73 lines
1.4 KiB
C
73 lines
1.4 KiB
C
/*
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* Doubly-linked list implementation with position marker
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* MD 2211 <md2211@users.sourceforge.net>, 2007
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*/
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#include <stdlib.h>
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#include "u_mem.h"
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#include "dl_list.h"
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dl_list *dl_init() {
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dl_list *list = d_malloc(sizeof(dl_list));
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list->first = NULL;
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list->last = NULL;
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list->current = NULL;
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list->size = 0;
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return list;
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}
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void dl_add(dl_list *list, void *data) {
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dl_item *item;
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item = d_malloc(sizeof(dl_item));
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item->data = data;
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item->prev = list->last;
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item->next = NULL;
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if (list->last != NULL) {
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list->last->next = item;
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}
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if (list->first == NULL) {
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list->first = item;
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list->current = item;
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}
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list->last = item;
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list->size++;
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}
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void dl_remove(dl_list *list, dl_item *item) {
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if (list->current == item) list->current = item->prev;
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if (list->first == item) list->first = item->next;
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else item->prev->next = item->next;
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if (list->last == item) list->last = item->prev;
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else item->next->prev = item->prev;
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d_free(item);
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list->size--;
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}
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int dl_is_empty(dl_list const *list) {
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return (list->first == NULL);
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}
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int dl_size(dl_list const *list) {
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return list->size;
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}
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int dl_forward(dl_list *list) {
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if (!dl_is_empty(list) && list->current->next != NULL) {
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list->current = list->current->next;
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return 1;
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}
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else return 0;
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}
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int dl_backward(dl_list *list) {
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if (!dl_is_empty(list) && list->current->prev != NULL) {
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list->current = list->current->prev;
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return 1;
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}
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else return 0;
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}
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