diff options
Diffstat (limited to 'src/list.c')
| -rw-r--r-- | src/list.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/src/list.c b/src/list.c new file mode 100644 index 0000000..d9180b7 --- /dev/null +++ b/src/list.c @@ -0,0 +1,105 @@ +/* + * Copyright 2007-2012 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 <colm/pdarun.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; +} + |