/*
 * 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,
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 * See the License for the specific language governing permissions and
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package org.apache.lucene.queries.function.valuesource;

import java.io.IOException;
import java.util.Map;

import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.index.PostingsEnum;
import org.apache.lucene.index.Terms;
import org.apache.lucene.index.TermsEnum;
import org.apache.lucene.queries.function.FunctionValues;
import org.apache.lucene.queries.function.docvalues.IntDocValues;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.util.BytesRef;

Function that returns PostingsEnum.freq() for the supplied term in every document.

If the term does not exist in the document, returns 0. If frequencies are omitted, returns 1.

/** * Function that returns {@link org.apache.lucene.index.PostingsEnum#freq()} for the * supplied term in every document. * <p> * If the term does not exist in the document, returns 0. * If frequencies are omitted, returns 1. */
public class TermFreqValueSource extends DocFreqValueSource { public TermFreqValueSource(String field, String val, String indexedField, BytesRef indexedBytes) { super(field, val, indexedField, indexedBytes); } @Override public String name() { return "termfreq"; } @Override public FunctionValues getValues(Map context, LeafReaderContext readerContext) throws IOException { final Terms terms = readerContext.reader().terms(indexedField); return new IntDocValues(this) { PostingsEnum docs ; int atDoc; int lastDocRequested = -1; { reset(); } public void reset() throws IOException { // no one should call us for deleted docs? if (terms != null) { final TermsEnum termsEnum = terms.iterator(); if (termsEnum.seekExact(indexedBytes)) { docs = termsEnum.postings(null); } else { docs = null; } } else { docs = null; } if (docs == null) { docs = new PostingsEnum() { @Override public int freq() { return 0; } @Override public int nextPosition() throws IOException { return -1; } @Override public int startOffset() throws IOException { return -1; } @Override public int endOffset() throws IOException { return -1; } @Override public BytesRef getPayload() throws IOException { throw new UnsupportedOperationException(); } @Override public int docID() { return DocIdSetIterator.NO_MORE_DOCS; } @Override public int nextDoc() { return DocIdSetIterator.NO_MORE_DOCS; } @Override public int advance(int target) { return DocIdSetIterator.NO_MORE_DOCS; } @Override public long cost() { return 0; } }; } atDoc = -1; } @Override public int intVal(int doc) { try { if (doc < lastDocRequested) { // out-of-order access.... reset reset(); } lastDocRequested = doc; if (atDoc < doc) { atDoc = docs.advance(doc); } if (atDoc > doc) { // term doesn't match this document... either because we hit the // end, or because the next doc is after this doc. return 0; } // a match! return docs.freq(); } catch (IOException e) { throw new RuntimeException("caught exception in function "+description()+" : doc="+doc, e); } } }; } }