EmbeddedFoldingStructureProvider.java

/*******************************************************************************
 * Copyright (c) 2011 Sebastian Benz 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:
 *     Sebastian Benz - initial API and implementation
 *******************************************************************************/
package org.xrepl.ui.embedded;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
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.folding.FoldedPosition;
import org.eclipse.xtext.ui.editor.folding.IFoldingRegionProvider;
import org.eclipse.xtext.ui.editor.folding.IFoldingStructureProvider;
import org.eclipse.xtext.ui.editor.model.IXtextModelListener;

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

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

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

	public void initialize() {
		calculateProjectionAnnotationModel(false);
	}

	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)
	 */
	public void modelChanged(XtextResource resource) {
		boolean existingSyntaxErrors = Iterables.any(resource.getErrors(),
				new Predicate<Diagnostic>() {
					public boolean apply(Diagnostic diagnostic) {
						return diagnostic instanceof XtextSyntaxDiagnostic;
					}
				});

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

	protected void handleProjectionEnabled() {
		handleProjectionDisabled();
		if (isInstalled()) {
			initialize();
			editor.getDocument().addModelListener(this);
		}
	}

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

	protected void calculateProjectionAnnotationModel(boolean allowCollapse) {
		ProjectionAnnotationModel projectionAnnotationModel = this.viewer
				.getProjectionAnnotationModel();
		if (projectionAnnotationModel != null) {
			Collection<FoldedPosition> foldingRegions = foldingRegionProvider
					.getFoldingRegions(editor.getDocument());
			HashBiMap<Position, FoldedPosition> positionsMap = toPositionIndexedMap(foldingRegions);
			Annotation[] newRegions = mergeFoldingRegions(positionsMap,
					projectionAnnotationModel);
			updateFoldingRegions(allowCollapse, projectionAnnotationModel,
					positionsMap, newRegions);
		}
	}

	protected HashBiMap<Position, FoldedPosition> toPositionIndexedMap(
			Collection<FoldedPosition> foldingRegions) {
		HashBiMap<Position, FoldedPosition> positionsMap = HashBiMap.create();
		for (FoldedPosition foldingRegion : foldingRegions) {
			positionsMap.put(toPosition(foldingRegion), foldingRegion);
		}
		return positionsMap;
	}

	@SuppressWarnings("unchecked")
	protected Annotation[] mergeFoldingRegions(
			HashBiMap<Position, FoldedPosition> positionsMap,
			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 (positionsMap.remove(position) == null) {
					deletions.add(annotation);
				}
			}
		}
		return deletions.toArray(new Annotation[deletions.size()]);
	}

	protected void updateFoldingRegions(boolean allowCollapse,
			ProjectionAnnotationModel model,
			HashBiMap<Position, FoldedPosition> positionsMap,
			Annotation[] deletions) {
		Map<ProjectionAnnotation, Position> additionsMap = new HashMap<ProjectionAnnotation, Position>();
		for (Iterator<FoldedPosition> iterator = positionsMap.values()
				.iterator(); iterator.hasNext();) {
			FoldedPosition foldingRegion = iterator.next();
			addProjectionAnnotation(allowCollapse, foldingRegion, additionsMap);
		}
		if (deletions.length != 0 || additionsMap.size() != 0) {
			model.modifyAnnotations(deletions, additionsMap,
					new Annotation[] {});
		}
	}

	protected void addProjectionAnnotation(boolean allowCollapse,
			FoldedPosition foldingRegion,
			Map<ProjectionAnnotation, Position> additionsMap) {
		ProjectionAnnotation projectionAnnotation = createProjectionAnnotation(
				allowCollapse, foldingRegion);
		additionsMap.put(projectionAnnotation, toPosition(foldingRegion));
	}

	private Position toPosition(FoldedPosition foldingRegion) {
		return new Position(foldingRegion.offset, foldingRegion.length);
	}

	protected ProjectionAnnotation createProjectionAnnotation(
			boolean allowCollapse, FoldedPosition foldingRegion) {
		return new ProjectionAnnotation(allowCollapse);
	}

	/**
	 * 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;
			}
		}

		public void projectionEnabled() {
			handleProjectionEnabled();
		}

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

	public void install(XtextEditor editor, ProjectionViewer viewer) {

	}
}