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Java > Open Source Codes > org > apache > lucene > search > spans > SpanTermQuery


1 package org.apache.lucene.search.spans;
2
3 /**
4  * Copyright 2004 The Apache Software Foundation
5  *
6  * Licensed under the Apache License, Version 2.0 (the "License");
7  * you may not use this file except in compliance with the License.
8  * You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing, software
13  * distributed under the License is distributed on an "AS IS" BASIS,
14  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15  * See the License for the specific language governing permissions and
16  * limitations under the License.
17  */
18
19 import java.io.IOException JavaDoc;
20
21 import java.util.Collection JavaDoc;
22 import java.util.ArrayList JavaDoc;
23
24 import org.apache.lucene.index.IndexReader;
25 import org.apache.lucene.index.Term;
26 import org.apache.lucene.index.TermPositions;
27 import org.apache.lucene.util.ToStringUtils;
28
29 /** Matches spans containing a term. */
30 public class SpanTermQuery extends SpanQuery {
31   private Term term;
32
33   /** Construct a SpanTermQuery matching the named term's spans. */
34   public SpanTermQuery(Term term) { this.term = term; }
35
36   /** Return the term whose spans are matched. */
37   public Term getTerm() { return term; }
38
39   public String JavaDoc getField() { return term.field(); }
40
41   public Collection JavaDoc getTerms() {
42     Collection JavaDoc terms = new ArrayList JavaDoc();
43     terms.add(term);
44     return terms;
45   }
46
47   public String JavaDoc toString(String JavaDoc field) {
48     StringBuffer JavaDoc buffer = new StringBuffer JavaDoc();
49     if (term.field().equals(field))
50       buffer.append(term.text());
51     else
52       buffer.append(term.toString());
53     buffer.append(ToStringUtils.boost(getBoost()));
54     return buffer.toString();
55   }
56
57   /** Returns true iff <code>o</code> is equal to this. */
58   public boolean equals(Object JavaDoc o) {
59     if (!(o instanceof SpanTermQuery))
60       return false;
61     SpanTermQuery other = (SpanTermQuery)o;
62     return (this.getBoost() == other.getBoost())
63       && this.term.equals(other.term);
64   }
65
66   /** Returns a hash code value for this object.*/
67   public int hashCode() {
68     return Float.floatToIntBits(getBoost()) ^ term.hashCode() ^ 0xD23FE494;
69   }
70
71   public Spans getSpans(final IndexReader reader) throws IOException JavaDoc {
72     return new Spans() {
73         private TermPositions positions = reader.termPositions(term);
74
75         private int doc = -1;
76         private int freq;
77         private int count;
78         private int position;
79
80         public boolean next() throws IOException JavaDoc {
81           if (count == freq) {
82             if (!positions.next()) {
83               doc = Integer.MAX_VALUE;
84               return false;
85             }
86             doc = positions.doc();
87             freq = positions.freq();
88             count = 0;
89           }
90           position = positions.nextPosition();
91           count++;
92           return true;
93         }
94
95         public boolean skipTo(int target) throws IOException JavaDoc {
96           // are we already at the correct position?
97 if (doc >= target) {
98             return true;
99           }
100
101           if (!positions.skipTo(target)) {
102             doc = Integer.MAX_VALUE;
103             return false;
104           }
105
106           doc = positions.doc();
107           freq = positions.freq();
108           count = 0;
109
110           position = positions.nextPosition();
111           count++;
112
113           return true;
114         }
115
116         public int doc() { return doc; }
117         public int start() { return position; }
118         public int end() { return position + 1; }
119
120         public String JavaDoc toString() {
121           return "spans(" + SpanTermQuery.this.toString() + ")@"+
122             (doc==-1?"START":(doc==Integer.MAX_VALUE)?"END":doc+"-"+position);
123         }
124
125       };
126   }
127
128 }
129
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