mirror of
https://github.com/nlohmann/json
synced 2024-12-02 08:20:11 +00:00
440 lines
14 KiB
C++
440 lines
14 KiB
C++
#pragma once
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#include <array> // array
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#include <cassert> // assert
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#include <cstddef> // size_t
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#include <cstdio> //FILE *
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#include <cstring> // strlen
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#include <istream> // istream
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#include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next
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#include <memory> // shared_ptr, make_shared, addressof
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#include <numeric> // accumulate
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#include <string> // string, char_traits
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#include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
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#include <utility> // pair, declval
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#include <nlohmann/detail/iterators/iterator_traits.hpp>
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#include <nlohmann/detail/macro_scope.hpp>
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namespace nlohmann
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{
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namespace detail
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{
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/// the supported input formats
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enum class input_format_t { json, cbor, msgpack, ubjson, bson };
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////////////////////
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// input adapters //
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////////////////////
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/*!
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Input adapter for stdio file access. This adapter read only 1 byte and do not use any
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buffer. This adapter is a very low level adapter.
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*/
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class file_input_adapter
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{
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public:
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using char_type = char;
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JSON_HEDLEY_NON_NULL(2)
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explicit file_input_adapter(std::FILE* f) noexcept
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: m_file(f)
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{}
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// make class move-only
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file_input_adapter(const file_input_adapter&) = delete;
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file_input_adapter(file_input_adapter&&) = default;
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file_input_adapter& operator=(const file_input_adapter&) = delete;
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file_input_adapter& operator=(file_input_adapter&&) = delete;
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std::char_traits<char>::int_type get_character() noexcept
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{
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return std::fgetc(m_file);
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}
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private:
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/// the file pointer to read from
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std::FILE* m_file;
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};
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/*!
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Input adapter for a (caching) istream. Ignores a UFT Byte Order Mark at
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beginning of input. Does not support changing the underlying std::streambuf
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in mid-input. Maintains underlying std::istream and std::streambuf to support
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subsequent use of standard std::istream operations to process any input
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characters following those used in parsing the JSON input. Clears the
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std::istream flags; any input errors (e.g., EOF) will be detected by the first
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subsequent call for input from the std::istream.
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*/
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class input_stream_adapter
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{
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public:
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using char_type = char;
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~input_stream_adapter()
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{
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// clear stream flags; we use underlying streambuf I/O, do not
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// maintain ifstream flags, except eof
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if (is)
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{
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is->clear(is->rdstate() & std::ios::eofbit);
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}
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}
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explicit input_stream_adapter(std::istream& i)
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: is(&i), sb(i.rdbuf())
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{}
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// delete because of pointer members
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input_stream_adapter(const input_stream_adapter&) = delete;
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input_stream_adapter& operator=(input_stream_adapter&) = delete;
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input_stream_adapter& operator=(input_stream_adapter&& rhs) = delete;
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input_stream_adapter(input_stream_adapter&& rhs) : is(rhs.is), sb(rhs.sb)
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{
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rhs.is = nullptr;
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rhs.sb = nullptr;
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}
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// std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
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// ensure that std::char_traits<char>::eof() and the character 0xFF do not
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// end up as the same value, eg. 0xFFFFFFFF.
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std::char_traits<char>::int_type get_character()
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{
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auto res = sb->sbumpc();
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// set eof manually, as we don't use the istream interface.
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if (res == EOF)
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{
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is->clear(is->rdstate() | std::ios::eofbit);
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}
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return res;
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}
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private:
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/// the associated input stream
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std::istream* is = nullptr;
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std::streambuf* sb = nullptr;
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};
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// General-purpose iterator-based adapter. It might not be as fast as
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// theoretically possible for some containers, but it is extremely versatile.
