/*
* 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.
*/
using System;
using Attribute = Lucene.Net.Util.Attribute;
using TokenStream = Lucene.Net.Analysis.TokenStream;
namespace Lucene.Net.Analysis.Tokenattributes
{
/// The positionIncrement determines the position of this token
/// relative to the previous Token in a , used in phrase
/// searching.
///
/// The default value is one.
///
/// Some common uses for this are:
///
/// - Set it to zero to put multiple terms in the same position. This is
/// useful if, e.g., a word has multiple stems. Searches for phrases
/// including either stem will match. In this case, all but the first stem's
/// increment should be set to zero: the increment of the first instance
/// should be one. Repeating a token with an increment of zero can also be
/// used to boost the scores of matches on that token.
///
/// - Set it to values greater than one to inhibit exact phrase matches.
/// If, for example, one does not want phrases to match across removed stop
/// words, then one could build a stop word filter that removes stop words and
/// also sets the increment to the number of stop words removed before each
/// non-stop word. Then exact phrase queries will only match when the terms
/// occur with no intervening stop words.
///
///
///
[Serializable]
public class PositionIncrementAttribute:Attribute, IPositionIncrementAttribute, System.ICloneable
{
private int positionIncrement = 1;
/// Set the position increment. The default value is one.
///
///
/// the distance from the prior term
public virtual int PositionIncrement
{
set
{
if (value < 0)
throw new System.ArgumentException("Increment must be zero or greater: " + value);
this.positionIncrement = value;
}
get { return positionIncrement; }
}
public override void Clear()
{
this.positionIncrement = 1;
}
public override bool Equals(System.Object other)
{
if (other == this)
{
return true;
}
if (other is PositionIncrementAttribute)
{
return positionIncrement == ((PositionIncrementAttribute) other).positionIncrement;
}
return false;
}
public override int GetHashCode()
{
return positionIncrement;
}
public override void CopyTo(Attribute target)
{
IPositionIncrementAttribute t = (IPositionIncrementAttribute) target;
t.PositionIncrement = positionIncrement;
}
override public System.Object Clone()
{
PositionIncrementAttribute impl = new PositionIncrementAttribute();
impl.positionIncrement = positionIncrement;
return impl;
}
}
}