98 lines
2.8 KiB
C++
98 lines
2.8 KiB
C++
/* -*-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
|