如何实现自动括弧关闭？

Question

I'm developing an eclipse plugin which contains a custom text editor.
I want to implement the functionality of auto closing brackets (and quotation marks) meaning that when the user types ( the editor should automatically insert the corresponding closing bracket ) .

My current approach is to add a IDocumentListener to the underlying IDocument and whenever the document is changed I look at the new character and if it is one I want to add a closing character to, I'm adding it by setting the text of the document but this always throws my this exception:

!SESSION 2015-12-22 15:03:53.517 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_45
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=de_DE
Framework arguments:  -product org.eclipse.sdk.ide
Command-line arguments:  -product org.eclipse.sdk.ide -data C:\Users\Robert Adam\Documents\eclipse.mars.pluginDev\workspace/../runtime-EclipseApplication(1) -dev file:C:/Users/Robert Adam/Documents/eclipse.mars.pluginDev/workspace/.metadata/.plugins/org.eclipse.pde.core/Eclipse Application (1)/dev.properties -os win32 -ws win32 -arch x86_64 -consoleLog

!ENTRY org.eclipse.text 4 2 2015-12-22 15:04:23.611
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.text".
!STACK 0
org.eclipse.core.runtime.AssertionFailedException: assertion failed: 
    at org.eclipse.core.runtime.Assert.isTrue(Assert.java:110)
    at org.eclipse.core.runtime.Assert.isTrue(Assert.java:96)
    at org.eclipse.ui.internal.texteditor.quickdiff.DocumentLineDiffer.handleAboutToBeChanged(DocumentLineDiffer.java:816)
    at org.eclipse.ui.internal.texteditor.quickdiff.DocumentLineDiffer.documentAboutToBeChanged(DocumentLineDiffer.java:785)
    at org.eclipse.jface.text.AbstractDocument.fireDocumentAboutToBeChanged(AbstractDocument.java:665)
    at org.eclipse.jface.text.AbstractDocument.set(AbstractDocument.java:1228)
    at org.eclipse.jface.text.AbstractDocument.set(AbstractDocument.java:1217)
    at raven.sqdev.editors.sqfeditor.SQFDocumentListener.handleAddition(SQFDocumentListener.java:61)
    at raven.sqdev.editors.sqfeditor.SQFDocumentListener.documentChanged(SQFDocumentListener.java:33)
    at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged2(AbstractDocument.java:769)
    at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged(AbstractDocument.java:736)
    at org.eclipse.jface.text.AbstractDocument.doFireDocumentChanged(AbstractDocument.java:721)
    at org.eclipse.jface.text.AbstractDocument.fireDocumentChanged(AbstractDocument.java:796)
    at org.eclipse.jface.text.AbstractDocument.replace(AbstractDocument.java:1191)
    at org.eclipse.jface.text.AbstractDocument.replace(AbstractDocument.java:1210)
    at org.eclipse.jface.text.DefaultDocumentAdapter.replaceTextRange(DefaultDocumentAdapter.java:248)
    at org.eclipse.swt.custom.StyledText.modifyContent(StyledText.java:7268)
    at org.eclipse.swt.custom.StyledText.sendKeyEvent(StyledText.java:8111)
    at org.eclipse.swt.custom.StyledText.doContent(StyledText.java:2481)
    at org.eclipse.swt.custom.StyledText.handleKey(StyledText.java:5955)
    at org.eclipse.swt.custom.StyledText.handleKeyDown(StyledText.java:5986)
    at org.eclipse.swt.custom.StyledText$7.handleEvent(StyledText.java:5663)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4353)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1061)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1085)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1070)
    at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1112)
    at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1108)
    at org.eclipse.swt.widgets.Widget.wmChar(Widget.java:1529)
    at org.eclipse.swt.widgets.Control.WM_CHAR(Control.java:4722)
    at org.eclipse.swt.widgets.Canvas.WM_CHAR(Canvas.java:343)
    at org.eclipse.swt.widgets.Control.windowProc(Control.java:4610)
    at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:339)
    at org.eclipse.swt.widgets.Display.windowProc(Display.java:5023)
    at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method)
    at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:2549)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3759)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
    at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
    at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
    at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
    at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
    at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:380)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
    at org.eclipse.equinox.launcher.Main.main(Main.java:1438)

As far as I know this is because I'm changing the text from the listener which is not a good idea as the change itself notifys the listener which can result in an infinite loop.
However I just can't come up with a better idea to implement this functionality.

I thought about that this kind of task may be associated with the ContentAssist but I can't find anything about it.

Does anybody know how to properly implement this functionality in my eclipse plugin?

Answer 1

After looking in the sourceCode of the org.eclipse.jdt.ui plugin I found out that they created this feature using a VerifyKeyListener on the SourceViewer of the editor. It catches all key inputs and has access to the respective text through the event.

However it turned out to be quite tricky to get to the SourceViewer of my editor as it is created after my editor and therefore the method getSourceViewer() returned null when called in the constructor of my editor.
The key was to override createSourceViewer() in my editor class that is declared in AbstractDecoratedTextEditor .
There I did something like this:

@Override
    public ISourceViewer createSourceViewer(Composite parent, IVerticalRuler ruler, int styles) {
        ISourceViewer viewer = super.createSourceViewer(parent, ruler, styles);

        if(viewer instanceof ITextViewerExtension) {
            ((ITextViewerExtension) viewer).appendVerifyKeyListener(<Listener>);
        }

        return viewer;
    }

I implemented my own VerifyKeyListern in which I handle finding pairing characters (like opening and closing brackets) and then used something like this inside of the verifyKey() -method:

StyledText text = (StyledText) event.getSource();

text.insert(String.valueOf(<pairingCharacter>));

As the typed in character (the opening character) is inserted to the text anyway I only add the corresponding closing charakter via the insert() -method which has the nice effekt that afterwards my cursor is in between these two characters