json/include/nlohmann/detail/meta/is_sax.hpp

329 lines
13 KiB
C++

// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.11.2
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#pragma once
#include <cstdint> // size_t
#include <utility> // declval
#include <string> // string
#include <nlohmann/detail/abi_macros.hpp>
#include <nlohmann/detail/meta/detected.hpp>
#include <nlohmann/detail/meta/type_traits.hpp>
NLOHMANN_JSON_NAMESPACE_BEGIN
namespace detail
{
// helper struct to call sax->next_token_start
//(we want this functionality as a type to ease passing it as template argument)
struct sax_call_next_token_start_pos_direct
{
template<typename SAX, typename...Ts>
static auto call(SAX* sax, Ts&& ...ts)
-> decltype(sax->next_token_start(std::forward<Ts>(ts)...))
{
sax->next_token_start(std::forward<Ts>(ts)...);
}
};
// helper struct to call sax->next_token_end
// (we want this functionality as a type to ease passing it as template argument)
struct sax_call_next_token_end_pos_direct
{
template<typename SAX, typename...Ts>
static auto call(SAX* sax, Ts&& ...ts)
-> decltype(sax->next_token_end(std::forward<Ts>(ts)...))
{
sax->next_token_end(std::forward<Ts>(ts)...);
}
};
// dispatch the calls to next_token_start next_token_end
// and drop the calls if the sax parser does not support these methods.
//
// DirectCaller can be set to one of sax_call_next_token_{start,end}_pos_direct to
// determine which method is called
template <typename DirectCaller, typename SAX, typename LexOrPos>
struct sax_call_function
{
// is the parameter a lexer or a byte position
static constexpr bool called_with_byte_pos = std::is_same<LexOrPos, std::size_t>::value;
template<typename SAX2, typename...Ts2>
using call_t = decltype(DirectCaller::call(std::declval<SAX2*>(), std::declval<Ts2>()...));
//the sax parser supports calls with a position
static constexpr bool detected_call_with_byte_pos =
is_detected_exact<void, call_t, SAX, std::size_t>::value;
//the sax parser supports calls with a lexer
static constexpr bool detected_call_with_lex_pos =
!called_with_byte_pos &&
is_detected_exact<void, call_t, SAX, const position_t >::value;
//there either has to be a version accepting a lexer or a position
static constexpr bool valid = detected_call_with_byte_pos || detected_call_with_lex_pos;
//called with byte pos and byte pos is method supported -> pass data on
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
valid &&
detected_call_with_byte_pos
>::type
call(SaxT* sax, std::size_t pos)
{
DirectCaller::call(sax, pos);
}
//the sax parser has no version of the method -> drop call
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
!valid
>::type
call(SaxT* /*unused*/, const LexOrPos& /*unused*/) {}
//called with lex and lex pos method is supported -> call with position from lexer
// the start pos in the lexer is last read char -> chars_read_total-1
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
valid &&
!called_with_byte_pos &&
detected_call_with_lex_pos &&
std::is_same<DirectCaller, sax_call_next_token_start_pos_direct>::value
>::type
call(SaxT* sax, const LexOrPos& lex)
{
JSON_ASSERT(lex.get_position().chars_read_total > 0);
JSON_ASSERT(lex.get_position().chars_read_current_line > 0);
//the lexer has already read the first char of the current element -> fix this
auto pos_copy = lex.get_position();
--pos_copy.chars_read_total;
--pos_copy.chars_read_current_line;
DirectCaller::call(sax, pos_copy);
}
//called with lex and lex pos method is supported -> pass data on
// the one past end pos in the lexer is the current index -> chars_read_total
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
valid &&
!called_with_byte_pos &&
detected_call_with_lex_pos &&
std::is_same<DirectCaller, sax_call_next_token_end_pos_direct>::value
>::type
call(SaxT* sax, const LexOrPos& lex)
{
DirectCaller::call(sax, lex.get_position());
}
// called with lex and only byte pos method is supported -> call with byte position from lexer
// the start pos in the lexer is last read char -> chars_read_total-1
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
valid &&
!called_with_byte_pos &&
!detected_call_with_lex_pos &&
std::is_same<DirectCaller, sax_call_next_token_start_pos_direct>::value
>::type
call(SaxT* sax, const LexOrPos& lex)
{
JSON_ASSERT(lex.get_position().chars_read_total > 0);
DirectCaller::call(sax, lex.get_position().chars_read_total - 1);
}
// called with lex and only byte pos method is supported -> call with byte position from lexer
// the one past end pos in the lexer is the current index -> chars_read_total
template<typename SaxT = SAX>
static typename std::enable_if <
std::is_same<SaxT, SAX>::value &&
valid &&
!called_with_byte_pos &&
!detected_call_with_lex_pos &&
std::is_same<DirectCaller, sax_call_next_token_end_pos_direct>::value
>::type
call(SaxT* sax, const LexOrPos& lex)
{
DirectCaller::call(sax, lex.get_position().chars_read_total);
}
};
//set the element start pos of a sax parser by calling any version of sax->next_token_start (if available)
template<class SAX, class LexOrPos>
void sax_call_next_token_start_pos(SAX* sax, const LexOrPos& lexOrPos)
{
using call_t = sax_call_function<sax_call_next_token_start_pos_direct, SAX, LexOrPos>;
call_t::call(sax, lexOrPos);
}
//set the element end pos of a sax parser by calling any version of sax->next_token_end (if available)
template<class SAX, class LexOrPos>
void sax_call_next_token_end_pos(SAX* sax, const LexOrPos& lexOrPos)
{
using call_t = sax_call_function<sax_call_next_token_end_pos_direct, SAX, LexOrPos>;
call_t::call(sax, lexOrPos);
}
//set the element start end pos of a sax parser by calling any version of
// sax->next_token_start and sax->next_token_end (if available)
template<class SAX, class LexOrPos1, class LexOrPos2>
void sax_call_next_token_start_end_pos(SAX* sax, const LexOrPos1& lexOrPos1, const LexOrPos2& lexOrPos2)
