Adlist 双向链表的实现 redis

/* adlist.h - A generic doubly linked list implementation

 *

 * Copyright (c) 2006-2012, 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__ */

 

#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, containing 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 penultimate

 * 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;

    /* Detach 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;

}