fix invalid current-grouping-key when called in new for-each

src/Xsl/Functions/CurrentGroupingKey.php

@@ -33,17 +33,18 @@ public function serialize(Lexer $lexer, DOMNode $currentElement): array
         }
 
         if ($currentElement->localName === 'sort' && $currentElement->namespaceURI === XslTransformations::URI) {
-            $resultTokens = ['current()'];
+            $lexer->seek($lexer->key() + 2);
+            return ['current()'];
         } else {
             if ($xslForEach instanceof DOMElement) {
-                $resultTokens = ['current()'];
+                $groupId = $xslForEach->getAttribute('group-id');
             } else {
                 throw new \UnexpectedValueException('Expecting DOMElement');
             }
         }
 
         $lexer->seek($lexer->key() + 2);
-        return $resultTokens;
+        return ['$current-grouping-key-' . $groupId];
     }
 
     /**

src/Xsl/Node/ElementForEachGroup.php

@@ -49,6 +49,7 @@ public function transform(DOMElement $element): void
         $document = $element->ownerDocument;
 
         $xslForEach = $this->createForEachStatement($element, $groupId);
+        $groupingKeyVariable = $this->createGroupingKeyVariable($element, $groupId);
         $unGroupedVariable = $this->createUnGroupedVariable($element, $groupId);
         $groupVariable = $this->createGroupVariable($element, $groupId);
 
@@ -61,6 +62,7 @@ public function transform(DOMElement $element): void
             }
         }
 
+        $xslForEach->appendChild($groupingKeyVariable);
         $xslForEach->appendChild($groupVariable);
 
         while ($element->childNodes->length > 0) {
@@ -124,6 +126,19 @@ private function createGroupVariable(DOMElement $element, string $groupId): DOME
         return $variable;
     }
 
+    /**
+     * @param DOMElement $element
+     * @param string $groupId
+     * @return DOMElement
+     */
+    private function createGroupingKeyVariable(DOMElement $element, string $groupId): DOMElement
+    {
+        $variable = $element->ownerDocument->createElementNS(XslTransformations::URI, 'xsl:variable');
+        $variable->setAttribute('name', 'current-grouping-key-' . $groupId);
+        $variable->setAttribute('select', 'current()');
+        return $variable;
+    }
+
     /**
      * @param DOMElement $element
      * @param string $groupId

test/Integration/Xsl/ForEachGroupTest.php

@@ -80,6 +80,20 @@ public function testByCurrentGroupingKey(): void
         $this->assertEquals('ComposerGenkgo', \trim($processor->transformToXml($data)));
     }
 
+    public function testByCurrentGroupingKeyInNewForEach(): void
+    {
+        $styleSheet = new DOMDocument();
+        $styleSheet->load('Stubs/Xsl/ForEachGroup/group-by-current-grouping-key-in-new-for-each.xsl');
+
+        $processor = new XsltProcessor(new NullCache());
+        $processor->importStyleSheet($styleSheet);
+
+        $data = new DOMDocument();
+        $data->load('Stubs/packages.xml');
+
+        $this->assertEquals('ComposerGenkgoGenkgoGenkgo', \trim($processor->transformToXml($data)));
+    }
+
     public function testByCurrentGroupingKeySort(): void
     {
         $styleSheet = new DOMDocument();

test/Stubs/Xsl/ForEachGroup/group-by-current-grouping-key-in-new-for-each.xsl

@@ -0,0 +1,15 @@
+<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
+
+    <xsl:output omit-xml-declaration="yes" />
+
+    <xsl:template match="packages">
+
+        <xsl:for-each-group select="package" group-by="author">
+            <xsl:for-each select="current-group()">
+                <xsl:value-of select="current-grouping-key()" />
+            </xsl:for-each>
+        </xsl:for-each-group>
+
+    </xsl:template>
+
+</xsl:stylesheet>