test.php

<?php

$iterations = 1000000;

$test_cases = array(
	array(
		'name' => 'class_implements, sensitive, uncached',
		'function' => function($className, $type) {
			$parents = class_parents($className, true) + class_implements($className, true);
			return (isset($parents[$type]));
		}
	),
	array(
		'name' => 'class_implements, sensitive, cached',
		'function' => function($className, $type) {
			static $isSubclassFuncCache = array();
			
			if (!array_key_exists($className, $isSubclassFuncCache)) {
				$isSubclassFuncCache[$className] = class_parents($className, true) + class_implements($className, true);
			}
			
			return (isset($isSubclassFuncCache[$className][$type]));
		}
	),
	array(
		'name' => 'class_implements, insensitive, uncached',
		'function' => function($className, $type) {
			$parents = array_change_key_case(class_parents($className, true) + class_implements($className, true), CASE_LOWER);
			return (isset($parents[strtolower($type)]));
		}
	),
	array(
		'name' => 'class_implements, insensitive, cached',
		'function' => function($className, $type) {
			static $isSubclassFuncCache = array();
			
			$type = strtolower($type);
			$caseInsensitiveParent = strtolower($className);
			
			if (!array_key_exists($caseInsensitiveParent, $isSubclassFuncCache)) {
				$isSubclassFuncCache[$caseInsensitiveParent] = array_change_key_case(class_parents($className, true) + class_implements($className, true), CASE_LOWER);
			}
			
			return (isset($isSubclassFuncCache[$caseInsensitiveParent][$type]));
		}
	),
	array(
		'name' => 'reflection, uncached',
		'function' => function($className, $type) {
			
			if (is_subclass_of($className, $type)) {
				return true;
			}
			
			if (!interface_exists($type)) {
				return false;
			}
			
			$r = new ReflectionClass($className);
			return $r->implementsInterface($type);
		}
	),
	array(
		'name' => 'reflection, cached',
		'function' => function($className, $type) {
			
			if (is_subclass_of($className, $type)) {
				return true;
			}
			
			if (!interface_exists($type)) {
				return false;
			}
			
			static $isSubclassFuncCache = array(); // null as unset, array when set
			
			$caseInsensitiveParent = strtolower($className);
			$caseInsensitiveChild  = strtolower($type);
			
			if (!array_key_exists($caseInsensitiveParent, $isSubclassFuncCache)) {
				$r = new ReflectionClass($className);
				if ($r->implementsInterface($type)) {
					$isSubclassFuncCache[$caseInsensitiveParent][$caseInsensitiveChild] = true;
				}
			}
			
			return (isset($isSubclassFuncCache[$caseInsensitiveParent][$caseInsensitiveChild]));
		
		}
	),
);


// our test cases
interface A {}

class B implements A {}

class C extends B {}

class D {}

foreach($test_cases as $test) {
	
	echo "{$test['name']}\n";
	
	$s = microtime(true);
	for ($j = 0; $j < $iterations; $j++ ) {
		$test['function']('B','A');
		$test['function']('C','A');
		$test['function']('D','A');
	}
	$e = microtime(true);
	
	$d = ($e - $s);
	$p = round(($d / $iterations) * 1000000, 4);
	
	echo "    $d seconds for $iterations iterations.\n";
	echo "    {$p}us per call.\n";
}