68 lines
1.9 KiB
Plaintext
68 lines
1.9 KiB
Plaintext
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//C++ header - Open Scene Graph - Copyright (C) 1998-2001 Robert Osfield
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//Distributed under the terms of the GNU Library General Public License (LGPL)
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//as published by the Free Software Foundation.
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#ifndef OSG_FAST_BACK_STACK
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#define OSG_FAST_BACK_STACK 1
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namespace osg {
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/** Simple stack implementation that keeps the back() cached locally for fast access
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* rather than at the back of the vector which is the traditional stack implementation.
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* A conventional std::vector<> stores the rest of the stack. The fast_back_stack
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* although contains a stl container it only implments the back push_back(),pop_back()
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* and back() methods so is not as general purpose as stl stack implementation.
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* The focus of the fast_back_stack is purly to maximize the speed at which the
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* back can be accessed.*/
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template<class T>
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class fast_back_stack
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{
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public:
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inline fast_back_stack():_value(),_stack(),_size(0) {}
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inline fast_back_stack(const T& value):_value(value),_stack(),_size(1) {}
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inline void clear() { _stack.clear(); _size = 0; }
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inline bool empty() const { return _size==0; }
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inline unsigned int size() const { return _size; }
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inline T& back() { return _value; }
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inline const T& back() const { return _value; }
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inline void push_back(const T& value)
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{
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if (_size>0)
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{
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_stack.push_back(_value);
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}
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_value = value;
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++_size;
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}
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inline void pop_back()
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{
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if (_size>0)
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{
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if (!_stack.empty())
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{
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_value = _stack.back();
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_stack.pop_back();
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}
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--_size;
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} // else error condition.
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}
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T _value;
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std::vector<T> _stack;
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unsigned int _size;
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};
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}
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#endif
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