From e4f762f41612d1bfddcb960c0d9aecdbda03964b Mon Sep 17 00:00:00 2001
From: =?utf8?q?V=C3=A1clav=20Slav=C3=ADk?= <vslavik@fastmail.fm>
Date: Mon, 7 May 2012 11:15:31 +0000
Subject: [PATCH] Fix performance of wxHtmlParser::SkipCommentTag() in UTF-8
 build.

Avoid computing the difference between two potentially distant
iterators, which is O(1) in wchar_t build, but O(n) in UTF-8 one.

See #13445.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71370 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/html/htmlpars.cpp | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/src/html/htmlpars.cpp b/src/html/htmlpars.cpp
index ed99a443b6..dad3f09a42 100644
--- a/src/html/htmlpars.cpp
+++ b/src/html/htmlpars.cpp
@@ -957,12 +957,14 @@ wxHtmlParser::SkipCommentTag(wxString::const_iterator& start,
 
     wxString::const_iterator p = start;
 
-    // comments begin with "<!--" in HTML 4.0
-    if ( end - start < 4 || *++p != '!' || *++p != '-' || *++p != '-' )
-    {
-        // not a comment at all
-        return false;
-    }
+    // Comments begin with "<!--" in HTML 4.0; anything shorter or not containing
+    // these characters is not a comment and we're not going to skip it.
+    if ( ++p == end || *p != '!' )
+      return false;
+    if ( ++p == end || *p != '-' )
+      return false;
+    if ( ++p == end || *p != '-' )
+      return false;
 
     // skip the start of the comment tag in any case, if we don't find the
     // closing tag we should ignore broken markup
-- 
2.45.2