OBLIST.CPP

//**************************************************************************** 
// 
//  SKIPPY! sample for Microsoft NetMeeting SDK 
// 
//  File:       oblist.cpp 
//  Content:    This file contains the list class functions. 
// 
//  Copyright (c) Microsoft Corporation 1997 
//  All rights reserved 
// 
//**************************************************************************** 
 
#include <windows.h> 
#include "oblist.h" 
 
//**************************************************************************** 
// void* COBLIST::GetTail() 
// 
// Returns the end of the list. 
// 
//**************************************************************************** 
VOID* COBLIST::GetTail() 
{ 
return m_pTail->pItem; 
} 
 
//**************************************************************************** 
// VOID* COBLIST::GetNext(POSITION& rPos) 
// 
// Returns the next item of the list. 
// 
//**************************************************************************** 
VOID* COBLIST::GetNext(POSITION& rPos) 
{ 
VOID* pReturn = rPos->pItem; 
rPos = rPos->pNext; 
return pReturn; 
} 
 
//**************************************************************************** 
// VOID* COBLIST::RemoveAt(POSITION Pos) 
// 
// Removes an item from the list. 
// 
//**************************************************************************** 
VOID* COBLIST::RemoveAt(POSITION Pos) 
{ 
VOID* pReturn = NULL; 
 
if (m_pHead) 
{ 
if (m_pHead == Pos) 
{ 
// Removing the first element in the list 
 
m_pHead = Pos->pNext; 
pReturn = Pos->pItem; 
delete Pos; 
 
if (NULL == m_pHead) 
{ 
// Removing the only element! 
m_pTail = NULL; 
} 
} 
else 
{ 
POSITION pCur = m_pHead; 
 
while (pCur && pCur->pNext) 
{ 
if (pCur->pNext == Pos) 
{ 
// Removing  
 
pCur->pNext = Pos->pNext; 
if (m_pTail == Pos) 
{ 
m_pTail = pCur; 
} 
pReturn = Pos->pItem; 
delete Pos; 
} 
 
pCur = pCur->pNext; 
} 
} 
} 
 
return pReturn; 
} 
 
 
//**************************************************************************** 
// POSITION COBLIST::AddTail(VOID* pItem) 
// 
// Add to the end of the list. 
// 
//**************************************************************************** 
POSITION COBLIST::AddTail(VOID* pItem) 
{ 
POSITION posRet = NULL; 
 
if (m_pTail) 
{ 
if (m_pTail->pNext = new COBNODE) 
{ 
m_pTail = m_pTail->pNext; 
m_pTail->pItem = pItem; 
m_pTail->pNext = NULL; 
} 
} 
else 
{ 
if (m_pHead = new COBNODE) 
{ 
m_pTail = m_pHead; 
m_pTail->pItem = pItem; 
m_pTail->pNext = NULL; 
} 
} 
 
return m_pTail; 
} 
 
//**************************************************************************** 
// POSITION COBLIST::EmpytList(VOID* pItem) 
// 
// Frees the entire list. 
// 
//**************************************************************************** 
void COBLIST::EmptyList() 
{ 
while (!IsEmpty()) { 
RemoveAt(GetHeadPosition()); 
} 
} 
 
 
//**************************************************************************** 
// POSITION COBLIST::GetPosition(VOID* _pItem) 
// 
// return the position of an item in the list 
// 
//**************************************************************************** 
POSITION COBLIST::GetPosition(void* _pItem) 
{ 
POSITION Position = m_pHead; 
 
while (Position) { 
if (Position->pItem == _pItem) { 
break; 
} 
GetNext(Position); 
} 
return Position; 
} 
 
//**************************************************************************** 
// POSITION COBLIST::Lookup(VOID* _pItem) 
// 
// 
//**************************************************************************** 
POSITION COBLIST::Lookup(void* pComparator) 
{ 
POSITION    Position = m_pHead; 
 
while (Position) { 
if (Compare(Position->pItem, pComparator)) { 
break; 
} 
GetNext(Position); 
} 
return Position; 
} 
 
 
//**************************************************************************** 
// POSITION COBLIST::SafeGetFromPosition(POSITION Pos) 
// 
// Safe way to validate that an entry is still in the list, 
// 
//**************************************************************************** 
void * COBLIST::SafeGetFromPosition(POSITION Pos) 
{ 
POSITION PosWork = m_pHead; 
 
while (PosWork) { 
if (PosWork == Pos) { 
return Pos->pItem; 
} 
GetNext(PosWork); 
} 
return NULL; 
}