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/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
*
* This library is open source and may be redistributed and/or modified under
* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
* (at your option) any later version. The full license is in LICENSE file
* included with this distribution, and on the openscenegraph.org website.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* OpenSceneGraph Public License for more details.
*/
#ifndef OSG_FAST_BACK_STACK
#define OSG_FAST_BACK_STACK 1
#include <vector>
namespace osg {
/** Simple stack implementation that keeps the back() cached locally for fast access
* rather than at the back of the vector which is the traditional stack implementation.
* A conventional std::vector<> stores the rest of the stack. Although fast_back_stack
* contains a stl container it only implements the back push_back(),pop_back()
* and back() methods so is not as general purpose as stl stack implementation.
* The focus of the fast_back_stack is purely to maximize the speed at which the
* back can be accessed.*/
template<class T>
class fast_back_stack
{
public:
inline fast_back_stack():_value(),_stack(),_size(0) {}
inline fast_back_stack(const fast_back_stack& fbs):_value(fbs._value),_stack(fbs._stack),_size(fbs._size) {}
inline fast_back_stack(const T& value):_value(value),_stack(),_size(1) {}
fast_back_stack& operator = (const fast_back_stack& fbs)
{
_value = fbs._value;
_stack = fbs._stack;
_size = fbs._size;
return *this;
}
inline void clear() { _stack.clear(); _size = 0; }
inline bool empty() const { return _size==0; }
inline unsigned int size() const { return _size; }
inline T& back() { return _value; }
inline const T& back() const { return _value; }
inline void push_back()
{
if (_size>0)
{
_stack.push_back(_value);
}
++_size;
}
inline void push_back(const T& value)
{
if (_size>0)
{
_stack.push_back(_value);
}
_value = value;
++_size;
}
inline void pop_back()
{
if (_size>0)
{
if (!_stack.empty())
{
_value = _stack.back();
_stack.pop_back();
}
--_size;
} // else error condition.
}
T _value;
std::vector<T> _stack;
unsigned int _size;
};
}
#endif