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#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. */
/*
* 创建一个新的链表
* 创建成功返回链表,失败返回 NULL 。
* T = O(1)
*/
list *listCreate(void) {
struct list *list;
// 分配内存
if ((list = zmalloc(sizeof(*list))) == NULL)
return NULL;
// 初始化属性
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.
* 释放整个链表,以及链表中所有节点
* T = O(N)
*/
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); // 调用值释放回调函数
zfree(current); // 逐个释放链表节点
current = next;
}
zfree(list); // 释放链表结构
}
/* 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.
*
* 将一个包含有给定值指针 value 的新节点添加到链表的表头
* 如果为新节点分配内存出错,那么不执行任何动作,仅返回 NULL
* 如果执行成功,返回传入的链表指针
* T = O(1)
*/
list *listAddNodeHead(list *list, void *value) {
listNode *node;
// 为节点分配内存
if ((node = zmalloc(sizeof(*node))) == NULL)
return NULL;
// 保存值指针
node->value = value;
if (list->len == 0) {
// 添加节点到空链表
list->head = list->tail = node;
node->prev = node->next = NULL;
} else {
// 添加节点到非空链表
node->prev = NULL;
node->next = list->head;
list->head->prev = node;
list->head = node;
}
list->len++; // 更新链表节点数
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.
*
* 将一个包含有给定值指针 value 的新节点添加到链表的表尾
* 如果为新节点分配内存出错,那么不执行任何动作,仅返回 NULL
* 如果执行成功,返回传入的链表指针
* T = O(1)
*/
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;
}
/*
* 创建一个包含值 value 的新节点,并将它插入到 old_node 的之前或之后
*
* 如果 after 为 0 ,将新节点插入到 old_node 之前。
* 如果 after 为 1 ,将新节点插入到 old_node 之后。
*
* T = O(1)
*/
list *listInsertNode(list *list, listNode *old_node, void *value, int after) {
listNode *node;
if ((node = zmalloc(sizeof(*node))) == NULL)
return NULL;
node->value = value;
// 修改新节点 prev next 指向
if (after) {
node->prev = old_node;
node->next = old_node->next;
// 给定节点是原表尾节点
if (list->tail == old_node) {
list->tail = node;
}
// 将新节点添加到给定节点之前
} else {
node->next = old_node;
node->prev = old_node->prev;
// 给定节点是原表头节点
if (list->head == old_node) {
list->head = node;
}
}
// 更新新节点的前置指针
if (node->prev != NULL) {
node->prev->next = node;
}
// 更新新节点的后置指针
if (node->next != NULL) {
node->next->prev = node;
}
// 更新链表节点数
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. */
/*
* 从链表 list 中删除给定节点 node
*
* 对节点私有值(private value of the node)的释放工作由调用者进行。
*
* T = O(1)
*/
void listDelNode(list *list, listNode *node) {
// 调整前置节点的指针
if (node->prev)
node->prev->next = node->next;
else
list->head = node->next;
// 调整后置节点的指针
if (node->next)
node->next->prev = node->prev;
else
list->tail = node->prev;
// 释放值
if (list->free) list->free(node->value);
// 释放节点
zfree(node);
// 链表数减一
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. */
/*
* 为给定链表创建一个迭代器,
* 之后每次对这个迭代器调用 listNext 都返回被迭代到的链表节点
*
* direction 参数决定了迭代器的迭代方向:
* AL_START_HEAD :从表头向表尾迭代
* AL_START_TAIL :从表尾想表头迭代
*
* T = O(1)
*/
listIter *listGetIterator(list *list, int direction) {
// 为迭代器分配内存
listIter *iter;
if ((iter = zmalloc(sizeof(*iter))) == NULL) return NULL;
// 根据迭代方向,设置迭代器的起始节点
if (direction == AL_START_HEAD)
iter->next = list->head;
else
iter->next = list->tail;
// 记录迭代方向
iter->direction = direction;
return iter;
}
/* Release the iterator memory */
/*
* 释放迭代器
*
* T = O(1)
*/
void listReleaseIterator(listIter *iter) {
zfree(iter);
}
/* Create an iterator in the list private iterator structure */
