Prevent templating being treated as attributes

src/Extension/Attributes/Util/AttributesHelper.php

@@ -24,7 +24,7 @@
 final class AttributesHelper
 {
     private const SINGLE_ATTRIBUTE = '\s*([.]-?[_a-z][^\s}]*|[#][^\s}]+|' . RegexHelper::PARTIAL_ATTRIBUTENAME . RegexHelper::PARTIAL_ATTRIBUTEVALUESPEC . '?)\s*';
-    private const ATTRIBUTE_LIST   = '/^{:?(' . self::SINGLE_ATTRIBUTE . ')+}/i';
+    private const ATTRIBUTE_LIST   = '/^{(?!{):?(' . self::SINGLE_ATTRIBUTE . ')+}(?!})/i';
 
     /**
      * @return array<string, mixed>

tests/functional/Extension/Attributes/data/special_attributes.html

@@ -13,3 +13,6 @@ <h2 class="main shine" id="the-site">The Site</h2>
 <p>Attributes without quote and non-whitespace char and a dot <a target="_blank" href="http://url.com" rel="noopener noreferrer">link</a>.</p>
 <p>Multiple attributes without quote and non-whitespace char and a dot <a class="class" id="id" target="_blank" href="http://url.com" rel="noopener noreferrer">link</a>.</p>
 <p><img valueless-attribute src="/assets/image.jpg" alt="image" /></p>
+<p>A paragraph containing {{ mustache }} templating</p>
+<p>A paragraph ending with {{ mustache }} templating</p>
+<p>{{ mustache }} A paragraph starting with mustache templating</p>

tests/functional/Extension/Attributes/data/special_attributes.md

@@ -30,3 +30,10 @@ Attributes without quote and non-whitespace char and a dot [link](http://url.com
 Multiple attributes without quote and non-whitespace char and a dot [link](http://url.com){#id .class target=_blank}.
 
 ![image](/assets/image.jpg){valueless-attribute}
+
+A paragraph containing {{ mustache }} templating
+
+A paragraph ending with {{ mustache }} templating
+
+{{ mustache }} A paragraph starting with mustache templating
+

tests/unit/Extension/Attributes/Util/AttributesHelperTest.php

@@ -101,6 +101,10 @@ public static function dataForTestParseAttributes(): iterable
         // Curly braces inside of values
         yield [new Cursor('{: data-json="{1,2,3}" }'), ['data-json' => '{1,2,3}']];
         yield [new Cursor('{data-json={1,2,3}} test'), ['data-json' => '{1,2,3}'], ' test'];
+
+        // Avoid mustache style templating language being parsed as attributes
+        yield [new Cursor('{{ foo }}'), [], '{{ foo }}'];
+        yield [new Cursor(' {{ foo }}'), [], ' {{ foo }}'];
     }
 
     /**