Lucene.Net  3.0.3
Lucene.Net is a port of the Lucene search engine library, written in C# and targeted at .NET runtime users.
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PositionIncrementAttribute.cs
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17 
18 using System;
19 using Attribute = Lucene.Net.Util.Attribute;
20 using TokenStream = Lucene.Net.Analysis.TokenStream;
21 
22 namespace Lucene.Net.Analysis.Tokenattributes
23 {
24 
25  /// <summary>The positionIncrement determines the position of this token
26  /// relative to the previous Token in a <see cref="TokenStream" />, used in phrase
27  /// searching.
28  ///
29  /// <p/>The default value is one.
30  ///
31  /// <p/>Some common uses for this are:<list>
32  ///
33  /// <item>Set it to zero to put multiple terms in the same position. This is
34  /// useful if, e.g., a word has multiple stems. Searches for phrases
35  /// including either stem will match. In this case, all but the first stem's
36  /// increment should be set to zero: the increment of the first instance
37  /// should be one. Repeating a token with an increment of zero can also be
38  /// used to boost the scores of matches on that token.</item>
39  ///
40  /// <item>Set it to values greater than one to inhibit exact phrase matches.
41  /// If, for example, one does not want phrases to match across removed stop
42  /// words, then one could build a stop word filter that removes stop words and
43  /// also sets the increment to the number of stop words removed before each
44  /// non-stop word. Then exact phrase queries will only match when the terms
45  /// occur with no intervening stop words.</item>
46  ///
47  /// </list>
48  /// </summary>
49  [Serializable]
51  {
52  private int positionIncrement = 1;
53 
54  /// <summary>Set the position increment. The default value is one.
55  ///
56  /// </summary>
57  /// <value> the distance from the prior term </value>
58  public virtual int PositionIncrement
59  {
60  set
61  {
62  if (value < 0)
63  throw new System.ArgumentException("Increment must be zero or greater: " + value);
64  this.positionIncrement = value;
65  }
66  get { return positionIncrement; }
67  }
68 
69  public override void Clear()
70  {
71  this.positionIncrement = 1;
72  }
73 
74  public override bool Equals(System.Object other)
75  {
76  if (other == this)
77  {
78  return true;
79  }
80 
81  if (other is PositionIncrementAttribute)
82  {
83  return positionIncrement == ((PositionIncrementAttribute) other).positionIncrement;
84  }
85 
86  return false;
87  }
88 
89  public override int GetHashCode()
90  {
91  return positionIncrement;
92  }
93 
94  public override void CopyTo(Attribute target)
95  {
97  t.PositionIncrement = positionIncrement;
98  }
99 
100  override public System.Object Clone()
101  {
103  impl.positionIncrement = positionIncrement;
104  return impl;
105  }
106  }
107 }