bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/dialogs/PatternFilter.java

/*******************************************************************************
 * Copyright (c) 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal.dialogs;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.ILabelProvider;
import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerFilter;
import org.eclipse.ui.internal.misc.StringMatcher;


/**
 * A filter used in conjunction with FilteredTree.  This filter is inefficient -
 * in order to see if a node should be filtered it must use the content provider
 * of the tree to do pattern matching on its children.  This causes the entire 
 * tree structure to be expanded.
 * 
 * @see org.eclipse.ui.dialogs.FilteredTree  
 * @since 3.0
 */
public class PatternFilter extends ViewerFilter {
    
    private Map cache = new HashMap();
    private StringMatcher matcher;

    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.ViewerFilter#filter(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object[])
     */
    public Object[] filter(Viewer viewer, Object parent, Object[] elements) {
        if (matcher == null)
            return elements;
        
        Object [] filtered = (Object [])cache.get(parent);
        if (filtered == null) {
            filtered = super.filter(viewer, parent, elements);
            cache.put(parent, filtered);
        }
        return filtered;
    }
    
    /* (non-Javadoc)
     * @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
     */
    public boolean select(Viewer viewer, Object parentElement, Object element) {
        Object [] children = ((ITreeContentProvider)((AbstractTreeViewer)viewer).getContentProvider()).getChildren(element);
        if (children.length > 0)       
            return filter(viewer, element, children).length > 0;
        
        String labelText = ((ILabelProvider)((StructuredViewer)viewer).getLabelProvider()).getText(element);
        return match(labelText);
    }
    
    /**
     * 
     * @param pattern
     */
    public void setPattern(String patternString) { 
        cache.clear();        
        if (patternString == null || patternString.equals("")) //$NON-NLS-1$
            matcher = null;
        else
            matcher = new StringMatcher(patternString + "*", true, false); //$NON-NLS-1$
    }
    
    /**
     * Answers whether the given String matches the pattern.
     * 
     * @param string the String to test
     * @return whether the string matches the pattern
     */
    protected boolean match(String string) {
    	return matcher.match(string);
    }
}