php 实现单操作符简单公式解析

<?php
$string = "#data_1 / #data_2";
class operate{
    private $params;
    private $dataarray;
    private $result;
    private function getResult() {
        return $this->result;
    }

    private function setResult($result) {
        $this->result = $result;
    }

    private function getDataarray() {
        return $this->dataarray;
    }

    private function setDataarray($dataarray) {
        $this->dataarray = $dataarray;
    }

    private function getParams() {
        return $this->params;
    }

    public function setParams($params) {
        $this->params = $params;
    }

    private function add($data_1,$data_2){
        return $data_1+$data_2;
    }
    private function minus($data_1,$data_2){
        return $data_1-$data_2;
    }
    private function multiply($data_1,$data_2){
        return $data_1*$data_2;
    }

    private function divide($data_1,$data_2){

            return $data_1/$data_2;

    }
    private function stringtoarray(){
        $params = $this->getParams();                
        $dataarray =  explode(" ", $params);
        $this->setDataarray($dataarray);

    }

    private function getpos($array){

        $pos = array();
        $nums = sizeof($array);
        for ($i=0;$i<$nums;$i++){
            if(!is_numeric($array[$i])){
                $pos[] = $i;
            }
        }
        return $pos;    
    }
    private function getdividepos(){
        $array = $this->getDataarray();// ||$expressionarray
        $pos = array();
        $nums = sizeof($array);
        for ($i=0;$i<$nums;$i++){
            if($array[$i]=="/"){
                $pos[] = $i;
            }
        }
        return $pos;
    }
    private function iszero(){
        $dataarray = $this->getDataarray();
        //print_r($dataarray);
        $array = $this->getdividepos(); // ||$devidpos
        //print_r($array);
        $nums = sizeof($array);
        echo "<br />iszero nums:".$nums."<br />";
        if ($nums==0){
            $this->setResult(1);
        }else{
            for ($i=0;$i<$nums;$i++){
                $key = $array[$i]+1;
                //$key = $i + 1;
                echo "<br />key :$key<br />";
                //echo "data:".$dataarray[$key];
                $data = (int)($dataarray[$key]);    
                echo "data:".$data."<br />";
                if ($data==0){                                  
                    $this->setResult(0);
                }
                else {
                    $this->setResult($data);
                }
            }
        }
    }

    public function main(){
        $this->stringtoarray();
        $dataarray = $this->getDataarray(); //array("#data_1","/","#data_2");
        print_r($dataarray);
        $dividepos = $this->iszero();
        $result = $this->getResult();
        echo "reslut:".$result."<br />";
        if($result==0){
            return 0;
        }else{
            $operatepos = $this->getpos($dataarray);
            $nums = sizeof($operatepos);
            for($i=0;$i<$nums;$i++){
                $pos = $operatepos[$i];     
                $operate = $dataarray[$pos]; 
                echo "operate:".$operate."<br />";
                switch ($operate){
                    case "+":
                        $key1 = $pos - 1;
                        $key2 = $pos + 1;
                        $data_1 = $dataarray[$key1];
                        $data_2 = $dataarray[$key2];
                        $tempdata = $this->add($data_1, $data_2);
                        return $tempdata;
                    case "-":
                        $key1 = $pos - 1;
                        $key2 = $pos + 1;
                        $data_1 = $dataarray[$key1];
                        $data_2 = $dataarray[$key2];
                        $tempdata = $this->minus($data_1, $data_2);
                        return $tempdata;
                    case "*":
                        $key1 = $pos - 1;
                        $key2 = $pos + 1;
                        $data_1 = $dataarray[$key1];
                        $data_2 = $dataarray[$key2];
                        $tempdata = $this->multiply($data_1, $data_2);
                        return $tempdata;
                    case "/":
                        $key1 = $pos - 1;
                        $key2 = $pos + 1;
                        $data_1 = $dataarray[$key1];
                        $data_2 = $dataarray[$key2];
                        $tempdata = $this->divide($data_1, $data_2);
                        return $tempdata;
                }

            }

        }

    }

}

$data_3 = "2 * 3";
$compute = new operate();
$compute ->setParams($data_3);
echo "result:".$compute->main();
//该片段来自于http://outofmemory.cn