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;
}