Added final_action file

include/final_action.h

@@ -0,0 +1,71 @@
+/////////////////////////////////////////////////////////////////////////////// 
+// 
+// Copyright (c) 2015 Microsoft Corporation. All rights reserved. 
+// 
+// This code is licensed under the MIT License (MIT). 
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
+// THE SOFTWARE. 
+// 
+///////////////////////////////////////////////////////////////////////////////
+
+#pragma once
+
+#ifndef GSL_FINAL_ACTION_H
+#define GSL_FINAL_ACTION_H
+
+#ifdef _MSC_VER
+// VS 2013 workarounds
+#if _MSC_VER <= 1800
+// noexcept is not understood 
+#define noexcept /* nothing */
+#endif // _MSC_VER <= 1800
+#endif // _MSC_VER
+
+namespace gsl
+{
+
+//
+// GSL.util: Utilities
+//////////////////////
+
+// This component is a `gsl` utility that allows you to ensure that an act
+// gets performed at the end of a scope
+template <class F>
+class final_action
+{
+public:
+    explicit final_action(F f) noexcept : f_(std::move(f)), invoke_(true) {}
+
+    final_action(final_action&& other) noexcept : f_(std::move(other.f_)), invoke_(true) { other.invoke_ = false; }
+
+    ~final_action() noexcept { if (invoke_) f_(); }
+
+private:
+	final_action(const final_action&) = delete;
+    final_action& operator=(const final_action&) = delete;
+
+private:
+    F f_;
+    bool invoke_;
+};
+
+//
+// Function name: finally
+//
+// This is convenience function to generate a final_action
+//
+template <class F>
+final_action<F> finally(const F& act) noexcept { return final_action<F>(act); }
+
+template <class F>
+final_action<F> finally(F&& act) noexcept {	return final_action<F>(std::forward<F>(act)); }
+
+} // close namespace gsl
+
+#endif // GSL_FINAL_ACTION_H