| package org.apache.lucene.search; |
| |
| /** |
| * 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. |
| */ |
| |
| import java.io.IOException; |
| import org.apache.lucene.index.Term; |
| import org.apache.lucene.index.TermDocs; |
| import org.apache.lucene.index.IndexReader; |
| |
| /** 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 Searcher searcher; |
| private float value; |
| private float idf; |
| private float queryNorm; |
| private float queryWeight; |
| |
| public TermWeight(Searcher searcher) { |
| this.searcher = searcher; |
| } |
| |
| public String toString() { return "weight(" + TermQuery.this + ")"; } |
| |
| public Query getQuery() { return TermQuery.this; } |
| public float getValue() { return value; } |
| |
| public float sumOfSquaredWeights() throws IOException { |
| idf = getSimilarity(searcher).idf(term, searcher); // compute idf |
| 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, getSimilarity(searcher), |
| reader.norms(term.field())); |
| } |
| |
| public Explanation explain(IndexReader reader, int doc) |
| throws IOException { |
| |
| Explanation result = new Explanation(); |
| result.setDescription("weight("+getQuery()+" in "+doc+"), product of:"); |
| |
| Explanation idfExpl = |
| new Explanation(idf, "idf(docFreq=" + searcher.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(); |
| Explanation fieldExpl = new Explanation(); |
| 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.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; |
| } |
| } |
| |
| /** 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) { |
| return new TermWeight(searcher); |
| } |
| |
| /** 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()); |
| if (getBoost() != 1.0f) { |
| buffer.append("^"); |
| buffer.append(Float.toString(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(); |
| } |
| |
| } |