Implementation of two-way linked list in redis

I have to say that the Code in the data structure book is not practical.

C language code is rarely written, so it records useful code.

Adlist. h:

/* adlist.h - A generic doubly linked list implementation * * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * *   * Redistributions of source code must retain the above copyright notice, *     this list of conditions and the following disclaimer. *   * Redistributions in binary form must reproduce the above copyright *     notice, this list of conditions and the following disclaimer in the *     documentation and/or other materials provided with the distribution. *   * Neither the name of Redis nor the names of its contributors may be used *     to endorse or promote products derived from this software without *     specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */#ifndef __ADLIST_H__#define __ADLIST_H__/* Node, List, and Iterator are the only data structures used currently. */typedef struct listNode {    struct listNode *prev;    struct listNode *next;    void *value;} listNode;typedef struct listIter {    listNode *next;    int direction;} listIter;typedef struct list {    listNode *head;    listNode *tail;    void *(*dup)(void *ptr);    void (*free)(void *ptr);    int (*match)(void *ptr, void *key);    unsigned long len;} list;/* Functions implemented as macros */#define listLength(l) ((l)->len)#define listFirst(l) ((l)->head)#define listLast(l) ((l)->tail)#define listPrevNode(n) ((n)->prev)#define listNextNode(n) ((n)->next)#define listNodeValue(n) ((n)->value)#define listSetDupMethod(l,m) ((l)->dup = (m))#define listSetFreeMethod(l,m) ((l)->free = (m))#define listSetMatchMethod(l,m) ((l)->match = (m))#define listGetDupMethod(l) ((l)->dup)#define listGetFree(l) ((l)->free)#define listGetMatchMethod(l) ((l)->match)/* Prototypes */list *listCreate(void);void listRelease(list *list);list *listAddNodeHead(list *list, void *value);list *listAddNodeTail(list *list, void *value);list *listInsertNode(list *list, listNode *old_node, void *value, int after);void listDelNode(list *list, listNode *node);listIter *listGetIterator(list *list, int direction);listNode *listNext(listIter *iter);void listReleaseIterator(listIter *iter);list *listDup(list *orig);listNode *listSearchKey(list *list, void *key);listNode *listIndex(list *list, long index);void listRewind(list *list, listIter *li);void listRewindTail(list *list, listIter *li);void listRotate(list *list);/* Directions for iterators */#define AL_START_HEAD 0#define AL_START_TAIL 1#endif /* __ADLIST_H__ */

Adlist. C:

