278 lines
5.0 KiB
C
278 lines
5.0 KiB
C
/******************************************************************
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**
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** IQUEUE.C:
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**
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** ADT Queue Iterator Implementation
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**
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** This file is part of Apt Abstrct Data Types (ADT)
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** Copyright (c) 1991 -- Apt Technologies
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** All rights reserved
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**
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** The concept of an iterator for an Abstract Data Type is derived
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** from research on Smalltalk.
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******************************************************************/
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/* ---------- C Headers */
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//#include "cheaders.h"
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/* ---------- Headers */
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#include "adterror.h"
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#include "allocate.h"
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#include "iqueue.h"
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/* ---------- Private Function Prototypes */
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#ifdef __ANSI_C__
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#else
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#endif
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/* ---------- Functions */
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/*
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**
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** QueueIteratorDispose
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void QueueIteratorDispose(QueueIterator qi)
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#else
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void QueueIteratorDispose(qi)
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QueueIterator qi;
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#endif
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{
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free(qi);
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}
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/*
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**
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** QueueIteratorNew
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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QueueIterator QueueIteratorNew(Queue q, int start)
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#else
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QueueIterator QueueIteratorNew(q,start)
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Queue q;
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int start;
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#endif
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{
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QueueIterator qi;
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if (q)
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qi = ((QueueIterator)Allocate(sizeof(_QueueIterator)));
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else {
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ADTError(ADT_QueueIter, E_NullQueue, "QueueIteratorNew");
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return NULL;
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}
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if (qi) {
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qi->queue = q;
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QueueIteratorAbsoluteSeek(qi, start);
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} else
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ADTError(ADT_QueueIter, E_Allocation, "QueueIteratorNew");
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return (qi);
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}
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/*
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**
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** QueueIteratorAtTop
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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int QueueIteratorAtTop(QueueIterator qi)
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#else
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int QueueIteratorAtTop(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorAtTop");
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return QueueIteratorAtPosition(qi,1);
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}
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/*
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**
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** QueueIteratorAtBottom
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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int QueueIteratorAtBottom(QueueIterator qi)
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#else
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int QueueIteratorAtBottom(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorAtBottom");
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return QueueIteratorAtPosition(qi,0);
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}
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/*
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**
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** QueueIteratorAtPosition
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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int QueueIteratorAtPosition(QueueIterator qi, int position)
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#else
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int QueueIteratorAtPosition(qi,position)
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QueueIterator qi;
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int position;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorAtPosition");
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if (position <= 0)
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position += (QueueSize(qi->queue) + 1);
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return qi->position == position;
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}
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/*
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**
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** QueueIteratorPosition
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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int QueueIteratorPosition(QueueIterator qi)
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#else
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int QueueIteratorPosition(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorPosition");
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return qi->position;
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}
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/*
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**
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** QueueIteratorCurrentData
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void *QueueIteratorCurrentData(QueueIterator qi)
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#else
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void *QueueIteratorCurrentData(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorCurrentData");
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return QueueItemElement(qi->currentItem);
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}
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/*
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**
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** QueueIteratorPreviousData
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void *QueueIteratorPreviousData(QueueIterator qi)
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#else
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void *QueueIteratorPreviousData(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorPreviousData");
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return QueueItemElement(qi->previousItem);
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}
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/*
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**
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** QueueIteratorAdvance
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void QueueIteratorAdvance(QueueIterator qi)
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#else
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void QueueIteratorAdvance(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorAdvance");
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qi->previousItem = qi->currentItem;
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qi->currentItem = QueueNext(qi->previousItem);
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if (qi->previousItem) qi->position++;
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}
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/*
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**
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** QueueIteratorBackup
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void QueueIteratorBackup(QueueIterator qi)
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#else
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void QueueIteratorBackup(qi)
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QueueIterator qi;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorBackup");
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QueueIteratorRelativeSeek(qi, -1);
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}
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/*
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**
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** QueueIteratorAbsoluteSeek
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void QueueIteratorAbsoluteSeek(QueueIterator qi, int position)
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#else
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void QueueIteratorAbsoluteSeek(qi,position)
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QueueIterator qi;
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int position;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorAbsoluteSeek");
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if (position <= 0)
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position += (QueueSize(qi->queue) + 1);
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if (position <= 0)
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ADTError(ADT_QueueIter, E_Seek, "QueueIteratorAbsoluteSeek");
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/* Here, we know position is positive */
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if (position > QueueSize(qi->queue) + 1)
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qi->position = QueueSize(qi->queue) + 1;
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else
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qi->position = position;
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qi->previousItem = QueueSeek(qi->queue,position-1);
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if (qi->previousItem)
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qi->currentItem = QueueNext(qi->previousItem);
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else
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qi->currentItem = QueueSeek(qi->queue,position);
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}
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/*
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**
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** QueueIteratorRelativeSeek
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**
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*/
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PUBLIC
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#ifdef __ANSI_C__
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void QueueIteratorRelativeSeek(QueueIterator qi,int disp)
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#else
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void QueueIteratorRelativeSeek(qi,disp)
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QueueIterator qi;
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int disp;
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#endif
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{
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if (!qi)
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ADTError(ADT_QueueIter, E_NullQueueIter, "QueueIteratorRelativeSeek");
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QueueIteratorAbsoluteSeek(qi,qi->position+disp);
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}
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