01: package org.apache.lucene.search.spans;
02:
03: /**
04: * Licensed to the Apache Software Foundation (ASF) under one or more
05: * contributor license agreements. See the NOTICE file distributed with
06: * this work for additional information regarding copyright ownership.
07: * The ASF licenses this file to You under the Apache License, Version 2.0
08: * (the "License"); you may not use this file except in compliance with
09: * the License. You may obtain a copy of the License at
10: *
11: * http://www.apache.org/licenses/LICENSE-2.0
12: *
13: * Unless required by applicable law or agreed to in writing, software
14: * distributed under the License is distributed on an "AS IS" BASIS,
15: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16: * See the License for the specific language governing permissions and
17: * limitations under the License.
18: */
19:
20: import java.io.IOException;
21:
22: /** Expert: an enumeration of span matches. Used to implement span searching.
23: * Each span represents a range of term positions within a document. Matches
24: * are enumerated in order, by increasing document number, within that by
25: * increasing start position and finally by increasing end position. */
26: public interface Spans {
27: /** Move to the next match, returning true iff any such exists. */
28: boolean next() throws IOException;
29:
30: /** Skips to the first match beyond the current, whose document number is
31: * greater than or equal to <i>target</i>. <p>Returns true iff there is such
32: * a match. <p>Behaves as if written: <pre>
33: * boolean skipTo(int target) {
34: * do {
35: * if (!next())
36: * return false;
37: * } while (target > doc());
38: * return true;
39: * }
40: * </pre>
41: * Most implementations are considerably more efficient than that.
42: */
43: boolean skipTo(int target) throws IOException;
44:
45: /** Returns the document number of the current match. Initially invalid. */
46: int doc();
47:
48: /** Returns the start position of the current match. Initially invalid. */
49: int start();
50:
51: /** Returns the end position of the current match. Initially invalid. */
52: int end();
53:
54: }
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