80 lines
2.4 KiB
C++
80 lines
2.4 KiB
C++
/*
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* Copyright (c) 2003-2008, John Wiegley. 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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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* - Neither the name of New Artisans LLC nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior 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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*/
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/**
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* @file pushvar.h
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* @author John Wiegley
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* @date Sun May 6 20:10:52 2007
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*
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* @brief Adds a facility to C++ for handling "scoped yet global".
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*/
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#ifndef _PUSHVAR_H
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#define _PUSHVAR_H
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template <typename T>
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class push_variable : public boost::noncopyable
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{
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push_variable();
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public:
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T& var;
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T prev;
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bool enabled;
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explicit push_variable(T& _var)
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: var(_var), prev(var), enabled(true) {
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TRACE_CTOR(push_variable, "T&");
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}
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explicit push_variable(T& _var, const T& value)
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: var(_var), prev(var), enabled(true) {
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TRACE_CTOR(push_variable, "T&, constT&");
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var = value;
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}
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~push_variable() throw() {
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TRACE_DTOR(push_variable);
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if (enabled)
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var = prev;
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}
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T& operator*() {
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return var;
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}
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T * operator->() {
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return &var;
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}
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void clear() {
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enabled = false;
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}
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};
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#endif // _PUSHVAR_H
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