/*
* 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 TermEnumLucene.Net.Index.TermEnum;
using ToStringUtilsLucene.Net.Util.ToStringUtils;
namespace Lucene.Net.Search{
/// <summary>A Query that matches documents containing terms with a specified prefix. A PrefixQuery
/// is built by QueryParser for input like <code>app*</code>.
/// </summary>
[Serializable]
public class PrefixQuery : Query
{
private Term prefix;
/// <summary>Constructs a query for terms starting with <code>prefix</code>. </summary>
public PrefixQuery(Term prefix)
{
this.prefix = prefix;
}
/// <summary>Returns the prefix of this query. </summary>
public virtual Term GetPrefix()
{
return prefix;
}
public override Query Rewrite(IndexReader reader)
{
BooleanQuery query = new BooleanQuery(true);
TermEnum enumerator = reader.Terms(prefix);
try
{
System.String prefixText = prefix.Text();
System.String prefixField = prefix.Field();
do
{
Term term = enumerator.Term();
if (term != null && term.Text().StartsWith(prefixText) && term.Field() == prefixField)
{
TermQuery tq = new TermQuery(term); // found a match
tq.SetBoost(GetBoost()); // set the boost
query.Add(tq, BooleanClause.Occur.SHOULD); // add to query
//System.out.println("added " + term);
}
else
{
break;
}
}
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 (!prefix.Field().Equals(field))
{
buffer.Append(prefix.Field());
buffer.Append(":");
}
buffer.Append(prefix.Text());
buffer.Append('*');
buffer.Append(ToStringUtils.Boost(GetBoost()));
return buffer.ToString();
}
/// <summary>Returns true iff <code>o</code> is equal to this. </summary>
public override bool Equals(System.Object o)
{
if (!(o is PrefixQuery))
return false;
PrefixQuery other = (PrefixQuery) o;
return (this.GetBoost() == other.GetBoost()) && this.prefix.Equals(other.prefix);
}
/// <summary>Returns a hash code value for this object.</summary>
public override int GetHashCode()
{
return BitConverter.ToInt32(BitConverter.GetBytes(GetBoost()), 0) ^ prefix.GetHashCode();
}
// {{Aroush-1.9}} Do we need this?!
override public System.Object Clone()
{
return null;
}
}
}
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