Java tutorial
/******************************************************************************* * Copyright (c) 2005, 2017 IBM Corporation and others. * * This program and the accompanying materials * are made available under the terms of the Eclipse Public License 2.0 * which accompanies this distribution, and is available at * https://www.eclipse.org/legal/epl-2.0/ * * SPDX-License-Identifier: EPL-2.0 * * Contributors: * IBM Corporation - initial API and implementation * Lars Vogel <Lars.Vogel@gmail.com> - Bug 430873 * Mikael Barbero (Eclipse Foundation) - Bug 254570 *******************************************************************************/ package org.eclipse.jface.viewers; import java.util.ArrayList; import java.util.List; import org.eclipse.core.runtime.Assert; /** * A concrete implementation of the <code>ITreeSelection</code> interface, * suitable for instantiating. * <p> * This class is not intended to be subclassed. * </p> * * @since 3.2 */ public class TreeSelection extends StructuredSelection implements ITreeSelection { /* Implementation note. This class extends StructuredSelection because many pre-existing * JFace viewer clients assumed that the only implementation of IStructuredSelection * was StructuredSelection. By extending StructuredSelection rather than implementing * ITreeSelection directly, we avoid this problem. * For more details, see Bug 121939 [Viewers] TreeSelection should subclass StructuredSelection. */ private TreePath[] paths = null; private CustomHashtable element2TreePaths = null; /** * The canonical empty selection. This selection should be used instead of * <code>null</code>. */ public static final TreeSelection EMPTY = new TreeSelection(); private static final TreePath[] EMPTY_TREE_PATHS = new TreePath[0]; private static class InitializeData { List selection; TreePath[] paths; CustomHashtable element2TreePaths; IElementComparer comparer; private InitializeData(TreePath[] paths, IElementComparer comparer) { this.paths = new TreePath[paths.length]; this.comparer = comparer; System.arraycopy(paths, 0, this.paths, 0, paths.length); element2TreePaths = new CustomHashtable(comparer); int size = paths.length; selection = new ArrayList(size); for (int i = 0; i < size; i++) { Object lastSegment = paths[i].getLastSegment(); // lastSegment is null when TreeSelections are created from TreePath // themself created with an empty "segments" array. if (lastSegment != null) { Object mapped = element2TreePaths.get(lastSegment); if (mapped == null) { selection.add(lastSegment); element2TreePaths.put(lastSegment, paths[i]); } else if (mapped instanceof List) { ((List) mapped).add(paths[i]); } else { List newMapped = new ArrayList(2); newMapped.add(mapped); newMapped.add(paths[i]); element2TreePaths.put(lastSegment, newMapped); } } } } } /** * Constructs a selection based on the elements identified by the given tree * paths. * * @param paths * tree paths */ public TreeSelection(TreePath[] paths) { this(new InitializeData(paths != null ? paths : EMPTY_TREE_PATHS, null)); } /** * Constructs a selection based on the elements identified by the given tree * paths. * * @param paths * tree paths * @param comparer * the comparer, or <code>null</code> if default equals is to be used */ public TreeSelection(TreePath[] paths, IElementComparer comparer) { this(new InitializeData(paths != null ? paths : EMPTY_TREE_PATHS, comparer)); } /** * Constructs a selection based on the elements identified by the given tree * path. * * @param treePath * tree path, or <code>null</code> for an empty selection */ public TreeSelection(TreePath treePath) { this(treePath != null ? new TreePath[] { treePath } : EMPTY_TREE_PATHS, null); } /** * Constructs a selection based on the elements identified by the given tree * path. * * @param treePath * tree path, or <code>null</code> for an empty selection * @param comparer * the comparer, or <code>null</code> if default equals is to be used */ public TreeSelection(TreePath treePath, IElementComparer comparer) { this(treePath != null ? new TreePath[] { treePath } : EMPTY_TREE_PATHS, comparer); } /** * Creates a new tree selection based on the initialization data. * * @param data the data */ private TreeSelection(InitializeData data) { super(data.selection, data.comparer); paths = data.paths; element2TreePaths = data.element2TreePaths; } /** * Creates a new empty selection. See also the static field * <code>EMPTY</code> which contains an empty selection singleton. * * @see #EMPTY */ public TreeSelection() { super(); } /** * Returns the element comparer passed in when the tree selection * has been created or <code>null</code> if no comparer has been * provided. * * @return the element comparer or <code>null</code> * * @since 3.2 */ public IElementComparer getElementComparer() { if (element2TreePaths == null) return null; return element2TreePaths.getComparer(); } @Override public boolean equals(Object obj) { if (!(obj instanceof TreeSelection)) { // Fall back to super implementation, see bug 135837. return super.equals(obj); } TreeSelection selection = (TreeSelection) obj; int size = getPaths().length; if (selection.getPaths().length == size) { IElementComparer comparerOrNull = (getElementComparer() == selection.getElementComparer()) ? getElementComparer() : null; if (size > 0) { for (int i = 0; i < paths.length; i++) { if (!paths[i].equals(selection.paths[i], comparerOrNull)) { return false; } } } return true; } return false; } @Override public TreePath[] getPaths() { return paths == null ? EMPTY_TREE_PATHS : (TreePath[]) paths.clone(); } @Override public TreePath[] getPathsFor(Object element) { Object value = element2TreePaths == null ? null : element2TreePaths.get(element); if (value == null) { return EMPTY_TREE_PATHS; } else if (value instanceof TreePath) { return new TreePath[] { (TreePath) value }; } else if (value instanceof List) { List<TreePath> l = (List<TreePath>) value; return l.toArray(new TreePath[l.size()]); } else { // should not happen: Assert.isTrue(false, "Unhandled case"); //$NON-NLS-1$ return null; } } }