fix(Validators): allow pipe in pattern regular expressions

The 'pattern:' argument of Validators::is() crashed on a valid regular
expression containing a pipe, e.g. Validators::is('a', 'pattern:(a|b)').

Two parsing bugs combined: the expression was split into validators on every
'|', tearing the regexp apart, and the pipe was also used as the PCRE
delimiter. A 'pattern:' argument now consumes the rest of the expression and
the delimiter is changed to '~', with the pattern anchored as a whole so bare
alternations work too. Pipe-as-OR semantics for combined validators are kept.

Fixes nette/utils#206

src/Utils/Validators.php

@@ -137,7 +137,9 @@ class Validators
 	 */
 	public static function is(mixed $value, string $expected): bool
 	{
-		foreach (explode('|', $expected) as $item) {
+		$items = explode('|', $expected);
+		for ($i = 0, $count = count($items); $i < $count; $i++) {
+			$item = $items[$i];
 			if (str_ends_with($item, '[]')) {
 				if (is_iterable($value) && self::everyIs($value, substr($item, 0, -2))) {
 					return true;
@@ -152,7 +154,17 @@ class Validators
 			}
 
 			[$type] = $item = explode(':', $item, 2);
-			if (isset(static::$validators[$type])) {
+			if ($type === 'pattern') {
+				// A regular expression may itself contain pipes, so the rest of the
+				// expression belongs to the pattern and must not be split into validators.
+				// The '~' delimiter is used so the pipe is not treated as a delimiter either.
+				$pattern = implode('|', array_merge(array_slice($item, 1), array_slice($items, $i + 1)));
+				if (Strings::match($value, '~^(?:' . $pattern . ')$~D')) {
+					return true;
+				}
+
+				break;
+			} elseif (isset(static::$validators[$type])) {
 				try {
 					if (!static::$validators[$type]($value)) {
 						continue;
@@ -160,12 +172,6 @@ class Validators
 				} catch (\TypeError) {
 					continue;
 				}
-			} elseif ($type === 'pattern') {
-				if (Strings::match($value, '|^' . ($item[1] ?? '') . '$|D')) {
-					return true;
-				}
-
-				continue;
 			} elseif (!$value instanceof $type) {
 				continue;
 			}

tests/Utils/Validators.is().phpt

@@ -259,6 +259,25 @@ test('validates string against a regular expression pattern', function () {
 });
 
 
+test('allows pipe inside a regular expression pattern', function () {
+	// grouped alternation, https://github.com/nette/utils/issues/206
+	Assert::true(Validators::is('a', 'pattern:(a|b)'));
+	Assert::true(Validators::is('b', 'pattern:(a|b)'));
+	Assert::false(Validators::is('c', 'pattern:(a|b)'));
+
+	// bare alternation must no longer throw and is anchored as a whole
+	Assert::true(Validators::is('a', 'pattern:a|b'));
+	Assert::true(Validators::is('b', 'pattern:a|b'));
+	Assert::false(Validators::is('c', 'pattern:a|b'));
+	Assert::false(Validators::is('ab', 'pattern:a|b'));
+
+	// a pattern combined with other validators
+	Assert::true(Validators::is(5, 'int|pattern:(a|b)'));
+	Assert::true(Validators::is('a', 'int|pattern:(a|b)'));
+	Assert::false(Validators::is('c', 'int|pattern:(a|b)'));
+});
+
+
 test('ensures alphanumeric string meets minimum length', function () {
 	Assert::false(Validators::is('', 'alnum'));
 	Assert::false(Validators::is('a-1', 'alnum'));