Add PHP Regex performance testing

code/regex/php/regex.php

@@ -0,0 +1,44 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * This File requires PHP >=7.0 to run
+ *
+ * @author Jan Pache <[email protected]>
+ * @see https://www.php.net/manual/en/regexp.reference.performance.php
+ */
+
+// Change some of PHP's default configuration settings
+@error_reporting(E_ALL);
+@ini_set('memory_limit', '-1');
+@ini_set('max_execution_time', '-1');
+
+// Explicitly remove limit for PCRE
+@ini_set('pcre.backtrack_limit', '-1');
+@ini_set('pcre.recursion_limit', '-1');
+
+$r1 = '';
+$r2 = '';
+$i = 0;
+
+// Tested maximum that PHP is capable of: 31
+const MAX_I = 26;
+
+if (PHP_SAPI !== 'cli') {
+    die('This is meant to be a console script only');
+}
+
+while ($i < MAX_I) {
+    $i++;
+    $r1 .= 'a?';
+    $r2 .= 'a';
+    $r = '/'.$r1.$r2.'/';
+    $startTime = microtime(true);
+
+    if (preg_match($r, $r2) !== false) {
+        $runtime = microtime(true) - $startTime;
+        echo sprintf('%1$s %2$s matches %3$s %4$s %5$f s%6$s', str_repeat(' ', MAX_I-$i), $r2, trim($r, '/'), str_repeat(' ', (MAX_I-$i)*3), $runtime, PHP_EOL);
+    } else {
+        echo 'matching failure'.PHP_EOL;
+    }
+}