IndexOutOfBoundsException when deleting whole text if last line is empty

[JFormDesigner]

Discovered an exception when first pressing Ctrl+A to select whole text and then press DEL key. It occurs only if the last line in the text area is empty.

Can be easily reproduced by starting this little app and pressing the DELkey:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.stage.Stage;
import org.fxmisc.flowless.VirtualizedScrollPane;
import org.fxmisc.richtext.CodeArea;

public class ClearBug extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception {
        CodeArea area = new CodeArea("abc\n");
        VirtualizedScrollPane<CodeArea> vsPane = new VirtualizedScrollPane<>(area);

        area.selectAll();
        
        Scene scene = new Scene(vsPane, 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();
    }
}

The exception:

Sep 07, 2017 5:34:37 PM javafx.beans.binding.Bindings$6 computeValue
WARNING: Exception while evaluating binding
java.lang.IndexOutOfBoundsException: 4 not in [0, 1]
	at org.reactfx.util.Lists.checkPosition(Lists.java:110)
	at org.reactfx.util.Lists.checkPosition(Lists.java:105)
	at org.reactfx.util.FingerTree$NonEmptyFingerTree.locateProgressively(FingerTree.java:51)
	at org.fxmisc.richtext.model.ReadOnlyStyledDocument$Pos.offsetBy(ReadOnlyStyledDocument.java:378)
	at org.fxmisc.richtext.SelectionImpl.lambda$2(SelectionImpl.java:133)
	at org.reactfx.value.MappedVal.computeValue(MappedVal.java:23)
	at org.reactfx.value.ValBase.getValue(ValBase.java:17)
	at org.reactfx.value.MappedVal.computeValue(MappedVal.java:22)
	at org.reactfx.value.ValBase.getValue(ValBase.java:17)
	at org.reactfx.value.MappedVal.computeValue(MappedVal.java:22)
	at org.reactfx.value.ValBase.getValue(ValBase.java:17)
	at org.reactfx.value.SuspendableValWrapper.getValue(SuspendableValWrapper.java:23)
	at org.fxmisc.richtext.SelectionImpl.getStartParagraphIndex(SelectionImpl.java:67)
	at org.fxmisc.richtext.CaretSelectionBindImpl.getStartParagraphIndex(CaretSelectionBindImpl.java:81)
	at org.fxmisc.richtext.GenericStyledArea.getParagraphSelection(GenericStyledArea.java:889)
	at org.fxmisc.richtext.GenericStyledArea.getParagraphSelection(GenericStyledArea.java:885)
	at org.fxmisc.richtext.GenericStyledArea.lambda$34(GenericStyledArea.java:1218)
	at javafx.beans.binding.Bindings$6.computeValue(Bindings.java:338)
	at javafx.beans.binding.ObjectBinding.get(ObjectBinding.java:153)
	at javafx.beans.binding.ObjectExpression.getValue(ObjectExpression.java:50)
	at javafx.beans.property.ObjectPropertyBase.get(ObjectPropertyBase.java:132)
	at javafx.beans.binding.ObjectExpression.getValue(ObjectExpression.java:50)
	at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:178)
	at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
	at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)
	at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
	at javafx.beans.property.ObjectPropertyBase.access$000(ObjectPropertyBase.java:51)
	at javafx.beans.property.ObjectPropertyBase$Listener.invalidated(ObjectPropertyBase.java:233)
	at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
	at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
	at javafx.beans.binding.ObjectBinding.invalidate(ObjectBinding.java:172)
	at com.sun.javafx.binding.BindingHelperObserver.invalidated(BindingHelperObserver.java:51)
	at org.reactfx.value.InvalidationListenerWrapper.accept(Val.java:765)
	at org.reactfx.util.AbstractReducingStreamNotifications.lambda$head$0(NotificationAccumulator.java:248)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:57)
	at org.reactfx.value.ValBase.invalidate(ValBase.java:32)
	at org.reactfx.value.SimpleVar.setValue(SimpleVar.java:59)
	at org.fxmisc.richtext.ParagraphBox.setIndex(ParagraphBox.java:71)
	at org.fxmisc.richtext.GenericStyledArea$2.updateIndex(GenericStyledArea.java:1231)
	at org.fxmisc.flowless.CellWrapper.updateIndex(CellWrapper.java:126)
	at org.fxmisc.flowless.CellWrapper.updateIndex(CellWrapper.java:126)
	at org.fxmisc.flowless.CellListManager.presentCellsChanged(CellListManager.java:99)
	at org.reactfx.util.ListNotifications.lambda$takeHead$0(NotificationAccumulator.java:317)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.collection.MemoizationListImpl$MemoizedView.publishNotifications(MemoizationList.java:58)
	at org.reactfx.collection.MemoizationListImpl$MemoizedView.access$300(MemoizationList.java:30)
	at org.reactfx.collection.MemoizationListImpl.sourceChanged(MemoizationList.java:89)
