解析PHP标准库SPL数据结构

SPL提供了双向链表、堆栈、队列、堆、降序堆、升序堆、优先级队列、定长数组、对象容器

SplQueue 队列类

进出异端，先进先出

<?PHP$obj = new SplQueue();//插入一个节点到top位置$obj->enqueue(1);
$obj->enqueue(2);
$obj->enqueue(3);/**
SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

)
*/$obj->offsetSet(0,'C');/**
SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 'C'
            [1] => 2
            [2] => 3
        )

)
*/$obj->rewind();//从队列中返回并删除bottom位置的元素$obj->dequeue();/**
'C'

SplQueue Object
(
    [flags:SplDoublyLinkedList:private] => 4
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 2
            [1] => 3
        )

)
*/复制代码

SplStack 堆栈类

单端进出时，后进先出，先进后出

$obj = new SplStack();/**
SplStack Object
(
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
        )

)
*///向堆栈放入一个节点到top位置$obj->push(1);
$obj->push(2);
$obj->push(3);/**
SplStack Object
(
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )

)
*///堆栈的offset = 0 是Top所在的位置，offset = 1 是top节点靠近bottom位置的相邻节点$obj->offsetSet(0,'C');/**
SplStack Object
(
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 'C'
        )

)
*/$obj->offsetSet(1,'B');/**
SplStack Object
(
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 1
            [1] => 'B'
            [2] => 'C'
        )

)
*///堆栈的rewind使指针指向top节点，而双向链表的rewind指向bottom节点$obj->rewind();//堆栈的next是使指针向bottom方向相邻的节点移动一位，而链表是向top方向移动$obj->next();//遍历堆栈$obj->rewind();while($obj->valid()){    echo $obj->key().'=>'.$obj->current();
    $obj->next();
}/**
2=>'C'
1=>'B'
0=>1
*///从堆栈中取出top位置的节点并删除$obj->pop();复制代码

SplDoublyLinkedList 双向链表类

$obj = new SplDoublyLinkedList();//SplDoublyLinkedList Object ( [flags:SplDoublyLinkedList:private] => 0 [dllist:SplDoublyLinkedList:private] => Array ( ) )//把新的节点数据添加到链表的顶部Top$obj->push(1);
$obj->push(2);
$obj->push(3);//把新的节点数据添加到链表底部bottom$obj->unshift(4);/**
SplDoublyLinkedList Object
(
    [flags:SplDoublyLinkedList:private] => 0
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => 4
            [1] => 1
            [2] => 2
            [3] => 3
        )

)
*///在没有调用rewind()方法之前输出为nullecho 'current'.$obj->current();//输出: null//把指针指向bottom节点$obj->rewind();//获取当前指针指向的节点$obj->current();//输出: 4//将执行挪到下一个$obj->next();
$obj->current();//输出: 1$obj->prev();
$obj->current();//输出: 4//越界了$obj->next();
$obj->next();
$obj->next();
$obj->next();
$obj->current();//输出: null//判断当前节点是否有效$obj->valid()//输出： false$obj->prev();
$obj->valid()//输出： true$obj->shift();//把top节点从链表中删除并返回$obj->pop();//输出 3//把bottom节点从链表中删除并返回$obj->shift();//输出 4//返回top节点$obj->top();//返回bottom节点$obj->bottom();复制代码

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