数据结构线性表代码

<?php
class ArrayList{
    private $list;
    private $size;
    public function __construct()
    {
        $this->list=array();
        $this->size=0;
    }
    //初始化链表
    public function InitList(){
        $this->list=array();
        $this->size=0;
    }
    //删除链表
    public function destoryList(){
        if (isset($this->list)){
            unset($this->list);
            $this->size=0;
        }
    }
    //清空链表
    public function clearList(){
        if (isset($this->list)){
            unset($this->list);
        }
        $this->list=array();
        $this->size=0;
    }
    //判断链表是否为空
    public function emptyList(){
        if (isset($this->list)){
            if ($this->size==0){
                return true;
            }else{
                return false;
            }
        }
    }
    //链表长度
    public function lengthList(){
        if (isset($this->list)){
            return $this->size;
        }else{
            return false;
        }
    }
    //取元素
    public function getElem($i){
        if ($i<1||$i>$this->size){
            die('failed');
        }
        if (isset($this->list)&&is_array($this->list)){
            return $this->list[$i-1];
        }
    }
    //是否在链表中
    public function locateElem($e){
        if (isset($this->list)&&is_array($this->list)){
            for ($i=0;$i<$this->size;$i++){
                if ($this->list[$i]==$e){
                    return $i+1;
                }
                return 0;
            }
        }
    }
    //前驱
    public function priorElem($i){
        if ($i<1||$i>$this->size){
            die('failed');
        }
        if ($i==1){
            die('no prior');
        }
        if (isset($this->list)&&is_array($this->list)){
            return $this->list[$i-2];
        }
    }
    //后继
    public function nextElem($i){
        if ($i<1||$i>$this->size){
            die('failed');
        }
        if ($i==$this->size){
            die('no next');
        }
        if (isset($this->list)&&is_array($this->list)){
            return $this->list[$i];
        }
    }
    //插入元素
    public function insertList($i,$e){
        if ($i<1||$i>$this->size){
            die('failed');
        }
        if (isset($this->list)&&is_array($this->list)){
            if ($this->size==0){
                $this->list[0]=$e;
                $this->size++;
            }else{
                for($j=$this->size-1;$j>=$i;$j--){
                    $this->list[$j]=$this->list[$j-1];
                }
                $this->list[$i-1]=$e;
                $this->size++;
            }
        }
    }
    //删除元素
    public function deleteList($i){
        if ($i<1||$i>$this->size){
            die('failed');
        }
        if (isset($this->list)&&is_array($this->list)){
            if ($i==$this->size){
                unset($this->list[$i-1]);
            }else{
                unset($this->list[$i-1]);
                for ($j=$i;$j<$this->size;$j++){
                    $this->list[$j-1]=$this->list[$j];
                }
            }
            $this->size--;
        }
    }
    //遍历
    public function printList(){
        if (isset($this->list)&&is_array($this->list)){
            foreach ($this->list as $value) {
                echo $value.' ';
            }
        }
    }
}