From f5ced7fe3963a1239b49a29be018388ff1b41f2a Mon Sep 17 00:00:00 2001
From: Michele Caini <michele.caini@gmail.com>
Date: Thu, 12 Dec 2019 16:02:58 +0100
Subject: [PATCH] core: (customizable) type_id[_v]

---
 src/entt/core/type_info.hpp  | 52 ++++++++++++++++++++++++++++++++++++
 src/entt/entt.hpp            |  1 +
 test/CMakeLists.txt          |  1 +
 test/entt/core/BUILD.bazel   | 10 +++++++
 test/entt/core/type_info.cpp |  9 +++++++
 5 files changed, 73 insertions(+)
 create mode 100644 src/entt/core/type_info.hpp
 create mode 100644 test/entt/core/type_info.cpp

diff --git a/src/entt/core/type_info.hpp b/src/entt/core/type_info.hpp
new file mode 100644
index 000000000..9e75eab65
--- /dev/null
+++ b/src/entt/core/type_info.hpp
@@ -0,0 +1,52 @@
+#ifndef ENTT_CORE_TYPE_INFO_HPP
+#define ENTT_CORE_TYPE_INFO_HPP
+
+
+#include <type_traits>
+#include "../config/config.h"
+#include "hashed_string.hpp"
+
+
+namespace entt {
+
+
+/**
+ * @brief Types identifiers.
+ * @tparam Type Type for which to generate an identifier.
+ */
+template<typename... Type>
+struct type_id {
+    static_assert(sizeof...(Type) == ((bool{true || sizeof(Type)}) + ...));
+
+#if defined _MSC_VER
+    /**
+     * @brief Returns the numeric representation of a given type.
+     * @return The numeric representation of the given type.
+     */
+    static constexpr ENTT_ID_TYPE value() ENTT_NOEXCEPT {
+        return entt::hashed_string{__FUNCSIG__};
+    }
+#elif defined __GNUC__
+    /**
+     * @brief Returns the numeric representation of a given type.
+     * @return The numeric representation of the given type.
+     */
+    static constexpr ENTT_ID_TYPE value() ENTT_NOEXCEPT {
+        return entt::hashed_string{__PRETTY_FUNCTION__};
+    }
+#endif
+};
+
+
+/**
+ * @brief Helper variable template.
+ * @tparam Type Type for which to generate an identifier.
+ */
+template<typename Type>
+static constexpr auto type_id_v = type_id<Type>::value();
+
+
+}
+
+
+#endif // ENTT_CORE_TYPE_INFO_HPP
diff --git a/src/entt/entt.hpp b/src/entt/entt.hpp
index 02eba4548..3065a3093 100644
--- a/src/entt/entt.hpp
+++ b/src/entt/entt.hpp
@@ -4,6 +4,7 @@
 #include "core/hashed_string.hpp"
 #include "core/ident.hpp"
 #include "core/monostate.hpp"
+#include "core/type_info.hpp"
 #include "core/type_traits.hpp"
 #include "core/utility.hpp"
 #include "entity/actor.hpp"
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index c24008f24..7a628fefa 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -131,6 +131,7 @@ SETUP_BASIC_TEST(family entt/core/family.cpp)
 SETUP_BASIC_TEST(hashed_string entt/core/hashed_string.cpp)
 SETUP_BASIC_TEST(ident entt/core/ident.cpp)
 SETUP_BASIC_TEST(monostate entt/core/monostate.cpp)
+SETUP_BASIC_TEST(type_info entt/core/type_info.cpp)
 SETUP_BASIC_TEST(type_traits entt/core/type_traits.cpp)
 SETUP_BASIC_TEST(utility entt/core/utility.cpp)
 
diff --git a/test/entt/core/BUILD.bazel b/test/entt/core/BUILD.bazel
index bf2d4934a..adea042a9 100644
--- a/test/entt/core/BUILD.bazel
+++ b/test/entt/core/BUILD.bazel
@@ -50,6 +50,16 @@ cc_test(
     ],
 )
 
+cc_test(
+    name = "type_info",
+    srcs = ["type_info.cpp"],
+    copts = entt_copts,
+    deps = [
+        "//:entt",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
 cc_test(
     name = "type_traits",
     srcs = ["type_traits.cpp"],
diff --git a/test/entt/core/type_info.cpp b/test/entt/core/type_info.cpp
new file mode 100644
index 000000000..a0f91293c
--- /dev/null
+++ b/test/entt/core/type_info.cpp
@@ -0,0 +1,9 @@
+#include <gtest/gtest.h>
+#include <entt/core/hashed_string.hpp>
+#include <entt/core/type_info.hpp>
+
+TEST(TypeId, Functionalities) {
+    ASSERT_NE(entt::type_id_v<int>, entt::type_id_v<const int>);
+    ASSERT_NE(entt::type_id_v<int>, entt::type_id_v<char>);
+    ASSERT_EQ(entt::type_id_v<int>, entt::type_id_v<int>);
+}