/*
* 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 TermPositionsLucene.Net.Index.TermPositions;
using ToStringUtilsLucene.Net.Util.ToStringUtils;
namespace Lucene.Net.Search{
/// <summary>A Query that matches documents containing a particular sequence of terms.
/// A PhraseQuery is built by QueryParser for input like <code>"new york"</code>.
///
/// <p>This query may be combined with other terms or queries with a {@link BooleanQuery}.
/// </summary>
[Serializable]
public class PhraseQuery : Query
{
private System.String field;
private System.Collections.ArrayList terms = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
private System.Collections.ArrayList positions = System.Collections.ArrayList.Synchronized(new System.Collections.ArrayList(10));
private int slop = 0;
/// <summary>Constructs an empty phrase query. </summary>
public PhraseQuery()
{
}
/// <summary>Sets the number of other words permitted between words in query phrase.
/// If zero, then this is an exact phrase search. For larger values this works
/// like a <code>WITHIN</code> or <code>NEAR</code> operator.
/// <p>The slop is in fact an edit-distance, where the units correspond to
/// moves of terms in the query phrase out of position. For example, to switch
/// the order of two words requires two moves (the first move places the words
/// atop one another), so to permit re-orderings of phrases, the slop must be
/// at least two.
/// <p>More exact matches are scored higher than sloppier matches, thus search
/// results are sorted by exactness.
/// <p>The slop is zero by default, requiring exact matches.
/// </summary>
public virtual void SetSlop(int s)
{
slop = s;
}
/// <summary>Returns the slop. See setSlop(). </summary>
public virtual int GetSlop()
{
return slop;
}
/// <summary> Adds a term to the end of the query phrase.
/// The relative position of the term is the one immediately after the last term added.
/// </summary>
public virtual void Add(Term term)
{
int position = 0;
if (positions.Count > 0)
position = ((System.Int32) positions[positions.Count - 1]) + 1;
Add(term, position);
}
/// <summary> Adds a term to the end of the query phrase.
/// The relative position of the term within the phrase is specified explicitly.
/// This allows e.g. phrases with more than one term at the same position
/// or phrases with gaps (e.g. in connection with stopwords).
///
/// </summary>
/// <param name="term">
/// </param>
/// <param name="position">
/// </param>
public virtual void Add(Term term, int position)
{
if (terms.Count == 0)
field = term.Field();
else if (term.Field() != field)
{
throw new System.ArgumentException("All phrase terms must be in the same field: " + term);
}
terms.Add(term);
positions.Add((System.Int32) position);
}
/// <summary>Returns the set of terms in this phrase. </summary>
public virtual Term[] GetTerms()
{
return (Term[]) terms.ToArray(typeof(Term));
}
/// <summary> Returns the relative positions of terms in this phrase.</summary>
public virtual int[] GetPositions()
{
int[] result = new int[positions.Count];
for (int i = 0; i < positions.Count; i++)
result[i] = ((System.Int32) positions[i]);
return result;
}
[Serializable]
private class PhraseWeight : Weight
{
private void InitBlock(PhraseQuery enclosingInstance)
{
this.enclosingInstance = enclosingInstance;
}
private PhraseQuery enclosingInstance;
public PhraseQuery Enclosing_Instance
{
get
{
return enclosingInstance;
}
}
private Similarity similarity;
private float value_Renamed;
private float idf;
private float queryNorm;
private float queryWeight;
public PhraseWeight(PhraseQuery enclosingInstance, Searcher searcher)
{
InitBlock(enclosingInstance);
this.similarity = Enclosing_Instance.GetSimilarity(searcher);
idf = similarity.Idf(Enclosing_Instance.terms, searcher);
}
public override System.String ToString()
{
return "weight(" + Enclosing_Instance + ")";
}
public virtual Query GetQuery()
{
return Enclosing_Instance;
}
public virtual float GetValue()
{
return value_Renamed;
}
public virtual float SumOfSquaredWeights()
{
queryWeight = idf * Enclosing_Instance.GetBoost(); // compute query weight
return queryWeight * queryWeight; // square it
}
public virtual void Normalize(float queryNorm)
{
this.queryNorm = queryNorm;
queryWeight *= queryNorm; // normalize query weight
value_Renamed = queryWeight * idf; // idf for document
}
public virtual Scorer Scorer(IndexReader reader)
{
if (Enclosing_Instance.terms.Count == 0)
// optimize zero-term case
return null;
