Add a scope guard template class.

src/README.md

@@ -12,6 +12,10 @@ A quick circular buffer template class.
 
 An improved version based on Onigmo 5.13.5. In particular, **the addition of iterator makes it possible to match gap buffer or nonadjacent memory blocks.** Please refer to the sample files for how to use.
 
+## ScopeGuard.h
+
+A class of which the sole purpose is to run the function f in its destructor. This is useful for guaranteeing your cleanup code is executed.
+
 ## Spin.h
 
 A high-performance spin mutex and locker.

src/ScopeGuard.h

@@ -0,0 +1,57 @@
+ /*
+ * Copyright 2020, WindTerm.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SCOPEGUARD_H
+#define SCOPEGUARD_H
+
+class ScopeGuard {
+	typedef std::function<void()> GuardFunction;
+
+public:
+	ScopeGuard(GuardFunction acquire, GuardFunction release)
+		: m_active(true)
+		, m_release(std::move(release))
+	{
+		acquire();
+	}
+
+	~ScopeGuard() {
+		if (m_active) {
+			m_release();
+		}
+	}
+
+	ScopeGuard() = delete;
+	ScopeGuard(const ScopeGuard &) = delete;
+	ScopeGuard &operator=(const ScopeGuard &) = delete;
+
+	ScopeGuard(ScopeGuard &&other)
+		: m_active(other.m_active)
+		, m_release(std::move(other.m_release))
+	{
+		other.cancel();
+	}
+
+	void cancel() {
+		m_active = false;
+	}
+	
+private:
+	bool m_active;
+	GuardFunction m_release;
+};
+
+#endif // SCOPEGUARD_H