mirror of
https://github.com/nlohmann/json.git
synced 2024-12-16 23:17:49 +08:00
319 lines
11 KiB
C++
319 lines
11 KiB
C++
#ifndef NLOHMANN_JSON_DETAIL_CONVERSIONS_FROM_JSON_HPP
|
|
#define NLOHMANN_JSON_DETAIL_CONVERSIONS_FROM_JSON_HPP
|
|
|
|
#include <algorithm> // transform
|
|
#include <array> // array
|
|
#include <ciso646> // and, not
|
|
#include <forward_list> // forward_list
|
|
#include <iterator> // inserter, front_inserter, end
|
|
#include <string> // string
|
|
#include <tuple> // tuple, make_tuple
|
|
#include <type_traits> // is_arithmetic, is_same, is_enum, underlying_type, is_convertible
|
|
#include <utility> // pair, declval
|
|
#include <valarray> // valarray
|
|
|
|
#include "detail/exceptions.hpp"
|
|
#include "detail/macro_scope.hpp"
|
|
#include "detail/meta.hpp"
|
|
#include "detail/value_t.hpp"
|
|
|
|
namespace nlohmann
|
|
{
|
|
namespace detail
|
|
{
|
|
// overloads for basic_json template parameters
|
|
template<typename BasicJsonType, typename ArithmeticType,
|
|
enable_if_t<std::is_arithmetic<ArithmeticType>::value and
|
|
not std::is_same<ArithmeticType, typename BasicJsonType::boolean_t>::value,
|
|
int> = 0>
|
|
void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val)
|
|
{
|
|
switch (static_cast<value_t>(j))
|
|
{
|
|
case value_t::number_unsigned:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
|
|
break;
|
|
}
|
|
case value_t::number_integer:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
|
|
break;
|
|
}
|
|
case value_t::number_float:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_float_t*>());
|
|
break;
|
|
}
|
|
|
|
default:
|
|
JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name())));
|
|
}
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::boolean_t& b)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_boolean()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be boolean, but is " + std::string(j.type_name())));
|
|
}
|
|
b = *j.template get_ptr<const typename BasicJsonType::boolean_t*>();
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::string_t& s)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_string()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be string, but is " + std::string(j.type_name())));
|
|
}
|
|
s = *j.template get_ptr<const typename BasicJsonType::string_t*>();
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val)
|
|
{
|
|
get_arithmetic_value(j, val);
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val)
|
|
{
|
|
get_arithmetic_value(j, val);
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t& val)
|
|
{
|
|
get_arithmetic_value(j, val);
|
|
}
|
|
|
|
template<typename BasicJsonType, typename EnumType,
|
|
enable_if_t<std::is_enum<EnumType>::value, int> = 0>
|
|
void from_json(const BasicJsonType& j, EnumType& e)
|
|
{
|
|
typename std::underlying_type<EnumType>::type val;
|
|
get_arithmetic_value(j, val);
|
|
e = static_cast<EnumType>(val);
|
|
}
|
|
|
|
template<typename BasicJsonType>
|
|
void from_json(const BasicJsonType& j, typename BasicJsonType::array_t& arr)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_array()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
|
|
}
|
|
arr = *j.template get_ptr<const typename BasicJsonType::array_t*>();
|
|
}
|
|
|
|
// forward_list doesn't have an insert method
|
|
template<typename BasicJsonType, typename T, typename Allocator,
|
|
enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
|
|
void from_json(const BasicJsonType& j, std::forward_list<T, Allocator>& l)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_array()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
|
|
}
|
|
std::transform(j.rbegin(), j.rend(),
|
|
std::front_inserter(l), [](const BasicJsonType & i)
|
|
{
|
|
return i.template get<T>();
|
|
});
|
|
}
|
|
|
|
// valarray doesn't have an insert method
|
|
template<typename BasicJsonType, typename T,
|
|
enable_if_t<std::is_convertible<BasicJsonType, T>::value, int> = 0>
|
|
void from_json(const BasicJsonType& j, std::valarray<T>& l)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_array()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
|
|
}
|
|
l.resize(j.size());
|
|
std::copy(j.m_value.array->begin(), j.m_value.array->end(), std::begin(l));
|
|
}
|
|
|
|
template<typename BasicJsonType, typename CompatibleArrayType>
|
|
void from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<0> /*unused*/)
|
|
{
|
|
using std::end;
|
|
|
|
std::transform(j.begin(), j.end(),
|
|
std::inserter(arr, end(arr)), [](const BasicJsonType & i)
|
|
{
|
|
// get<BasicJsonType>() returns *this, this won't call a from_json
|
|
// method when value_type is BasicJsonType
|
|
return i.template get<typename CompatibleArrayType::value_type>();
|
|
});
|
|
}
|
|
|
|
template<typename BasicJsonType, typename CompatibleArrayType>
|
|
auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<1> /*unused*/)
|
|
-> decltype(
|
|
arr.reserve(std::declval<typename CompatibleArrayType::size_type>()),
|
|
void())
|
|
{
|
|
using std::end;
|
|
|
|
arr.reserve(j.size());
|
|
std::transform(j.begin(), j.end(),
|
|
std::inserter(arr, end(arr)), [](const BasicJsonType & i)
|
|
{
|
|
// get<BasicJsonType>() returns *this, this won't call a from_json
|
|
// method when value_type is BasicJsonType
|
|
