90 lines
3.4 KiB
C++
90 lines
3.4 KiB
C++
// Copyright (c) 2014 Marshall A. Greenblatt. Portions copyright (c) 2011
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// Google Inc. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the name Chromium Embedded
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// Framework nor the names of its contributors may be used to endorse
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// or promote products derived from this software without specific prior
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// written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// base::AutoReset<> is useful for setting a variable to a new value only within
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// a particular scope. An base::AutoReset<> object resets a variable to its
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// original value upon destruction, making it an alternative to writing
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// "var = false;" or "var = old_val;" at all of a block's exit points.
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//
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// This should be obvious, but note that an base::AutoReset<> instance should
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// have a shorter lifetime than its scoped_variable, to prevent invalid memory
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// writes when the base::AutoReset<> object is destroyed.
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#ifndef CEF_INCLUDE_BASE_CEF_AUTO_RESET_H_
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#define CEF_INCLUDE_BASE_CEF_AUTO_RESET_H_
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#pragma once
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#if defined(USING_CHROMIUM_INCLUDES)
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// When building CEF include the Chromium header directly.
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#include "base/auto_reset.h"
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#else // !USING_CHROMIUM_INCLUDES
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// The following is substantially similar to the Chromium implementation.
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// If the Chromium implementation diverges the below implementation should be
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// updated to match.
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#include <utility>
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namespace base {
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template <typename T>
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class AutoReset {
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public:
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template <typename U>
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AutoReset(T* scoped_variable, U&& new_value)
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: scoped_variable_(scoped_variable),
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original_value_(
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std::exchange(*scoped_variable_, std::forward<U>(new_value))) {}
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AutoReset(AutoReset&& other)
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: scoped_variable_(std::exchange(other.scoped_variable_, nullptr)),
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original_value_(std::move(other.original_value_)) {}
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AutoReset& operator=(AutoReset&& rhs) {
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scoped_variable_ = std::exchange(rhs.scoped_variable_, nullptr);
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original_value_ = std::move(rhs.original_value_);
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return *this;
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}
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~AutoReset() {
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if (scoped_variable_)
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*scoped_variable_ = std::move(original_value_);
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}
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private:
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T* scoped_variable_;
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T original_value_;
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};
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} // namespace base
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#endif // !USING_CHROMIUM_INCLUDES
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#endif // CEF_INCLUDE_BASE_CEF_AUTO_RESET_H_
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