org.eclipse.jface.viewers.ViewerFilter.java Source code

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Here is the source code for org.eclipse.jface.viewers.ViewerFilter.java

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/*******************************************************************************
 * Copyright (c) 2000, 2016 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
 *     Jeanderson Candido <http://jeandersonbc.github.io> - Bug 434153
 *******************************************************************************/
package org.eclipse.jface.viewers;

import java.util.ArrayList;

/**
 * A viewer filter is used by a structured viewer to extract a subset of
 * elements provided by its content provider.
 * <p>
 * Subclasses must implement the <code>select</code> method and may implement
 * the <code>isFilterProperty</code> method.
 * </p>
 *
 * @see IStructuredContentProvider
 * @see StructuredViewer
 */
public abstract class ViewerFilter {
    /**
     * Creates a new viewer filter.
     */
    protected ViewerFilter() {
    }

    /**
     * Filters the given elements for the given viewer. The input array is not
     * modified.
     * <p>
     * The default implementation of this method calls <code>select</code> on
     * each element in the array, and returns only those elements for which
     * <code>select</code> returns <code>true</code>.
     * </p>
     *
     * @param viewer
     *            the viewer
     * @param parent
     *            the parent element
     * @param elements
     *            the elements to filter
     * @return the filtered elements
     */
    public Object[] filter(Viewer viewer, Object parent, Object[] elements) {
        int size = elements.length;
        ArrayList<Object> out = new ArrayList<>(size);
        for (int i = 0; i < size; ++i) {
            Object element = elements[i];
            if (select(viewer, parent, element)) {
                out.add(element);
            }
        }
        return out.toArray();
    }

    /**
     * Filters the given elements for the given viewer. The input array is not
     * modified.
     * <p>
     * The default implementation of this method calls
     * {@link #filter(Viewer, Object, Object[])} with the parent from the path.
     * Subclasses may override
     * </p>
     *
     * @param viewer
     *            the viewer
     * @param parentPath
     *            the path of the parent element
     * @param elements
     *            the elements to filter
     * @return the filtered elements
     * @since 3.2
     */
    public Object[] filter(Viewer viewer, TreePath parentPath, Object[] elements) {
        return filter(viewer, parentPath.getLastSegment(), elements);
    }

    /**
     * Returns whether this viewer filter would be affected by a change to the
     * given property of the given element.
     * <p>
     * The default implementation of this method returns <code>false</code>.
     * Subclasses should reimplement.
     * </p>
     *
     * @param element
     *            the element
     * @param property
     *            the property
     * @return <code>true</code> if the filtering would be affected, and
     *         <code>false</code> if it would be unaffected
     */
    public boolean isFilterProperty(Object element, String property) {
        return false;
    }

    /**
     * Returns whether the given element makes it through this filter.
     *
     * @param viewer
     *            the viewer
     * @param parentElement
     *            the parent element
     * @param element
     *            the element
     * @return <code>true</code> if element is included in the filtered set, and
     *         <code>false</code> if excluded
     */
    public abstract boolean select(Viewer viewer, Object parentElement, Object element);
}