Eclipse plugin development - Add own QuickAssist -> Extract to local variable

Question

I would like to add an own quick assist to eclipse. I found out that I need to extend IQuickAssistProcessor to achieve the goal. Because the entry and the logic is rather similar to the "extract to local variable" quick assist I would like to find the corresponding code to see how that works. Can anyone point me to the corresponding implementation of that quick fix?

Answer 1

This is the only code in Eclipse 4.2 that I could find that implements IQuickAssistProcessor. It's in the org.eclipse.ui.workbench.texteditor.source jar.

Perhaps you need to use IQuickAssistAssistant instead?

/*******************************************************************************
 * Copyright (c) 2006, 2009 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.texteditor.spelling;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.contentassist.ICompletionProposal;
import org.eclipse.jface.text.quickassist.IQuickAssistInvocationContext;
import org.eclipse.jface.text.quickassist.IQuickAssistProcessor;
import org.eclipse.jface.text.source.Annotation;
import org.eclipse.jface.text.source.IAnnotationModel;
import org.eclipse.jface.text.source.ISourceViewer;
import org.eclipse.jface.text.source.TextInvocationContext;

import org.eclipse.ui.internal.texteditor.spelling.NoCompletionsProposal;


/**
 * Spelling correction processor used to show quick
 * fixes for spelling problems.
 *
 * @since 3.3
 */
public final class SpellingCorrectionProcessor implements IQuickAssistProcessor {


    private static final ICompletionProposal[] fgNoSuggestionsProposal=  new ICompletionProposal[] { new NoCompletionsProposal() };


    /*
     * @see IContentAssistProcessor#computeCompletionProposals(ITextViewer, int)
     */
    public ICompletionProposal[] computeQuickAssistProposals(IQuickAssistInvocationContext quickAssistContext) {
        ISourceViewer viewer= quickAssistContext.getSourceViewer();
        int documentOffset= quickAssistContext.getOffset();

        int length= viewer != null ? viewer.getSelectedRange().y : -1;
        TextInvocationContext context= new TextInvocationContext(viewer, documentOffset, length);


        IAnnotationModel model= viewer.getAnnotationModel();
        if (model == null)
            return fgNoSuggestionsProposal;

        List proposals= computeProposals(context, model);
        if (proposals.isEmpty())
            return fgNoSuggestionsProposal;

        return (ICompletionProposal[]) proposals.toArray(new ICompletionProposal[proposals.size()]);
    }

    private boolean isAtPosition(int offset, Position pos) {
        return (pos != null) && (offset >= pos.getOffset() && offset <= (pos.getOffset() +  pos.getLength()));
    }

    private List computeProposals(IQuickAssistInvocationContext context, IAnnotationModel model) {
        int offset= context.getOffset();
        ArrayList annotationList= new ArrayList();
        Iterator iter= model.getAnnotationIterator();
        while (iter.hasNext()) {
            Annotation annotation= (Annotation)iter.next();
            if (canFix(annotation)) {
                Position pos= model.getPosition(annotation);
                if (isAtPosition(offset, pos)) {
                    collectSpellingProblems(annotation, annotationList);
                }
            }
        }
        SpellingProblem[] spellingProblems= (SpellingProblem[]) annotationList.toArray(new SpellingProblem[annotationList.size()]);
        return computeProposals(context, spellingProblems);
    }

    private void collectSpellingProblems(Annotation annotation, List problems) {
        if (annotation instanceof SpellingAnnotation)
            problems.add(((SpellingAnnotation)annotation).getSpellingProblem());
    }

    private List computeProposals(IQuickAssistInvocationContext context, SpellingProblem[] spellingProblems) {
        List proposals= new ArrayList();
        for (int i= 0; i < spellingProblems.length; i++)
            proposals.addAll(Arrays.asList(spellingProblems[i].getProposals(context)));

        return proposals;
    }

    /*
     * @see IContentAssistProcessor#getErrorMessage()
     */
    public String getErrorMessage() {
        return null;
    }

    /*
     * @see org.eclipse.jface.text.quickassist.IQuickAssistProcessor#canFix(org.eclipse.jface.text.source.Annotation)
     */
    public boolean canFix(Annotation annotation) {
        return annotation instanceof SpellingAnnotation && !annotation.isMarkedDeleted();
    }

    /*
     * @see org.eclipse.jface.text.quickassist.IQuickAssistProcessor#canAssist(org.eclipse.jface.text.quickassist.IQuickAssistInvocationContext)
     */
    public boolean canAssist(IQuickAssistInvocationContext invocationContext) {
        return false;
    }

}