/* adlist.c - A generic doubly linked list implementation * * Copyright (c) 2006-2010, Salvatore Sanfilippo <antirez at gmail dot com> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * *   * Redistributions of source code must retain the above copyright notice, *     this list of conditions and the following disclaimer. *   * Redistributions in binary form must reproduce the above copyright *     notice, this list of conditions and the following disclaimer in the *     documentation and/or other materials provided with the distribution. *   * Neither the name of Redis nor the names of its contributors may be used *     to endorse or promote products derived from this software without *     specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */#include <stdlib.h>#include "adlist.h"#include "zmalloc.h"/* Create a new list. The created list can be freed with * AlFreeList(), but private value of every node need to be freed * by the user before to call AlFreeList(). * * On error, NULL is returned. Otherwise the pointer to the new list. */list *listCreate(void){    struct list *list;    if ((list = zmalloc(sizeof(*list))) == NULL)        return NULL;    list->head = list->tail = NULL;    list->len = 0;    list->dup = NULL;    list->free = NULL;    list->match = NULL;    return list;}/* Free the whole list. * * This function can't fail. */void listRelease(list *list){    unsigned long len;    listNode *current, *next;    current = list->head;    len = list->len;    while(len--) {        next = current->next;        if (list->free) list->free(current->value);        zfree(current);        current = next;    }    zfree(list);}/* Add a new node to the list, to head, contaning the specified 'value' * pointer as value. * * On error, NULL is returned and no operation is performed (i.e. the * list remains unaltered). * On success the 'list' pointer you pass to the function is returned. */list *listAddNodeHead(list *list, void *value){    listNode *node;    if ((node = zmalloc(sizeof(*node))) == NULL)        return NULL;    node->value = value;    if (list->len == 0) {        list->head = list->tail = node;        node->prev = node->next = NULL;    } else {        node->prev = NULL;        node->next = list->head;        list->head->prev = node;        list->head = node;    }    list->len++;    return list;}/* Add a new node to the list, to tail, contaning the specified 'value' * pointer as value. * * On error, NULL is returned and no operation is performed (i.e. the * list remains unaltered). * On success the 'list' pointer you pass to the function is returned. */list *listAddNodeTail(list *list, void *value){    listNode *node;    if ((node = zmalloc(sizeof(*node))) == NULL)        return NULL;    node->value = value;    if (list->len == 0) {        list->head = list->tail = node;        node->prev = node->next = NULL;    } else {        node->prev = list->tail;        node->next = NULL;        list->tail->next = node;        list->tail = node;    }    list->len++;    return list;}list *listInsertNode(list *list, listNode *old_node, void *value, int after) {    listNode *node;    if ((node = zmalloc(sizeof(*node))) == NULL)        return NULL;    node->value = value;    if (after) {        node->prev = old_node;        node->next = old_node->next;        if (list->tail == old_node) {            list->tail = node;        }    } else {        node->next = old_node;        node->prev = old_node->prev;        if (list->head == old_node) {            list->head = node;        }    }    if (node->prev != NULL) {        node->prev->next = node;    }    if (node->next != NULL) {        node->next->prev = node;    }    list->len++;    return list;}/* Remove the specified node from the specified list. * It's up to the caller to free the private value of the node. * * This function can't fail. */void listDelNode(list *list, listNode *node){    if (node->prev)        node->prev->next = node->next;    else        list->head = node->next;    if (node->next)        node->next->prev = node->prev;    else        list->tail = node->prev;    if (list->free) list->free(node->value);    zfree(node);    list->len--;}/* Returns a list iterator 'iter'. After the initialization every * call to listNext() will return the next element of the list. * * This function can't fail. */listIter *listGetIterator(list *list, int direction){    listIter *iter;        if ((iter = zmalloc(sizeof(*iter))) == NULL) return NULL;    if (direction == AL_START_HEAD)        iter->next = list->head;    else        iter->next = list->tail;    iter->direction = direction;    return iter;}/* Release the iterator memory */void listReleaseIterator(listIter *iter) {    zfree(iter);}/* Create an iterator in the list private iterator structure */void listRewind(list *list, listIter *li) {    li->next = list->head;    li->direction = AL_START_HEAD;}void listRewindTail(list *list, listIter *li) {    li->next = list->tail;    li->direction = AL_START_TAIL;}/* Return the next element of an iterator. * It's valid to remove the currently returned element using * listDelNode(), but not to remove other elements. * * The function returns a pointer to the next element of the list, * or NULL if there are no more elements, so the classical usage patter * is: * * iter = listGetIterator(list,<direction>); * while ((node = listNext(iter)) != NULL) { *     doSomethingWith(listNodeValue(node)); * } * * */listNode *listNext(listIter *iter){    listNode *current = iter->next;    if (current != NULL) {        if (iter->direction == AL_START_HEAD)            iter->next = current->next;        else            iter->next = current->prev;    }    return current;}/* Duplicate the whole list. On out of memory NULL is returned. * On success a copy of the original list is returned. * * The 'Dup' method set with listSetDupMethod() function is used * to copy the node value. Otherwise the same pointer value of * the original node is used as value of the copied node. * * The original list both on success or error is never modified. */list *listDup(list *orig){    list *copy;    listIter *iter;    listNode *node;    if ((copy = listCreate()) == NULL)        return NULL;    copy->dup = orig->dup;    copy->free = orig->free;    copy->match = orig->match;    iter = listGetIterator(orig, AL_START_HEAD);    while((node = listNext(iter)) != NULL) {        void *value;        if (copy->dup) {            value = copy->dup(node->value);            if (value == NULL) {                listRelease(copy);                listReleaseIterator(iter);                return NULL;            }        } else            value = node->value;        if (listAddNodeTail(copy, value) == NULL) {            listRelease(copy);            listReleaseIterator(iter);            return NULL;        }    }    listReleaseIterator(iter);    return copy;}/* Search the list for a node matching a given key. * The match is performed using the 'match' method * set with listSetMatchMethod(). If no 'match' method * is set, the 'value' pointer of every node is directly * compared with the 'key' pointer. * * On success the first matching node pointer is returned * (search starts from head). If no matching node exists * NULL is returned. */listNode *listSearchKey(list *list, void *key){    listIter *iter;    listNode *node;    iter = listGetIterator(list, AL_START_HEAD);    while((node = listNext(iter)) != NULL) {        if (list->match) {            if (list->match(node->value, key)) {                listReleaseIterator(iter);                return node;            }        } else {            if (key == node->value) {                listReleaseIterator(iter);                return node;            }        }    }    listReleaseIterator(iter);    return NULL;}/* Return the element at the specified zero-based index * where 0 is the head, 1 is the element next to head * and so on. Negative integers are used in order to count * from the tail, -1 is the last element, -2 the penultimante * and so on. If the index is out of range NULL is returned. */listNode *listIndex(list *list, long index) {    listNode *n;    if (index < 0) {        index = (-index)-1;        n = list->tail;        while(index-- && n) n = n->prev;    } else {        n = list->head;        while(index-- && n) n = n->next;    }    return n;}/* Rotate the list removing the tail node and inserting it to the head. */void listRotate(list *list) {    listNode *tail = list->tail;    if (listLength(list) <= 1) return;    /* Detatch current tail */    list->tail = tail->prev;    list->tail->next = NULL;    /* Move it as head */    list->head->prev = tail;    tail->prev = NULL;    tail->next = list->head;    list->head = tail;}