125 lines
2.2 KiB
C
125 lines
2.2 KiB
C
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// generic queue class
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// usage:
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// QueueOf<char *> charq;
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#ifndef _QUEUE_H_
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#define _QUEUE_H_
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template <class T>
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class QueueOf
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{
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public:
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QueueOf(): m_maxItems(8),m_iFirst(0),m_iLast(0)
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{
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// m_maxItems is always a power of 2
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m_List = new T [m_maxItems];
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}
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// returns TRUE if the queue is empty and FALSE otherwise
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BOOL IsEmpty(void) { return (m_iLast == m_iFirst);}
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// add an element to the tail of the queue
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// makes a copy of the element
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BOOL Put(const T &itemT)
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{
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int inext;
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inext = (m_iLast+1)&(m_maxItems-1);
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if (inext == m_iFirst)
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{
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// too many items
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if (!Grow())
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{
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return FALSE;
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}
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inext = (m_iLast+1)&(m_maxItems-1);
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}
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m_List[m_iLast] = itemT;
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m_iLast = inext;
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return TRUE;
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}
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// get the first element in the queue
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BOOL Get(T *pT)
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{
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if (IsEmpty())
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return FALSE; // nothing in queue
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else
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{
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if (pT)
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*pT = m_List[m_iFirst];
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m_iFirst = (m_iFirst+1)&(m_maxItems-1);
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return TRUE;
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}
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}
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// get the ith element in the queue without removing it
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BOOL Peek(T *pT, UINT pos=0)
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{
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if (pos >= GetCount())
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return FALSE;
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else
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{
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*pT = m_List[(m_iFirst+pos)&(m_maxItems-1)];
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return TRUE;
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}
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}
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// delete the ith element in the queue (this is not an efficient function!)
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BOOL Remove(UINT pos)
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{
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if (pos >= GetCount())
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return FALSE;
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else
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{
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int i1 = (m_iFirst+(int)pos)&(m_maxItems-1);
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int i2 = (i1+1)&(m_maxItems-1);
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// shift left to fill the gap
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for (; i2 != m_iLast; i1=i2,i2=(i2+1)&(m_maxItems-1))
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{
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m_List[i1] = m_List[i2];
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}
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m_iLast = i1; // i1 = m_iLast-1
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return TRUE;
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}
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}
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// return the number of elements in the queue
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UINT GetCount(void)
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{
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return (m_iLast >= m_iFirst ? m_iLast-m_iFirst : m_iLast+m_maxItems-m_iFirst);
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}
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~QueueOf()
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{
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delete []m_List;
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}
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private:
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BOOL Grow(void)
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{
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int i,j;
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// double the size of the queue array
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T* pNewList = new T [m_maxItems*2];
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if (!pNewList)
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return FALSE;
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for (i=0, j=m_iFirst; j != m_iLast; i++, j = ((++j)&(m_maxItems-1)))
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{
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pNewList[i] = m_List[j];
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}
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m_iFirst = 0;
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m_iLast = i;
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m_maxItems = m_maxItems*2;
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delete [] m_List;
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m_List = pNewList;
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return TRUE;
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}
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int m_maxItems;
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int m_iFirst;
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int m_iLast;
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T *m_List;
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};
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;
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#endif
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