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/*
* Copyright 2007 Adrian Thurston <thurston@complang.org>
*/
/* This file is part of Colm.
*
* Colm is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* Colm is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Colm; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "pdarun2.h"
void listAddAfter( List *list, ListEl *prev_el, ListEl *new_el )
{
/* Set the previous pointer of new_el to prev_el. We do
* this regardless of the state of the list. */
new_el->prev = prev_el;
/* Set forward pointers. */
if (prev_el == 0) {
/* There was no prev_el, we are inserting at the head. */
new_el->next = list->head;
list->head = new_el;
}
else {
/* There was a prev_el, we can access previous next. */
new_el->next = prev_el->next;
prev_el->next = new_el;
}
/* Set reverse pointers. */
if (new_el->next == 0) {
/* There is no next element. Set the tail pointer. */
list->tail = new_el;
}
else {
/* There is a next element. Set it's prev pointer. */
new_el->next->prev = new_el;
}
/* Update list length. */
list->listLen++;
}
void listAddBefore( List *list, ListEl *next_el, ListEl *new_el)
{
/* Set the next pointer of the new element to next_el. We do
* this regardless of the state of the list. */
new_el->next = next_el;
/* Set reverse pointers. */
if (next_el == 0) {
/* There is no next elememnt. We are inserting at the tail. */
new_el->prev = list->tail;
list->tail = new_el;
}
else {
/* There is a next element and we can access next's previous. */
new_el->prev = next_el->prev;
next_el->prev = new_el;
}
/* Set forward pointers. */
if (new_el->prev == 0) {
/* There is no previous element. Set the head pointer.*/
list->head = new_el;
}
else {
/* There is a previous element, set it's next pointer to new_el. */
new_el->prev->next = new_el;
}
list->listLen++;
}
ListEl *listDetach( List *list, ListEl *el )
{
/* Set forward pointers to skip over el. */
if (el->prev == 0)
list->head = el->next;
else
el->prev->next = el->next;
/* Set reverse pointers to skip over el. */
if (el->next == 0)
list->tail = el->prev;
else
el->next->prev = el->prev;
/* Update List length and return element we detached. */
list->listLen--;
return el;
}
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