Squashed 'external/entt/entt/' content from commit fef92113

git-subtree-dir: external/entt/entt
git-subtree-split: fef921132cae7588213d0f9bcd2fb9c8ffd8b7fc

test/example/entity_copy.cpp

@@ -0,0 +1,78 @@
+#include <gtest/gtest.h>
+#include <entt/core/hashed_string.hpp>
+#include <entt/entity/registry.hpp>
+
+enum class my_entity : entt::id_type {};
+
+TEST(Example, EntityCopy) {
+    using namespace entt::literals;
+
+    entt::registry registry{};
+    auto &&custom = registry.storage<double>("custom"_hs);
+
+    const auto src = registry.create();
+    const auto dst = registry.create();
+    const auto other = registry.create();
+
+    custom.emplace(src, 1.);
+    registry.emplace<int>(src, 42);
+    registry.emplace<char>(src, 'c');
+    registry.emplace<double>(other, 3.);
+
+    ASSERT_TRUE(custom.contains(src));
+    ASSERT_FALSE(registry.all_of<double>(src));
+    ASSERT_TRUE((registry.all_of<int, char>(src)));
+    ASSERT_FALSE((registry.any_of<int, char, double>(dst)));
+    ASSERT_FALSE(custom.contains(dst));
+
+    for(auto [id, storage]: registry.storage()) {
+        // discard the custom storage because why not, this is just an example after all
+        if(id != "custom"_hs && storage.contains(src)) {
+            storage.emplace(dst, storage.get(src));
+        }
+    }
+
+    ASSERT_TRUE((registry.all_of<int, char>(dst)));
+    ASSERT_FALSE((registry.all_of<double>(dst)));
+    ASSERT_FALSE(custom.contains(dst));
+
+    ASSERT_EQ(registry.get<int>(dst), 42);
+    ASSERT_EQ(registry.get<char>(dst), 'c');
+}
+
+TEST(Example, DifferentRegistryTypes) {
+    using namespace entt::literals;
+
+    entt::basic_registry<entt::entity> src{};
+    entt::basic_registry<my_entity> dst{};
+
+    /*
+        TODO These are currently needed to ensure that the source and
+             target registries have the proper storage initialized
+             prior to copying, as this isn't done automatically
+             when emplacing storages (as is done below).
+
+             There is an open issue about this, and these two
+             lines should be removed when a fix is properly landed.
+             https://github.com/skypjack/entt/issues/827
+    */
+    static_cast<void>(src.storage<double>());
+    static_cast<void>(dst.storage<int>());
+
+    const auto entity = src.create();
+    const auto copy = dst.create();
+
+    src.emplace<int>(entity, 42);
+    src.emplace<char>(entity, 'c');
+
+    for(auto [id, storage]: src.storage()) {
+        if(auto *other = dst.storage(id); other && storage.contains(entity)) {
+            other->emplace(copy, storage.get(entity));
+        }
+    }
+
+    ASSERT_TRUE((src.all_of<int, char>(entity)));
+    ASSERT_FALSE(dst.all_of<char>(copy));
+    ASSERT_TRUE(dst.all_of<int>(copy));
+    ASSERT_EQ(dst.get<int>(copy), 42);
+}