org.apache.lucene.search.MatchNoDocsQuery.java Source code

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Here is the source code for org.apache.lucene.search.MatchNoDocsQuery.java

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/*
 * 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.
 */
package org.apache.lucene.search;

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

import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.Term;

/**
 * A query that matches no documents.
 */

public class MatchNoDocsQuery extends Query {

    private final String reason;

    /** Default constructor */
    public MatchNoDocsQuery() {
        this("");
    }

    /** Provides a reason explaining why this query was used */
    public MatchNoDocsQuery(String reason) {
        this.reason = reason;
    }

    @Override
    public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException {
        return new Weight(this) {
            @Override
            public void extractTerms(Set<Term> terms) {
            }

            @Override
            public Explanation explain(LeafReaderContext context, int doc) throws IOException {
                return Explanation.noMatch(reason);
            }

            @Override
            public Scorer scorer(LeafReaderContext context) throws IOException {
                return null;
            }

            @Override
            public boolean isCacheable(LeafReaderContext ctx) {
                return true;
            }
        };
    }

    @Override
    public void visit(QueryVisitor visitor) {
        visitor.visitLeaf(this);
    }

    @Override
    public String toString(String field) {
        return "MatchNoDocsQuery(\"" + reason + "\")";
    }

    @Override
    public boolean equals(Object o) {
        return sameClassAs(o);
    }

    @Override
    public int hashCode() {
        return classHash();
    }
}