parser: Skip most of Parser::finalizeHeadings when no header found

When the regex does not find <h1-6> tags, most of the function does not
need to initialize variables for the empty loop run.
In this case the NO_TOC output flag is no longer set.

This should improve message parsing as the short text snippet from
messages often does not provide headers

Bug: T378764
Change-Id: Ib22c40f10494f7fbe5cb27602a17a365642607e8

1 files changed, 5 insertions, 3 deletions

diff --git a/includes/parser/Parser.php b/includes/parser/Parser.php
index 75110882d6f1..d8f265737c5e 100644
--- a/includes/parser/Parser.php
+++ b/includes/parser/Parser.php
@@ -4317,6 +4317,10 @@ class Parser {
 			$enoughToc = true;
 		}
 
+		if ( !$numMatches ) {
+			return $text;
+		}
+
 		# headline counter
 		$headlineCount = 0;
 		$haveTocEntries = false;
@@ -4337,11 +4341,9 @@ class Parser {
 		$cpOffset = 0;
 		$refers = [];
 
-		$headlines = $numMatches !== false ? $matches[3] : [];
-
 		$maxTocLevel = $this->svcOptions->get( MainConfigNames::MaxTocLevel );
 		$domDocument = DOMUtils::parseHTML( '' );
-		foreach ( $headlines as $headline ) {
+		foreach ( $matches[3] as $headline ) {
 			// $headline is half-parsed HTML
 			$isTemplate = false;
 			$titleText = false;