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

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Here is the source code for org.apache.lucene.search.PhraseMatcher.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;

/**
 * Base class for exact and sloppy phrase matching
 *
 * To find matches on a document, first advance {@link #approximation} to the
 * relevant document, then call {@link #reset()}.  Clients can then call
 * {@link #nextMatch()} to iterate over the matches
 */
abstract class PhraseMatcher {

    private final float matchCost;

    PhraseMatcher(float matchCost) {
        this.matchCost = matchCost;
    }

    /**
     * Approximation that only matches documents that have all terms.
     */
    abstract DocIdSetIterator approximation();

    /**
     * Approximation that is aware of impacts.
     */
    abstract ImpactsDISI impactsApproximation();

    /**
     * An upper bound on the number of possible matches on this document
     */
    abstract float maxFreq() throws IOException;

    /**
     * Called after {@link #approximation} has been advanced
     */
    public abstract void reset() throws IOException;

    /**
     * Find the next match on the current document, returning {@code false} if there
     * are none.
     */
    public abstract boolean nextMatch() throws IOException;

    /**
     * The slop-adjusted weight of the current match
     *
     * The sum of the slop-adjusted weights is used as the freq for scoring
     */
    abstract float sloppyWeight();

    /**
     * The start position of the current match
     */
    abstract int startPosition();

    /**
     * The end position of the current match
     */
    abstract int endPosition();

    /**
     * The start offset of the current match
     */
    abstract int startOffset() throws IOException;

    /**
     * The end offset of the current match
     */
    abstract int endOffset() throws IOException;

    /**
     * An estimate of the average cost of finding all matches on a document
     *
     * @see TwoPhaseIterator#matchCost()
     */
    public float getMatchCost() {
        return matchCost;
    }

}