Online PHP editor | perf for 8XLge

@ 2014-01-24T14:50:02Z

<?php

class ExpressionCalculator {
	private $operators = array(
        function ($leftOperand, $rightOperand) {
            return $leftOperand + $rightOperand;
        }, 
        function ($leftOperand, $rightOperand) {
            return $leftOperand - $rightOperand;
        }, 
        function ($leftOperand, $rightOperand) {
            return $leftOperand * $rightOperand;
        }, 
        function ($leftOperand, $rightOperand) {
            return $leftOperand / $rightOperand;
        }
    );

	public function calc($expression) {
		$operands = array();

        while (($token = strtok($expression, ' ')) !== false) {
			if (isOperator($token)) {
				$rightOperand = array_pop($operands);
				$leftOperand = array_pop($operands);
                $result = $this->execute($token, $leftOperand, $rightOperand);
                array_push($operands, $result);
            } else if (is_numeric($token)) {
				array_push($operands, $token);
            } else {
				throw new InvalidArgumentException('Expression has invalid token: ' + $token);
            }
        }

		return $result;
    }

	private function isOperator($token) {
		return isset($operators[$token]);
    }

    private function execute($operator, $leftOperand, $rightOperand) {
		return call_user_func($operators[$operator], $leftOperand, $rightOperand);
    }
}

$calc = new ExpressionCalculator();
echo $calc->calc('5 1 2 + 4 * + 3 -'); // 14

Here you find the average performance (time & memory) of each version. A grayed out version indicates it didn't complete successfully (based on exit-code).

Version	System time (s)	User time (s)	Memory (MiB)
5.4.24	0.009	0.042	12.39
5.4.23	0.008	0.037	12.38
5.4.22	0.007	0.036	12.38
5.4.21	0.011	0.039	12.38
5.4.20	0.005	0.045	12.38
5.4.19	0.009	0.039	12.38
5.4.18	0.005	0.044	12.38
5.4.17	0.008	0.041	12.38
5.4.16	0.006	0.038	12.38
5.4.15	0.005	0.039	12.37
5.4.14	0.006	0.043	12.07
5.4.13	0.008	0.036	12.04
5.4.12	0.011	0.042	12.01
5.4.11	0.008	0.041	12.01
5.4.10	0.007	0.035	12.01
5.4.9	0.006	0.043	12.01
5.4.8	0.004	0.042	12.01
5.4.7	0.005	0.042	12.00
5.4.6	0.006	0.039	12.00
5.4.5	0.005	0.042	12.00
5.4.4	0.007	0.038	11.99
5.4.3	0.008	0.038	11.99
5.4.2	0.007	0.046	11.98
5.4.1	0.005	0.037	11.99
5.4.0	0.008	0.037	11.48
5.3.28	0.009	0.037	12.71
5.3.27	0.007	0.038	12.72
5.3.26	0.007	0.042	12.71
5.3.25	0.008	0.039	12.72
5.3.24	0.007	0.047	12.72
5.3.23	0.009	0.041	12.71
5.3.22	0.007	0.041	12.68
5.3.21	0.009	0.037	12.68
5.3.20	0.005	0.046	12.68
5.3.19	0.007	0.046	12.68
5.3.18	0.008	0.042	12.67
5.3.17	0.007	0.040	12.67
5.3.16	0.009	0.041	12.67
5.3.15	0.004	0.041	12.68
5.3.14	0.006	0.038	12.66
5.3.13	0.007	0.039	12.66
5.3.12	0.004	0.043	12.66
5.3.11	0.005	0.043	12.66
5.3.10	0.007	0.036	12.12
5.3.9	0.008	0.036	12.09
5.3.8	0.004	0.039	12.08
5.3.7	0.010	0.037	12.08
5.3.6	0.011	0.039	12.07
5.3.5	0.008	0.038	12.01
5.3.4	0.005	0.040	12.01
5.3.3	0.008	0.033	11.96
5.3.2	0.009	0.034	11.74
5.3.1	0.005	0.039	11.71
5.3.0	0.007	0.036	11.69

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