Add fly::size_of_type_is trait

Author: trflynn89

fly/traits/traits.hpp

@@ -106,6 +106,16 @@ template <typename T, typename A, typename... As>
 // NOLINTNEXTLINE(readability-identifier-naming)
 inline constexpr bool any_same_v = any_same<T, A, As...>::value;
 
+/**
+ * Trait for testing if the size of a given type is the provided size.
+ */
+template <typename T, std::size_t Size>
+using size_of_type_is = std::bool_constant<sizeof(T) == Size>;
+
+template <typename T, std::size_t Size>
+// NOLINTNEXTLINE(readability-identifier-naming)
+inline constexpr bool size_of_type_is_v = size_of_type_is<T, Size>::value;
+
 /**
  * Overloaded visitation pattern for std::visit. Allows providing a variadic list of lambdas for
  * overload resolution in a call to std::visit. Example:

test/traits/traits.cpp

@@ -241,7 +241,7 @@ CATCH_TEST_CASE("Traits", "[traits]")
         CATCH_CHECK(is_class_or_pointer(&f));
     }
 
-    CATCH_SECTION("Variadic all_same trait")
+    CATCH_SECTION("Trait: all_same")
     {
         CATCH_CHECK(fly::all_same_v<int, int>);
         CATCH_CHECK(fly::all_same_v<int, const int>);
@@ -279,7 +279,7 @@ CATCH_TEST_CASE("Traits", "[traits]")
         CATCH_CHECK_FALSE(fly::all_same_v<FooClass, FooClass, std::string>);
     }
 
-    CATCH_SECTION("Variadic any_same trait")
+    CATCH_SECTION("Trait: any_same")
     {
         CATCH_CHECK(fly::any_same_v<int, int>);
         CATCH_CHECK(fly::any_same_v<int, const int>);
@@ -320,6 +320,21 @@ CATCH_TEST_CASE("Traits", "[traits]")
         CATCH_CHECK_FALSE(fly::any_same_v<FooClass, std::string>);
     }
 
+    CATCH_SECTION("Trait: size_of_type_is")
+    {
+        CATCH_CHECK(fly::size_of_type_is_v<int, sizeof(int)>);
+        CATCH_CHECK(fly::size_of_type_is_v<bool, sizeof(bool)>);
+        CATCH_CHECK(fly::size_of_type_is_v<FooClass, sizeof(FooClass)>);
+
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<int, sizeof(int) - 1>);
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<bool, sizeof(bool) - 1>);
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<FooClass, sizeof(FooClass) - 1>);
+
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<int, sizeof(int) + 1>);
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<bool, sizeof(bool) + 1>);
+        CATCH_CHECK_FALSE(fly::size_of_type_is_v<FooClass, sizeof(FooClass) + 1>);
+    }
+
     CATCH_SECTION("Overloaded visitation pattern")
     {
         using TestVariant = std::variant<int, bool, std::string>;