Implemented scoped defer utility

Author: jonjondev

engine/utils/Defer.h

@@ -0,0 +1,54 @@
+//
+// Copyright (c) 2023 Jonathan Moallem (@J-Mo63) & Aryeh Zinn (@Raelr)
+//
+// This code is released under an unmodified zlib license.
+// For conditions of distribution and use, please see:
+//     https://opensource.org/licenses/Zlib
+//
+
+#ifndef SIEGE_ENGINE_DEFER_H
+#define SIEGE_ENGINE_DEFER_H
+
+#include <functional>
+
+#include "Macros.h"
+
+namespace Siege
+{
+
+/**
+ * A basic deferred call object implementation that executes its provided callable on scope exit.
+ */
+struct ScopedDefer
+{
+    /**
+     * Explicitly deleted zero-param constructor
+     */
+    ScopedDefer() = delete;
+
+    /**
+     * Constructor, specifying owned callable
+     * @param callable - the void-returning, parameterless callable to execute
+     */
+    explicit ScopedDefer(const std::function<void()>& callable) : callable(callable) {}
+
+    /**
+     * Destructor, executing callable on scope exit
+     */
+    ~ScopedDefer()
+    {
+        callable();
+    }
+
+    /**
+     * Held void-retuning, parameterless callable
+     */
+    std::function<void()> callable;
+};
+
+#define _DEFER_VAR_NAME CONCAT_SYMBOL(_defer_, __COUNTER__)
+#define defer(callable) auto _DEFER_VAR_NAME = Siege::ScopedDefer(callable)
+
+} // namespace Siege
+
+#endif // SIEGE_ENGINE_DEFER_H