001 package gate.creole.annic.apache.lucene.search;
002
003 /**
004 * Copyright 2004 The Apache Software Foundation
005 *
006 * Licensed under the Apache License, Version 2.0 (the "License");
007 * you may not use this file except in compliance with the License.
008 * You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 import java.io.IOException;
020 import gate.creole.annic.apache.lucene.index.Term;
021 import gate.creole.annic.apache.lucene.index.TermDocs;
022 import gate.creole.annic.apache.lucene.index.IndexReader;
023
024 /** A Query that matches documents containing a term.
025 This may be combined with other terms with a {@link BooleanQuery}.
026 */
027 public class TermQuery extends Query {
028 private Term term;
029
030 private class TermWeight implements Weight {
031 private Searcher searcher;
032 private float value;
033 private float idf;
034 private float queryNorm;
035 private float queryWeight;
036
037 public TermWeight(Searcher searcher) {
038 this.searcher = searcher;
039 }
040
041 public String toString() { return "weight(" + TermQuery.this + ")"; }
042
043 public Query getQuery() { return TermQuery.this; }
044 public float getValue() { return value; }
045
046 public float sumOfSquaredWeights() throws IOException {
047 idf = getSimilarity(searcher).idf(term, searcher); // compute idf
048 queryWeight = idf * getBoost(); // compute query weight
049 return queryWeight * queryWeight; // square it
050 }
051
052 public void normalize(float queryNorm) {
053 this.queryNorm = queryNorm;
054 queryWeight *= queryNorm; // normalize query weight
055 value = queryWeight * idf; // idf for document
056 }
057
058 public Scorer scorer(IndexReader reader, Searcher searcher) throws IOException {
059 this.searcher = searcher;
060 TermDocs termDocs = reader.termDocs(term);
061
062 if (termDocs == null)
063 return null;
064
065 return new TermScorer(this, termDocs, getSimilarity(searcher),
066 reader.norms(term.field()), term);
067 }
068
069 public Explanation explain(IndexReader reader, int doc)
070 throws IOException {
071
072 Explanation result = new Explanation();
073 result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");
074
075 Explanation idfExpl =
076 new Explanation(idf, "idf(docFreq=" + searcher.docFreq(term) + ")");
077
078 // explain query weight
079 Explanation queryExpl = new Explanation();
080 queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");
081
082 Explanation boostExpl = new Explanation(getBoost(), "boost");
083 if (getBoost() != 1.0f)
084 queryExpl.addDetail(boostExpl);
085 queryExpl.addDetail(idfExpl);
086
087 Explanation queryNormExpl = new Explanation(queryNorm,"queryNorm");
088 queryExpl.addDetail(queryNormExpl);
089
090 queryExpl.setValue(boostExpl.getValue() *
091 idfExpl.getValue() *
092 queryNormExpl.getValue());
093
094 result.addDetail(queryExpl);
095
096 // explain field weight
097 String field = term.field();
098 Explanation fieldExpl = new Explanation();
099 fieldExpl.setDescription("fieldWeight("+term+" in "+doc+
100 "), product of:");
101
102 Explanation tfExpl = scorer(reader, this.searcher).explain(doc);
103 fieldExpl.addDetail(tfExpl);
104 fieldExpl.addDetail(idfExpl);
105
106 Explanation fieldNormExpl = new Explanation();
107 byte[] fieldNorms = reader.norms(field);
108 float fieldNorm =
109 fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
110 fieldNormExpl.setValue(fieldNorm);
111 fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
112 fieldExpl.addDetail(fieldNormExpl);
113
114 fieldExpl.setValue(tfExpl.getValue() *
115 idfExpl.getValue() *
116 fieldNormExpl.getValue());
117
118 result.addDetail(fieldExpl);
119
120 // combine them
121 result.setValue(queryExpl.getValue() * fieldExpl.getValue());
122
123 if (queryExpl.getValue() == 1.0f)
124 return fieldExpl;
125
126 return result;
127 }
128 }
129
130 /** Constructs a query for the term <code>t</code>. */
131 public TermQuery(Term t) {
132 term = t;
133 }
134
135 /** Returns the term of this query. */
136 public Term getTerm() { return term; }
137
138 protected Weight createWeight(Searcher searcher) {
139 return new TermWeight(searcher);
140 }
141
142 /** Prints a user-readable version of this query. */
143 public String toString(String field) {
144 StringBuffer buffer = new StringBuffer();
145 if (!term.field().equals(field)) {
146 buffer.append(term.field());
147 buffer.append(":");
148 }
149 buffer.append(term.text());
150 if (getBoost() != 1.0f) {
151 buffer.append("^");
152 buffer.append(Float.toString(getBoost()));
153 }
154 return buffer.toString();
155 }
156
157 /** Returns true iff <code>o</code> is equal to this. */
158 public boolean equals(Object o) {
159 if (!(o instanceof TermQuery))
160 return false;
161 TermQuery other = (TermQuery)o;
162 try {
163 throw new Exception("My Error");
164 } catch(Exception e) {
165 e.printStackTrace();
166 }
167
168 return (this.getBoost() == other.getBoost())
169 && this.term.equals(other.term);
170 }
171
172 /** Returns a hash code value for this object.*/
173 public int hashCode() {
174 return Float.floatToIntBits(getBoost()) ^ term.hashCode();
175 }
176
177 }
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