/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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 IndexReaderLucene.Net.Index.IndexReader;
using TermLucene.Net.Index.Term;
using ToStringUtilsLucene.Net.Util.ToStringUtils;
namespace Lucene.Net.Search{
/// <summary> A {@link Query} that matches documents containing a subset of terms provided
/// by a {@link FilteredTermEnum} enumeration.
/// <P>
/// <code>MultiTermQuery</code> is not designed to be used by itself.
/// <BR>
/// The reason being that it is not intialized with a {@link FilteredTermEnum}
/// enumeration. A {@link FilteredTermEnum} enumeration needs to be provided.
/// <P>
/// For example, {@link WildcardQuery} and {@link FuzzyQuery} extend
/// <code>MultiTermQuery</code> to provide {@link WildcardTermEnum} and
/// {@link FuzzyTermEnum}, respectively.
/// </summary>
[Serializable]
public abstract class MultiTermQuery:Query
{
private Term term;
/// <summary>Constructs a query for terms matching <code>term</code>. </summary>
public MultiTermQuery(Term term)
{
this.term = term;
}
/// <summary>Returns the pattern term. </summary>
public virtual Term GetTerm()
{
return term;
}
/// <summary>Construct the enumeration to be used, expanding the pattern term. </summary>
protected internal abstract FilteredTermEnum GetEnum(IndexReader reader);
public override Query Rewrite(IndexReader reader)
{
FilteredTermEnum enumerator = GetEnum(reader);
BooleanQuery query = new BooleanQuery(true);
try
{
do
{
Term t = enumerator.Term();
if (t != null)
{
TermQuery tq = new TermQuery(t); // found a match
tq.SetBoost(GetBoost() * enumerator.Difference()); // set the boost
query.Add(tq, BooleanClause.Occur.SHOULD); // add to query
}
}
while (enumerator.Next());
}
finally
{
enumerator.Close();
}
return query;
}
/// <summary>Prints a user-readable version of this query. </summary>
public override System.String ToString(System.String field)
{
System.Text.StringBuilder buffer = new System.Text.StringBuilder();
if (!term.Field().Equals(field))
{
buffer.Append(term.Field());
buffer.Append(":");
}
buffer.Append(term.Text());
buffer.Append(ToStringUtils.Boost(GetBoost()));
return buffer.ToString();
}
public override bool Equals(System.Object o)
{
if (this == o)
return true;
if (!(o is MultiTermQuery))
return false;
MultiTermQuery multiTermQuery = (MultiTermQuery) o;
if (!term.Equals(multiTermQuery.term))
return false;
return GetBoost() == multiTermQuery.GetBoost();
}
public override int GetHashCode()
{
return term.GetHashCode();
}
}
}
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