return i.template get<typename CompatibleArrayType::value_type>();
|
|
});
|
|
}
|
|
|
|
template<typename BasicJsonType, typename T, std::size_t N>
|
|
void from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr, priority_tag<2> /*unused*/)
|
|
{
|
|
for (std::size_t i = 0; i < N; ++i)
|
|
{
|
|
arr[i] = j.at(i).template get<T>();
|
|
}
|
|
}
|
|
|
|
template<typename BasicJsonType, typename CompatibleArrayType,
|
|
enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
|
|
std::is_convertible<BasicJsonType, typename CompatibleArrayType::value_type>::value and
|
|
not std::is_same<typename BasicJsonType::array_t, CompatibleArrayType>::value, int> = 0>
|
|
void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_array()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be array, but is " + std::string(j.type_name())));
|
|
}
|
|
|
|
from_json_array_impl(j, arr, priority_tag<2> {});
|
|
}
|
|
|
|
template<typename BasicJsonType, typename CompatibleObjectType,
|
|
enable_if_t<is_compatible_object_type<BasicJsonType, CompatibleObjectType>::value, int> = 0>
|
|
void from_json(const BasicJsonType& j, CompatibleObjectType& obj)
|
|
{
|
|
if (JSON_UNLIKELY(not j.is_object()))
|
|
{
|
|
JSON_THROW(type_error::create(302, "type must be object, but is " + std::string(j.type_name())));
|
|
}
|
|
|
|
auto inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
|
|
using value_type = typename CompatibleObjectType::value_type;
|
|
std::transform(
|
|
inner_object->begin(), inner_object->end(),
|
|
std::inserter(obj, obj.begin()),
|
|
[](typename BasicJsonType::object_t::value_type const & p)
|
|
{
|
|
return value_type(p.first, p.second.template get<typename CompatibleObjectType::mapped_type>());
|
|
});
|
|
}
|
|
|
|
// overload for arithmetic types, not chosen for basic_json template arguments
|
|
// (BooleanType, etc..); note: Is it really necessary to provide explicit
|
|
// overloads for boolean_t etc. in case of a custom BooleanType which is not
|
|
// an arithmetic type?
|
|
template<typename BasicJsonType, typename ArithmeticType,
|
|
enable_if_t <
|
|
std::is_arithmetic<ArithmeticType>::value and
|
|
not std::is_same<ArithmeticType, typename BasicJsonType::number_unsigned_t>::value and
|
|
not std::is_same<ArithmeticType, typename BasicJsonType::number_integer_t>::value and
|
|
not std::is_same<ArithmeticType, typename BasicJsonType::number_float_t>::value and
|
|
not std::is_same<ArithmeticType, typename BasicJsonType::boolean_t>::value,
|
|
int> = 0>
|
|
void from_json(const BasicJsonType& j, ArithmeticType& val)
|
|
{
|
|
switch (static_cast<value_t>(j))
|
|
{
|
|
case value_t::number_unsigned:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_unsigned_t*>());
|
|
break;
|
|
}
|
|
case value_t::number_integer:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_integer_t*>());
|
|
break;
|
|
}
|
|
case value_t::number_float:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::number_float_t*>());
|
|
break;
|
|
}
|
|
case value_t::boolean:
|
|
{
|
|
val = static_cast<ArithmeticType>(*j.template get_ptr<const typename BasicJsonType::boolean_t*>());
|
|
break;
|
|
}
|
|
|
|
default:
|
|
JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name())));
|
|
}
|
|
}
|
|
|
|
template<typename BasicJsonType, typename A1, typename A2>
|
|
void from_json(const BasicJsonType& j, std::pair<A1, A2>& p)
|
|
{
|
|
p = {j.at(0).template get<A1>(), j.at(1).template get<A2>()};
|
|
}
|
|
|
|
template<typename BasicJsonType, typename Tuple, std::size_t... Idx>
|
|
void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence<Idx...>)
|
|
{
|
|
t = std::make_tuple(j.at(Idx).template get<typename std::tuple_element<Idx, Tuple>::type>()...);
|
|
}
|
|
|
|
template<typename BasicJsonType, typename... Args>
|
|
void from_json(const BasicJsonType& j, std::tuple<Args...>& t)
|
|
{
|
|
from_json_tuple_impl(j, t, index_sequence_for<Args...> {});
|
|
}
|
|
|
|
struct from_json_fn
|
|
{
|
|
private:
|
|
template<typename BasicJsonType, typename T>
|
|
auto call(const BasicJsonType& j, T& val, priority_tag<1> /*unused*/) const
|
|
noexcept(noexcept(from_json(j, val)))
|
|
-> decltype(from_json(j, val), void())
|
|
{
|
|
return from_json(j, val);
|
|
}
|
|
|
|
template<typename BasicJsonType, typename T>
|
|
void call(const BasicJsonType& /*unused*/, T& /*unused*/, priority_tag<0> /*unused*/) const noexcept
|
|
{
|
|
static_assert(sizeof(BasicJsonType) == 0,
|
|
"could not find from_json() method in T's namespace");
|
|
#ifdef _MSC_VER
|
|
// MSVC does not show a stacktrace for the above assert
|
|
using decayed = uncvref_t<T>;
|
|
static_assert(sizeof(typename decayed::force_msvc_stacktrace) == 0,
|
|
"forcing MSVC stacktrace to show which T we're talking about.");
|
|
#endif
|
|
}
|
|
|
|
public:
|
|
template<typename BasicJsonType, typename T>
|
|
void operator()(const BasicJsonType& j, T& val) const
|
|
noexcept(noexcept(std::declval<from_json_fn>().call(j, val, priority_tag<1> {})))
|
|
{
|
|
return call(j, val, priority_tag<1> {});
|
|
}
|
|
};
|
|
}
|
|
|
|
/// namespace to hold default `from_json` function
|
|
/// to see why this is required:
|
|
/// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4381.html
|
|
namespace
|
|
{
|
|
constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::value;
|
|
}
|
|
}
|
|
|
|
#endif
|