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What is PHP bidirectional queue? Using PHP to write a two-way queue is actually examining several built-in array functions in PHP. Let's take a look at the specific code below.
用PHP写一个双向队列queue,$value); } /** * 尾部出队 * @return [type] [description] */ public function removeLast(){ return array_pop($this->queue); } /** * 头部入队 * @param [type] $value [description] */ public function addFirst($value){ return array_unshift($this->queue, $value); } /** * 头部出队 * @return [type] [description] */ public function removeFirst(){ return array_shift($this->queue); } /** * 清空队列 * @return [type] [description] */ public function makeEmpty(){ unset($this->queue); } /** * 获取列头 * @return [type] [description] */ public function getFirst(){ return reset($this->queue); } /** * 获取列尾 * @return [type] [description] */ public function getLast(){ return end($this->queue); } /** * 获取长度 * @return [type] [description] */ public function getLength(){ return count($this->queue); } } ?>加上一些限制条件后:_type = in_array($type, array(1,2,3,4,5,6))? $type : 1; $this->_maxLength = intval($maxlength); } // 前端入列 // @param Mixed $data 数据 //@return boolean public function frontAdd($data=null){ if($this->_type==3){ // 前端输入限制 return false; } if(isset($data) && !$this->isFull()){ array_unshift($this->_queue, $data); $this->setAddNum(1); return true; } return false; } //前端出列 //@return Array public function frontRemove(){ if($this->_type==2){ // 前端输出限制 return null; } if(!$this->checkRemove(1)){ // 检查是否依赖输入 return null; } $data = null; if($this->getLength()>0){ $data = array_shift($this->_queue); $this->setRemoveNum(1); } return $data; } // 后端入列 // @param Mixed $data 数据 //@return boolean public function rearAdd($data=null){ if($this->_type==5){ // 后端输入限制 return false; } if(isset($data) && !$this->isFull()){ array_push($this->_queue, $data); $this->setAddNum(2); return true; } return false; } // 后端出列 // @return Array public function rearRemove(){ if($this->_type==4){ // 后端输出限制 return null; } if(!$this->checkRemove(2)){ // 检查是否依赖输入 return null; } $data = null; if($this->getLength()>0){ $data = array_pop($this->_queue); $this->setRemoveNum(2); } return $data; } //清空对列 //@return boolean public function clear(){ $this->_queue = array(); $this->_frontNum = 0; $this->_rearNum = 0; return true; } //判断对列是否已满 //@return boolean public function isFull(){ $bIsFull = false; if($this->_maxLength!=0 && $this->_maxLength==$this->getLength()){ $bIsFull = true; } return $bIsFull; } //获取当前对列长度 //@return int private function getLength(){ return count($this->_queue); } //记录入列,输出依赖输入时调用 // @param int $endpoint 端点 1:front 2:rear private function setAddNum($endpoint){ if($this->_type==6){ if($endpoint==1){ $this->_frontNum ++; }else{ $this->_rearNum ++; } } } //记录出列,输出依赖输入时调用 //@param int $endpoint 端点 1:front 2:rear private function setRemoveNum($endpoint){ if($this->_type==6){ if($endpoint==1){ $this->_frontNum --; }else{ $this->_rearNum --; } } } //检查是否输出依赖输入 //@param int $endpoint 端点 1:front 2:rear private function checkRemove($endpoint){ if($this->_type==6){ if($endpoint==1){ return $this->_frontNum>0; }else{ return $this->_rearNum>0; } } return true; } } // class end ?>
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