mirror of
https://github.com/ToruNiina/toml11.git
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259 lines
8.7 KiB
C++
259 lines
8.7 KiB
C++
// Copyright Toru Niina 2017.
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// Distributed under the MIT License.
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#ifndef TOML11_TRAITS_HPP
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#define TOML11_TRAITS_HPP
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#include <type_traits>
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#include <utility>
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#include <chrono>
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#include <tuple>
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#include <string>
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#if __cplusplus >= 201703L
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#if __has_include(<string_view>)
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#include <string_view>
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#endif // has_include(<string_view>)
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#endif // cplusplus >= C++17
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namespace toml
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{
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template<typename C, template<typename ...> class T, template<typename ...> class A>
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class basic_value;
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namespace detail
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{
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// ---------------------------------------------------------------------------
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// check whether type T is a kind of container/map class
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struct has_iterator_impl
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{
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template<typename T> static std::true_type check(typename T::iterator*);
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template<typename T> static std::false_type check(...);
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};
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struct has_value_type_impl
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{
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template<typename T> static std::true_type check(typename T::value_type*);
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template<typename T> static std::false_type check(...);
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};
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struct has_key_type_impl
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{
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template<typename T> static std::true_type check(typename T::key_type*);
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template<typename T> static std::false_type check(...);
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};
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struct has_mapped_type_impl
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{
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template<typename T> static std::true_type check(typename T::mapped_type*);
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template<typename T> static std::false_type check(...);
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};
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struct has_resize_method_impl
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{
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constexpr static std::size_t dummy=0;
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template<typename T> static std::true_type check(decltype(std::declval<T>().resize(dummy))*);
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template<typename T> static std::false_type check(...);
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};
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struct is_comparable_impl
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{
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template<typename T> static std::true_type check(decltype(std::declval<T>() < std::declval<T>())*);
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template<typename T> static std::false_type check(...);
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};
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struct has_from_toml_method_impl
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{
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template<typename T, typename C,
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template<typename ...> class Tb, template<typename ...> class A>
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static std::true_type check(
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decltype(std::declval<T>().from_toml(
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std::declval<::toml::basic_value<C, Tb, A>>()))*);
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template<typename T, typename C,
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template<typename ...> class Tb, template<typename ...> class A>
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static std::false_type check(...);
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};
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struct has_into_toml_method_impl
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{
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template<typename T>
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static std::true_type check(decltype(std::declval<T>().into_toml())*);
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template<typename T>
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static std::false_type check(...);
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};
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/// Intel C++ compiler can not use decltype in parent class declaration, here
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/// is a hack to work around it. https://stackoverflow.com/a/23953090/4692076
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#ifdef __INTEL_COMPILER
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#define decltype(...) std::enable_if<true, decltype(__VA_ARGS__)>::type
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#endif
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template<typename T>
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struct has_iterator : decltype(has_iterator_impl::check<T>(nullptr)){};
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template<typename T>
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struct has_value_type : decltype(has_value_type_impl::check<T>(nullptr)){};
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template<typename T>
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struct has_key_type : decltype(has_key_type_impl::check<T>(nullptr)){};
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template<typename T>
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struct has_mapped_type : decltype(has_mapped_type_impl::check<T>(nullptr)){};
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template<typename T>
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struct has_resize_method : decltype(has_resize_method_impl::check<T>(nullptr)){};
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template<typename T>
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struct is_comparable : decltype(is_comparable_impl::check<T>(nullptr)){};
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template<typename T, typename C,
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template<typename ...> class Tb, template<typename ...> class A>
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struct has_from_toml_method
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: decltype(has_from_toml_method_impl::check<T, C, Tb, A>(nullptr)){};
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template<typename T>
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struct has_into_toml_method
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: decltype(has_into_toml_method_impl::check<T>(nullptr)){};
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#ifdef __INTEL_COMPILER
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#undef decltype(...)
