From e0c02c14f0106037c526ae52d594fdbd7627d0ce Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= Date: Mon, 14 Aug 2017 16:33:55 +0200 Subject: [PATCH] add detail/conversions/from_json.hpp --- Makefile | 4 +- src/detail/conversions/from_json.hpp | 316 +++++++++++++++++++++++++++ src/detail/meta.hpp | 10 + src/json.hpp | 302 +------------------------ 4 files changed, 331 insertions(+), 301 deletions(-) create mode 100644 src/detail/conversions/from_json.hpp diff --git a/Makefile b/Makefile index f10899f5..22df2ff2 100644 --- a/Makefile +++ b/Makefile @@ -7,7 +7,9 @@ SRCS = ${SRCDIR}/json.hpp \ ${SRCDIR}/detail/macro_unscope.hpp \ ${SRCDIR}/detail/meta.hpp \ ${SRCDIR}/detail/exceptions.hpp \ - ${SRCDIR}/detail/value_t.hpp + ${SRCDIR}/detail/value_t.hpp \ + ${SRCDIR}/detail/conversions/from_json.hpp + diff --git a/src/detail/conversions/from_json.hpp b/src/detail/conversions/from_json.hpp new file mode 100644 index 00000000..471c1320 --- /dev/null +++ b/src/detail/conversions/from_json.hpp @@ -0,0 +1,316 @@ +#ifndef NLOHMANN_JSON_DETAIL_CONVERSIONS_FROM_JSON_HPP +#define NLOHMANN_JSON_DETAIL_CONVERSIONS_FROM_JSON_HPP + +#include +#include +#include +#include + +#include "detail/exceptions.hpp" +#include "detail/macro_scope.hpp" +#include "detail/meta.hpp" +#include "detail/value_t.hpp" + +namespace nlohmann +{ +namespace detail +{ +/////////////// +// from_json // +/////////////// + +// overloads for basic_json template parameters +template::value and + not std::is_same::value, + int> = 0> +void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val) +{ + switch (static_cast(j)) + { + case value_t::number_unsigned: + { + val = static_cast(*j.template get_ptr()); + break; + } + case value_t::number_integer: + { + val = static_cast(*j.template get_ptr()); + break; + } + case value_t::number_float: + { + val = static_cast(*j.template get_ptr()); + break; + } + + default: + JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name()))); + } +} + +template +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(); +} + +template +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(); +} + +template +void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val) +{ + get_arithmetic_value(j, val); +} + +template +void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val) +{ + get_arithmetic_value(j, val); +} + +template +void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t& val) +{ + get_arithmetic_value(j, val); +} + +template::value, int> = 0> +void from_json(const BasicJsonType& j, EnumType& e) +{ + typename std::underlying_type::type val; + get_arithmetic_value(j, val); + e = static_cast(val); +} + +template +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(); +} + +// forward_list doesn't have an insert method +template::value, int> = 0> +void from_json(const BasicJsonType& j, std::forward_list& 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(); + }); +} + +// valarray doesn't have an insert method +template::value, int> = 0> +void from_json(const BasicJsonType& j, std::valarray& 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 +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() returns *this, this won't call a from_json + // method when value_type is BasicJsonType + return i.template get(); + }); +} + +template +auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<1> /*unused*/) +-> decltype( + arr.reserve(std::declval()), + void()) +{ + using std::end; + + arr.reserve(j.size()); + std::transform(j.begin(), j.end(), + std::inserter(arr, end(arr)), [](const BasicJsonType & i) + { + // get() returns *this, this won't call a from_json + // method when value_type is BasicJsonType + return i.template get(); + }); +} + +template +void from_json_array_impl(const BasicJsonType& j, std::array& arr, priority_tag<2> /*unused*/) +{ + for (std::size_t i = 0; i < N; ++i) + { + arr[i] = j.at(i).template get(); + } +} + +template::value and + std::is_convertible::value and + not std::is_same::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::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(); + 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()); + }); +} + +// 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::value and + not std::is_same::value and + not std::is_same::value and + not std::is_same::value and + not std::is_same::value, + int> = 0> +void from_json(const BasicJsonType& j, ArithmeticType& val) +{ + switch (static_cast(j)) + { + case value_t::number_unsigned: + { + val = static_cast(*j.template get_ptr()); + break; + } + case value_t::number_integer: + { + val = static_cast(*j.template get_ptr()); + break; + } + case value_t::number_float: + { + val = static_cast(*j.template get_ptr()); + break; + } + case value_t::boolean: + { + val = static_cast(*j.template get_ptr()); + break; + } + + default: + JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name()))); + } +} + +template +void from_json(const BasicJsonType& j, std::pair& p) +{ + p = {j.at(0).template get(), j.at(1).template get()}; +} + +template +void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence) +{ + t = std::make_tuple(j.at(Idx).template get::type>()...); +} + +template +void from_json(const BasicJsonType& j, std::tuple& t) +{ + from_json_tuple_impl(j, t, index_sequence_for {}); +} + +struct from_json_fn +{ + private: + template + 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 + 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; + static_assert(sizeof(typename decayed::force_msvc_stacktrace) == 0, + "forcing MSVC stacktrace to show which T we're talking about."); +#endif + } + + public: + template + void operator()(const BasicJsonType& j, T& val) const + noexcept(noexcept(std::declval().