Error in Preview of Custom Eclipse refactoring
eclipse, eclipse-plugin, java, refactoring
Solution
I found the eclipse.org article the most helpful to get me started.
A good place to get started debugging the code is to set breakpoints on org.eclipse.jdt.core.dom.rewrite.ASTRewrite, particularly the rewriteAST() method, then trigger some refactorings.
Here are a few you might find useful. Are you looking for anything in particular or a general sense of how to process the AST?
http://www.ibm.com/developerworks/opensource/library/os-ast/
http://blog.sahits.ch/?p=228
http://www.vogella.com/articles/EclipseJDT/article.html
Problem
I am implementing an new eclipse refactoring. This will enable developers to Pull-up the preconditions statements from a child method to the parent method. This all works perfectly when I select "Finish" in the refactoring wizard, but when I select "Preview" I get an error "No target edit provided." This seems to be caused by a problem in the `TextEdit` returned from `ASTRewrite.rewriteAST()`. However I cannot figure out why. The stack trace of the exception happens after my `Refactoring.createChange()` code is run, and the change is used to generate the preview. ``` org.eclipse.text.edits.MalformedTreeException: No target edit provided. at org.eclipse.text.edits.MoveSourceEdit.performConsistencyCheck(MoveSourceEdit.java:208) at org.eclipse.text.edits.TextEdit.traverseConsistencyCheck(TextEdit.java:873) at org.eclipse.text.edits.MoveSourceEdit.traverseConsistencyCheck(MoveSourceEdit.java:183) at org.eclipse.text.edits.TextEdit.traverseConsistencyCheck(TextEdit.java:869) at org.eclipse.text.edits.TextEdit.traverseConsistencyCheck(TextEdit.java:869) at org.eclipse.text.edits.TextEditProcessor.checkIntegrityDo(TextEditProcessor.java:176) at org.eclipse.text.edits.TextEdit.dispatchCheckIntegrity(TextEdit.java:743) at org.eclipse.text.edits.TextEditProcessor.performEdits(TextEditProcessor.java:151) at org.eclipse.ltk.core.refactoring.TextChange.getPreviewDocument(TextChange.java:534) at org.eclipse.ltk.core.refactoring.TextChange.getPreviewDocument(TextChange.java:403) at org.eclipse.ltk.core.refactoring.TextChange.getPreviewContent(TextChange.java:411) at org.eclipse.ltk.internal.ui.refactoring.TextEditChangePreviewViewer.setInput(TextEditChangePreviewViewer.java:209) at org.eclipse.ltk.internal.ui.refactoring.AbstractChangeNode.feedInput(AbstractChangeNode.java:99) at org.eclipse.ltk.internal.ui.refactoring.PreviewWizardPage.showPreview(PreviewWizardPage.java:598) at org.eclipse.ltk.internal.ui.refactoring.PreviewWizardPage.access$6(PreviewWizardPage.java:583) at org.eclipse.ltk.internal.ui.refactoring.PreviewWizardPage$7.selectionChanged(PreviewWizardPage.java:574) at org.eclipse.jface.viewers.Viewer$2.run(Viewer.java:162) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.core.runtime.Platform.run(Platform.java:888) at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48) at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175) at org.eclipse.jface.viewers.Viewer.fireSelectionChanged(Viewer.java:160) at org.eclipse.jface.viewers.StructuredViewer.updateSelection(StructuredViewer.java:2132) at org.eclipse.jface.viewers.StructuredViewer.setSelection(StructuredViewer.java:1669) at org.eclipse.jface.viewers.TreeViewer.setSelection(TreeViewer.java:1124) at org.eclipse.jface.viewers.Viewer.setSelection(Viewer.java:392) at org.eclipse.ltk.internal.ui.refactoring.PreviewWizardPage.setVisible(PreviewWizardPage.java:505) at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.makeVisible(RefactoringWizardDialog2.java:762) at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.showCurrentPage(RefactoringWizardDialog2.java:477) at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.nextOrPreviewPressed(RefactoringWizardDialog2.java:507) at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2.access$2(RefactoringWizardDialog2.java:492) at org.eclipse.ltk.internal.ui.refactoring.RefactoringWizardDialog2$1.widgetSelected(RefactoringWizardDialog2.java:691) at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:228) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3880) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3473) at org.eclipse.jface.window.Window.runEventLoop(Window.java:825) at org.eclipse.jface.window.Window.open(Window.java:801) at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation$1.run(RefactoringWizardOpenOperation.java:143) at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70) at org.eclipse.ltk.ui.refactoring.RefactoringWizardOpenOperation.run(RefactoringWizardOpenOperation.java:155) at org.jmlspecs.eclipse.refactor.action.AbstractMethodActionDelegate.run(AbstractMethodActionDelegate.java:78) at org.jmlspecs.eclipse.refactor.action.AbstractMethodActionDelegate.run(AbstractMethodActionDelegate.java:67) at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251) at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584) at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501) at org.eclipse.jface.action.ActionContributionItem$6.handleEvent(ActionContributionItem.java:452) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3880) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3473) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) 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:559) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514) at org.eclipse.equinox.launcher.Main.run(Main.java:1311) at org.eclipse.equinox.launcher.Main.main(Main.java:1287) ``` Currently the code that performs the change looks like this: ``` CompilationUnit sourceNode = ... ASTRewrite sourceRewrite = ASTRewrite.create(sourceNode.getAST()); Statement statement = ... sourceRewrite.createMoveTarget(statement); CompilationUnit destinationNode = ... MethodDeclaration destinationMethod = ... ASTRewrite destinationRewrite = ASTRewrite.create(destinationNode.getAST()); ListRewrite lrw = destinationRewrite.getListRewrite(destinationMethod.getBody(), Block.STATEMENTS_PROPERTY); lrw.insertFirst(statement, null); ``` I know that the way `createMoveTarget` is used is not how it is documented, but when I follow the documentation like below, the statement is deleted from the source but not moved to the destination and I still get the same error in the preview. ``` CompilationUnit sourceNode = ... ASTRewrite sourceRewrite = ASTRewrite.create(sourceNode.getAST()); Statement statement = ... Statement replacement = sourceRewrite.createMoveTarget(statement); sourceRewrite.remove(statement, null); CompilationUnit destinationNode = ... MethodDeclaration destinationMethod = ... ASTRewrite destinationRewrite = ASTRewrite.create(destinationNode.getAST()); ListRewrite lrw = destinationRewrite.getListRewrite(destinationMethod.getBody(), Block.STATEMENTS_PROPERTY); lrw.insertFirst(replacement, null); ``` Here is an example of the Refactoring being performed. Before: ``` class A { foo(int a) { return a * 2; } } class B { foo(int a) { JC.requires(a > 1); return a * 3; } } ``` After: ``` class A { foo(int a) { JC.requires(a > 1); return a * 2; } } class B extends A { foo(int a) { return a * 3; } } ```