	at org.reactfx.util.ListNotifications.lambda$takeHead$0(NotificationAccumulator.java:317)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:57)
	at org.reactfx.collection.MappedList.sourceChanged(MappedList.java:41)
	at org.reactfx.util.ListNotifications.lambda$takeHead$0(NotificationAccumulator.java:317)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.SuspendableBase.resume(SuspendableBase.java:64)
	at org.reactfx.CloseableOnceGuard.close(Guard.java:49)
	at org.reactfx.MultiGuard.close(Guard.java:83)
	at org.reactfx.Suspendable$1.resumeSource(Suspendable.java:118)
	at org.reactfx.Suspendable$1.suspendSource(Suspendable.java:104)
	at org.reactfx.util.NonAccumulativeStreamNotifications.lambda$head$0(NotificationAccumulator.java:134)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:57)
	at org.reactfx.ProperEventStream.emit(ProperEventStream.java:18)
	at org.reactfx.EventStreams$3.lambda$observeInputs$0(EventStreams.java:105)
	at org.reactfx.value.ChangeListenerWrapper.accept(Val.java:786)
	at org.reactfx.util.AbstractReducingStreamNotifications.lambda$head$0(NotificationAccumulator.java:248)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:68)
	at org.reactfx.ObservableBase.notifyObservers(ObservableBase.java:57)
	at org.reactfx.value.ValBase.invalidate(ValBase.java:32)
	at org.reactfx.SuspendableBoolean.release(SuspendableBoolean.java:24)
	at org.reactfx.CloseableOnceGuard.close(Guard.java:49)
	at org.reactfx.Suspendable.suspendWhile(Suspendable.java:49)
	at org.fxmisc.richtext.model.GenericEditableStyledDocumentBase.update(GenericEditableStyledDocumentBase.java:218)
	at org.reactfx.util.Tuple3.exec(Tuple3.java:43)
	at org.fxmisc.richtext.model.GenericEditableStyledDocumentBase.replace(GenericEditableStyledDocumentBase.java:125)
	at org.fxmisc.richtext.model.SimpleEditableStyledDocument.replace(SimpleEditableStyledDocument.java:1)
	at org.fxmisc.richtext.GenericStyledArea.replace(GenericStyledArea.java:1132)
	at org.fxmisc.richtext.GenericStyledArea.replaceText(GenericStyledArea.java:1127)
	at org.fxmisc.richtext.model.TextEditingArea.replaceText(TextEditingArea.java:292)
	at org.fxmisc.richtext.model.EditActions.replaceSelection(EditActions.java:164)
	at org.fxmisc.richtext.GenericStyledAreaBehavior.deleteForward(GenericStyledAreaBehavior.java:348)
	at org.fxmisc.wellbehaved.event.template.InputMapTemplate.lambda$consume$32(InputMapTemplate.java:107)
	at org.fxmisc.wellbehaved.event.template.PatternActionTemplate.lambda$null$44(InputMapTemplate.java:242)
	at java.util.Optional.map(Optional.java:215)
	at org.fxmisc.wellbehaved.event.template.PatternActionTemplate.lambda$getInputHandlerTemplateMap$45(InputMapTemplate.java:242)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputMapTemplate$2.lambda$null$35(InputMapTemplate.java:180)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputMapTemplate$1.lambda$null$30(InputMapTemplate.java:92)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputMapTemplate$1.lambda$null$30(InputMapTemplate.java:92)
	at org.fxmisc.wellbehaved.event.template.InputHandlerTemplateMap.lambda$sequence$39(InputHandlerTemplateMap.java:24)
	at org.fxmisc.wellbehaved.event.template.InputMapTemplate$HandlerTemplateConsumer$1.lambda$accept$29(InputMapTemplate.java:36)
	at org.fxmisc.wellbehaved.event.InputHandler.handle(InputHandler.java:15)
	at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
	at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
	at javafx.event.Event.fireEvent(Event.java:198)
	at javafx.scene.Scene$KeyHandler.process(Scene.java:3964)
	at javafx.scene.Scene$KeyHandler.access$1800(Scene.java:3910)
	at javafx.scene.Scene.impl_processKeyEvent(Scene.java:2040)
	at javafx.scene.Scene$ScenePeerListener.keyEvent(Scene.java:2501)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:217)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler$KeyEventNotification.run(GlassViewEventHandler.java:149)
	at java.security.AccessController.doPrivileged(Native Method)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleKeyEvent$353(GlassViewEventHandler.java:248)
	at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
	at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleKeyEvent(GlassViewEventHandler.java:247)
	at com.sun.glass.ui.View.handleKeyEvent(View.java:546)
	at com.sun.glass.ui.View.notifyKey(View.java:966)
	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
	at java.lang.Thread.run(Thread.java:748)