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template<typename IteratorType>
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class iterator_input_adapter
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{
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public:
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using char_type = typename std::iterator_traits<IteratorType>::value_type;
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iterator_input_adapter(IteratorType first, IteratorType last)
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: current(std::move(first)), end(std::move(last)) {}
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typename std::char_traits<char_type>::int_type get_character()
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{
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if (current != end)
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{
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auto result = std::char_traits<char_type>::to_int_type(*current);
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std::advance(current, 1);
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return result;
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}
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else
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{
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return std::char_traits<char_type>::eof();
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}
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}
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private:
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IteratorType current;
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IteratorType end;
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template<typename BaseInputAdapter, size_t T>
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friend class wide_string_input_helper;
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bool empty() const
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{
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return current == end;
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}
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};
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template<typename BaseInputAdapter, size_t T>
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struct wide_string_input_helper;
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template<typename BaseInputAdapter>
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struct wide_string_input_helper<BaseInputAdapter, 4>
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{
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// UTF-32
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static void fill_buffer(BaseInputAdapter& input,
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std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
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size_t& utf8_bytes_index,
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size_t& utf8_bytes_filled)
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{
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utf8_bytes_index = 0;
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if (input.empty())
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{
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utf8_bytes[0] = std::char_traits<char>::eof();
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utf8_bytes_filled = 1;
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}
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else
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{
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// get the current character
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const auto wc = input.get_character();
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// UTF-32 to UTF-8 encoding
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if (wc < 0x80)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
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utf8_bytes_filled = 1;
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}
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else if (wc <= 0x7FF)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((wc >> 6u) & 0x1Fu));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
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utf8_bytes_filled = 2;
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}
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else if (wc <= 0xFFFF)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((wc >> 12u) & 0x0Fu));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
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utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
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utf8_bytes_filled = 3;
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}
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else if (wc <= 0x10FFFF)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | ((wc >> 18u) & 0x07u));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 12u) & 0x3Fu));
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utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
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utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
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utf8_bytes_filled = 4;
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}
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else
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{
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// unknown character
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
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utf8_bytes_filled = 1;
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}
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}
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}
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};
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template<typename BaseInputAdapter>
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struct wide_string_input_helper<BaseInputAdapter, 2>
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{
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// UTF-16
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static void fill_buffer(BaseInputAdapter& input,
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std::array<std::char_traits<char>::int_type, 4>& utf8_bytes,
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size_t& utf8_bytes_index,
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size_t& utf8_bytes_filled)
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{
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utf8_bytes_index = 0;
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if (input.empty())
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{
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utf8_bytes[0] = std::char_traits<char>::eof();
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utf8_bytes_filled = 1;
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}
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else
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{
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// get the current character
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const auto wc = input.get_character();
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// UTF-16 to UTF-8 encoding
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if (wc < 0x80)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
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utf8_bytes_filled = 1;
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}
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else if (wc <= 0x7FF)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xC0u | ((wc >> 6u)));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
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utf8_bytes_filled = 2;
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}
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else if (0xD800 > wc or wc >= 0xE000)
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xE0u | ((wc >> 12u)));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((wc >> 6u) & 0x3Fu));
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utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | (wc & 0x3Fu));
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utf8_bytes_filled = 3;
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}
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else
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{
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if (!input.empty())
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{
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const auto wc2 = static_cast<unsigned int>(input.get_character());
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const auto charcode = 0x10000u + (((wc & 0x3FFu) << 10u) | (wc2 & 0x3FFu));
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(0xF0u | (charcode >> 18u));
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utf8_bytes[1] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 12u) & 0x3Fu));
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utf8_bytes[2] = static_cast<std::char_traits<char>::int_type>(0x80u | ((charcode >> 6u) & 0x3Fu));
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utf8_bytes[3] = static_cast<std::char_traits<char>::int_type>(0x80u | (charcode & 0x3Fu));
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utf8_bytes_filled = 4;
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}
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else
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{
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utf8_bytes[0] = static_cast<std::char_traits<char>::int_type>(wc);
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utf8_bytes_filled = 1;
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}
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}
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}
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}
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};
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// Wraps another input apdater to convert wide character types into individual bytes.
