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Java > Open Source Codes > org > apache > lucene > index > TermDocs


1 package org.apache.lucene.index;
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 /** TermDocs provides an interface for enumerating <document, frequency>
22  pairs for a term. <p> The document portion names each document containing
23  the term. Documents are indicated by number. The frequency portion gives
24  the number of times the term occurred in each document. <p> The pairs are
25  ordered by document number.
26
27  @see IndexReader#termDocs()
28  */
29
30 public interface TermDocs {
31   /** Sets this to the data for a term.
32    * The enumeration is reset to the start of the data for this term.
33    */
34   void seek(Term term) throws IOException JavaDoc;
35
36   /** Sets this to the data for the current term in a {@link TermEnum}.
37    * This may be optimized in some implementations.
38    */
39   void seek(TermEnum termEnum) throws IOException JavaDoc;
40
41   /** Returns the current document number. <p> This is invalid until {@link
42    #next()} is called for the first time.*/
43   int doc();
44
45   /** Returns the frequency of the term within the current document. <p> This
46    is invalid until {@link #next()} is called for the first time.*/
47   int freq();
48
49   /** Moves to the next pair in the enumeration. <p> Returns true iff there is
50    such a next pair in the enumeration. */
51   boolean next() throws IOException JavaDoc;
52
53   /** Attempts to read multiple entries from the enumeration, up to length of
54    * <i>docs</i>. Document numbers are stored in <i>docs</i>, and term
55    * frequencies are stored in <i>freqs</i>. The <i>freqs</i> array must be as
56    * long as the <i>docs</i> array.
57    *
58    * <p>Returns the number of entries read. Zero is only returned when the
59    * stream has been exhausted. */
60   int read(int[] docs, int[] freqs) throws IOException JavaDoc;
61
62   /** Skips entries to the first beyond the current whose document number is
63    * greater than or equal to <i>target</i>. <p>Returns true iff there is such
64    * an entry. <p>Behaves as if written: <pre>
65    * boolean skipTo(int target) {
66    * do {
67    * if (!next())
68    * return false;
69    * } while (target > doc());
70    * return true;
71    * }
72    * </pre>
73    * Some implementations are considerably more efficient than that.
74    */
75   boolean skipTo(int target) throws IOException JavaDoc;
76
77   /** Frees associated resources. */
78   void close() throws IOException JavaDoc;
79 }
80
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