PatternFilter


1   /*******************************************************************************
2    * Copyright (c) 2004, 2007 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  package org.eclipse.ui.dialogs;
12  
13  import java.util.ArrayList  ;
14  import java.util.HashMap  ;
15  import java.util.List  ;
16  import java.util.Map  ;
17  
18  import org.eclipse.jface.viewers.AbstractTreeViewer;
19  import org.eclipse.jface.viewers.ILabelProvider;
20  import org.eclipse.jface.viewers.ITreeContentProvider;
21  import org.eclipse.jface.viewers.StructuredViewer;
22  import org.eclipse.jface.viewers.Viewer;
23  import org.eclipse.jface.viewers.ViewerFilter;
24  import org.eclipse.ui.internal.misc.StringMatcher;
25  
26  import com.ibm.icu.text.BreakIterator;
27  
28  /**
29   * A filter used in conjunction with <code>FilteredTree</code>.  In order to 
30   * determine if a node should be filtered it uses the content provider of the 
31   * tree to do pattern matching on its children.  This causes the entire tree
32   * structure to be realized.
33   *  
34   * @see org.eclipse.ui.dialogs.FilteredTree  
35   * @since 3.2
36   */
37  public class PatternFilter extends ViewerFilter {
38      /*
39       * Cache of filtered elements in the tree
40       */
41      private Map   cache = new HashMap  ();
42      
43      /*
44       * Maps parent elements to TRUE or FALSE
45       */
46      private Map   foundAnyCache = new HashMap  ();
47      
48      private boolean useCache = false;
49      
50      /**
51       * Whether to include a leading wildcard for all provided patterns.  A
52       * trailing wildcard is always included.
53       */
54      private boolean includeLeadingWildcard = false;
55  
56      /**
57       * The string pattern matcher used for this pattern filter.  
58       */
59      private StringMatcher matcher;
60      
61      private boolean useEarlyReturnIfMatcherIsNull = true;
62      
63      private static Object  [] EMPTY = new Object  [0];
64  
65      /* (non-Javadoc)
66       * @see org.eclipse.jface.viewers.ViewerFilter#filter(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object[])
67       */
68      public final Object  [] filter(Viewer viewer, Object   parent, Object  [] elements) {
69          // we don't want to optimize if we've extended the filter ... this
70          // needs to be addressed in 3.4
71          // https://bugs.eclipse.org/bugs/show_bug.cgi?id=186404
72          if (matcher == null && useEarlyReturnIfMatcherIsNull) {
73              return elements;
74          }
75  
76          if (!useCache) {
77              return super.filter(viewer, parent, elements);
78          }
79          
80          Object  [] filtered = (Object  []) cache.get(parent);
81          if (filtered == null) {
82              Boolean   foundAny = (Boolean  ) foundAnyCache.get(parent);
83              if (foundAny != null && !foundAny.booleanValue()) {
84                  filtered = EMPTY;
85              } else {
86                  filtered = super.filter(viewer, parent, elements);
87              }
88              cache.put(parent, filtered);
89          }
90          return filtered;
91      }
92  
93      /**
94       * Returns true if any of the elements makes it through the filter.
95       * This method uses caching if enabled; the computation is done in
96       * computeAnyVisible.
97       *  
98       * @param viewer
99       * @param parent
100      * @param elements the elements (must not be an empty array)
101      * @return true if any of the elements makes it through the filter.
102      */
103     private boolean isAnyVisible(Viewer viewer, Object   parent, Object  [] elements) {
104         if (matcher == null) {
105             return true;
106         }
107         
108         if (!useCache) {
109             return computeAnyVisible(viewer, elements);
110         }
111         
112         Object  [] filtered = (Object  []) cache.get(parent);
113         if (filtered != null) {
114             return filtered.length > 0;
115         }
116         Boolean   foundAny = (Boolean  ) foundAnyCache.get(parent);
117         if (foundAny == null) {
118             foundAny = computeAnyVisible(viewer, elements) ? Boolean.TRUE : Boolean.FALSE;
119             foundAnyCache.put(parent, foundAny);
120         }
121         return foundAny.booleanValue();
122     }
123 
124     /**
125      * Returns true if any of the elements makes it through the filter.
126      * @param viewer
127      * @param elements
128      * @return
129      */
130     private boolean computeAnyVisible(Viewer viewer, Object  [] elements) {
131         boolean elementFound = false;
132         for (int i = 0; i < elements.length && !elementFound; i++) {
133             Object   element = elements[i];
134             elementFound = isElementVisible(viewer, element);
135         }
136         return elementFound;
137     }
138     
139     /* (non-Javadoc)
140      * @see org.eclipse.jface.viewers.ViewerFilter#select(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
141      */
142     public final boolean select(Viewer viewer, Object   parentElement,
143             Object   element) {
144         return isElementVisible(viewer, element);
145     }
146     
147     /**
148      * Sets whether a leading wildcard should be attached to each pattern
149      * string.
150      * 
151      * @param includeLeadingWildcard
152      *            Whether a leading wildcard should be added.
153      */
154     public final void setIncludeLeadingWildcard(
155             final boolean includeLeadingWildcard) {
156         this.includeLeadingWildcard = includeLeadingWildcard;
157     }
158 
159     /**
160      * The pattern string for which this filter should select 
161      * elements in the viewer.
