| /* |
| * Copyright (C) 2011 Google Inc. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * |
| * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY |
| * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
| * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY |
| * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
| * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| #ifndef TemporaryChange_h |
| #define TemporaryChange_h |
| |
| #include <wtf/Noncopyable.h> |
| |
| namespace WTF { |
| |
| // TemporaryChange<> is useful for setting a variable to a new value only within a |
| // particular scope. An TemporaryChange<> object changes a variable to its original |
| // value upon destruction, making it an alternative to writing "var = false;" |
| // or "var = oldVal;" at all of a block's exit points. |
| // |
| // This should be obvious, but note that an TemporaryChange<> instance should have a |
| // shorter lifetime than its scopedVariable, to prevent invalid memory writes |
| // when the TemporaryChange<> object is destroyed. |
| |
| template<typename T> |
| class TemporaryChange { |
| WTF_MAKE_NONCOPYABLE(TemporaryChange); |
| public: |
| TemporaryChange(T& scopedVariable, T newValue) |
| : m_scopedVariable(scopedVariable) |
| , m_originalValue(scopedVariable) |
| { |
| m_scopedVariable = newValue; |
| } |
| |
| ~TemporaryChange() |
| { |
| m_scopedVariable = m_originalValue; |
| } |
| |
| |
| private: |
| T& m_scopedVariable; |
| T m_originalValue; |
| }; |
| |
| } |
| |
| using WTF::TemporaryChange; |
| |
| #endif |