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::value; +} +} + +#endif diff --git a/src/detail/meta.hpp b/src/detail/meta.hpp index 9a3a97fa..a9b20443 100644 --- a/src/detail/meta.hpp +++ b/src/detail/meta.hpp @@ -220,6 +220,16 @@ struct has_to_json static constexpr bool value = std::is_integral>()))>::value; }; + +// taken from ranges-v3 +template +struct static_const +{ + static constexpr T value{}; +}; + +template +constexpr T static_const::value; } } diff --git a/src/json.hpp b/src/json.hpp index 6d50dff2..e7ce109a 100644 --- a/src/json.hpp +++ b/src/json.hpp @@ -56,6 +56,7 @@ SOFTWARE. #include "detail/meta.hpp" #include "detail/exceptions.hpp" #include "detail/value_t.hpp" +#include "detail/conversions/from_json.hpp" /*! @brief namespace for Niels Lohmann @@ -347,261 +348,6 @@ void to_json(BasicJsonType& j, const std::tuple& t) to_json_tuple_impl(j, t, index_sequence_for {}); } -/////////////// -// from_json // -/////////////// - -// overloads for basic_json template parameters -template::value and - not std::is_same::value, - int> = 0> -void get_arithmetic_value(const BasicJsonType& j, ArithmeticType& val) -{ - switch (static_cast(j)) - { - case value_t::number_unsigned: - { - val = static_cast(*j.template get_ptr()); - break; - } - case value_t::number_integer: - { - val = static_cast(*j.template get_ptr()); - break; - } - case value_t::number_float: - { - val = static_cast(*j.template get_ptr()); - break; - } - - default: - JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name()))); - } -} - -template -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(); -} - -template -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(); -} - -template -void from_json(const BasicJsonType& j, typename BasicJsonType::number_float_t& val) -{ - get_arithmetic_value(j, val); -} - -template -void from_json(const BasicJsonType& j, typename BasicJsonType::number_unsigned_t& val) -{ - get_arithmetic_value(j, val); -} - -template -void from_json(const BasicJsonType& j, typename BasicJsonType::number_integer_t& val) -{ - get_arithmetic_value(j, val); -} - -template::value, int> = 0> -void from_json(const BasicJsonType& j, EnumType& e) -{ - typename std::underlying_type::type val; - get_arithmetic_value(j, val); - e = static_cast(val); -} - -template -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(); -} - -// forward_list doesn't have an insert method -template::value, int> = 0> -void from_json(const BasicJsonType& j, std::forward_list& 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(); - }); -} - -// valarray doesn't have an insert method -template::value, int> = 0> -void from_json(const BasicJsonType& j, std::valarray& 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 -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() returns *this, this won't call a from_json - // method when value_type is BasicJsonType - return i.template get(); - }); -} - -template -auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, priority_tag<1> /*unused*/) --> decltype( - arr.reserve(std::declval()), - void()) -{ - using std::end; - - arr.reserve(j.size()); - std::transform(j.begin(), j.end(), - std::inserter(arr, end(arr)), [](const BasicJsonType & i) - { - // get() returns *this, this won't call a from_json - // method when value_type is BasicJsonType - return i.template get(); - }); -} - -template -void from_json_array_impl(const BasicJsonType& j, std::array& arr, priority_tag<2> /*unused*/) -{ - for (std::size_t i = 0; i < N; ++i) - { - arr[i] = j.at(i).template get(); - } -} - -template::value and - std::is_convertible::value and - not std::is_same::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::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(); - 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()); - }); -} - -// 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::value and - not std::is_same::value and - not std::is_same::value and - not std::is_same::value and - not std::is_same::value, - int> = 0> -void from_json(const BasicJsonType& j, ArithmeticType& val) -{ - switch (static_cast(j)) - { - case value_t::number_unsigned: - { - val = static_cast(*j.template get_ptr()); - break; - } - case value_t::number_integer: - { - val = static_cast(*j.template get_ptr()); - break; - } - case value_t::number_float: - { - val = static_cast(*j.template get_ptr()); - break; - } - case value_t::boolean: - { - val = static_cast(*j.template get_ptr()); - break; - } - - default: - JSON_THROW(type_error::create(302, "type must be number, but is " + std::string(j.type_name()))); - } -} - -template -void from_json(const BasicJsonType& j, std::pair& p) -{ - p = {j.at(0).template get(), j.at(1).template get()}; -} - -template -void from_json_tuple_impl(const BasicJsonType& j, Tuple& t, index_sequence) -{ - t = std::make_tuple(j.at(Idx).template get::type>()...); -} - -template -void from_json(const BasicJsonType& j, std::tuple& t) -{ - from_json_tuple_impl(j, t, index_sequence_for {}); -} - struct to_json_fn { private: @@ -635,49 +381,6 @@ struct to_json_fn } }; -struct from_json_fn -{ - private: - template - 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 - 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; - static_assert(sizeof(typename decayed::force_msvc_stacktrace) == 0, - "forcing MSVC stacktrace to show which T we're talking about."); -#endif - } - - public: - template - void operator()(const BasicJsonType& j, T& val) const - noexcept(noexcept(std::declval().call(j, val, priority_tag<1> {}))) - { - return call(j, val, priority_tag<1> {}); - } -}; - -// taken from ranges-v3 -template -struct static_const -{ - static constexpr T value{}; -}; - -template -constexpr T static_const::value; - //////////////////// // input adapters // //////////////////// @@ -6181,11 +5884,10 @@ class json_ref } // namespace detail -/// namespace to hold default `to_json` / `from_json` functions +/// namespace to hold default `to_json` function namespace { constexpr const auto& to_json = detail::static_const::value; -constexpr const auto& from_json = detail::static_const::value; } template