org.apache.lucene.queries.function.valuesource.TermFreqValueSource.java Source code

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Here is the source code for org.apache.lucene.queries.function.valuesource.TermFreqValueSource.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.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 {@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);
                }
            }
        };
    }
}