From f364f5ac5a4aa17c2af5a2d94d7b7f478e58ac43 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= Date: Mon, 14 Aug 2017 15:06:35 +0200 Subject: [PATCH] add detail/meta.hpp --- Makefile | 4 +- src/detail/meta.hpp | 226 ++++++++++++++++++++++++++++++++++++++++++++ src/json.hpp | 212 +---------------------------------------- 3 files changed, 230 insertions(+), 212 deletions(-) create mode 100644 src/detail/meta.hpp diff --git a/Makefile b/Makefile index 3f1e3337..6600e00b 100644 --- a/Makefile +++ b/Makefile @@ -4,7 +4,9 @@ SRCDIR = src SRCS = ${SRCDIR}/json.hpp \ ${SRCDIR}/json_fwd.hpp \ ${SRCDIR}/detail/macro_scope.hpp \ - ${SRCDIR}/detail/macro_unscope.hpp + ${SRCDIR}/detail/macro_unscope.hpp \ + ${SRCDIR}/detail/meta.hpp + # main target all: diff --git a/src/detail/meta.hpp b/src/detail/meta.hpp new file mode 100644 index 00000000..9a3a97fa --- /dev/null +++ b/src/detail/meta.hpp @@ -0,0 +1,226 @@ +#ifndef NLOHMANN_JSON_DETAIL_META_HPP +#define NLOHMANN_JSON_DETAIL_META_HPP + +#include +#include +#include // add_pointer, conditional, decay, enable_if, false_type, integral_constant, is_arithmetic, is_base_of, is_const, is_constructible, is_convertible, is_default_constructible, is_enum, is_floating_point, is_integral, is_nothrow_move_assignable, is_nothrow_move_constructible, is_pointer, is_reference, is_same, is_scalar, is_signed, remove_const, remove_cv, remove_pointer, remove_reference, true_type, underlying_type +#include + +#include "json_fwd.hpp" +#include "detail/macro_scope.hpp" + +namespace nlohmann +{ +/*! +@brief detail namespace with internal helper functions + +This namespace collects functions that should not be exposed, +implementations of some @ref basic_json methods, and meta-programming helpers. + +@since version 2.1.0 +*/ +namespace detail +{ +///////////// +// helpers // +///////////// + +template struct is_basic_json : std::false_type {}; + +NLOHMANN_BASIC_JSON_TPL_DECLARATION +struct is_basic_json : std::true_type {}; + +// alias templates to reduce boilerplate +template +using enable_if_t = typename std::enable_if::type; + +template +using uncvref_t = typename std::remove_cv::type>::type; + +// implementation of C++14 index_sequence and affiliates +// source: https://stackoverflow.com/a/32223343 +template +struct index_sequence +{ + using type = index_sequence; + using value_type = std::size_t; + static constexpr std::size_t size() noexcept + { + return sizeof...(Ints); + } +}; + +template +struct merge_and_renumber; + +template +struct merge_and_renumber, index_sequence> + : index_sequence < I1..., (sizeof...(I1) + I2)... > {}; + +template +struct make_index_sequence + : merge_and_renumber < typename make_index_sequence < N / 2 >::type, + typename make_index_sequence < N - N / 2 >::type > {}; + +template<> struct make_index_sequence<0> : index_sequence<> {}; +template<> struct make_index_sequence<1> : index_sequence<0> {}; + +template +using index_sequence_for = make_index_sequence; + +/* +Implementation of two C++17 constructs: conjunction, negation. This is needed +to avoid evaluating all the traits in a condition + +For example: not std::is_same::value and has_value_type::value +will not compile when T = void (on MSVC at least). Whereas +conjunction>, has_value_type>::value will +stop evaluating if negation<...>::value == false + +Please note that those constructs must be used with caution, since symbols can +become very long quickly (which can slow down compilation and cause MSVC +internal compiler errors). Only use it when you have to (see example ahead). +*/ +template struct conjunction : std::true_type {}; +template struct conjunction : B1 {}; +template +struct conjunction : std::conditional, B1>::type {}; + +template struct negation : std::integral_constant {}; + +// dispatch utility (taken from ranges-v3) +template struct priority_tag : priority_tag < N - 1 > {}; +template<> struct priority_tag<0> {}; + +//////////////////////// +// has_/is_ functions // +//////////////////////// + +NLOHMANN_JSON_HAS_HELPER(mapped_type); +NLOHMANN_JSON_HAS_HELPER(key_type); +NLOHMANN_JSON_HAS_HELPER(value_type); +NLOHMANN_JSON_HAS_HELPER(iterator); + +template +struct is_compatible_object_type_impl : std::false_type {}; + +template +struct is_compatible_object_type_impl +{ + static constexpr auto value = + std::is_constructible::value and + std::is_constructible::value; +}; + +template +struct is_compatible_object_type +{ + static auto constexpr value = is_compatible_object_type_impl < + conjunction>, + has_mapped_type, + has_key_type>::value, + typename BasicJsonType::object_t, CompatibleObjectType >::value; +}; + +template +struct is_basic_json_nested_type +{ + static auto constexpr value = std::is_same::value or + std::is_same::value or + std::is_same::value or + std::is_same::value; +}; + +template +struct is_compatible_array_type +{ + static auto constexpr value = + conjunction>, + negation>, + negation>, + negation>, + has_value_type, + has_iterator>::value; +}; + +template +struct is_compatible_integer_type_impl : std::false_type {}; + +template +struct is_compatible_integer_type_impl +{ + // is there an assert somewhere on overflows? + using RealLimits = std::numeric_limits; + using CompatibleLimits = std::numeric_limits; + + static constexpr auto value = + std::is_constructible::value and + CompatibleLimits::is_integer and + RealLimits::is_signed == CompatibleLimits::is_signed; +}; + +template +struct is_compatible_integer_type +{ + static constexpr auto value = + is_compatible_integer_type_impl < + std::is_integral::value and + not std::is_same::value, + RealIntegerType, CompatibleNumberIntegerType > ::value; +}; + + +// trait checking if JSONSerializer::from_json(json const&, udt&) exists +template +struct has_from_json +{ + private: + // also check the return type of from_json + template::from_json( + std::declval(), std::declval()))>::value>> + static int detect(U&&); + static void detect(...); + + public: + static constexpr bool value = std::is_integral>()))>::value; +}; + +// This trait checks if JSONSerializer::from_json(json const&) exists +// this overload is used for non-default-constructible user-defined-types +template +struct has_non_default_from_json +{ + private: + template < + typename U, + typename = enable_if_t::from_json(std::declval()))>::value >> + static int detect(U&&); + static void detect(...); + + public: + static constexpr bool value = std::is_integral>()))>::value; +}; + +// This trait checks if BasicJsonType::json_serializer::to_json exists +template +struct has_to_json +{ + private: + template::to_json( + std::declval(), std::declval()))> + static int detect(U&&); + static void detect(...); + + public: + static constexpr bool value = std::is_integral>()))>::value; +}; +} +} + +#endif diff --git a/src/json.hpp b/src/json.hpp index 3555400a..7b37521a 100644 --- a/src/json.hpp +++ b/src/json.hpp @@ -48,12 +48,12 @@ SOFTWARE. #include // locale #include // accumulate #include // stringstream -#include // add_pointer, conditional, decay, enable_if, false_type, integral_constant, is_arithmetic, is_base_of, is_const, is_constructible, is_convertible, is_default_constructible, is_enum, is_floating_point, is_integral, is_nothrow_move_assignable, is_nothrow_move_constructible, is_pointer, is_reference, is_same, is_scalar, is_signed, remove_const, remove_cv, remove_pointer, remove_reference, true_type, underlying_type #include // declval, forward, make_pair, move, pair, swap #include // valarray #include "json_fwd.hpp" #include "detail/macro_scope.hpp" +#include "detail/meta.hpp" /*! @brief namespace for Niels Lohmann @@ -62,14 +62,6 @@ SOFTWARE. */ namespace nlohmann { -/*! -@brief unnamed namespace with internal helper functions - -This namespace collects some functions that could not be defined inside the -@ref basic_json class. - -@since version 2.1.0 -*/ namespace detail { //////////////// @@ -455,79 +447,6 @@ inline bool operator<(const value_t lhs, const value_t rhs) noexcept return l_index < order.size() and r_index < order.size() and order[l_index] < order[r_index]; } - -///////////// -// helpers // -///////////// - -template struct is_basic_json : std::false_type {}; - -NLOHMANN_BASIC_JSON_TPL_DECLARATION -struct is_basic_json : std::true_type {}; - -// alias templates to reduce boilerplate -template -using enable_if_t = typename std::enable_if::type; - -template -using uncvref_t = typename std::remove_cv::type>::type; - -// implementation of C++14 index_sequence and affiliates -// source: https://stackoverflow.com/a/32223343 -template -struct index_sequence -{ - using type = index_sequence; - using value_type = std::size_t; - static constexpr std::size_t size() noexcept - { - return sizeof...