Expression analysis

expression-analysis.php

<?php
$operators=array("+","-","*","/");
$numbers=array("0","1","2","3","4","5","6","7","8","9");
$a=array();



function findNodesFirst($exp,&$buff,&$nums,&$op){
	//Check $exp is empty?
	$newExp="";
	$pos=0;
	$q=0;
	$p=false;
	$nStart=0;
	$nStop=0;
	while($pos<strlen($exp)){
		if($exp[$pos]=="("){
			if($q==0){
				$nStart=$pos;
				$newExp=$newExp.substr($exp,$nStop,$nStart-$nStop);
			}
			$q++;
			$pos++;
			continue;
		}
		if($exp[$pos]==")"){
			if($q==1){
				$nStart++;
				$newExp=$newExp."NODE".findNodesFirst(substr($exp,$nStart,$pos-$nStart),$buff,$nums,$op);
				$pos++;
				$nStop=$pos;
			}
			$q--;
			$pos++;
			continue;
		}
		
		//Find numers
		if($q==0){
			if(!$p&&in_array($exp[$pos],$nums)){
				$nStart=$pos;
				$newExp=$newExp.substr($exp,$nStop,$nStart-$nStop);
				$p=true;
				$pos++;
				if($pos==strlen($exp)){
					$nStop=$pos;
					$nNum=count($buff);
					$buff["NODE".$nNum]=$exp[$pos-1];
					$newExp=$newExp."NODE".$nNum;
					$p=false;
				}
				continue;
			}else{
				$flag=false;
				if(($pos+1)==strlen($exp)){
					$flag=true;
					$pos++;
				}else{
					if(!(in_array($exp[$pos],$nums)||$exp[$pos]==".")){
						$flag=true;
					}else{
						$pos++;
						continue;
					}
				}				
				if($flag){
					$nStop=$pos;
					$nNum=count($buff);
					$buff["NODE".$nNum]=substr($exp,$nStart,$nStop-$nStart);
					
					$newExp=$newExp."NODE".$nNum;
					$pos++;
					$p=false;
					continue 1;
				}
			}
		}
		$pos++;
	}
	$nNum=count($buff);
	$buff["NODE".$nNum]=$newExp;
	return $nNum;
}
	
$str=findNodesFirst("15.18*789+(5872+7)+3203*((1+2+3.1)*(3+4))+(7-(70/(10+5)))*7781",$a,$numbers,$operators);
print_r($a);
?>