Add zstd.

3rdparty/zstd-1.5.0/contrib/pzstd/utils/ScopeGuard.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ */
+#pragma once
+
+#include <utility>
+
+namespace pzstd {
+
+/**
+ * Dismissable scope guard.
+ * `Function` must be callable and take no parameters.
+ * Unless `dissmiss()` is called, the callable is executed upon destruction of
+ * `ScopeGuard`.
+ *
+ * Example:
+ *
+ *   auto guard = makeScopeGuard([&] { cleanup(); });
+ */
+template <typename Function>
+class ScopeGuard {
+  Function function;
+  bool dismissed;
+
+ public:
+  explicit ScopeGuard(Function&& function)
+      : function(std::move(function)), dismissed(false) {}
+
+  void dismiss() {
+    dismissed = true;
+  }
+
+  ~ScopeGuard() noexcept {
+    if (!dismissed) {
+      function();
+    }
+  }
+};
+
+/// Creates a scope guard from `function`.
+template <typename Function>
+ScopeGuard<Function> makeScopeGuard(Function&& function) {
+  return ScopeGuard<Function>(std::forward<Function>(function));
+}
+}