1 files changed, 58 insertions, 0 deletions
diff --git a/deps/include/entt/meta/policy.hpp b/deps/include/entt/meta/policy.hpp
new file mode 100644
index 0000000..2974b89
--- /dev/null
+++ b/deps/include/entt/meta/policy.hpp
@@ -0,0 +1,58 @@
+#ifndef ENTT_META_POLICY_HPP
+#define ENTT_META_POLICY_HPP
+
+#include <type_traits>
+
+namespace entt {
+
+/*! @brief Empty class type used to request the _as ref_ policy. */
+struct as_ref_t final {
+    /*! @cond TURN_OFF_DOXYGEN */
+    template<typename Type>
+    static constexpr bool value = std::is_reference_v<Type> && !std::is_const_v<std::remove_reference_t<Type>>;
+    /*! @endcond */
+};
+
+/*! @brief Empty class type used to request the _as cref_ policy. */
+struct as_cref_t final {
+    /*! @cond TURN_OFF_DOXYGEN */
+    template<typename Type>
+    static constexpr bool value = std::is_reference_v<Type>;
+    /*! @endcond */
+};
+
+/*! @brief Empty class type used to request the _as-is_ policy. */
+struct as_is_t final {
+    /*! @cond TURN_OFF_DOXYGEN */
+    template<typename>
+    static constexpr bool value = true;
+    /*! @endcond */
+};
+
+/*! @brief Empty class type used to request the _as void_ policy. */
+struct as_void_t final {
+    /*! @cond TURN_OFF_DOXYGEN */
+    template<typename>
+    static constexpr bool value = true;
+    /*! @endcond */
+};
+
+/**
+ * @brief Provides the member constant `value` to true if a type also is a meta
+ * policy, false otherwise.
+ * @tparam Type Type to check.
+ */
+template<typename Type>
+struct is_meta_policy
+    : 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>> {};
+
+/**
+ * @brief Helper variable template.
+ * @tparam Type Type to check.
+ */
+template<typename Type>
+inline constexpr bool is_meta_policy_v = is_meta_policy<Type>::value;
+
+} // namespace entt
+
+#endif