/*
* 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 Lucene.Net.Support;
using IndexReader = Lucene.Net.Index.IndexReader;
using Term = Lucene.Net.Index.Term;
using TermPositions = Lucene.Net.Index.TermPositions;
using ToStringUtils = Lucene.Net.Util.ToStringUtils;
using IDFExplanation = Lucene.Net.Search.Explanation.IDFExplanation;
namespace Lucene.Net.Search
{
/// A Query that matches documents containing a particular sequence of terms.
/// A PhraseQuery is built by QueryParser for input like "new york".
///
/// This query may be combined with other terms or queries with a .
///
[Serializable]
public class PhraseQuery:Query
{
private System.String field;
private EquatableList terms = new EquatableList(4);
private EquatableList positions = new EquatableList(4);
private int maxPosition = 0;
private int slop = 0;
/// Constructs an empty phrase query.
public PhraseQuery()
{
}
/// 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 WITHIN or NEAR operator.
/// 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.
/// More exact matches are scored higher than sloppier matches, thus search
/// results are sorted by exactness.
/// The slop is zero by default, requiring exact matches.
///
public virtual int Slop
{
get { return slop; }
set { slop = value; }
}
/// 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.
///
public virtual void Add(Term term)
{
int position = 0;
if (positions.Count > 0)
position = positions[positions.Count - 1] + 1;
Add(term, position);
}
/// 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).
///
///
///
///
///
///
public virtual void Add(Term term, int position)
{
if (terms.Count == 0)
field = term.Field;
else if ((System.Object) term.Field != (System.Object) field)
{
throw new System.ArgumentException("All phrase terms must be in the same field: " + term);
}
terms.Add(term);
positions.Add(position);
if (position > maxPosition)
maxPosition = position;
}
/// Returns the set of terms in this phrase.
public virtual Term[] GetTerms()
{
return terms.ToArray();
}
/// Returns the relative positions of terms in this phrase.
public virtual int[] GetPositions()
{
int[] result = new int[positions.Count];
for (int i = 0; i < positions.Count; i++)
result[i] = 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;
private IDFExplanation idfExp;
public PhraseWeight(PhraseQuery enclosingInstance, Searcher searcher)
{
InitBlock(enclosingInstance);
this.similarity = Enclosing_Instance.GetSimilarity(searcher);
idfExp = similarity.IdfExplain(Enclosing_Instance.terms, searcher);
idf = idfExp.Idf;
}
public override System.String ToString()
{
return "weight(" + Enclosing_Instance + ")";
}
public override Query Query
{
get { return Enclosing_Instance; }
}
public override float Value
{
get { return value_Renamed; }
}
public override float GetSumOfSquaredWeights()
{
queryWeight = idf*Enclosing_Instance.Boost; // compute query weight
return queryWeight*queryWeight; // square it
}
public override void Normalize(float queryNorm)
{
this.queryNorm = queryNorm;
queryWeight *= queryNorm; // normalize query weight
value_Renamed = queryWeight * idf; // idf for document
}
public override Scorer Scorer(IndexReader reader, bool scoreDocsInOrder, bool topScorer)
{
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(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 override Explanation Explain(IndexReader reader, int doc)
{
Explanation result = new Explanation();
result.Description = "weight(" + Query + " in " + doc + "), product of:";
System.Text.StringBuilder docFreqs = new System.Text.StringBuilder();
System.Text.StringBuilder query = new System.Text.StringBuilder();
query.Append('\"');
docFreqs.Append(idfExp.Explain());
for (int i = 0; i < Enclosing_Instance.terms.Count; i++)