(Ints); - } -}; - -template -struct merge_and_renumber; - -template -struct merge_and_renumber, index_sequence> - : index_sequence < I1..., (sizeof...(I1) + I2)... > {}; - -template -struct make_index_sequence - : merge_and_renumber < typename make_index_sequence < N / 2 >::type, - typename make_index_sequence < N - N / 2 >::type > {}; - -template<> struct make_index_sequence<0> : index_sequence<> {}; -template<> struct make_index_sequence<1> : index_sequence<0> {}; - -template -using index_sequence_for = make_index_sequence; - -/* -Implementation of two C++17 constructs: conjunction, negation. This is needed -to avoid evaluating all the traits in a condition - -For example: not std::is_same::value and has_value_type::value -will not compile when T = void (on MSVC at least). Whereas -conjunction>, has_value_type>::value will -stop evaluating if negation<...>::value == false - -Please note that those constructs must be used with caution, since symbols can -become very long quickly (which can slow down compilation and cause MSVC -internal compiler errors). Only use it when you have to (see example ahead). -*/ -template struct conjunction : std::true_type {}; -template struct conjunction : B1 {}; -template -struct conjunction : std::conditional, B1>::type {}; - -template struct negation : std::integral_constant {}; - -// dispatch utility (taken from ranges-v3) -template struct priority_tag : priority_tag < N - 1 > {}; -template<> struct priority_tag<0> {}; - - ////////////////// // constructors // ////////////////// @@ -690,135 +609,6 @@ struct external_constructor } }; - -//////////////////////// -// has_/is_ functions // -//////////////////////// - -NLOHMANN_JSON_HAS_HELPER(mapped_type); -NLOHMANN_JSON_HAS_HELPER(key_type); -NLOHMANN_JSON_HAS_HELPER(value_type); -NLOHMANN_JSON_HAS_HELPER(iterator); - -template -struct is_compatible_object_type_impl : std::false_type {}; - -template -struct is_compatible_object_type_impl -{ - static constexpr auto value = - std::is_constructible::value and - std::is_constructible::value; -}; - -template -struct is_compatible_object_type -{ - static auto constexpr value = is_compatible_object_type_impl < - conjunction>, - has_mapped_type, - has_key_type>::value, - typename BasicJsonType::object_t, CompatibleObjectType >::value; -}; - -template -struct is_basic_json_nested_type -{ - static auto constexpr value = std::is_same::value or - std::is_same::value or - std::is_same::value or - std::is_same::value; -}; - -template -struct is_compatible_array_type -{ - static auto constexpr value = - conjunction>, - negation>, - negation>, - negation>, - has_value_type, - has_iterator>::value; -}; - -template -struct is_compatible_integer_type_impl : std::false_type {}; - -template -struct is_compatible_integer_type_impl -{ - // is there an assert somewhere on overflows? - using RealLimits = std::numeric_limits; - using CompatibleLimits = std::numeric_limits; - - static constexpr auto value = - std::is_constructible::value and - CompatibleLimits::is_integer and - RealLimits::is_signed == CompatibleLimits::is_signed; -}; - -template -struct is_compatible_integer_type -{ - static constexpr auto value = - is_compatible_integer_type_impl < - std::is_integral::value and - not std::is_same::value, - RealIntegerType, CompatibleNumberIntegerType >::value; -}; - - -// trait checking if JSONSerializer::from_json(json const&, udt&) exists -template -struct has_from_json -{ - private: - // also check the return type of from_json - template::from_json( - std::declval(), std::declval()))>::value>> - static int detect(U&&); - static void detect(...); - - public: - static constexpr bool value = std::is_integral>()))>::value; -}; - -// This trait checks if JSONSerializer::from_json(json const&) exists -// this overload is used for non-default-constructible user-defined-types -template -struct has_non_default_from_json -{ - private: - template::from_json(std::declval()))>::value>> - static int detect(U&&); - static void detect(...); - - public: - static constexpr bool value = std::is_integral>()))>::value; -}; - -// This trait checks if BasicJsonType::json_serializer::to_json exists -template -struct has_to_json -{ - private: - template::to_json( - std::declval(), std::declval()))> - static int detect(U&&); - static void detect(...); - - public: - static constexpr bool value = std::is_integral>()))>::value; -}; - - ///////////// // to_json // /////////////