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#endif
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// ---------------------------------------------------------------------------
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// C++17 and/or/not
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template<typename ...> struct conjunction : std::true_type{};
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template<typename T> struct conjunction<T> : T{};
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template<typename T, typename ... Ts>
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struct conjunction<T, Ts...> :
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std::conditional<static_cast<bool>(T::value), conjunction<Ts...>, T>::type
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{};
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template<typename ...> struct disjunction : std::false_type{};
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template<typename T> struct disjunction<T> : T {};
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template<typename T, typename ... Ts>
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struct disjunction<T, Ts...> :
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std::conditional<static_cast<bool>(T::value), T, disjunction<Ts...>>::type
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{};
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template<typename T>
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struct negation : std::integral_constant<bool, !static_cast<bool>(T::value)>{};
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// ---------------------------------------------------------------------------
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// type checkers
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template<typename T> struct is_std_pair : std::false_type{};
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template<typename T1, typename T2>
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struct is_std_pair<std::pair<T1, T2>> : std::true_type{};
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template<typename T> struct is_std_tuple : std::false_type{};
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template<typename ... Ts>
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struct is_std_tuple<std::tuple<Ts...>> : std::true_type{};
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template<typename T> struct is_chrono_duration: std::false_type{};
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template<typename Rep, typename Period>
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struct is_chrono_duration<std::chrono::duration<Rep, Period>>: std::true_type{};
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template<typename T>
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struct is_map : conjunction< // map satisfies all the following conditions
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has_iterator<T>, // has T::iterator
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has_value_type<T>, // has T::value_type
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has_key_type<T>, // has T::key_type
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has_mapped_type<T> // has T::mapped_type
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>{};
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template<typename T> struct is_map<T&> : is_map<T>{};
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template<typename T> struct is_map<T const&> : is_map<T>{};
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template<typename T> struct is_map<T volatile&> : is_map<T>{};
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template<typename T> struct is_map<T const volatile&> : is_map<T>{};
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template<typename T>
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struct is_container : conjunction<
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negation<is_map<T>>, // not a map
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negation<std::is_same<T, std::string>>, // not a std::string
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#if __cplusplus >= 201703L
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negation<std::is_same<T, std::string_view>>, // not a std::string_view
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#endif
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has_iterator<T>, // has T::iterator
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has_value_type<T> // has T::value_type
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>{};
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template<typename T> struct is_container<T&> : is_container<T>{};
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template<typename T> struct is_container<T const&> : is_container<T>{};
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template<typename T> struct is_container<T volatile&> : is_container<T>{};
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template<typename T> struct is_container<T const volatile&> : is_container<T>{};
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template<typename T>
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struct is_basic_value: std::false_type{};
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template<typename T> struct is_basic_value<T&> : is_basic_value<T>{};
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template<typename T> struct is_basic_value<T const&> : is_basic_value<T>{};
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template<typename T> struct is_basic_value<T volatile&> : is_basic_value<T>{};
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template<typename T> struct is_basic_value<T const volatile&> : is_basic_value<T>{};
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template<typename C, template<typename ...> class M, template<typename ...> class V>
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struct is_basic_value<::toml::basic_value<C, M, V>>: std::true_type{};
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// ---------------------------------------------------------------------------
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// C++14 index_sequence
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template<std::size_t ... Ns> struct index_sequence{};
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template<typename IS, std::size_t N> struct push_back_index_sequence{};
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template<std::size_t N, std::size_t ... Ns>
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struct push_back_index_sequence<index_sequence<Ns...>, N>
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{
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typedef index_sequence<Ns..., N> type;
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};
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template<std::size_t N>
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struct index_sequence_maker
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{
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typedef typename push_back_index_sequence<
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typename index_sequence_maker<N-1>::type, N>::type type;
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};
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template<>
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struct index_sequence_maker<0>
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{
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typedef index_sequence<0> type;
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};
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template<std::size_t N>
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using make_index_sequence = typename index_sequence_maker<N-1>::type;
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// ---------------------------------------------------------------------------
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// C++14 enable_if_t
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template<bool B, typename T>
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using enable_if_t = typename std::enable_if<B, T>::type;
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// ---------------------------------------------------------------------------
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// return_type_of_t
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#if __cplusplus >= 201703L
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template<typename F, typename ... Args>
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using return_type_of_t = std::invoke_result_t<F, Args...>;
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#else
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// result_of is deprecated after C++17
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template<typename F, typename ... Args>
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using return_type_of_t = typename std::result_of<F(Args...)>::type;
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#endif
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// ---------------------------------------------------------------------------
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// is_string_literal
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//
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// to use this, pass `typename remove_reference<T>::type` to T.
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template<typename T>
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struct is_string_literal:
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disjunction<
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std::is_same<const char*, T>,
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conjunction<
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std::is_array<T>,
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std::is_same<const char, typename std::remove_extent<T>::type>
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>
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>{};
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// ---------------------------------------------------------------------------
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// C++20 remove_cvref_t
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template<typename T>
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struct remove_cvref
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{
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using type = typename std::remove_cv<
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typename std::remove_reference<T>::type>::type;
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};
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template<typename T>
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using remove_cvref_t = typename remove_cvref<T>::type;
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}// detail
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}//toml
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#endif // TOML_TRAITS
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