Add trait isProxyReference

alpaka-group · Jul 1, 2022 · 9dfe9b8 · 9dfe9b8
1 parent 173563d
commit 9dfe9b8
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Showing 2 changed files with 52 additions and 4 deletions.
diff --git a/include/llama/Concepts.hpp b/include/llama/Concepts.hpp
@@ -9,9 +9,9 @@
 #if __has_include(<concepts>)
 #    include <concepts>
 #endif
-#ifdef __cpp_lib_concepts
 namespace llama
 {
+#ifdef __cpp_lib_concepts
     // clang-format off
     template <typename M>
     concept Mapping = requires(M m) {
@@ -50,7 +50,7 @@ namespace llama
     concept ProxyReference = requires(R r) {
         typename R::value_type;
         { static_cast<typename R::value_type>(r) } -> std::same_as<typename R::value_type>;
-        { r = typename R::value_type{} } -> std::same_as<R&>;
+        { r = std::declval<typename R::value_type>() } -> std::same_as<R&>;
     };
 
     template <typename R>
@@ -100,7 +100,31 @@ namespace llama
     concept BlobAllocator = requires(BA ba, std::integral_constant<std::size_t, 16> alignment, std::size_t size) {
         { ba(alignment, size) } -> Blob;
     };
-    // clang-format on
-} // namespace llama
+        // clang-format on
+#endif
 
+    namespace internal
+    {
+        template<typename R, typename = void>
+        struct IsProxyReferenceImpl : std::false_type
+        {
+        };
+
+        template<typename R>
+        struct IsProxyReferenceImpl<
+            R,
+            std::void_t<
+                typename R::value_type,
+                decltype(static_cast<typename R::value_type>(std::declval<R&>())),
+                decltype(std::declval<R&>() = std::declval<typename R::value_type>())>> : std::true_type
+        {
+        };
+    } // namespace internal
+
+    template<typename R>
+#ifdef __cpp_lib_concepts
+    inline constexpr bool isProxyReference = ProxyReference<R>;
+#else
+    inline constexpr bool isProxyReference = internal::IsProxyReferenceImpl<R>::value;
 #endif
+} // namespace llama
diff --git a/tests/core.cpp b/tests/core.cpp
@@ -508,3 +508,27 @@ TEST_CASE("divCeil")
     STATIC_REQUIRE(llama::divCeil(17, 16) == 2);
     STATIC_REQUIRE(llama::divCeil(300, 16) == 19);
 }
+
+TEST_CASE("isProxyReference")
+{
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<int&>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<int&>);
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<std::string>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<std::string>);
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<std::vector<int>>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<std::vector<int>>);
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<std::vector<bool>::reference>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<std::vector<bool>::reference>); // misses a value_type alias
+
+    using One = llama::One<Vec3I>;
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<One>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<One>);
+    STATIC_REQUIRE(!llama::internal::IsProxyReferenceImpl<decltype(One{}())>::value);
+    STATIC_REQUIRE(!llama::isProxyReference<decltype(One{}())>);
+
+    auto mapping = llama::mapping::BitPackedIntSoA<llama::ArrayExtents<int, 4>, Vec3I>{{}, 17};
+    auto v = llama::allocView(mapping);
+    [[maybe_unused]] auto ref = v(1)(tag::X{});
+    STATIC_REQUIRE(llama::internal::IsProxyReferenceImpl<decltype(ref)>::value);
+    STATIC_REQUIRE(llama::isProxyReference<decltype(ref)>);
+}