{
if (i != 0)
{
query.Append(" ");
}
Term term = Enclosing_Instance.terms[i];
query.Append(term.Text);
}
query.Append('\"');
Explanation idfExpl = new Explanation(idf, "idf(" + Enclosing_Instance.field + ":" + docFreqs + ")");
// explain query weight
Explanation queryExpl = new Explanation();
queryExpl.Description = "queryWeight(" + Query + "), product of:";
Explanation boostExpl = new Explanation(Enclosing_Instance.Boost, "boost");
if (Enclosing_Instance.Boost != 1.0f)
queryExpl.AddDetail(boostExpl);
queryExpl.AddDetail(idfExpl);
Explanation queryNormExpl = new Explanation(queryNorm, "queryNorm");
queryExpl.AddDetail(queryNormExpl);
queryExpl.Value = boostExpl.Value * idfExpl.Value * queryNormExpl.Value;
result.AddDetail(queryExpl);
// explain field weight
Explanation fieldExpl = new Explanation();
fieldExpl.Description = "fieldWeight(" + Enclosing_Instance.field + ":" + query + " in " + doc + "), product of:";
PhraseScorer scorer = (PhraseScorer)Scorer(reader, true, false);
if (scorer == null)
{
return new Explanation(0.0f, "no matching docs");
}
Explanation tfExplanation = new Explanation();
int d = scorer.Advance(doc);
float phraseFreq = (d == doc) ? scorer.CurrentFreq() : 0.0f;
tfExplanation.Value = similarity.Tf(phraseFreq);
tfExplanation.Description = "tf(phraseFreq=" + phraseFreq + ")";
fieldExpl.AddDetail(tfExplanation);
fieldExpl.AddDetail(idfExpl);
Explanation fieldNormExpl = new Explanation();
byte[] fieldNorms = reader.Norms(Enclosing_Instance.field);
float fieldNorm = fieldNorms != null?Similarity.DecodeNorm(fieldNorms[doc]):1.0f;
fieldNormExpl.Value = fieldNorm;
fieldNormExpl.Description = "fieldNorm(field=" + Enclosing_Instance.field + ", doc=" + doc + ")";
fieldExpl.AddDetail(fieldNormExpl);
fieldExpl.Value = tfExplanation.Value * idfExpl.Value * fieldNormExpl.Value;
result.AddDetail(fieldExpl);
// combine them
result.Value = queryExpl.Value * fieldExpl.Value;
if (queryExpl.Value == 1.0f)
return fieldExpl;
return result;
}
}
public override Weight CreateWeight(Searcher searcher)
{
if (terms.Count == 1)
{
// optimize one-term case
Term term = terms[0];
Query termQuery = new TermQuery(term);
termQuery.Boost = Boost;
return termQuery.CreateWeight(searcher);
}
return new PhraseWeight(this, searcher);
}
///
///
public override void ExtractTerms(System.Collections.Generic.ISet queryTerms)
{
queryTerms.UnionWith(terms);
}
/// Prints a user-readable version of this query.
public override System.String ToString(System.String f)
{
System.Text.StringBuilder buffer = new System.Text.StringBuilder();
if (field != null && !field.Equals(f))
{
buffer.Append(field);
buffer.Append(":");
}
buffer.Append("\"");
System.String[] pieces = new System.String[maxPosition + 1];
for (int i = 0; i < terms.Count; i++)
{
int pos = positions[i];
System.String s = pieces[pos];
if (s == null)
{
s = terms[i].Text;
}
else
{
s = s + "|" + terms[i].Text;
}
pieces[pos] = s;
}
for (int i = 0; i < pieces.Length; i++)
{
if (i > 0)
{
buffer.Append(' ');
}
System.String s = pieces[i];
if (s == null)
{
buffer.Append('?');
}
else
{
buffer.Append(s);
}
}
buffer.Append("\"");
if (slop != 0)
{
buffer.Append("~");
buffer.Append(slop);
}
buffer.Append(ToStringUtils.Boost(Boost));
return buffer.ToString();
}
/// Returns true iff o is equal to this.
public override bool Equals(System.Object o)
{
if (!(o is PhraseQuery))
return false;
PhraseQuery other = (PhraseQuery) o;
return (this.Boost == other.Boost) && (this.slop == other.slop) && this.terms.Equals(other.terms) && this.positions.Equals(other.positions);
}
/// Returns a hash code value for this object.
public override int GetHashCode()
{
return BitConverter.ToInt32(BitConverter.GetBytes(Boost), 0) ^ slop ^ terms.GetHashCode() ^ positions.GetHashCode();
}
}
}