package org.apache.lucene.search;
/**
* 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.
*/
import java.io.IOException;
import java.util.Set;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.util.ToStringUtils;
/** A Query that matches documents containing a term.
This may be combined with other terms with a {@link BooleanQuery}.
*/
public class TermQuery extends Query {
private Term term;
private class TermWeight implements Weight {
private Similarity similarity;
private float value;
private float idf;
private float queryNorm;
private float queryWeight;
public TermWeight(Searcher searcher)
throws IOException {
this.similarity = getSimilarity(searcher);
idf = similarity.idf(term, searcher); // compute idf
}
public String toString() { return "weight(" + TermQuery.this + ")"; }
public Query getQuery() { return TermQuery.this; }
public float getValue() { return value; }
public float sumOfSquaredWeights() {
queryWeight = idf * getBoost(); // compute query weight
return queryWeight * queryWeight; // square it
}
public void normalize(float queryNorm) {
this.queryNorm = queryNorm;
queryWeight *= queryNorm; // normalize query weight
value = queryWeight * idf; // idf for document
}
public Scorer scorer(IndexReader reader) throws IOException {
TermDocs termDocs = reader.termDocs(term);
if (termDocs == null)
return null;
return new TermScorer(this, termDocs, similarity,
reader.norms(term.field()));
}
public Explanation explain(IndexReader reader, int doc)
throws IOException {
ComplexExplanation result = new ComplexExplanation();
result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");
Explanation idfExpl =
new Explanation(idf, "idf(docFreq=" + reader.docFreq(term) + ")");
// explain query weight
Explanation queryExpl = new Explanation();
queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");
Explanation boostExpl = new Explanation(getBoost(), "boost");
if (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
String field = term.field();
ComplexExplanation fieldExpl = new ComplexExplanation();
fieldExpl.setDescription("fieldWeight("+term+" in "+doc+
"), product of:");
Explanation tfExpl = scorer(reader).explain(doc);
fieldExpl.addDetail(tfExpl);
fieldExpl.addDetail(idfExpl);
Explanation fieldNormExpl = new Explanation();
byte[] fieldNorms = reader.norms(field);
float fieldNorm =
fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
fieldNormExpl.setValue(fieldNorm);
fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
fieldExpl.addDetail(fieldNormExpl);
fieldExpl.setMatch(Boolean.valueOf(tfExpl.isMatch()));
fieldExpl.setValue(tfExpl.getValue() *
idfExpl.getValue() *
fieldNormExpl.getValue());
result.addDetail(fieldExpl);
result.setMatch(fieldExpl.getMatch());
// combine them
result.setValue(queryExpl.getValue() * fieldExpl.getValue());
if (queryExpl.getValue() == 1.0f)
return fieldExpl;
return result;
}
}
/** Constructs a query for the term <code>t</code>. */
public TermQuery(Term t) {
term = t;
}
/** Returns the term of this query. */
public Term getTerm() { return term; }
protected Weight createWeight(Searcher searcher) throws IOException {
return new TermWeight(searcher);
}
public void extractTerms(Set terms) {
terms.add(getTerm());
}
/** Prints a user-readable version of this query. */
public String toString(String field) {
StringBuffer buffer = new StringBuffer();
if (!term.field().equals(field)) {
buffer.append(term.field());
buffer.append(":");
}
buffer.append(term.text());
buffer.append(ToStringUtils.boost(getBoost()));
return buffer.toString();
}
/** Returns true iff <code>o</code> is equal to this. */
public boolean equals(Object o) {
if (!(o instanceof TermQuery))
return false;
TermQuery other = (TermQuery)o;
return (this.getBoost() == other.getBoost())
&& this.term.equals(other.term);
}
/** Returns a hash code value for this object.*/
public int hashCode() {
return Float.floatToIntBits(getBoost()) ^ term.hashCode();
}
}
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