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template<typename BaseInputAdapter, typename WideCharType>
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class wide_string_input_adapter
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{
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public:
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wide_string_input_adapter(BaseInputAdapter base)
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: base_adapter(base) {}
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typename std::char_traits<char>::int_type get_character() noexcept
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{
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// check if buffer needs to be filled
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if (utf8_bytes_index == utf8_bytes_filled)
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{
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fill_buffer<sizeof(WideCharType)>();
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assert(utf8_bytes_filled > 0);
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assert(utf8_bytes_index == 0);
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}
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// use buffer
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assert(utf8_bytes_filled > 0);
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assert(utf8_bytes_index < utf8_bytes_filled);
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return utf8_bytes[utf8_bytes_index++];
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}
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private:
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BaseInputAdapter base_adapter;
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template<size_t T>
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void fill_buffer()
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{
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wide_string_input_helper<BaseInputAdapter, T>::fill_buffer(base_adapter, utf8_bytes, utf8_bytes_index, utf8_bytes_filled);
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}
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/// a buffer for UTF-8 bytes
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std::array<std::char_traits<char>::int_type, 4> utf8_bytes = {{0, 0, 0, 0}};
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/// index to the utf8_codes array for the next valid byte
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std::size_t utf8_bytes_index = 0;
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/// number of valid bytes in the utf8_codes array
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std::size_t utf8_bytes_filled = 0;
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};
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template<typename IteratorType, typename Enable = void>
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struct iterator_input_adapter_factory
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{
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using iterator_type = IteratorType;
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using char_type = typename std::iterator_traits<iterator_type>::value_type;
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using adapter_type = iterator_input_adapter<iterator_type>;
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static adapter_type create(IteratorType begin, IteratorType end)
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{
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return adapter_type(std::move(begin), std::move(end));
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}
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};
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template<typename IteratorType>
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struct iterator_input_adapter_factory<IteratorType,
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typename std::enable_if<(sizeof(typename std::iterator_traits<IteratorType>::value_type)>1)>::type >
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{
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using iterator_type = IteratorType;
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using char_type = typename std::iterator_traits<iterator_type>::value_type;
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using base_adapter_type = iterator_input_adapter<iterator_type>;
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using adapter_type = wide_string_input_adapter<base_adapter_type, char_type>;
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static adapter_type create(IteratorType begin, IteratorType end)
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{
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return adapter_type(base_adapter_type(std::move(begin), std::move(end)));
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}
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};
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// General purpose iterator-based input
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template<typename IteratorType>
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typename iterator_input_adapter_factory<IteratorType>::adapter_type input_adapter(IteratorType begin, IteratorType end)
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{
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using factory_type = iterator_input_adapter_factory<IteratorType>;
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return factory_type::create(begin, end);
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}
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// Convenience shorthand from container to iterator
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template<typename ContainerType>
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auto input_adapter(const ContainerType& container) -> decltype(input_adapter(begin(container), end(container)))
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{
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// Enable ADL
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using std::begin;
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using std::end;
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return input_adapter(begin(container), end(container));
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}
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// Special cases with fast paths
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inline file_input_adapter input_adapter(std::FILE* file)
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{
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return file_input_adapter(file);
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}
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inline input_stream_adapter input_adapter(std::istream& stream)
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{
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return input_stream_adapter(stream);
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}
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inline input_stream_adapter input_adapter(std::istream&& stream)
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{
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return input_stream_adapter(stream);
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}
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using contiguous_bytes_input_adapter = decltype(input_adapter(std::declval<const char*>(), std::declval<const char*>()));
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// Null-delimited strings, and the like.
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template<typename CharT,
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typename std::enable_if<
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std::is_pointer<CharT>::value and
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std::is_integral<typename std::remove_pointer<CharT>::type>::value and
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sizeof(typename std::remove_pointer<CharT>::type) == 1,
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int>::type = 0>
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contiguous_bytes_input_adapter input_adapter(CharT b)
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{
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auto length = std::strlen(reinterpret_cast<const char*>(b));
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auto ptr = reinterpret_cast<const char*>(b);
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return input_adapter(ptr, ptr + length);
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}
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// This class only handles inputs of input_buffer_adapter type.
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// It's required so that expressions like {ptr, len} can be implicitely casted
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// to the correct adapter.
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class span_input_adapter
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{
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public:
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template<typename CharT,
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typename std::enable_if<
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std::is_pointer<CharT>::value and
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std::is_integral<typename std::remove_pointer<CharT>::type>::value and
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sizeof(typename std::remove_pointer<CharT>::type) == 1,
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int>::type = 0>
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span_input_adapter(CharT b, std::size_t l)
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: ia(reinterpret_cast<const char*>(b), reinterpret_cast<const char*>(b) + l) {}
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template<class IteratorType,
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typename std::enable_if<
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std::is_same<typename iterator_traits<IteratorType>::iterator_category, std::random_access_iterator_tag>::value,
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int>::type = 0>
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span_input_adapter(IteratorType first, IteratorType last)
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: ia(input_adapter(first, last)) {}
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contiguous_bytes_input_adapter&& get()
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{
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return std::move(ia);
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}
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private:
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contiguous_bytes_input_adapter ia;
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};
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} // namespace detail
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} // namespace nlohmann
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