1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.search.lucene.query;
25
26 import java.io.IOException;
27 import org.apache.lucene.index.IndexReader;
28 import org.apache.lucene.search.Explanation;
29 import org.apache.lucene.search.Query;
30 import org.apache.lucene.search.Scorer;
31 import org.apache.lucene.search.Searcher;
32 import org.apache.lucene.search.Similarity;
33 import org.apache.lucene.search.Weight;
34
35 /**
36 * A Lucene {@link Query} implementation that is used to represent a NOT expression of another wrapped Query object. This query
37 * implementation works by using the {@link Query#weight(Searcher) weight} and
38 * {@link Weight#scorer(IndexReader, boolean, boolean) scorer} of the wrapped query to score (and return) only those documents
39 * that were <i>not</i> scored by the wrapped query. In other words, if the wrapped query ended up scoring any document, that
40 * document is <i>not</i> scored (i.e., skipped) by this query.
41 */
42 public class NotQuery extends Query {
43
44 private static final long serialVersionUID = 1L;
45
46 /**
47 * The operand that is being negated by this query.
48 */
49 protected final Query operand;
50
51 /**
52 * Construct a NOT(x) constraint where the 'x' operand is supplied.
53 *
54 * @param operand the operand being negated
55 */
56 public NotQuery( Query operand ) {
57 this.operand = operand;
58 }
59
60 /**
61 * {@inheritDoc}
62 *
63 * @see org.apache.lucene.search.Query#createWeight(org.apache.lucene.search.Searcher)
64 */
65 @Override
66 public Weight createWeight( Searcher searcher ) {
67 return new NotWeight(searcher);
68 }
69
70 /**
71 * {@inheritDoc}
72 *
73 * @see org.apache.lucene.search.Query#clone()
74 */
75 @Override
76 public Object clone() {
77 return new NotQuery(operand);
78 }
79
80 /**
81 * {@inheritDoc}
82 *
83 * @see org.apache.lucene.search.Query#toString(java.lang.String)
84 */
85 @Override
86 public String toString( String field ) {
87 return "NOT(" + operand.toString(field) + ")";
88 }
89
90 /**
91 * Calculates query weights and builds query scores for our NOT queries.
92 */
93 protected class NotWeight extends Weight {
94 private static final long serialVersionUID = 1L;
95 private final Searcher searcher;
96
97 protected NotWeight( Searcher searcher ) {
98 this.searcher = searcher;
99 assert this.searcher != null;
100 }
101
102 /**
103 * {@inheritDoc}
104 *
105 * @see org.apache.lucene.search.Weight#getQuery()
106 */
107 @Override
108 public Query getQuery() {
109 return NotQuery.this;
110 }
111
112 /**
113 * {@inheritDoc}
114 * <p>
115 * This implementation always returns a weight factor of 1.0.
116 * </p>
117 *
118 * @see org.apache.lucene.search.Weight#getValue()
119 */
120 @Override
121 public float getValue() {
122 return 1.0f; // weight factor of 1.0
123 }
124
125 /**
126 * {@inheritDoc}
127 * <p>
128 * This implementation always returns a normalization factor of 1.0.
129 * </p>
130 *
131 * @see org.apache.lucene.search.Weight#sumOfSquaredWeights()
132 */
133 @Override
134 public float sumOfSquaredWeights() {
135 return 1.0f; // normalization factor of 1.0
136 }
137
138 /**
139 * {@inheritDoc}
140 * <p>
141 * This implementation always does nothing, as there is nothing to normalize.
142 * </p>
143 *
144 * @see org.apache.lucene.search.Weight#normalize(float)
145 */
146 @Override
147 public void normalize( float norm ) {
148 // No need to do anything here
149 }
150
151 /**
152 * {@inheritDoc}
153 *
154 * @see org.apache.lucene.search.Weight#scorer(org.apache.lucene.index.IndexReader, boolean, boolean)
155 */
156 @Override
157 public Scorer scorer( IndexReader reader,
158 boolean scoreDocsInOrder,
159 boolean topScorer ) throws IOException {
160 // Get the operand's score, and set this on the NOT query
161 Scorer operandScorer = operand.weight(searcher).scorer(reader, scoreDocsInOrder, topScorer);
162 // Return a custom scorer ...
163 return new NotScorer(operandScorer, reader);
164 }
165
166 /**
167 * {@inheritDoc}
168 *
169 * @see org.apache.lucene.search.Weight#explain(org.apache.lucene.index.IndexReader, int)
170 */
171 @Override
172 public Explanation explain( IndexReader reader,
173 int doc ) throws IOException {
174 Explanation operandExplanation = operand.weight(searcher).explain(reader, doc);
175 String desc = operandExplanation.getDescription();
176 return new Explanation(getValue(), "NOT(" + desc + ")");
177 }
178 }
179
180 /**
181 * A scorer for the NOT query that iterates over documents (in increasing docId order), using the given scorer implementation
182 * for the operand of the NOT.
183 */
184 protected static class NotScorer extends Scorer {
185 private int docId = -1;
186 private int nextScoredDocId = -1;
187 private final Scorer operandScorer;
188 private final IndexReader reader;
189 private final int pastMaxDocId;
190
191 /**
192 * @param operandScorer the scorer that is used to score the documents based upon the operand of the NOT; may not be null
193 * @param reader the reader that has access to all the docs ...
194 */
195 protected NotScorer( Scorer operandScorer,
196 IndexReader reader ) {
197 // We don't care which Similarity we have, because we don't use it. So get the default.
198 super(Similarity.getDefault());
199 this.operandScorer = operandScorer;
200 this.reader = reader;
201 assert this.operandScorer != null;
202 assert this.reader != null;
203 this.pastMaxDocId = this.reader.maxDoc();
204 }
205
206 /**
207 * {@inheritDoc}
208 *
209 * @see org.apache.lucene.search.DocIdSetIterator#docID()
210 */
211 @Override
212 public int docID() {
213 return docId;
214 }
215
216 /**
217 * {@inheritDoc}
218 *
219 * @see org.apache.lucene.search.DocIdSetIterator#nextDoc()
220 */
221 @Override
222 public int nextDoc() throws IOException {
223 if (nextScoredDocId == -1) {
224 // Find the first document that is scored by the operand's scorer ...
225 nextScoredDocId = operandScorer.nextDoc();
226 }
227 do {
228 ++docId;
229 if (docId == pastMaxDocId) {
230 // We're aleady to the end of the documents in the index, so return no more docs
231 return Scorer.NO_MORE_DOCS;
232 }
233 if (docId == nextScoredDocId) {
234 // Find the next document that is scored by the operand's scorer ...
235 nextScoredDocId = operandScorer.nextDoc();
236 continue;
237 }
238 if (reader.isDeleted(docId)) {
239 // We should skip this document ...
240 continue;
241 }
242 return docId;
243 } while (true);
244 }
245
246 /**
247 * {@inheritDoc}
248 *
249 * @see org.apache.lucene.search.DocIdSetIterator#advance(int)
250 */
251 @Override
252 public int advance( int target ) throws IOException {
253 if (target == Scorer.NO_MORE_DOCS) return target;
254 while (true) {
255 int doc = nextDoc();
256 if (doc >= target) return doc;
257 }
258 }
259
260 /**
261 * {@inheritDoc}
262 * <p>
263 * This method always returns a score of 1.0 for the current document, since only those documents that satisfy the NOT are
264 * scored by this scorer.
265 * </p>
266 *
267 * @see org.apache.lucene.search.Scorer#score()
268 */
269 @Override
270 public float score() {
271 return 1.0f;
272 }
273 }
274 }