StringBalance.php

<?php

class StringBalance {

    private $startBrace = "(";
    private $endBrace = ")";
    public $debug = false;

    private $startBraceFound;
    private $endBraceFound;
    private $startBraceCharPositions;
    private $endBraceCharPositions;
    private $string;

    public function __construct($string = '')
    {

        if ($this->debug) {
            error_reporting(E_ALL);
            ini_set('display_errors', 1);
        }

        if (!empty($string)) {
            $this->string = $string;
        }

        $this->cleanString();

    }

    private function cleanString()
    {
        $this->string = preg_replace("/[^\(|\)]/", '', $this->string);
    }

    private function setCharPositions()
    {
        $x = count_chars($this->string, 1);
        $startBraceFound = $x[ord($this->startBrace)];
        $endBraceFound = $x[ord($this->endBrace)];
        $startBraceCharPositions = array();
        $endBraceCharPositions = array();

        $lastStrPos = 0;
        for ($i=1; $i <= $startBraceFound; $i++) {
            if(($strpos = strpos($this->string, $this->startBrace, $lastStrPos)) !== false) {
                $lastStrPos = $strpos+1;
                $startBraceCharPositions[] = $strpos;
            }
        }

        $lastStrPos = 0;
        for ($i=1; $i <= $endBraceFound; $i++) {
            if(($strpos = strpos($this->string, $this->endBrace, $lastStrPos)) !== false) {
                $lastStrPos = $strpos+1;
                $endBraceCharPositions[] = $strpos;
            }
        }

        $this->startBraceFound = $startBraceFound;
        $this->endBraceFound = $endBraceFound;
        $this->startBraceCharPositions = $startBraceCharPositions;
        $this->endBraceCharPositions = $endBraceCharPositions;
    }

    private function setCharPositions2()
    {
        $chars = str_split($this->string);

        $startBraceCharPositions = array();
        $endBraceCharPositions = array();

        foreach ($chars as $key => $value) {
            switch ($value) {
                case $this->startBrace:
                    $startBraceCharPositions[] = $key;
                    break;
                case $this->endBrace:
                    $endBraceCharPositions[] = $key;
                    break;
            }
        }

        $this->startBraceFound = count($startBraceCharPositions);
        $this->endBraceFound = count($endBraceCharPositions);
        $this->startBraceCharPositions = $startBraceCharPositions;
        $this->endBraceCharPositions = $endBraceCharPositions;

    }

    private function checkBraces()
    {

        if($this->startBraceFound !== $this->endBraceFound || empty($this->startBraceCharPositions)) {
            return false;
        }

        foreach ($this->startBraceCharPositions as $key => $value) {
            if ($this->startBraceCharPositions[$key] > $this->endBraceCharPositions[$key]) {
                return false;
            }
        }

        return true;
    }

    public function isBalanced()
    {
        if (empty($this->string)) {
            return true;
        }

        $this->setCharPositions();

        return $this->checkBraces();
    }

}

$str = "Hell(o Wor)ld";
$x = new StringBalance($str);
var_dump($x->isBalanced());