[JordanMartinez]

I'm going to guess that the bug occurs due to #564.

[JordanMartinez]

Actually, no. It probably occurs because getSelectionInParagraph now adds 1 to the returned IndexRange's end to account for the newline issue I addressed in 564

It'd take a closer look.

[JordanMartinez]

Aye, the bug is caused by an order issue. The emitted plainTextChange that updates the selection's index range occurs after SelectionImpl uses its own outdated selection value to determine what its (TwoDimensional) positions are.

[JordanMartinez]

SelectionImpl uses its outdated selection value because the paragraph update causes a new ParagraphBox to be created, which needs to know the area's selection range so that it can update the selection value whenever that should change. In other words, we have a cyclical situation going on here...

[JordanMartinez]

The quick and dirty approach is just to remove the 2DPostion-related properties in Selection. The correct fix will take much longer as it will probably entail refactoring the code a bit more so that Selection is responsible for rendering itself in a ParagraphBox, rather than relying up ParagraphBox to do that.

[JordanMartinez]

I tried running the test before the CaretSelectionBind code was integrated into the area. This console output shows that the code was handled differently than it is now:

 ==== Replacing text with 'abc\n' ===
either box's index or the selection changed
Getting paragraph selection for paragraph: 1
Selection start 2d: 0 | 0
Selection end 2d:   0 | 0
Emitting plain text change: PlainTextChange{
	position: 0
	removed: 
	inserted: abc

}
internal selection invalidated and is now: 4, 4
selectionStart2D is: major: 1, minor: 0
selectionEnd2D is:   major: 1, minor: 0
either box's index or the selection changed
Getting paragraph selection for paragraph: 1
Selection start 2d: 1 | 0
Selection end 2d:   1 | 0
either box's index or the selection changed
Getting paragraph selection for paragraph: 0
Selection start 2d: 1 | 0
Selection end 2d:   1 | 0

 ==== Selecting all text ===
internal selection invalidated and is now: 0, 4
selectionStart2D is: major: 0, minor: 0
selectionEnd2D is:   major: 1, minor: 0
either box's index or the selection changed
Getting paragraph selection for paragraph: 1
Selection start 2d: 0 | 0
Selection end 2d:   1 | 0
either box's index or the selection changed
Getting paragraph selection for paragraph: 0
Selection start 2d: 0 | 0
Selection end 2d:   1 | 0

 ==== Pushing delete ===
either box's index or the selection changed
Getting paragraph selection for paragraph: 0
Selection start 2d: 0 | 0
Selection end 2d:   1 | 0
Emitting plain text change: PlainTextChange{
	position: 0
	removed: abc

	inserted: 
}
internal selection invalidated and is now: 0, 0
selectionStart2D is: major: 0, minor: 0
selectionEnd2D is:   major: 0, minor: 0
either box's index or the selection changed
Getting paragraph selection for paragraph: 0
Selection start 2d: 0 | 0
Selection end 2d:   0 | 0

[JFormDesigner]

Thx 👍