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82 lines
2.1 KiB
C++
82 lines
2.1 KiB
C++
#ifndef ENTT_META_POLICY_HPP
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#define ENTT_META_POLICY_HPP
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#include "../stl/type_traits.hpp"
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namespace entt {
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/*! @cond ENTT_INTERNAL */
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namespace internal {
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struct meta_policy {};
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} // namespace internal
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/*! @endcond */
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/*! @brief Empty class type used to request the _as-is_ policy. */
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struct as_value_t final: private internal::meta_policy {
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/*! @cond ENTT_INTERNAL */
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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: private internal::meta_policy {
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/*! @cond ENTT_INTERNAL */
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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 ref_ policy. */
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struct as_ref_t final: private internal::meta_policy {
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/*! @cond ENTT_INTERNAL */
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template<typename Type>
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static constexpr bool value = stl::is_reference_v<Type> && !stl::is_const_v<stl::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: private internal::meta_policy {
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/*! @cond ENTT_INTERNAL */
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template<typename Type>
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static constexpr bool value = stl::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 auto_ policy. */
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struct as_is_t final: private internal::meta_policy {
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/*! @cond ENTT_INTERNAL */
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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` equal to true if a type also is a
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* meta 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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: stl::bool_constant<stl::is_base_of_v<internal::meta_policy, Type>> {};
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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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/**
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* @brief Specifies whether a type is a meta policy.
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* @tparam Type Type to check.
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*/
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template<typename Type>
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concept meta_policy = is_meta_policy_v<Type>;
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} // namespace entt
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#endif
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