test: tracked_memory_resource utility

test/entt/common/tracked_memory_resource.hpp

@@ -0,0 +1,59 @@
+#ifndef ENTT_COMMON_TRACKED_MEMORY_RESOURCE_HPP
+#define ENTT_COMMON_TRACKED_MEMORY_RESOURCE_HPP
+
+#ifdef ENTT_HAS_HEADER_VERSION
+#    include <version>
+#
+#    if defined(__cpp_lib_memory_resource) && __cpp_lib_memory_resource >= 201603L
+#        define ENTT_HAS_TRACKED_MEMORY_RESOURCE
+#
+#        include <cstddef>
+#        include <memory_resource>
+#        include <string>
+#        include <entt/config/config.h>
+
+namespace test {
+
+class tracked_memory_resource: public std::pmr::memory_resource {
+    void *do_allocate(std::size_t bytes, std::size_t alignment) override {
+        ++alloc_counter;
+        return std::pmr::get_default_resource()->allocate(bytes, alignment);
+    }
+
+    void do_deallocate(void *value, std::size_t bytes, std::size_t alignment) override {
+        ++dealloc_counter;
+        std::pmr::get_default_resource()->deallocate(value, bytes, alignment);
+    }
+
+    bool do_is_equal(const std::pmr::memory_resource &) const ENTT_NOEXCEPT override {
+        return true;
+    }
+
+public:
+    using string_type = std::pmr::string;
+    using size_type = std::size_t;
+
+    size_type do_allocate_counter() const ENTT_NOEXCEPT {
+        return alloc_counter;
+    }
+
+    size_type do_deallocate_counter() const ENTT_NOEXCEPT {
+        return dealloc_counter;
+    }
+
+    void reset() ENTT_NOEXCEPT {
+        alloc_counter = 0u;
+        dealloc_counter = 0u;
+    }
+
+private:
+    size_type alloc_counter{};
+    size_type dealloc_counter{};
+};
+
+} // namespace test
+
+#    endif
+#endif
+
+#endif