/* -*- Mode: C; tab-width: 4 -*-
*
* Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
File: GenLinkedList.c
Contains: implementation of generic linked lists.
Version: 1.0
Tabs: 4 spaces
*/
#include "GenLinkedList.h"
// Return the link pointer contained within element e at offset o.
#define GETLINK( e, o) ( *(void**)((char*) (e) + (o)) )
// Assign the link pointer l to element e at offset o.
#define ASSIGNLINK( e, l, o) ( *((void**)((char*) (e) + (o))) = (l))
// GenLinkedList /////////////////////////////////////////////////////////////
void InitLinkedList( GenLinkedList *pList, size_t linkOffset)
/* Initialize the block of memory pointed to by pList as a linked list. */
{
pList->Head = NULL;
pList->Tail = NULL;
pList->LinkOffset = linkOffset;
}
void AddToTail( GenLinkedList *pList, void *elem)
/* Add a linked list element to the tail of the list. */
{
if ( pList->Tail) {
ASSIGNLINK( pList->Tail, elem, pList->LinkOffset);
} else
pList->Head = elem;
ASSIGNLINK( elem, NULL, pList->LinkOffset);
pList->Tail = elem;
}
void AddToHead( GenLinkedList *pList, void *elem)
/* Add a linked list element to the head of the list. */
{
ASSIGNLINK( elem, pList->Head, pList->LinkOffset);
if ( pList->Tail == NULL)
pList->Tail = elem;
pList->Head = elem;
}
int RemoveFromList( GenLinkedList *pList, void *elem)
/* Remove a linked list element from the list. Return 0 if it was not found. */
/* If the element is removed, its link will be set to NULL. */
{
void *iElem, *lastElem;
for ( iElem = pList->Head, lastElem = NULL; iElem; iElem = GETLINK( iElem, pList->LinkOffset)) {
if ( iElem == elem) {
if ( lastElem) { // somewhere past the head
ASSIGNLINK( lastElem, GETLINK( elem, pList->LinkOffset), pList->LinkOffset);
} else { // at the head
pList->Head = GETLINK( elem, pList->LinkOffset);
}
if ( pList->Tail == elem)
pList->Tail = lastElem ? lastElem : NULL;
ASSIGNLINK( elem, NULL, pList->LinkOffset); // maybe catch a stale reference bug.
return 1;
}
lastElem = iElem;
}
return 0;
}
int ReplaceElem( GenLinkedList *pList, void *elemInList, void *newElem)
/* Replace an element in the list with a new element, in the same position. */
{
void *iElem, *lastElem;
if ( elemInList == NULL || newElem == NULL)
return 0;
for ( iElem = pList->Head, lastElem = NULL; iElem; iElem = GETLINK( iElem, pList->LinkOffset))
{
if ( iElem == elemInList)
{
ASSIGNLINK( newElem, GETLINK( elemInList, pList->LinkOffset), pList->LinkOffset);
if ( lastElem) // somewhere past the head
{
ASSIGNLINK( lastElem, newElem, pList->LinkOffset);
}
else // at the head
{
pList->Head = newElem;
}
if ( pList->Tail == elemInList)
pList->Tail = newElem;
return 1;
}
lastElem = iElem;
}
return 0;
}
// GenDoubleLinkedList /////////////////////////////////////////////////////////
void InitDoubleLinkedList( GenDoubleLinkedList *pList, size_t fwdLinkOffset,
size_t backLinkOffset)
/* Initialize the block of memory pointed to by pList as a double linked list. */
{
pList->Head = NULL;
pList->Tail = NULL;
pList->FwdLinkOffset = fwdLinkOffset;
pList->BackLinkOffset = backLinkOffset;
}
void DLLAddToHead( GenDoubleLinkedList *pList, void *elem)
/* Add a linked list element to the head of the list. */
{
void *pNext;
pNext = pList->Head;
// fix up the forward links
ASSIGNLINK( elem, pList->Head, pList->FwdLinkOffset);
pList->Head = elem;
// fix up the backward links
if ( pNext) {
ASSIGNLINK( pNext, elem, pList->BackLinkOffset);
} else
pList->Tail = elem;
ASSIGNLINK( elem, NULL, pList->BackLinkOffset);
}
void DLLRemoveFromList( GenDoubleLinkedList *pList, void *elem)
/* Remove a linked list element from the list. */
/* When the element is removed, its link will be set to NULL. */
{
void *pNext, *pPrev;
pNext = GETLINK( elem, pList->FwdLinkOffset);
pPrev = GETLINK( elem, pList->BackLinkOffset);
// fix up the forward links
if ( pPrev)
ASSIGNLINK( pPrev, pNext, pList->FwdLinkOffset);
else
pList->Head = pNext;
// fix up the backward links
if ( pNext)
ASSIGNLINK( pNext, pPrev, pList->BackLinkOffset);
else
pList->Tail = pPrev;
ASSIGNLINK( elem, NULL, pList->FwdLinkOffset);
ASSIGNLINK( elem, NULL, pList->BackLinkOffset);
}
// GenLinkedOffsetList /////////////////////////////////////////////////////
// Extract the Next offset from element
#define GETOFFSET( e, o) ( *(size_t*)((char*) (e) + (o)) )
static void AssignOffsetLink( void *elem, void *link, size_t linkOffset);
static void AssignOffsetLink( void *elem, void *link, size_t linkOffset)
// Assign link to elem as an offset from elem. Assign 0 to elem if link is NULL.
