[ticket/13680] Updated quote notifications

Added get_quote_authors() to text_formatter.utils service to retrieve
the names used in first-level quotes

PHPBB3-13680

phpBB/phpbb/textformatter/s9e/utils.php

@@ -34,6 +34,31 @@ class utils implements \phpbb\textformatter\utils_interface
 		return \s9e\TextFormatter\Utils::removeFormatting($xml);
 	}
 
+	/**
+	* Get a list of quote authors, limited to the first level of quotes
+	*
+	* @param  string   $xml Parsed text
+	* @return string[]      List of authors
+	*/
+	public function get_quote_authors($xml)
+	{
+		$authors = array();
+		if (strpos($xml, '<QUOTE ') === false)
+		{
+			return $authors;
+		}
+
+		$dom = new \DOMDocument;
+		$dom->loadXML($xml);
+		$xpath = new \DOMXPath($dom);
+		foreach ($xpath->query('//QUOTE[not(ancestor::QUOTE)]/@author') as $author)
+		{
+			$authors[] = $author->textContent;
+		}
+
+		return $authors;
+	}
+
 	/**
 	* Remove given BBCode and its content, at given nesting depth
 	*