{
sax_call_next_token_start_pos(sax, lexOrPos1);
sax_call_next_token_end_pos(sax, lexOrPos2);
}
//set the element start end pos of a sax parser by calling any version of
// sax->next_token_start and sax->next_token_end (if available)
template<class SAX, class LexOrPos>
void sax_call_next_token_start_end_pos(SAX* sax, const LexOrPos& lexOrPos)
{
sax_call_next_token_start_pos(sax, lexOrPos);
sax_call_next_token_end_pos(sax, lexOrPos);
}
template<typename T>
using null_function_t = decltype(std::declval<T&>().null());
template<typename T>
using boolean_function_t =
decltype(std::declval<T&>().boolean(std::declval<bool>()));
template<typename T, typename Integer>
using number_integer_function_t =
decltype(std::declval<T&>().number_integer(std::declval<Integer>()));
template<typename T, typename Unsigned>
using number_unsigned_function_t =
decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()));
template<typename T, typename Float, typename String>
using number_float_function_t = decltype(std::declval<T&>().number_float(
std::declval<Float>(), std::declval<const String&>()));
template<typename T, typename String>
using string_function_t =
decltype(std::declval<T&>().string(std::declval<String&>()));
template<typename T, typename Binary>
using binary_function_t =
decltype(std::declval<T&>().binary(std::declval<Binary&>()));
template<typename T>
using start_object_function_t =
decltype(std::declval<T&>().start_object(std::declval<std::size_t>()));
template<typename T, typename String>
using key_function_t =
decltype(std::declval<T&>().key(std::declval<String&>()));
template<typename T>
using end_object_function_t = decltype(std::declval<T&>().end_object());
template<typename T>
using start_array_function_t =
decltype(std::declval<T&>().start_array(std::declval<std::size_t>()));
template<typename T>
using end_array_function_t = decltype(std::declval<T&>().end_array());
template<typename T, typename Exception>
using parse_error_function_t = decltype(std::declval<T&>().parse_error(
std::declval<std::size_t>(), std::declval<const std::string&>(),
std::declval<const Exception&>()));
template<typename SAX, typename BasicJsonType>
struct is_sax
{
private:
static_assert(is_basic_json<BasicJsonType>::value,
"BasicJsonType must be of type basic_json<...>");
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
using string_t = typename BasicJsonType::string_t;
using binary_t = typename BasicJsonType::binary_t;
using exception_t = typename BasicJsonType::exception;
public:
static constexpr bool value =
is_detected_exact<bool, null_function_t, SAX>::value &&
is_detected_exact<bool, boolean_function_t, SAX>::value &&
is_detected_exact<bool, number_integer_function_t, SAX, number_integer_t>::value &&
is_detected_exact<bool, number_unsigned_function_t, SAX, number_unsigned_t>::value &&
is_detected_exact<bool, number_float_function_t, SAX, number_float_t, string_t>::value &&
is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
is_detected_exact<bool, binary_function_t, SAX, binary_t>::value &&
is_detected_exact<bool, start_object_function_t, SAX>::value &&
is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
is_detected_exact<bool, end_object_function_t, SAX>::value &&
is_detected_exact<bool, start_array_function_t, SAX>::value &&
is_detected_exact<bool, end_array_function_t, SAX>::value &&
is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
};
template<typename SAX, typename BasicJsonType>
struct is_sax_static_asserts
{
private:
static_assert(is_basic_json<BasicJsonType>::value,
"BasicJsonType must be of type basic_json<...>");
using number_integer_t = typename BasicJsonType::number_integer_t;
using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
using number_float_t = typename BasicJsonType::number_float_t;
using string_t = typename BasicJsonType::string_t;
using binary_t = typename BasicJsonType::binary_t;
using exception_t = typename BasicJsonType::exception;
public:
static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
"Missing/invalid function: bool null()");
static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
"Missing/invalid function: bool boolean(bool)");
static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
"Missing/invalid function: bool boolean(bool)");
static_assert(
is_detected_exact<bool, number_integer_function_t, SAX,
number_integer_t>::value,
"Missing/invalid function: bool number_integer(number_integer_t)");
static_assert(
is_detected_exact<bool, number_unsigned_function_t, SAX,
number_unsigned_t>::value,
"Missing/invalid function: bool number_unsigned(number_unsigned_t)");
static_assert(is_detected_exact<bool, number_float_function_t, SAX,
number_float_t, string_t>::value,
"Missing/invalid function: bool number_float(number_float_t, const string_t&)");
static_assert(
is_detected_exact<bool, string_function_t, SAX, string_t>::value,
"Missing/invalid function: bool string(string_t&)");
static_assert(
is_detected_exact<bool, binary_function_t, SAX, binary_t>::value,
"Missing/invalid function: bool binary(binary_t&)");
static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
"Missing/invalid function: bool start_object(std::size_t)");
static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
"Missing/invalid function: bool key(string_t&)");
static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
"Missing/invalid function: bool end_object()");
static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
"Missing/invalid function: bool start_array(std::size_t)");
static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
"Missing/invalid function: bool end_array()");
static_assert(
is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
"Missing/invalid function: bool parse_error(std::size_t, const "
"std::string&, const exception&)");
};
} // namespace detail
NLOHMANN_JSON_NAMESPACE_END