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


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 /** Expert: an enumeration of span matches. Used to implement span searching.
22  * Each span represents a range of term positions within a document. Matches
23  * are enumerated in order, by increasing document number, within that by
24  * increasing start position and finally by increasing end position. */
25 public interface Spans {
26   /** Move to the next match, returning true iff any such exists. */
27   boolean next() throws IOException JavaDoc;
28
29   /** Skips to the first match beyond the current, whose document number is
30    * greater than or equal to <i>target</i>. <p>Returns true iff there is such
31    * a match. <p>Behaves as if written: <pre>
32    * boolean skipTo(int target) {
33    * do {
34    * if (!next())
35    * return false;
36    * } while (target > doc());
37    * return true;
38    * }
39    * </pre>
40    * Most implementations are considerably more efficient than that.
41    */
42   boolean skipTo(int target) throws IOException JavaDoc;
43
44   /** Returns the document number of the current match. Initially invalid. */
45   int doc();
46
47   /** Returns the start position of the current match. Initially invalid. */
48   int start();
49
50   /** Returns the end position of the current match. Initially invalid. */
51   int end();
52
53 }
54
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