162      * 
163      * @param patternString
164      */
165     public void setPattern(String   patternString) {
166         // these 2 strings allow the PatternFilter to be extended in
167         // 3.3 - https://bugs.eclipse.org/bugs/show_bug.cgi?id=186404
168         if ("org.eclipse.ui.keys.optimization.true".equals(patternString)) { //$NON-NLS-1$
169             useEarlyReturnIfMatcherIsNull = true;
170             return;
171         } else if ("org.eclipse.ui.keys.optimization.false".equals(patternString)) { //$NON-NLS-1$
172             useEarlyReturnIfMatcherIsNull = false;
173             return;
174         }
175         clearCaches();
176         if (patternString == null || patternString.equals("")) { //$NON-NLS-1$
177             matcher = null;
178         } else {
179             String   pattern = patternString + "*"; //$NON-NLS-1$
180             if (includeLeadingWildcard) {
181                 pattern = "*" + pattern; //$NON-NLS-1$
182             }
183             matcher = new StringMatcher(pattern, true, false);
184         }
185     }
186 
187     /**
188      * Clears the caches used for optimizing this filter. Needs to be called whenever
189      * the tree content changes.
190      */
191     /* package */ void clearCaches() {
192         cache.clear();
193         foundAnyCache.clear();
194     }
195 
196     /**
197      * Answers whether the given String matches the pattern.
198      * 
199      * @param string the String to test
200      * 
201      * @return whether the string matches the pattern
202      */
203     private boolean match(String   string) {
204         if (matcher == null) {
205             return true;
206         }
207         return matcher.match(string);
208     }
209     
210     /**
211      * Answers whether the given element is a valid selection in 
212      * the filtered tree.  For example, if a tree has items that 
213      * are categorized, the category itself may  not be a valid 
214      * selection since it is used merely to organize the elements.
215      * 
216      * @param element
217      * @return true if this element is eligible for automatic selection
218      */
219     public boolean isElementSelectable(Object   element){
220         return element != null;
221     }
222     
223     /**
224      * Answers whether the given element in the given viewer matches
225      * the filter pattern.  This is a default implementation that will 
226      * show a leaf element in the tree based on whether the provided  
227      * filter text matches the text of the given element's text, or that 
228      * of it's children (if the element has any).  
229      * 
230      * Subclasses may override this method.
231      * 
232      * @param viewer the tree viewer in which the element resides
233      * @param element the element in the tree to check for a match
234      * 
235      * @return true if the element matches the filter pattern
236      */
237     public boolean isElementVisible(Viewer viewer, Object   element){
238         return isParentMatch(viewer, element) || isLeafMatch(viewer, element);
239     }
240     
241     /**
242      * Check if the parent (category) is a match to the filter text.  The default 
243      * behavior returns true if the element has at least one child element that is 
244      * a match with the filter text.
245      * 
246      * Subclasses may override this method.
247      * 
248      * @param viewer the viewer that contains the element
249      * @param element the tree element to check
250      * @return true if the given element has children that matches the filter text
251      */
252     protected boolean isParentMatch(Viewer viewer, Object   element){
253         Object  [] children = ((ITreeContentProvider) ((AbstractTreeViewer) viewer)
254                 .getContentProvider()).getChildren(element);
255 
256         if ((children != null) && (children.length > 0)) {
257             return isAnyVisible(viewer, element, children);
258         }   
259         return false;
260     }
261     
262     /**
263      * Check if the current (leaf) element is a match with the filter text.  
264      * The default behavior checks that the label of the element is a match. 
265      * 
266      * Subclasses should override this method.
267      * 
268      * @param viewer the viewer that contains the element
269      * @param element the tree element to check
270      * @return true if the given element's label matches the filter text
271      */
272     protected boolean isLeafMatch(Viewer viewer, Object   element){
273         String   labelText = ((ILabelProvider) ((StructuredViewer) viewer)
274                 .getLabelProvider()).getText(element);
275         
276         if(labelText == null) {
277             return false;
278         }
279         return wordMatches(labelText);  
280     }
281     
282     /**
283      * Take the given filter text and break it down into words using a 
284      * BreakIterator.  
285      * 
286      * @param text
287      * @return an array of words
288      */
289     private String  [] getWords(String   text){
290         List   words = new ArrayList  ();
291         // Break the text up into words, separating based on whitespace and
292         // common punctuation.
293         // Previously used String.split(..., "\\W"), where "\W" is a regular
294         // expression (see the Javadoc for class Pattern).
295         // Need to avoid both String.split and regular expressions, in order to
296         // compile against JCL Foundation (bug 80053).
297         // Also need to do this in an NL-sensitive way. The use of BreakIterator
298         // was suggested in bug 90579.
299         BreakIterator iter = BreakIterator.getWordInstance();
300         iter.setText(text);
301         int i = iter.first();
302         while (i != java.text.BreakIterator.DONE && i < text.length()) {
303             int j = iter.following(i);
304             if (j == java.text.BreakIterator.DONE) {
305                 j = text.length();
306             }
307             // match the word
308             if (Character.isLetterOrDigit(text.charAt(i))) {
309                 String   word = text.substring(i, j);
310                 words.add(word);
311             }
312             i = j;
313         }
314         return (String  []) words.toArray(new String  [words.size()]);
315     }
316     
317     /**
318      * Return whether or not if any of the words in text satisfy the
319      * match critera.
320      * 
321      * @param text the text to match
322      * @return boolean <code>true</code> if one of the words in text 
323      *                  satisifes the match criteria.
324      */
325     protected boolean wordMatches(String   text) {
326         if (text == null) {
327             return false;
328         }
329         
330         //If the whole text matches we are all set
331         if(match(text)) {
332             return true;
333         }
334         
335         // Otherwise check if any of the words of the text matches
336         String  [] words = getWords(text);
337         for (int i = 0; i < words.length; i++) {
338             String   word = words[i];
339             if (match(word)) {
340                 return true;
341             }
342         }
343 
344         return false;
345     }
346 
347     /**
348      * Can be called by the filtered tree to turn on caching.
349      * 
350      * @param useCache The useCache to set.
351      */
352     void setUseCache(boolean useCache) {
353         this.useCache = useCache;
354     }    
355 }
356
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