/*******************************************************************************
* Copyright (c) 2004, 2010 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
* Tasktop Technologies - generalization for structured viewers
*******************************************************************************/
package org.eclipse.equinox.internal.p2.ui.discovery.util;
import com.ibm.icu.text.BreakIterator;
import java.util.*;
import org.eclipse.jface.viewers.*;
import org.eclipse.ui.internal.misc.StringMatcher;
/**
* A filter used in conjunction with <code>FilteredTree</code>. In order to determine if a node should be filtered it
* uses the content and label provider of the tree to do pattern matching on its children. This causes the entire tree
* structure to be realized. Note that the label provider must implement ILabelProvider.
*
* @see org.eclipse.ui.dialogs.FilteredTree
* @since 3.2
*/
public class PatternFilter extends ViewerFilter {
/*
* Cache of filtered elements in the tree
*/
private final Map cache = new HashMap();
/*
* Maps parent elements to TRUE or FALSE
*/
private final Map foundAnyCache = new HashMap();
private boolean useCache = false;
/**
* Whether to include a leading wildcard for all provided patterns. A trailing wildcard is always included.
*/
private boolean includeLeadingWildcard = false;
/**
* The string pattern matcher used for this pattern filter.
*/
private StringMatcher matcher;
private boolean useEarlyReturnIfMatcherIsNull = true;
private static Object[] EMPTY = new Object[0];
/* (non-Javadoc)
* @see org.eclipse.jface.viewers.ViewerFilter#filter(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object[])
*/
@Override
public final Object[] filter(Viewer viewer, Object parent, Object[] elements) {
// we don't want to optimize if we've extended the filter ... this
// needs to be addressed in 3.4
// https://bugs.eclipse.org/bugs/show_bug.cgi?id=186404
if (matcher == null && useEarlyReturnIfMatcherIsNull) {
return elements;
}
if (!useCache) {
return super.filter(viewer, parent, elements);
}
Object[] filtered = (Object[]) cache.get(parent);
if (filtered == null) {
Boolean foundAny = (Boolean) foundAnyCache.get(parent);
if (foundAny != null && !foundAny.booleanValue()) {
filtered = EMPTY;
} else {
filtered = super.filter(viewer, parent, elements);
}
cache.put(parent, filtered);
}
return filtered;
}
/**
* Returns true if any of the elements makes it through the filter. This method uses caching if enabled; the
* computation is done in computeAnyVisible.
*
* @param viewer
* @param parent
* @param elements
* the elements (must not be an empty array)
* @return true if any of the elements makes it through the filter.
*/
private boolean isAnyVisible(Viewer viewer, Object parent, Object[] elements) {
if (matcher == null) {
return true;
}
if (!useCache) {
return computeAnyVisible(viewer, elements);
}
Object[] filtered = (Object[]) cache.get(parent);
if (filtered != null) {
return filtered.length > 0;
}
Boolean foundAny = (Boolean) foundAnyCache.get(parent);
if (foundAny == null) {
foundAny = computeAnyVisible(viewer, elements) ? Boolean.TRUE : Boolean.FALSE;
foundAnyCache.put(parent, foundAny);
}
return foundAny.booleanValue();
}
/**
* Returns true if any of the elements makes it through the filter.
*
* @param viewer
* the viewer
* @param elements
* the elements to test
* @return <code>true</code> if any of the elements makes it through the filter
*/
private boolean computeAnyVisible(Viewer viewer, Object[] elements) {
boolean elementFound = false;
for (int i = 0; i < elements.length && !elementFound; i++) {
Object element = elements[i];
elementFound = isElementVisible(viewer, element);
}
return elementFound;
}
/* (non-Javadoc)
* @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
*/
@Override
public final boolean select(Viewer viewer, Object parentElement, Object element) {
return isElementVisible(viewer, element);
}
/**
* Sets whether a leading wildcard should be attached to each pattern string.
*
* @param includeLeadingWildcard
* Whether a leading wildcard should be added.
*/
public final void setIncludeLeadingWildcard(final boolean includeLeadingWildcard) {
this.includeLeadingWildcard = includeLeadingWildcard;
}
/**
* The pattern string for which this filter should select elements in the viewer.
