[ Posted by David Thomson ] recursion truth test

fiddle_015079.php

<?php
class Compare
{
    private static $instance = null;
    private function __construct()
    {
    }
    public function is($a, $b, $condition)
    {
        $meth = array(
            'AND' => 'checkAnd',
            'OR' => 'checkOr',
        );
        if ($method = $meth[$condition]) {
            return $this->$method($a, $b);
        }
        return false;
    }
    private function checkAnd($a, $b)
    {
        return $a && $b;
    }
    private function checkOr($a, $b)
    {
        return $a || $b;
    }
    public static function getInstance()
    {
        if (self::$instance == null) {
            self::$instance = new Compare();
        }
        return self::$instance;
    }
}
class ParenthesisTest
{
    public function __construct()
    {
    }
    public function testParenthesis($currentAr, $unclosedAr)
    {
        if (count($currentAr) === 0) {
            return false;
        }
        $element = array_pop($currentAr);
        switch ($element) {
            case '(':
            array_push($unclosedAr, array($element));
            break;
            case 'OR':
            case 'AND':
            case 'true':
            case 'false':
            $endElem = array_pop($unclosedAr);
            array_push($endElem, $element);
            array_push($unclosedAr, $endElem);
            break;
            case ')':
            $endElem = array_pop($unclosedAr);
            array_push($endElem, $element);
            $result = $this->evaluateParenthisisCase($endElem);
            if(count($unclosedAr) ===0){
                return $result;
            }
            $endElem = array_pop($unclosedAr);
            array_push($endElem, $result);
            array_push($unclosedAr, $endElem);
            break;
            default:
            break;
        }
        $result = null;
        $result = $this->testParenthesis($currentAr, $unclosedAr);
        if($result !== null){
            return $result;
        }
    }
    private function normaliseValue($value){
        if($value === 'true' || $value === true){
            return true;
        }else{
            return false;
        }
    }
    private function evaluateParenthisisCase($testArr)
    {
        $cp = Compare::getInstance();
        $latestConditionResult = null;
        for ($i = 1; $i < count($testArr) -1; $i++) {
            if($latestConditionResult !== null){
                $a = $latestConditionResult;
                $i = $i-1;
            }else{
                $a = $this->normaliseValue($testArr[$i]);
            }
            $condition = $testArr[$i+1];
            $b =$this->normaliseValue($testArr[$i+2]);
            $valid = $this->checkComparisonVariables($a, $b, $condition);
            if($valid){
                $latestConditionResult = $cp->is($a,$b,$condition);
            }
            $i = $i+2;
        }
        if($latestConditionResult === null){
            throw new Exception('evaluateParenthisisCase untestable');
        }
        return $latestConditionResult;
    }
    private function checkComparisonVariables($a, $b, $condition){
        $allowedConditions = array('OR', 'AND');
        if(in_array($a, $allowedConditions, true) || in_array($b, $allowedConditions, true) || !in_array($condition, $allowedConditions, true)){
            throw new Exception('checkComparisonVariables untestable');
        }
        return true;
    }
}
$testString = '( ( ( ( true OR false AND ( true AND true ) ) AND true ) AND ( ( true OR false ) AND true ) ) AND ( ( true AND true ) OR true ) )';
$stringArray = explode(' ', $testString);
$revStringArray = array_reverse($stringArray);
$pt = new ParenthesisTest();
$result = $pt->testParenthesis($revStringArray, array());
var_dump($result);
?>