fix uvalue index traits

ref: https://github.com/BlackMATov/meta.hpp/issues/100

develop/untests/meta_utilities/value4_tests.cpp

@@ -46,6 +46,8 @@ namespace
     };
 }
 
+META_HPP_DECLARE_COPY_TRAITS_FOR(clazz_throw_dtor)
+
 TEST_CASE("meta/meta_utilities/value4") {
     namespace meta = meta_hpp;
 

develop/untests/meta_utilities/value_tests.cpp

@@ -38,6 +38,10 @@ namespace
             return *this;
         }
 
+        int operator[](std::size_t i) const noexcept {
+            return i == 0 ? x : y;
+        }
+
         ivec2& operator=(ivec2&& other) = delete;
         ivec2& operator=(const ivec2& other) = delete;
     public:
@@ -118,6 +122,8 @@ META_HPP_DECLARE_COPY_TRAITS_FOR(ivec2_big)
 
 META_HPP_DECLARE_DEREF_TRAITS_FOR(deref_custom_class)
 
+META_HPP_DECLARE_INDEX_TRAITS_FOR(ivec2)
+
 TEST_CASE("meta/meta_utilities/value/_") {
     namespace meta = meta_hpp;
 
@@ -978,6 +984,23 @@ TEST_CASE("meta/meta_utilities/value/arrays") {
         CHECK(v[2].as<int>() == 3);
         CHECK_FALSE(v[3]);
     }
+
+    SUBCASE("ivec2/ivec3") {
+        {
+            meta::uvalue v{ivec2{1,2}};
+            CHECK(v.get_type() == meta::resolve_type<ivec2>());
+            CHECK(v.has_index_op());
+
+            CHECK(v[0].as<int>() == 1);
+            CHECK(v[1].as<int>() == 2);
+        }
+        {
+            meta::uvalue v{ivec3{1,2,3}};
+            CHECK(v.get_type() == meta::resolve_type<ivec3>());
+            CHECK_FALSE(v.has_index_op());
+            CHECK_THROWS(std::ignore = v[0]);
+        }
+    }
 }
 
 TEST_CASE("meta/meta_utilities/value/functions") {

headers/meta.hpp/meta_detail/value_traits/index_traits.hpp

@@ -9,6 +9,8 @@
 #include "../../meta_base.hpp"
 #include "../../meta_uvalue.hpp"
 
+#include "copy_traits.hpp"
+
 namespace meta_hpp::detail
 {
     template < typename T >
@@ -22,7 +24,7 @@ namespace meta_hpp::detail
 namespace meta_hpp::detail
 {
     template < typename T >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<T*> {
         uvalue operator()(T* v, std::size_t i) const {
             // NOLINTNEXTLINE(*-pointer-arithmetic)
@@ -31,7 +33,7 @@ namespace meta_hpp::detail
     };
 
     template < typename T, std::size_t Size >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<std::array<T, Size>> {
         uvalue operator()(const std::array<T, Size>& v, std::size_t i) const {
             return i < v.size() ? uvalue{v[i]} : uvalue{};
@@ -39,7 +41,7 @@ namespace meta_hpp::detail
     };
 
     template < typename T, typename Traits, typename Allocator >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<std::basic_string<T, Traits, Allocator>> {
         uvalue operator()(const std::basic_string<T, Traits, Allocator>& v, std::size_t i) const {
             return i < v.size() ? uvalue{v[i]} : uvalue{};
@@ -47,7 +49,7 @@ namespace meta_hpp::detail
     };
 
     template < typename T, typename Traits >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<std::basic_string_view<T, Traits>> {
         uvalue operator()(const std::basic_string_view<T, Traits>& v, std::size_t i) const {
             return i < v.size() ? uvalue{v[i]} : uvalue{};
@@ -55,7 +57,7 @@ namespace meta_hpp::detail
     };
 
     template < typename T, std::size_t Extent >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<std::span<T, Extent>> {
         uvalue operator()(const std::span<T, Extent>& v, std::size_t i) const {
             return i < v.size() ? uvalue{v[i]} : uvalue{};
@@ -63,10 +65,21 @@ namespace meta_hpp::detail
     };
 
     template < typename T, typename Allocator >
-        requires std::is_copy_constructible_v<T>
+        requires has_copy_traits<T>
     struct index_traits<std::vector<T, Allocator>> {
         uvalue operator()(const std::vector<T, Allocator>& v, std::size_t i) const {
             return i < v.size() ? uvalue{v[i]} : uvalue{};
         }
     };
 }
+
+#define META_HPP_DECLARE_INDEX_TRAITS_FOR(T) \
+    namespace meta_hpp::detail \
+    { \
+        template <> \
+        struct index_traits<T> { \
+            uvalue operator()(const T& v, std::size_t i) const { \
+                return uvalue{v[i]}; \
+            } \
+        }; \
+    }