Refactor code

Create a common method for a similar code.
Simplify some logical operations.

Change-Id: If25703c51ea96fe5a64698f6fa3ffd6f5cb1b2c5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

src/plugins/diffeditor/diffeditorwidget.h

@@ -129,6 +129,10 @@ private:
             QTextCursor &cursor,
             const QMap<int, int> &positions) const;
     void colorDiff(const FileData &fileData);
+    QList<TextLineData> assemblyRows(const QStringList &lines,
+                                                       const QMap<int, int> &lineSpans,
+                                                       const QMap<int, int> &changedPositions,
+                                                       QMap<int, int> *outputChangedPositions) const;
     ChunkData calculateOriginalData(const QList<Diff> &diffList) const;
     FileData calculateContextData(const ChunkData &originalData) const;
     void showDiff();