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349 lines
9.6 KiB
349 lines
9.6 KiB
#ifndef __CLIST_H__
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#define __CLIST_H__
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//
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// TFList - a class for handling templated lists. Lists support adding
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// and removing items from the front and back of the list. The item on
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// the front or back can be examined. Using iterator the list can
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// be traversed easily (see the block comment below).
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//
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// The objects that this list hold should have this form:
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//
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// CListObject {
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// public:
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// CListObject *m_pNext; // for use by TFList<CListObject>
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// CListObject *m_pPrev; // for use by TFList<CListObject>
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// // other object parameters
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// }
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//
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// The constructor for the object should set m_pNext and m_pPrev to NULL
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// in debug builds to avoid hitting _ASSERTs.
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//
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// To construct the list you need to pass in the offsets for the m_pNext
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// and m_pPrev members using C++'s member offset syntax. Here is an
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// example:
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// TFList<CListObject> list(&CListObject::m_pPrev, &CListObject::m_pNext);
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//
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template <class Data> class TFList {
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public:
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typedef Data *Data::*NEXTPTR;
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protected:
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Data *m_pHead; // the head of the list
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Data *m_pTail; // the tail of the list
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NEXTPTR m_pNext; // offset to the next pointer
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NEXTPTR m_pPrev; // offset to the prev pointer
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public:
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TFList(NEXTPTR pPrev, NEXTPTR pNext) {
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m_pHead = NULL;
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m_pTail = NULL;
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m_pNext = pNext;
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m_pPrev = pPrev;
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}
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~TFList() {
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// the user should empty the list before deleting it
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_ASSERT(m_pHead == NULL);
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_ASSERT(m_pTail == NULL);
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}
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// see if the list is empty
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bool IsEmpty() {
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bool f = (m_pHead == NULL);
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// if the head is null then the tail has to be null
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_ASSERT(!f || m_pTail == NULL);
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return f;
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}
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// push an element onto the front of the list
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void PushFront(Data *node) {
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_ASSERT(node != NULL);
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// you can't put an entry into the list that is already in it
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_ASSERT(node->*m_pNext == NULL);
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_ASSERT(node->*m_pPrev == NULL);
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// set the next and prev pointers
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node->*m_pPrev = NULL;
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node->*m_pNext = m_pHead;
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// if the list is empty then this new item is the tail too
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if (IsEmpty()) {
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_ASSERT(m_pTail == NULL);
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m_pTail = node;
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} else {
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_ASSERT(m_pHead->*m_pPrev == NULL);
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m_pHead->*m_pPrev = node;
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}
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m_pHead = node;
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}
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// push an element onto the back of the list
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void PushBack(Data* node) {
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_ASSERT(node != NULL);
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// you can't put an entry into the list that is already in it
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_ASSERT(node->*m_pNext == NULL);
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_ASSERT(node->*m_pPrev == NULL);
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// set the next and prev pointers
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node->*m_pNext = NULL;
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node->*m_pPrev = m_pTail;
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// if the list is empty then this new item is the head too
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if (IsEmpty()) {
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_ASSERT(m_pHead == NULL);
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m_pHead = node;
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} else {
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_ASSERT(m_pTail->*m_pNext == NULL);
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m_pTail->*m_pNext = node;
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}
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m_pTail = node;
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}
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// remove the item from the front of the list
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Data *PopFront() {
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if (m_pHead == NULL) return NULL;
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Data *node = m_pHead;
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m_pHead = node->*m_pNext;
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if (m_pHead == NULL) m_pTail = NULL;
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else m_pHead->*m_pPrev = NULL;
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node->*m_pNext = NULL;
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node->*m_pPrev = NULL;
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return node;
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}
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// remove the item from the back of the list
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Data *PopBack() {
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if (m_pTail == NULL) return NULL;
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Data *node = m_pTail;
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m_pTail = node->*m_pPrev;
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if (m_pTail == NULL) m_pHead = NULL;
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else (m_pTail)->*m_pNext = NULL;
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node->*m_pNext = NULL;
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node->*m_pPrev = NULL;
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return node;
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}
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// get the item on the front of the list
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Data* GetFront() { return m_pHead; }
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// get the item on the back of the list
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Data* GetBack() { return m_pTail; }
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public:
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//
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// The Iterator object is used to walk the list and modify members
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// that are in the middle of the list. It is declared using this
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// syntax:
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// TFList<CListObject>::Iterator it(&list);
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//
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class Iterator {
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protected:
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Data *m_pCur; // our cursor
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int m_fForward; // TRUE for forward, FALSE for back
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TFList<Data> *m_pList; // the list that we are iterating
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NEXTPTR m_pPrev, m_pNext;
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public:
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//
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// create a new iterator object
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//
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// arguments:
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// pList - the list to iterate across
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// fForward - TRUE to start at the front, and go forward.
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// FALSE to start at the back, and go backwards.
