org.eclipse.xtext.ui.editor.folding.DefaultFoldingStructureProvider.java Source code

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Here is the source code for org.eclipse.xtext.ui.editor.folding.DefaultFoldingStructureProvider.java

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/*******************************************************************************
 * Copyright (c) 2010 Michael Clay 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
 *
 *******************************************************************************/
package org.eclipse.xtext.ui.editor.folding;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.eclipse.core.runtime.Assert;
import org.eclipse.emf.ecore.resource.Resource.Diagnostic;
import org.eclipse.jface.text.Position;
import org.eclipse.jface.text.source.Annotation;
import org.eclipse.jface.text.source.projection.IProjectionListener;
import org.eclipse.jface.text.source.projection.ProjectionAnnotation;
import org.eclipse.jface.text.source.projection.ProjectionAnnotationModel;
import org.eclipse.jface.text.source.projection.ProjectionViewer;
import org.eclipse.xtext.resource.XtextResource;
import org.eclipse.xtext.resource.XtextSyntaxDiagnostic;
import org.eclipse.xtext.ui.editor.XtextEditor;
import org.eclipse.xtext.ui.editor.model.IXtextDocument;
import org.eclipse.xtext.ui.editor.model.IXtextModelListener;

import com.google.common.base.Predicate;
import com.google.common.collect.Iterables;
import com.google.common.collect.Maps;
import com.google.common.collect.Sets;
import com.google.inject.Inject;

/**
 * Default implementation of interface {@link IFoldingStructureProvider}/
 * 
 * @author Michael Clay - Initial contribution and API
 */
public class DefaultFoldingStructureProvider implements IFoldingStructureProvider, IXtextModelListener {
    @Inject
    private IFoldingRegionProvider foldingRegionProvider;
    private XtextEditor editor;
    private ProjectionViewer viewer;
    private ProjectionChangeListener projectionListener;

    @Override
    public void install(XtextEditor editor, ProjectionViewer viewer) {
        Assert.isNotNull(editor);
        Assert.isNotNull(viewer);
        uninstall();
        this.editor = editor;
        this.viewer = viewer;
        projectionListener = new ProjectionChangeListener(viewer);
    }

    @Override
    public void initialize() {
        calculateProjectionAnnotationModel(true);
    }

    @Override
    public void uninstall() {
        if (isInstalled()) {
            handleProjectionDisabled();
            projectionListener.dispose();
            projectionListener = null;
            editor = null;
        }
    }

    /**
     * Returns <code>true</code> if the provider is installed, <code>false</code> otherwise.
     * 
     * @return <code>true</code> if the provider is installed, <code>false</code> otherwise
     */
    protected final boolean isInstalled() {
        return editor != null;
    }

    /**
     * @see org.eclipse.xtext.ui.editor.model.IXtextModelListener#modelChanged(org.eclipse.xtext.resource.XtextResource)
     */
    @Override
    public void modelChanged(XtextResource resource) {
        if (resource == null)
            return;
        boolean existingSyntaxErrors = Iterables.any(resource.getErrors(), new Predicate<Diagnostic>() {
            @Override
            public boolean apply(Diagnostic diagnostic) {
                return diagnostic instanceof XtextSyntaxDiagnostic;
            }
        });

        if (!existingSyntaxErrors) {
            calculateProjectionAnnotationModel(false);
        }
    }

    protected void handleProjectionEnabled() {
        handleProjectionDisabled();
        if (isInstalled()) {
            initialize();
            IXtextDocument document = editor.getDocument();
            if (document != null) {
                document.addModelListener(this);
            }
        }
    }

    protected void handleProjectionDisabled() {
        if (editor != null) {
            IXtextDocument document = editor.getDocument();
            if (document != null) {
                document.removeModelListener(this);
            }
        }
    }

    protected void calculateProjectionAnnotationModel(boolean allowCollapse) {
        ProjectionAnnotationModel projectionAnnotationModel = this.viewer.getProjectionAnnotationModel();
        if (projectionAnnotationModel != null) {
            // make a defensive copy as we modify the folded positions in subsequent operations
            Collection<FoldedPosition> foldedPositions = Sets
                    .newLinkedHashSet(foldingRegionProvider.getFoldingRegions(editor.getDocument()));
            Annotation[] newRegions = mergeFoldingRegions(foldedPositions, projectionAnnotationModel);
            updateFoldingRegions(allowCollapse, projectionAnnotationModel, foldedPositions, newRegions);
        }
    }

    @SuppressWarnings("unchecked")
    protected Annotation[] mergeFoldingRegions(Collection<FoldedPosition> foldedPositions,
            ProjectionAnnotationModel projectionAnnotationModel) {
        List<Annotation> deletions = new ArrayList<Annotation>();
        for (Iterator<Annotation> iterator = projectionAnnotationModel.getAnnotationIterator(); iterator
                .hasNext();) {
            Annotation annotation = iterator.next();
            if (annotation instanceof ProjectionAnnotation) {
                Position position = projectionAnnotationModel.getPosition(annotation);
                if (!foldedPositions.remove(position)) {
                    deletions.add(annotation);
                }
            }
        }
        return deletions.toArray(new Annotation[deletions.size()]);
    }

    protected void updateFoldingRegions(boolean allowCollapse, ProjectionAnnotationModel model,
            Collection<FoldedPosition> foldedPositions, Annotation[] deletions) {
        Map<ProjectionAnnotation, Position> additionsMap = Maps.newHashMap();
        for (FoldedPosition foldedPosition : foldedPositions) {
            addProjectionAnnotation(allowCollapse, foldedPosition, additionsMap);
        }
        if (deletions.length != 0 || additionsMap.size() != 0) {
            model.modifyAnnotations(deletions, additionsMap, new Annotation[] {});
        }
    }

    protected void addProjectionAnnotation(boolean allowCollapse, Position foldingRegion,
            Map<ProjectionAnnotation, Position> additionsMap) {
        boolean collapse = allowCollapse && (foldingRegion instanceof DefaultFoldedPosition)
                && ((DefaultFoldedPosition) foldingRegion).isInitiallyFolded();
        ProjectionAnnotation projectionAnnotation = createProjectionAnnotation(collapse, foldingRegion);
        additionsMap.put(projectionAnnotation, foldingRegion);
    }

    protected ProjectionAnnotation createProjectionAnnotation(boolean isCollapsed, Position foldedRegion) {
        return new ProjectionAnnotation(isCollapsed);
    }

    /**
     * Internal projection listener.
     */
    public class ProjectionChangeListener implements IProjectionListener {
        private ProjectionViewer projectionViewer;

        /**
         * Registers the listener with the viewer.
         * 
         * @param viewer
         *            the viewer to register a listener with
         */
        public ProjectionChangeListener(ProjectionViewer viewer) {
            Assert.isLegal(viewer != null);
            projectionViewer = viewer;
            projectionViewer.addProjectionListener(this);
        }

        /**
         * Disposes of this listener and removes the projection listener from the viewer.
         */
        public void dispose() {
            if (projectionViewer != null) {
                projectionViewer.removeProjectionListener(this);
                projectionViewer = null;
            }
        }

        @Override
        public void projectionEnabled() {
            handleProjectionEnabled();
        }

        @Override
        public void projectionDisabled() {
            handleProjectionDisabled();
        }
    }
}