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

diff --git a/src/html/htmlpars.cpp b/src/html/htmlpars.cpp
index ed99a443b69d5f3b89858becad6c98ec097890f5..dad3f09a427a6e554b0da5dd4b74d618c27d99ae 100644 (file)
--- 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;
 
 
     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
 
     // skip the start of the comment tag in any case, if we don't find the
     // closing tag we should ignore broken markup