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Lucene example source code file (MatchAllDocsQuery.java)

This example Lucene source code file (MatchAllDocsQuery.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

explanation, explanation, io, ioexception, ioexception, matchalldocsquery, matchalldocsquery, matchalldocsweight, matchallscorer, no_more_docs, override, override, string, stringbuilder, util, weight

The Lucene MatchAllDocsQuery.java source code

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 org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermDocs;
import org.apache.lucene.util.ToStringUtils;

import java.util.Set;
import java.io.IOException;

/**
 * A query that matches all documents.
 *
 */
public class MatchAllDocsQuery extends Query {

  public MatchAllDocsQuery() {
    this(null);
  }

  private final String normsField;

  /**
   * @param normsField Field used for normalization factor (document boost). Null if nothing.
   */
  public MatchAllDocsQuery(String normsField) {
    this.normsField = normsField;
  }

  private class MatchAllScorer extends Scorer {
    final TermDocs termDocs;
    final float score;
    final byte[] norms;
    private int doc = -1;
    
    MatchAllScorer(IndexReader reader, Similarity similarity, Weight w,
        byte[] norms) throws IOException {
      super(similarity,w);
      this.termDocs = reader.termDocs(null);
      score = w.getValue();
      this.norms = norms;
    }

    @Override
    public int docID() {
      return doc;
    }

    @Override
    public int nextDoc() throws IOException {
      return doc = termDocs.next() ? termDocs.doc() : NO_MORE_DOCS;
    }
    
    @Override
    public float score() {
      return norms == null ? score : score * getSimilarity().decodeNormValue(norms[docID()]);
    }

    @Override
    public int advance(int target) throws IOException {
      return doc = termDocs.skipTo(target) ? termDocs.doc() : NO_MORE_DOCS;
    }
  }

  private class MatchAllDocsWeight extends Weight {
    private Similarity similarity;
    private float queryWeight;
    private float queryNorm;

    public MatchAllDocsWeight(Searcher searcher) {
      this.similarity = searcher.getSimilarity();
    }

    @Override
    public String toString() {
      return "weight(" + MatchAllDocsQuery.this + ")";
    }

    @Override
    public Query getQuery() {
      return MatchAllDocsQuery.this;
    }

    @Override
    public float getValue() {
      return queryWeight;
    }

    @Override
    public float sumOfSquaredWeights() {
      queryWeight = getBoost();
      return queryWeight * queryWeight;
    }

    @Override
    public void normalize(float queryNorm) {
      this.queryNorm = queryNorm;
      queryWeight *= this.queryNorm;
    }

    @Override
    public Scorer scorer(IndexReader reader, boolean scoreDocsInOrder, boolean topScorer) throws IOException {
      return new MatchAllScorer(reader, similarity, this,
          normsField != null ? reader.norms(normsField) : null);
    }

    @Override
    public Explanation explain(IndexReader reader, int doc) {
      // explain query weight
      Explanation queryExpl = new ComplexExplanation
        (true, getValue(), "MatchAllDocsQuery, product of:");
      if (getBoost() != 1.0f) {
        queryExpl.addDetail(new Explanation(getBoost(),"boost"));
      }
      queryExpl.addDetail(new Explanation(queryNorm,"queryNorm"));

      return queryExpl;
    }
  }

  @Override
  public Weight createWeight(Searcher searcher) {
    return new MatchAllDocsWeight(searcher);
  }

  @Override
  public void extractTerms(Set<Term> terms) {
  }

  @Override
  public String toString(String field) {
    StringBuilder buffer = new StringBuilder();
    buffer.append("*:*");
    buffer.append(ToStringUtils.boost(getBoost()));
    return buffer.toString();
  }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof MatchAllDocsQuery))
      return false;
    MatchAllDocsQuery other = (MatchAllDocsQuery) o;
    return this.getBoost() == other.getBoost();
  }

  @Override
  public int hashCode() {
    return Float.floatToIntBits(getBoost()) ^ 0x1AA71190;
  }
}

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