/*
* 将迭代器的方向设置为 AL_START_HEAD ,
* 并将迭代指针重新指向表头节点。
*
* T = O(1)
*/
void listRewind(list *list, listIter *li) {
li->next = list->head;
li->direction = AL_START_HEAD;
}
/*
* 将迭代器的方向设置为 AL_START_TAIL ,
* 并将迭代指针重新指向表尾节点。
*
* T = O(1)
*/
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));
* }
*
* */
/*
* 返回迭代器当前所指向的节点。
*
* 删除当前节点是允许的,但不能修改链表里的其他节点。
*
* 函数要么返回一个节点,要么返回 NULL ,常见的用法是:
*
* iter = listGetIterator(list,<direction>);
* while ((node = listNext(iter)) != NULL) {
* doSomethingWith(listNodeValue(node));
* }
*
* T = O(1)
*/
listNode *listNext(listIter *iter) {
listNode *current = iter->next;
if (current != NULL) {
// 根据方向选择下一个节点
if (iter->direction == AL_START_HEAD)
// 保存下一个节点,防止当前节点被删除而造成指针丢失
iter->next = current->next;
else
// 保存下一个节点,防止当前节点被删除而造成指针丢失
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. */
/*
* 复制整个链表。
*
* 复制成功返回输入链表的副本,
* 如果因为内存不足而造成复制失败,返回 NULL 。
*
* 如果链表有设置值复制函数 dup ,那么对值的复制将使用复制函数进行,
* 否则,新节点将和旧节点共享同一个指针。
*
* 无论复制是成功还是失败,输入节点都不会修改。
*
* T = O(N)
*/
list *listDup(list *orig) {
list *copy;
listIter *iter;
listNode *node;
// 创建新链表
if ((copy = listCreate()) == NULL)
return NULL;
// 设置节点值处理函数
copy->dup = orig->dup;
copy->free = orig->free;
copy->match = orig->match;
// 迭代整个输入链表
iter = listGetIterator(orig, AL_START_HEAD);
while ((node = listNext(iter)) != NULL) {
void *value;
// 复制节点值到新节点
if (copy->dup) {
value = copy->dup(node->value);
if (value == NULL) {
listRelease(copy);
listReleaseIterator(iter);
return NULL;
}
} else
value = node->value;
// 将节点添加到链表
if (listAddNodeTail(copy, value) == NULL) {
listRelease(copy);
listReleaseIterator(iter);
return NULL;
}
}
// 释放迭代器
listReleaseIterator(iter);
// 返回副本
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. */
/*
* 查找链表 list 中值和 key 匹配的节点。
*
* 对比操作由链表的 match 函数负责进行,
* 如果没有设置 match 函数,
* 那么直接通过对比值的指针来决定是否匹配。
*
* 如果匹配成功,那么第一个匹配的节点会被返回。
* 如果没有匹配任何节点,那么返回 NULL 。
*
* T = O(N)
*/
listNode *listSearchKey(list *list, void *key) {
listIter *iter;
listNode *node;
// 迭代整个链表
iter = listGetIterator(list, AL_START_HEAD);
while ((node = listNext(iter)) != NULL) {
// 定义过值比较函数则调用
if (list->match) {
if (list->match(node->value, key)) { // 匹配则释放迭代器
listReleaseIterator(iter);
return node;
}
} else {
if (key == node->value) {
listReleaseIterator(iter); // 否则就强制地址是否相同
return node;
}
}
}
listReleaseIterator(iter);
return NULL; // 未找到
}
/* 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. */
/*
* 返回链表在给定索引上的值。
*
* 索引以 0 为起始,也可以是负数, -1 表示链表最后一个节点,诸如此类。
*
* 如果索引超出范围(out of range),返回 NULL 。
*
* T = O(N)
*/
listNode *listIndex(list *list, long index) {
listNode *n;
// 如果索引为负数,从表尾开始查找
if (index < 0) {
index = (-index) - 1;
n = list->tail;
while (index-- && n) n = n->prev;
// 如果索引为正数,从表头开始查找
} 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. */
/*
* 取出链表的表尾节点,并将它移动到表头,成为新的表头节点。
*
* T = O(1)
*/
void listRotate(list *list) {
listNode *tail = list->tail;
if (listLength(list) <= 1) return;
/* Detach current tail */
// 取出表尾节点
list->tail = tail->prev;
list->tail->next = NULL;
/* Move it as head */
// 插入到表头
list->head->prev = tail;
tail->prev = NULL;
tail->next = list->head;
list->head = tail;
}
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