bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetSorter.java

/*******************************************************************************
 * Copyright (c) 2005 Gunnar Wagenknecht 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:
 *    Gunnar Wagenknecht - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.views.properties;

import java.text.Collator;
import java.util.Arrays;
import java.util.Comparator;

/**
 * Class used by {@link org.eclipse.ui.views.properties.PropertySheetPage} to
 * sort properties.
 * <p>
 * The default implementation sorts alphabetically. Subclasses may overwrite to
 * implement custom sorting.
 * </p>
 *
 * @since 3.1
 */
public class PropertySheetSorter  {

	/**
	 * The collator used to sort strings.
	 */
	private Collator collator;

	/**
	 * Creates a new sorter, which uses the default collator to sort strings.
	 */
	public PropertySheetSorter() {
		this(Collator.getInstance());
	}

	/**
	 * Creates a new sorter, which uses the given collator to sort strings.
	 * 
	 * @param collator
	 *            the collator to use to sort strings
	 */
	public PropertySheetSorter(Collator collator) {
		this.collator = collator;
	}

	/**
	 * Returns a negative, zero, or positive number depending on whether the
	 * first element is less than, equal to, or greater than the second element.
	 * <p>
	 * The default implementation of this method uses the collator to
	 * compare the display names. Subclasses may override.
	 * </p>
	 * 
	 * @param entryA
	 *            the first element
	 * @param entryB
	 *            the second element
	 * @return a negative number if the first element is less than the second
	 *         element; the value <code>0</code> if the first element is equal
	 *         to the second element; and a positive number if the first element
	 *         is greater than the second element
	 */
	public int compare(IPropertySheetEntry entryA, IPropertySheetEntry entryB) {
		return getCollator().compare(entryA.getDisplayName(),
				entryB.getDisplayName());
	}

	/**
	 * Returns a negative, zero, or positive number depending on whether the
	 * first element is less than, equal to, or greater than the second element.
	 * <p>
	 * The default implementation of this method uses the collator to
	 * compare the strings. Subclasses may override.
	 * </p>
	 * 
	 * @param categoryA
	 *            the first element
	 * @param categoryB
	 *            the second element
	 * @return a negative number if the first element is less than the second
	 *         element; the value <code>0</code> if the first element is equal
	 *         to the second element; and a positive number if the first element
	 *         is greater than the second element
	 */
	public int compareCategories(String categoryA, String categoryB) {
		return getCollator().compare(categoryA, categoryB);
	}

	/**
	 * Returns the collator used to sort strings.
	 * 
	 * @return the collator used to sort strings
	 */
	protected Collator getCollator() {
		return collator;
	}

	/**
	 * Sorts the given elements in-place, modifying the given array.
	 * <p>
	 * The default implementation of this method uses the java.util.Arrays#sort
	 * algorithm on the given array, calling <code>compare</code> to compare
	 * elements.
	 * </p>
	 * <p>
	 * Subclasses may reimplement this method to provide a more optimized
	 * implementation.
	 * </p>
	 * 
	 * @param entries
	 *            the elements to sort
	 */
	public void sort(IPropertySheetEntry[] entries) {
		Arrays.sort(entries, new Comparator() {
			public int compare(Object a, Object b) {
				return PropertySheetSorter.this.compare(
						(IPropertySheetEntry) a, (IPropertySheetEntry) b);
			}
		});
	}

	/**
	 * Sorts the given categories in-place, modifying the given array.
	 * 
	 * @param categories
	 *            the categories to sort
	 */
	void sort(PropertySheetCategory[] categories) {
		Arrays.sort(categories, new Comparator() {
			public int compare(Object a, Object b) {
				return PropertySheetSorter.this.compareCategories(
						((PropertySheetCategory) a).getCategoryName(),
						((PropertySheetCategory) b).getCategoryName());
			}
		});
	}
}