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//
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Iterator(TFList<Data> *pList, BOOL fForward = TRUE) {
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_ASSERT(pList != NULL);
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m_pList = pList;
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m_fForward = fForward;
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m_pCur = (fForward) ? pList->m_pHead : pList->m_pTail;
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m_pPrev = pList->m_pPrev;
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m_pNext = pList->m_pNext;
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}
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void ResetHeader( TFList<Data> *pList ) {
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_ASSERT( pList != NULL );
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m_pList = pList;
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m_pCur = (m_fForward) ? m_pList->m_pHead : m_pList->m_pTail;
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m_pPrev = m_pList->m_pPrev;
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m_pNext = m_pList->m_pNext;
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}
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//
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// get a pointer to the current item
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//
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Data *Current() {
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return m_pCur;
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}
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//
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// go to the previous item in the list
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//
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void Prev() {
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if (m_pCur != NULL) {
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m_pCur = m_pCur->*m_pPrev;
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} else {
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// if they switch direction and are at the end of
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// the list then they need to get to a legal place
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if (m_fForward) m_pCur = m_pList->m_pTail;
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}
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m_fForward = FALSE;
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}
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//
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// go to the next item in the list
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//
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void Next() {
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if (m_pCur != NULL) {
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m_pCur = m_pCur->*m_pNext;
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} else {
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// if they switch direction and are at the end of
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// the list then they need to get to a legal place
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if (!m_fForward) m_pCur = m_pList->m_pHead;
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}
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m_fForward = TRUE;
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}
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//
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// Go to the head of the list
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//
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void Front() {
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m_pCur = m_pList->m_pHead;
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m_fForward = TRUE;
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}
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//
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// Go to the tail of the list
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//
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void Back() {
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m_pCur = m_pList->m_pTail;
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m_fForward = FALSE;
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}
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//
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// unlinks an item from the linked list
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//
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// cursor updates:
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// if the last movement in this list was forward then the
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// iterator will point towards the pPrev item in the list.
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// visa-versa if the last movement was backward. this is
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// so that a for loop over an iterator still works as
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// expected.
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//
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// returns:
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// a pointer to the item that was unlinked.
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//
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Data *RemoveItem(void) {
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Data *pTemp;
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if (m_pCur == NULL) return NULL;
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pTemp = m_pCur;
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// update cur
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if (m_fForward) Next(); else Prev();
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// fix head and tail pointers if necessary
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if (m_pList->m_pHead == pTemp)
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m_pList->m_pHead = pTemp->*m_pNext;
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if (m_pList->m_pTail == pTemp)
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m_pList->m_pTail = pTemp->*m_pPrev;
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// fix up the links on the adjacent elements
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if (pTemp->*m_pNext != NULL)
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pTemp->*m_pNext->*m_pPrev = pTemp->*m_pPrev;
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if (pTemp->*m_pPrev != NULL)
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pTemp->*m_pPrev->*m_pNext = pTemp->*m_pNext;
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// clean up the next and prev pointers
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pTemp->*m_pNext = NULL;
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pTemp->*m_pPrev = NULL;
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// return the item
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return pTemp;
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}
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//
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// insert a new item before the current item.
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//
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// Cursor updates:
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// If you use this method to insert an item then it should
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// not be visited if the next cursor movement is a Next().
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// If the next cursor movement is a Prev() then it should
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// be visited.
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//
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void InsertBefore(Data* pNode) {
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// this entry shouldn't be linked into the list
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_ASSERT(pNode->*m_pNext == NULL);
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_ASSERT(pNode->*m_pPrev == NULL);
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if (m_pCur == NULL) {
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// if we are at the head of the list then we'll insert
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// before the head
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if (m_fForward) {
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m_pList->PushFront(pNode);
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// set the current pointer to this item, so that
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// if we iterate forward we dont' see this item
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m_pCur = pNode;
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} else {
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// invalid operation. do nothing
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_ASSERT(FALSE);
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}
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} else {
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pNode->*m_pNext = m_pCur;
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pNode->*m_pPrev = m_pCur->*m_pPrev;
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m_pCur->*m_pPrev = pNode;
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if (pNode->*m_pPrev != NULL)
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pNode->*m_pPrev->*m_pNext = pNode;
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if (m_pList->m_pHead == m_pCur)
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m_pList->m_pHead = pNode;
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}
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}
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//
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// insert a new item after the current item.
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//
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// Cursor updates are the opposite of InsertBefore().
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//
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void InsertAfter(Data *pNode) {
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// this entry shouldn't be linked into the list
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_ASSERT(pNode->*m_pNext == NULL);
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_ASSERT(pNode->*m_pPrev == NULL);
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if (m_pCur == NULL) {
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// if we are at the tail of the list then we'll insert
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// before the tail
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if (!m_fForward) {
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m_pList->PushBack(pNode);
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// set the current pointer to this item, so that
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// if we iterate backwards we dont' see this item
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m_pCur = pNode;
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} else {
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// invalid operation. do nothing
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_ASSERT(FALSE);
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}
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} else {
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pNode->*m_pPrev = m_pCur;
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pNode->*m_pNext = m_pCur->*m_pNext;
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m_pCur->*m_pNext = pNode;
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if (pNode->*m_pNext != NULL)
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pNode->*m_pNext->*m_pPrev = pNode;
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if (m_pList->m_pTail == m_pCur)
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m_pList->m_pTail = pNode;
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}
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}
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//
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// see if we are at either the front or back of the list
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//
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bool AtEnd() {
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return (m_pCur == NULL);
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}
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};
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friend class TFList<Data>::Iterator;
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};
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#endif
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