tdf#97635 Added unindentation using shift-tab (mimicked eclipse behavior)

Change-Id: Iaf64451c92f3465751032dde9c283141e548b3ca
Reviewed-on: https://gerrit.libreoffice.org/72228
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>
diff --git a/scripting/java/com/sun/star/script/framework/provider/beanshell/PlainSourceView.java b/scripting/java/com/sun/star/script/framework/provider/beanshell/PlainSourceView.java
index f75b1e7..581ef48 100644
--- a/scripting/java/com/sun/star/script/framework/provider/beanshell/PlainSourceView.java
+++ b/scripting/java/com/sun/star/script/framework/provider/beanshell/PlainSourceView.java
@@ -45,6 +45,9 @@ import javax.swing.undo.UndoManager;
import java.util.List;
import java.util.ArrayList;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PlainSourceView extends JScrollPane implements
    ScriptSourceView, DocumentListener {

@@ -171,6 +174,25 @@ public class PlainSourceView extends JScrollPane implements
        ta.addKeyListener(new KeyAdapter(){
            @Override
            public void keyReleased(KeyEvent ke){
                // if shift + tab was pressed, remove the first tab before any code begins
                if (ke.isShiftDown() && ke.getKeyCode() == KeyEvent.VK_TAB) {
                    try {
                        int caretOffset = ta.getCaretPosition();
                        int lineOffset = ta.getLineOfOffset(caretOffset);
                        int startOffset = ta.getLineStartOffset(lineOffset);
                        int endOffset = ta.getLineEndOffset(lineOffset);

                        Pattern pattern = Pattern.compile("^ *(\\t)");
                        Matcher matcher = pattern.matcher(ta.getText(startOffset, endOffset - startOffset));

                        if (matcher.find()) {
                            ta.replaceRange(null, startOffset + matcher.start(1), startOffset + matcher.end(1));
                        }
                    } catch (BadLocationException e) {
                        // could not find correct location of the tab
                    }
                }

                if(ke.getKeyCode() == KeyEvent.VK_SPACE || ke.getKeyCode() == KeyEvent.VK_ENTER){
                    compoundEdit.end();
                    undoManager.addEdit(compoundEdit);