/*
* 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.index;
import java.io.IOException;
import org.apache.lucene.search.DocIdSetIterator;
import org.apache.lucene.util.AttributeSource;
import org.apache.lucene.util.BytesRef;
/** Iterates through the postings.
* NOTE: you must first call {@link #nextDoc} before using
* any of the per-doc methods. */
public abstract class PostingsEnum extends DocIdSetIterator {
/**
* Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)} if you don't
* require per-document postings in the returned enum.
*/
public static final short NONE = 0;
/** Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)}
* if you require term frequencies in the returned enum. */
public static final short FREQS = 1 << 3;
/** Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)}
* if you require term positions in the returned enum. */
public static final short POSITIONS = FREQS | 1 << 4;
/** Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)}
* if you require offsets in the returned enum. */
public static final short OFFSETS = POSITIONS | 1 << 5;
/** Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)}
* if you require payloads in the returned enum. */
public static final short PAYLOADS = POSITIONS | 1 << 6;
/**
* Flag to pass to {@link TermsEnum#postings(PostingsEnum, int)}
* to get positions, payloads and offsets in the returned enum
*/
public static final short ALL = OFFSETS | PAYLOADS;
/**
* Returns true if the given feature is requested in the flags, false otherwise.
*/
public static boolean featureRequested(int flags, short feature) {
return (flags & feature) == feature;
}
private AttributeSource atts = null;
/** Sole constructor. (For invocation by subclass
* constructors, typically implicit.) */
protected PostingsEnum() {
}
/**
* Returns term frequency in the current document, or 1 if the field was
* indexed with {@link IndexOptions#DOCS}. Do not call this before
* {@link #nextDoc} is first called, nor after {@link #nextDoc} returns
* {@link DocIdSetIterator#NO_MORE_DOCS}.
*
* <p>
* <b>NOTE:</b> if the {@link PostingsEnum} was obtain with {@link #NONE},
* the result of this method is undefined.
*/
public abstract int freq() throws IOException;
/** Returns the related attributes. */
public AttributeSource attributes() {
if (atts == null) atts = new AttributeSource();
return atts;
}
/**
* Returns the next position, or -1 if positions were not indexed.
* Calling this more than {@link #freq()} times is undefined.
*/
public abstract int nextPosition() throws IOException;
/** Returns start offset for the current position, or -1
* if offsets were not indexed. */
public abstract int startOffset() throws IOException;
/** Returns end offset for the current position, or -1 if
* offsets were not indexed. */
public abstract int endOffset() throws IOException;
/** Returns the payload at this position, or null if no
* payload was indexed. You should not modify anything
* (neither members of the returned BytesRef nor bytes
* in the byte[]). */
public abstract BytesRef getPayload() throws IOException;
}