C++11

[Mark Kretschmann]

On Wed, May 8, 2013 at 3:51 PM, Edward Toroshchin
<edward.hades at gmail.com> wrote:
> On Wed, May 08, 2013 at 02:50:26PM +0200, Mark Kretschmann wrote:
>> I'd really like to start using some C++11 features in Amarok. It has been
>> argued that only few compilers support all of C++11's features at this
>> point, and that we therefore couldn't use C++11.
>
> I support going to C++11.

I'm sometimes doing little experiments with C++11 usage in Amarok,
just to see how much it could improve our code. When I was hacking on
this crash workaround for the Wikipedia applet, I found the code
particularly awkward to work with. Lots of redundancy.

With some Lambda usage, it becomes a good deal more readable and
pleasant to work with, and less error prone. This is how it could look
instead:


>From 7cca04eb25169e5befb3e5d6a1290795c3e651b8 Mon Sep 17 00:00:00 2001
From: Mark Kretschmann <kretschmann at kde.org>
Date: Thu, 9 May 2013 19:08:24 +0200
Subject: [PATCH] Replace redundant code with one Lambda function.

---
 src/context/engines/wikipedia/WikipediaEngine.cpp | 68 ++++++-----------------
 1 file changed, 17 insertions(+), 51 deletions(-)

diff --git a/src/context/engines/wikipedia/WikipediaEngine.cpp
b/src/context/engines/wikipedia/WikipediaEngine.cpp
index 0692b8d..e70c1a2 100644
--- a/src/context/engines/wikipedia/WikipediaEngine.cpp
+++ b/src/context/engines/wikipedia/WikipediaEngine.cpp
@@ -776,61 +776,27 @@ WikipediaEnginePrivate::wikiParse( QString &wiki )
     wikiRef = wiki.midRef( wikiRef.position(), wiki.indexOf(
QLatin1String("<div class=\"printfooter\">"), wikiRef.position() ) -
wikiRef.position() );
     wiki = wikiRef.toString();

-    { // lets remove the warning box
-        const QString wBox    = QLatin1String("<table
class=\"metadata plainlinks ambox");
-        const QString wBoxEnd = QLatin1String("</table>");
-        const int wBoxEndSize = wBoxEnd.size();
-        int matchIndex = 0;
-        QStringMatcher mboxMatcher( wBox );
-        while( (matchIndex = mboxMatcher.indexIn(wiki, matchIndex)) != -1 )
-        {
-            const int nToBoxEnd = wiki.indexOf( wBoxEnd, matchIndex )
- matchIndex;
-            QStringRef wBoxRef = wiki.midRef( matchIndex, nToBoxEnd +
wBoxEndSize );
-            wiki.remove( wBoxRef.toString() );
-        }
-    }
-
-    { // remove protection policy (we don't do edits)
-        const QString protec = QLatin1String("<div><a
href=\"/wiki/Wikipedia:Protection_policy") ;
-        const QString protecEnd = QLatin1String("</a></div>") ;
-        const int protecEndSize = protecEnd.size();
-        int matchIndex = 0;
-        QStringMatcher protecMatcher( protec );
-        while( (matchIndex = protecMatcher.indexIn(wiki, matchIndex)) != -1 )
-        {
-            const int nToBoxEnd = wiki.indexOf( protecEnd, matchIndex
) - matchIndex;
-            QStringRef pRef = wiki.midRef( matchIndex, nToBoxEnd +
protecEndSize );
-            wiki.remove( pRef.toString() );
-        }
-    }
-
-    { // lets also remove the "lock" image
-        const QString topIcon = QLatin1String("<div class=\"metadata
topicon\" ");
-        const QString topIconEnd = QLatin1String("</a></div>");
-        const int topIconEndSize = topIconEnd.size();
-        int matchIndex = 0;
-        QStringMatcher topIconMatcher( topIcon );
-        while( (matchIndex = topIconMatcher.indexIn(wiki, matchIndex)) != -1 )
-        {
-            const int nToBoxEnd = wiki.indexOf( topIconEnd,
matchIndex ) - matchIndex;
-            QStringRef tRef = wiki.midRef( matchIndex, nToBoxEnd +
topIconEndSize );
-            wiki.remove( tRef.toString() );
-        }
-    }
-
-    { // remove <audio> tags (can lead to crashes in QtWebKit)
-        const QString tag    = QLatin1String("<audio");
-        const QString tagEnd = QLatin1String("</audio>");
+    auto removeTag = [] ( QString& text, const QString& tagStart,
const QString& tagEnd )
+    {
         const int tagEndSize = tagEnd.size();
         int matchIndex = 0;
-        QStringMatcher tagMatcher( tag );
-        while( (matchIndex = tagMatcher.indexIn(wiki, matchIndex)) != -1 )
+        const QStringMatcher tagMatcher( tagStart );
+        while( ( matchIndex = tagMatcher.indexIn( text, matchIndex ) ) != -1 )
         {
-            const int nToTagEnd = wiki.indexOf( tagEnd, matchIndex )
- matchIndex;
-            QStringRef tagRef = wiki.midRef( matchIndex, nToTagEnd +
tagEndSize );
-            wiki.remove( tagRef.toString() );
+            const int nToTagEnd = text.indexOf( tagEnd, matchIndex )
- matchIndex;
+            const QStringRef tagRef = text.midRef( matchIndex,
nToTagEnd + tagEndSize );
+            text.remove( tagRef.toString() );
         }
-    }
+    };
+
+    // lets remove the warning box
+    removeTag( wiki, "<table class=\"metadata plainlinks ambox", "</table>" );
+    // remove protection policy (we don't do edits)
+    removeTag( wiki, "<div><a
href=\"/wiki/Wikipedia:Protection_policy", "</a></div>" );
+    // lets also remove the "lock" image
+    removeTag( wiki, "<div class=\"metadata topicon\" ", "</a></div>" );
+    // remove <audio> tags (can lead to crashes in QtWebKit)
+    removeTag( wiki, "<audio", "</audio>" );

     // Adding back style and license information
     wiki = QLatin1String("<div id=\"bodyContent\"") + wiki;
--
1.8.1.2