list.c

   1 /* evilwm - Minimalist Window Manager for X
   2  * Copyright (C) 1999-2009 Ciaran Anscomb <evilwm@6809.org.uk>
   3  * see README for license and other details. */
   4
   5 /* Basic linked list handling code.  Operations that modify the list
   6  * return the new list head.  */
   7
   8 #include <stdlib.h>
   9 #include "list.h"
  10
  11 /* Wrap data in a new list container */
  12 static struct list *list_new(void *data) {
  13         struct list *new;
  14         new = malloc(sizeof(struct list));
  15         if (!new) return NULL;
  16         new->next = NULL;
  17         new->data = data;
  18         return new;
  19 }
  20
  21 /* Add new data to head of list */
  22 struct list *list_prepend(struct list *list, void *data) {
  23         struct list *elem = list_new(data);
  24         if (!elem) return list;
  25         elem->next = list;
  26         return elem;
  27 }
  28
  29 /* Add new data to tail of list */
  30 struct list *list_append(struct list *list, void *data) {
  31         struct list *elem = list_new(data);
  32         struct list *iter;
  33         if (!elem) return list;
  34         if (!list) return elem;
  35         for (iter = list; iter->next; iter = iter->next);
  36         iter->next = elem;
  37         return list;
  38 }
  39
  40 /* Delete list element containing data */
  41 struct list *list_delete(struct list *list, void *data) {
  42         struct list **elemp;
  43         if (!data) return list;
  44         for (elemp = &list; *elemp; elemp = &(*elemp)->next) {
  45                 if ((*elemp)->data == data) break;
  46         }
  47         if (*elemp) {
  48                 struct list *elem = *elemp;
  49                 *elemp = elem->next;
  50                 free(elem);
  51         }
  52         return list;
  53 }
  54
  55 /* Move existing list element containing data to head of list */
  56 struct list *list_to_head(struct list *list, void *data) {
  57         if (!data) return list;
  58         list = list_delete(list, data);
  59         return list_prepend(list, data);
  60 }
  61
  62 /* Move existing list element containing data to tail of list */
  63 struct list *list_to_tail(struct list *list, void *data) {
  64         if (!data) return list;
  65         list = list_delete(list, data);
  66         return list_append(list, data);
  67 }
  68
  69 /* Find list element containing data */
  70 struct list *list_find(struct list *list, void *data) {
  71         struct list *elem;
  72         for (elem = list; elem; elem = elem->next) {
  73                 if (elem->data == data)
  74                         return elem;
  75         }
  76         return NULL;
  77 }