{
GETOFFSET( elem, linkOffset) = link ? (size_t) link - (size_t) elem : 0;
}
void *GetHeadPtr( GenLinkedOffsetList *pList)
/* Return a pointer to the head element of a list, or NULL if none. */
{
return pList->Head ? ( (char*) (pList) + pList->Head) : NULL;
}
void *GetTailPtr( GenLinkedOffsetList *pList)
/* Return a pointer to the tail element of a list, or NULL if none. */
{
return pList->Tail ? ( (char*) (pList) + pList->Tail) : NULL;
}
void *GetOffsetLink( GenLinkedOffsetList *pList, void *elem)
/* Return the link pointer contained within element e for pList, or NULL if it is 0. */
{
size_t nextOffset;
nextOffset = GETOFFSET( elem, pList->LinkOffset);
return nextOffset ? (char*) elem + nextOffset : NULL;
}
void InitLinkedOffsetList( GenLinkedOffsetList *pList, size_t linkOffset)
/* Initialize the block of memory pointed to by pList as a linked list. */
{
pList->Head = 0;
pList->Tail = 0;
pList->LinkOffset = linkOffset;
}
void OffsetAddToTail( GenLinkedOffsetList *pList, void *elem)
/* Add a linked list element to the tail of the list. */
{
if ( pList->Tail) {
AssignOffsetLink( GetTailPtr( pList), elem, pList->LinkOffset);
} else
pList->Head = (size_t) elem - (size_t) pList;
AssignOffsetLink( elem, NULL, pList->LinkOffset);
pList->Tail = (size_t) elem - (size_t) pList;
}
void OffsetAddToHead( GenLinkedOffsetList *pList, void *elem)
/* Add a linked list element to the head of the list. */
{
AssignOffsetLink( elem, GetHeadPtr( pList), pList->LinkOffset);
if ( pList->Tail == 0)
pList->Tail = (size_t) elem - (size_t) pList;
pList->Head = (size_t) elem - (size_t) pList;
}
int OffsetRemoveFromList( GenLinkedOffsetList *pList, void *elem)
/* Remove a linked list element from the list. Return 0 if it was not found. */
/* If the element is removed, its link will be set to NULL. */
{
void *iElem, *lastElem;
for ( iElem = GetHeadPtr( pList), lastElem = NULL; iElem;
iElem = GetOffsetLink( pList, iElem))
{
if ( iElem == elem) {
if ( lastElem) { // somewhere past the head
AssignOffsetLink( lastElem, GetOffsetLink( pList, elem), pList->LinkOffset);
} else { // at the head
iElem = GetOffsetLink( pList, elem);
pList->Head = iElem ? (size_t) iElem - (size_t) pList : 0;
}
if ( GetTailPtr( pList) == elem)
pList->Tail = lastElem ? (size_t) lastElem - (size_t) pList : 0;
AssignOffsetLink( elem, NULL, pList->LinkOffset); // maybe catch a stale reference bug.
return 1;
}
lastElem = iElem;
}
return 0;
}
int OffsetReplaceElem( GenLinkedOffsetList *pList, void *elemInList, void *newElem)
/* Replace an element in the list with a new element, in the same position. */
{
void *iElem, *lastElem;
if ( elemInList == NULL || newElem == NULL)
return 0;
for ( iElem = GetHeadPtr( pList), lastElem = NULL; iElem;
iElem = GetOffsetLink( pList, iElem))
{
if ( iElem == elemInList)
{
AssignOffsetLink( newElem, GetOffsetLink( pList, elemInList), pList->LinkOffset);
if ( lastElem) // somewhere past the head
{
AssignOffsetLink( lastElem, newElem, pList->LinkOffset);
}
else // at the head
{
pList->Head = (size_t) newElem - (size_t) pList;
}
if ( GetTailPtr( pList) == elemInList)
pList->Tail = (size_t) newElem - (size_t) pList;
return 1;
}
lastElem = iElem;
}
return 0;
}