*
* @param patternString
*/
public void setPattern(String patternString) {
// these 2 strings allow the PatternFilter to be extended in
// 3.3 - https://bugs.eclipse.org/bugs/show_bug.cgi?id=186404
if ("org.eclipse.ui.keys.optimization.true".equals(patternString)) { //$NON-NLS-1$
useEarlyReturnIfMatcherIsNull = true;
return;
} else if ("org.eclipse.ui.keys.optimization.false".equals(patternString)) { //$NON-NLS-1$
useEarlyReturnIfMatcherIsNull = false;
return;
}
clearCaches();
if (patternString == null || patternString.equals("")) { //$NON-NLS-1$
matcher = null;
} else {
String pattern = patternString + "*"; //$NON-NLS-1$
if (includeLeadingWildcard) {
pattern = "*" + pattern; //$NON-NLS-1$
}
matcher = new StringMatcher(pattern, true, false);
}
}
/**
* Clears the caches used for optimizing this filter. Needs to be called whenever the tree content changes.
*/
/* package */void clearCaches() {
cache.clear();
foundAnyCache.clear();
}
/**
* Answers whether the given String matches the pattern.
*
* @param string
* the String to test
* @return whether the string matches the pattern
*/
private boolean match(String string) {
if (matcher == null) {
return true;
}
return matcher.match(string);
}
/**
* Answers whether the given element is a valid selection in the filtered tree. For example, if a tree has items
* that are categorized, the category itself may not be a valid selection since it is used merely to organize the
* elements.
*
* @param element
* @return true if this element is eligible for automatic selection
*/
public boolean isElementSelectable(Object element) {
return element != null;
}
/**
* Answers whether the given element in the given viewer matches the filter pattern. This is a default
* implementation that will show a leaf element in the tree based on whether the provided filter text matches the
* text of the given element's text, or that of it's children (if the element has any). Subclasses may override this
* method.
*
* @param viewer
* the tree viewer in which the element resides
* @param element
* the element in the tree to check for a match
* @return true if the element matches the filter pattern
*/
public boolean isElementVisible(Viewer viewer, Object element) {
return isParentMatch(viewer, element) || isLeafMatch(viewer, element);
}
/**
* Check if the parent (category) is a match to the filter text. The default behavior returns true if the element
* has at least one child element that is a match with the filter text. Subclasses may override this method.
*
* @param viewer
* the viewer that contains the element
* @param element
* the tree element to check
* @return true if the given element has children that matches the filter text
*/
protected boolean isParentMatch(Viewer viewer, Object element) {
Object[] children = getChildren(element);
if ((children != null) && (children.length > 0)) {
return isAnyVisible(viewer, element, children);
}
return false;
}
protected Object[] getChildren(Object element) {
return null;
}
/**
* Check if the current (leaf) element is a match with the filter text. The default behavior checks that the label
* of the element is a match. Subclasses should override this method.
*
* @param viewer
* the viewer that contains the element
* @param element
* the tree element to check
* @return true if the given element's label matches the filter text
*/
protected boolean isLeafMatch(Viewer viewer, Object element) {
String labelText = ((ILabelProvider) ((StructuredViewer) viewer).getLabelProvider()).getText(element);
if (labelText == null) {
return false;
}
return wordMatches(labelText);
}
/**
* Take the given filter text and break it down into words using a BreakIterator.
*
* @param text
* @return an array of words
*/
private String[] getWords(String text) {
List words = new ArrayList();
// Break the text up into words, separating based on whitespace and
// common punctuation.
// Previously used String.split(..., "\\W"), where "\W" is a regular
// expression (see the Javadoc for class Pattern).
// Need to avoid both String.split and regular expressions, in order to
// compile against JCL Foundation (bug 80053).
// Also need to do this in an NL-sensitive way. The use of BreakIterator
// was suggested in bug 90579.
BreakIterator iter = BreakIterator.getWordInstance();
iter.setText(text);
int i = iter.first();
while (i != java.text.BreakIterator.DONE && i < text.length()) {
int j = iter.following(i);
if (j == java.text.BreakIterator.DONE) {
j = text.length();
}
// match the word
if (Character.isLetterOrDigit(text.charAt(i))) {
String word = text.substring(i, j);
words.add(word);
}
i = j;
}
return (String[]) words.toArray(new String[words.size()]);
}
/**
* Return whether or not if any of the words in text satisfy the match critera.
*
* @param text
* the text to match
* @return boolean <code>true</code> if one of the words in text satisifes the match criteria.
*/
protected boolean wordMatches(String text) {
if (text == null) {
return false;
}
//If the whole text matches we are all set
if (match(text)) {
return true;
}
// Otherwise check if any of the words of the text matches
String[] words = getWords(text);
for (String word : words) {
if (match(word)) {
return true;
}
}
return false;
}
/**
* Can be called by the filtered tree to turn on caching.
*
* @param useCache
* The useCache to set.
*/
void setUseCache(boolean useCache) {
this.useCache = useCache;
}
}