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/* Standard C */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
/* Project */
#include "util.h"
typedef int T;
struct list_node {
struct list_node *next;
T data;
};
struct list {
struct list_node *head, *tail;
};
void
list_init(struct list *list)
{
list->head = NULL;
}
static struct list_node *
create_node(struct list_node *next, T data)
{
struct list_node *node = malloc(sizeof *node);
if ( node != NULL ) {
node->next = next;
node->data = data;
}
return node;
}
void
list_push_back(struct list *list, T data)
{
struct list_node *node = create_node(NULL, data);
if ( node != NULL ) {
if ( list->head == NULL ) {
list->head = node;
}
else {
list->tail->next = node;
}
list->tail = node;
}
else {
ERROR("out of memory");
}
}
void
list_push_front(struct list *list, T data)
{
struct list_node *node = create_node(list->head, data);
if ( node != NULL ) {
if ( list->head == NULL ) { // Einfügen in eine leere Liste?
list->tail = node;
}
list->head = node;
}
else {
ERROR("out of memory");
}
}
bool
list_pop_front(struct list *list, T *data)
{
if ( list->head != NULL ) {
struct list_node *next = list->head->next;
*data = list->head->data;
free(list->head);
list->head = next;
return true;
}
else
return false;
}
bool
list_empty(struct list *list)
{
return list->head == NULL;
}
void
list_free(struct list *list)
{
struct list_node *item, *next;
for ( item = list->head; item; item = next ) {
next = item->next;
free(item);
}
}
int
main()
{
struct list list[1];
list_init(list);
for ( int i = 0; i != 10; ++i )
list_push_front(list, -i);
for ( int i = 0; i != 10; ++i )
list_push_back(list, i);
while ( !list_empty(list) ) {
int i;
if ( list_pop_front(list, &i) )
printf("%d\n", i);
else
ERROR("this shouldn't happen!");
}
list_free(list);
return EXIT_SUCCESS;
}
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