blob: c5f7694d39c365ab7f6ab5c4f0202c2792022cfe (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
|
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
namespace Lucene.Net.Analysis
{
/// <summary> This class can be used if the token attributes of a TokenStream
/// are intended to be consumed more than once. It caches
/// all token attribute states locally in a List.
///
/// <p/>CachingTokenFilter implements the optional method
/// <see cref="TokenStream.Reset()" />, which repositions the
/// stream to the first Token.
/// </summary>
public sealed class CachingTokenFilter : TokenFilter
{
private System.Collections.Generic.LinkedList<State> cache = null;
private System.Collections.Generic.IEnumerator<State> iterator = null;
private State finalState;
public CachingTokenFilter(TokenStream input):base(input)
{
}
public override bool IncrementToken()
{
if (cache == null)
{
// fill cache lazily
cache = new System.Collections.Generic.LinkedList<State>();
FillCache();
iterator = cache.GetEnumerator();
}
if (!iterator.MoveNext())
{
// the cache is exhausted, return false
return false;
}
// Since the TokenFilter can be reset, the tokens need to be preserved as immutable.
RestoreState(iterator.Current);
return true;
}
public override void End()
{
if (finalState != null)
{
RestoreState(finalState);
}
}
public override void Reset()
{
if (cache != null)
{
iterator = cache.GetEnumerator();
}
}
private void FillCache()
{
while (input.IncrementToken())
{
cache.AddLast(CaptureState());
}
// capture final state
input.End();
finalState = CaptureState();
}
}
}
|