TermPositions[] tps = new TermPositions[Enclosing_Instance.terms.Count];
for (int i = 0; i < Enclosing_Instance.terms.Count; i++)
{
TermPositions p = reader.TermPositions((Term) Enclosing_Instance.terms[i]);
if (p == null)
return null;
tps[i] = p;
}
if (Enclosing_Instance.slop == 0)
// optimize exact case
return new ExactPhraseScorer(this, tps, Enclosing_Instance.GetPositions(), similarity, reader.Norms(Enclosing_Instance.field));
else
return new SloppyPhraseScorer(this, tps, Enclosing_Instance.GetPositions(), similarity, Enclosing_Instance.slop, reader.Norms(Enclosing_Instance.field));
}
public virtual Explanation Explain(IndexReader reader, int doc)
{
Explanation result = new Explanation();
result.SetDescription("weight(" + GetQuery() + " in " + doc + "), product of:");
System.Text.StringBuilder docFreqs = new System.Text.StringBuilder();
System.Text.StringBuilder query = new System.Text.StringBuilder();
query.Append('\"');
for (int i = 0; i < Enclosing_Instance.terms.Count; i++)
{
if (i != 0)
{
docFreqs.Append(" ");
query.Append(" ");
}
Term term = (Term) Enclosing_Instance.terms[i];
docFreqs.Append(term.Text());
docFreqs.Append("=");
docFreqs.Append(reader.DocFreq(term));
query.Append(term.Text());
}
query.Append('\"');
Explanation idfExpl = new Explanation(idf, "idf(" + Enclosing_Instance.field + ": " + docFreqs + ")");
// explain query weight
Explanation queryExpl = new Explanation();
queryExpl.SetDescription("queryWeight(" + GetQuery() + "), product of:");
Explanation boostExpl = new Explanation(Enclosing_Instance.GetBoost(), "boost");
if (Enclosing_Instance.GetBoost() != 1.0f)
queryExpl.AddDetail(boostExpl);
queryExpl.AddDetail(idfExpl);
Explanation queryNormExpl = new Explanation(queryNorm, "queryNorm");
queryExpl.AddDetail(queryNormExpl);
queryExpl.SetValue(boostExpl.GetValue() * idfExpl.GetValue() * queryNormExpl.GetValue());
result.AddDetail(queryExpl);
// explain field weight
Explanation fieldExpl = new Explanation();
fieldExpl.SetDescription("fieldWeight(" + Enclosing_Instance.field + ":" + query + " in " + doc + "), product of:");
Explanation tfExpl = Scorer(reader).Explain(doc);
fieldExpl.AddDetail(tfExpl);
fieldExpl.AddDetail(idfExpl);
Explanation fieldNormExpl = new Explanation();
byte[] fieldNorms = reader.Norms(Enclosing_Instance.field);
float fieldNorm = fieldNorms != null?Similarity.DecodeNorm(fieldNorms[doc]):0.0f;
fieldNormExpl.SetValue(fieldNorm);
fieldNormExpl.SetDescription("fieldNorm(field=" + Enclosing_Instance.field + ", doc=" + doc + ")");
fieldExpl.AddDetail(fieldNormExpl);
fieldExpl.SetValue(tfExpl.GetValue() * idfExpl.GetValue() * fieldNormExpl.GetValue());
result.AddDetail(fieldExpl);
// combine them
result.SetValue(queryExpl.GetValue() * fieldExpl.GetValue());
if (queryExpl.GetValue() == 1.0f)
return fieldExpl;
return result;
}
}
protected internal override Weight CreateWeight(Searcher searcher)
{
if (terms.Count == 1)
{
// optimize one-term case
Term term = (Term) terms[0];
Query termQuery = new TermQuery(term);
termQuery.SetBoost(GetBoost());
return termQuery.CreateWeight(searcher);
}
return new PhraseWeight(this, searcher);
}
/// <seealso cref="Lucene.Net.search.Query.ExtractTerms(java.util.Set)">
/// </seealso>
public override void ExtractTerms(System.Collections.Hashtable queryTerms)
{
foreach (Term term in terms)
{
queryTerms.Add(term, term);
}
}
/// <summary>Prints a user-readable version of this query. </summary>
public override System.String ToString(System.String f)
{
System.Text.StringBuilder buffer = new System.Text.StringBuilder();
if (!field.Equals(f))
{
buffer.Append(field);
buffer.Append(":");
}
buffer.Append("\"");
for (int i = 0; i < terms.Count; i++)
{
buffer.Append(((Term) terms[i]).Text());
if (i != terms.Count - 1)
buffer.Append(" ");
}
buffer.Append("\"");
if (slop != 0)
{
buffer.Append("~");
buffer.Append(slop);
}
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 PhraseQuery))
return false;
PhraseQuery other = (PhraseQuery) o;
return (this.GetBoost() == other.GetBoost()) &&
(this.slop == other.slop) &&
this.terms.Equals(other.terms) &&
this.positions.Equals(other.positions);
}
/// <summary>Returns a hash code value for this object.</summary>
public override int GetHashCode()
{
return BitConverter.ToInt32(BitConverter.GetBytes(GetBoost()), 0) ^ slop ^ terms.GetHashCode() ^ positions.GetHashCode();
}
// {{Aroush-1.9}} Do we need this?!
override public System.Object Clone()
{
return null;
}
}
}
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