59 lines
1.6 KiB
C++
59 lines
1.6 KiB
C++
#ifndef ENTT_META_POLICY_HPP
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#define ENTT_META_POLICY_HPP
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#include <type_traits>
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namespace entt {
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/*! @brief Empty class type used to request the _as ref_ policy. */
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struct as_ref_t final {
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/*! @cond TURN_OFF_DOXYGEN */
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template<typename Type>
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static constexpr bool value = std::is_reference_v<Type> && !std::is_const_v<std::remove_reference_t<Type>>;
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/*! @endcond */
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};
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/*! @brief Empty class type used to request the _as cref_ policy. */
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struct as_cref_t final {
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/*! @cond TURN_OFF_DOXYGEN */
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template<typename Type>
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static constexpr bool value = std::is_reference_v<Type>;
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/*! @endcond */
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};
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/*! @brief Empty class type used to request the _as-is_ policy. */
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struct as_is_t final {
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/*! @cond TURN_OFF_DOXYGEN */
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template<typename>
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static constexpr bool value = true;
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/*! @endcond */
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};
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/*! @brief Empty class type used to request the _as void_ policy. */
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struct as_void_t final {
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/*! @cond TURN_OFF_DOXYGEN */
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template<typename>
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static constexpr bool value = true;
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/*! @endcond */
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};
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/**
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* @brief Provides the member constant `value` to true if a type also is a meta
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* policy, false otherwise.
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* @tparam Type Type to check.
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*/
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template<typename Type>
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struct is_meta_policy
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: std::bool_constant<std::is_same_v<Type, as_ref_t> || std::is_same_v<Type, as_cref_t> || std::is_same_v<Type, as_is_t> || std::is_same_v<Type, as_void_t>> {};
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/**
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* @brief Helper variable template.
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* @tparam Type Type to check.
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*/
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template<typename Type>
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inline constexpr bool is_meta_policy_v = is_meta_policy<Type>::value;
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} // namespace entt
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#endif
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