = static_cast<std::size_t>(rhs);
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return l_index < order.size() && r_index < order.size() && order[l_index] < order[r_index];
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}
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} // namespace detail
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} // namespace nlohmann
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