Fix quadratic complexity deactivating link openers

Author: colinodell

CHANGELOG.md

@@ -104,6 +104,7 @@ Updates should follow the [Keep a CHANGELOG](https://keepachangelog.com/) princi
 - Fixed quadratic complexity parsing unclosed inline links
 - Fixed quadratic complexity finding the bottom opener for emphasis and strikethrough delimiters
 - Fixed issue where having 500,000+ delimiters could trigger a [known segmentation fault issue in PHP's garbage collection](https://bugs.php.net/bug.php?id=68606)
+- Fixed quadratic complexity deactivating link openers
 
 ## [2.4.1] - 2023-08-30
 

src/Delimiter/Bracket.php

@@ -64,6 +64,9 @@ public function isImage(): bool
         return $this->image;
     }
 
+    /**
+     * Only valid in the context of non-images (links)
+     */
     public function isActive(): bool
     {
         return $this->active;

src/Delimiter/DelimiterStack.php

@@ -159,10 +159,8 @@ public function removeEarlierMatches(string $character): void
     public function deactivateLinkOpeners(): void
     {
         $opener = $this->brackets;
-        while ($opener !== null) {
-            if (! $opener->isImage()) {
-                $opener->setActive(false);
-            }
+        while ($opener !== null && $opener->isActive()) {
+            $opener->setActive(false);
             $opener = $opener->getPrevious();
         }
     }

src/Extension/CommonMark/Parser/Inline/CloseBracketParser.php

@@ -52,7 +52,7 @@ public function parse(InlineParserContext $inlineContext): bool
             return false;
         }
 
-        if (! $opener->isActive()) {
+        if (! $opener->isImage() && ! $opener->isActive()) {
             // no matched opener; remove from stack
             $inlineContext->getDelimiterStack()->removeBracket();
 

tests/unit/Delimiter/DelimiterStackTest.php

@@ -324,7 +324,7 @@ public function testDeactivateLinkOpeners(): void
         $this->assertSame($bracket3, $stack->getLastBracket());
 
         $this->assertFalse($bracket1->isActive());
-        $this->assertTrue($bracket2->isActive());
+        $this->assertFalse($bracket2->isActive());
         $this->assertFalse($bracket3->isActive());
     }
 }