From 86a3fbd78bd4cf339fd169e15363e3e7894e1fd2 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Tue, 23 Dec 2025 09:05:30 +0100
Subject: [PATCH 1/2] Cache ast-parsing in RegexGroupParser

---
 src/Type/Regex/RegexGroupParser.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/Type/Regex/RegexGroupParser.php b/src/Type/Regex/RegexGroupParser.php
index 3162a1c783..c7af3af1da 100644
--- a/src/Type/Regex/RegexGroupParser.php
+++ b/src/Type/Regex/RegexGroupParser.php
@@ -44,6 +44,9 @@ final class RegexGroupParser
 
 	private static ?Parser $parser = null;
 
+	/** @var array<string, TreeNode> */
+	private static array $parsedAst = [];
+
 	public function __construct(
 		private PhpVersion $phpVersion,
 		private RegexExpressionHelper $regexExpressionHelper,
@@ -77,7 +80,7 @@ public function parseGroups(string $regex): ?RegexAstWalkResult
 
 		$rawRegex = $this->regexExpressionHelper->removeDelimitersAndModifiers($regex);
 		try {
-			$ast = self::$parser->parse($rawRegex);
+			$ast = self::$parsedAst[$rawRegex] ??= self::$parser->parse($rawRegex);
 		} catch (Exception) {
 			return null;
 		}

From 087eb8b29316cafbe15472b155216a7dacc5c198 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Tue, 23 Dec 2025 09:59:38 +0100
Subject: [PATCH 2/2] cache earlier

---
 src/Type/Regex/RegexGroupParser.php | 52 +++++++++++++++++------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/src/Type/Regex/RegexGroupParser.php b/src/Type/Regex/RegexGroupParser.php
index c7af3af1da..74bdadf540 100644
--- a/src/Type/Regex/RegexGroupParser.php
+++ b/src/Type/Regex/RegexGroupParser.php
@@ -21,6 +21,7 @@
 use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use function array_key_exists;
 use function array_values;
 use function count;
 use function in_array;
@@ -44,7 +45,7 @@ final class RegexGroupParser
 
 	private static ?Parser $parser = null;
 
-	/** @var array<string, TreeNode> */
+	/** @var array<string, ?TreeNode> */
 	private static array $parsedAst = [];
 
 	public function __construct(
@@ -59,30 +60,39 @@ public function parseGroups(string $regex): ?RegexAstWalkResult
 		/** @throws void */
 		self::$parser ??= Llk::load(new Read(__DIR__ . '/../../../resources/RegexGrammar.pp'));
 
-		try {
-			Strings::match('', $regex);
-		} catch (RegexpException) {
-			// pattern is invalid, so let the RegularExpressionPatternRule report it
-			return null;
-		}
-
-		$modifiers = $this->regexExpressionHelper->getPatternModifiers($regex) ?? '';
-		foreach (self::NOT_SUPPORTED_MODIFIERS as $notSupportedModifier) {
-			if (str_contains($modifiers, $notSupportedModifier)) {
+		if (array_key_exists($regex, self::$parsedAst)) {
+			$ast = self::$parsedAst[$regex];
+			if ($ast === null) {
 				return null;
 			}
-		}
 
-		if (str_contains($modifiers, 'x')) {
-			// in freespacing mode the # character starts a comment and runs until the end of the line
-			$regex = preg_replace('/(?<!\?)#.*/', '', $regex) ?? '';
-		}
+			$modifiers = $this->regexExpressionHelper->getPatternModifiers($regex) ?? '';
+		} else {
+			try {
+				Strings::match('', $regex);
+			} catch (RegexpException) {
+				// pattern is invalid, so let the RegularExpressionPatternRule report it
+				return self::$parsedAst[$regex] = null;
+			}
 
-		$rawRegex = $this->regexExpressionHelper->removeDelimitersAndModifiers($regex);
-		try {
-			$ast = self::$parsedAst[$rawRegex] ??= self::$parser->parse($rawRegex);
-		} catch (Exception) {
-			return null;
+			$modifiers = $this->regexExpressionHelper->getPatternModifiers($regex) ?? '';
+			foreach (self::NOT_SUPPORTED_MODIFIERS as $notSupportedModifier) {
+				if (str_contains($modifiers, $notSupportedModifier)) {
+					return self::$parsedAst[$regex] = null;
+				}
+			}
+
+			if (str_contains($modifiers, 'x')) {
+				// in freespacing mode the # character starts a comment and runs until the end of the line
+				$regex = preg_replace('/(?<!\?)#.*/', '', $regex) ?? '';
+			}
+
+			$rawRegex = $this->regexExpressionHelper->removeDelimitersAndModifiers($regex);
+			try {
+				$ast = self::$parsedAst[$regex] = self::$parser->parse($rawRegex);
+			} catch (Exception) {
+				return self::$parsedAst[$regex] = null;
+			}
 		}
 
 		$this->updateAlternationAstRemoveVerticalBarsAndAddEmptyToken($ast);