/*******************************************************************************
* Copyright (c) 2000, 2016 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
* Mikael Barbero (Eclipse Foundation) - Bug 254570
*******************************************************************************/
package org.eclipse.jface.viewers;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import org.eclipse.core.runtime.Assert;
import org.eclipse.jface.resource.JFaceResources;
/**
* A concrete implementation of the <code>IStructuredSelection</code> interface,
* suitable for instantiating.
* <p>
* This class is not intended to be subclassed.
* </p>
* @noextend This class is not intended to be subclassed by clients.
*/
public class StructuredSelection implements IStructuredSelection {
/**
* The element that make up this structured selection.
*/
private final Object[] elements;
/**
* The element comparer, or <code>null</code>
*/
private final IElementComparer comparer;
/**
* The canonical empty selection. This selection should be used instead of
* <code>null</code>.
*/
public static final StructuredSelection EMPTY = new StructuredSelection();
/**
* Creates a new empty selection.
* See also the static field <code>EMPTY</code> which contains an empty selection singleton.
*
* @see #EMPTY
*/
public StructuredSelection() {
this.elements = null;
this.comparer = null;
}
/**
* Creates a structured selection from the given elements.
* The given element array must not be <code>null</code>.
*
* @param elements an array of elements
*/
public StructuredSelection(Object[] elements) {
Assert.isNotNull(elements);
this.elements = new Object[elements.length];
System.arraycopy(elements, 0, this.elements, 0, elements.length);
this.comparer = null;
}
/**
* Creates a structured selection containing a single object.
* The object must not be <code>null</code>.
*
* @param element the element
*/
public StructuredSelection(Object element) {
Assert.isNotNull(element);
this.elements = new Object[] { element };
this.comparer = null;
}
/**
* Creates a structured selection from the given <code>List</code>.
* @param elements list of selected elements
*/
public StructuredSelection(List elements) {
this(elements, null);
}
/**
* Creates a structured selection from the given <code>List</code> and
* element comparer. If an element comparer is provided, it will be used to
* determine equality between structured selection objects provided that
* they both are based on the same (identical) comparer. See bug
*
* @param elements
* list of selected elements
* @param comparer
* the comparer, or null
* @since 3.4
*/
public StructuredSelection(List elements, IElementComparer comparer) {
Assert.isNotNull(elements);
this.elements = elements.toArray();
this.comparer = comparer;
}
/**
* Returns whether this structured selection is equal to the given object.
* Two structured selections are equal if they contain the same elements
* in the same order.
*
* @param o the other object
* @return <code>true</code> if they are equal, and <code>false</code> otherwise
*/
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
//null and other classes
if (!(o instanceof StructuredSelection)) {
return false;
}
StructuredSelection s2 = (StructuredSelection) o;
// either or both empty?
if (isEmpty()) {
return s2.isEmpty();
}
if (s2.isEmpty()) {
return false;
}
boolean useComparer = comparer != null && comparer == s2.comparer;
//size
int myLen = elements.length;
if (myLen != s2.elements.length) {
return false;
}
//element comparison
for (int i = 0; i < myLen; i++) {
if (useComparer) {
if (!comparer.equals(elements[i], s2.elements[i])) {
return false;
}
} else {
if (!elements[i].equals(s2.elements[i])) {
return false;
}
}
}
return true;
}
@Override
public int hashCode() {
if (isEmpty()) {
return 31 + Objects.hashCode(comparer);
}
int r;
if (comparer != null) {
r = 31 + comparer.hashCode();
for (Object e : elements) {
r = 31 * r + (e == null ? 0 : comparer.hashCode(e));
}
} else {
r = Arrays.hashCode(elements);
}
return r;
}
@Override
public Object getFirstElement() {
return isEmpty() ? null : elements[0];
}
@Override
public boolean isEmpty() {
return elements == null || elements.length == 0;
}
@Override
public Iterator iterator() {
return Arrays.asList(elements == null ? new Object[0] : elements)
.iterator();
}
@Override
public int size() {
return elements == null ? 0 : elements.length;
}
@Override
public Object[] toArray() {
return elements == null ? new Object[0] : (Object[]) elements.clone();
}
@Override
public List toList() {
return Arrays.asList(elements == null ? new Object[0] : elements);
}
/**
* Internal method which returns a string representation of this
* selection suitable for debug purposes only.
*
* @return debug string
*/
@Override
public String toString() {
return isEmpty() ? JFaceResources.getString("<empty_selection>") : toList().toString(); //$NON-NLS-1$
}
}