The Lucene Spans.java source code
package org.apache.lucene.search.spans;
/**
* 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.
*/
import java.io.IOException;
import java.util.Collection;
/** Expert: an enumeration of span matches. Used to implement span searching.
* Each span represents a range of term positions within a document. Matches
* are enumerated in order, by increasing document number, within that by
* increasing start position and finally by increasing end position. */
public abstract class Spans {
/** Move to the next match, returning true iff any such exists. */
public abstract boolean next() throws IOException;
/** Skips to the first match beyond the current, whose document number is
* greater than or equal to <i>target. Returns true iff there is such
* a match. <p>Behaves as if written:
* boolean skipTo(int target) {
* do {
* if (!next())
* return false;
* } while (target > doc());
* return true;
* }
* </pre>
* Most implementations are considerably more efficient than that.
*/
public abstract boolean skipTo(int target) throws IOException;
/** Returns the document number of the current match. Initially invalid. */
public abstract int doc();
/** Returns the start position of the current match. Initially invalid. */
public abstract int start();
/** Returns the end position of the current match. Initially invalid. */
public abstract int end();
/**
* Returns the payload data for the current span.
* This is invalid until {@link #next()} is called for
* the first time.
* This method must not be called more than once after each call
* of {@link #next()}. However, most payloads are loaded lazily,
* so if the payload data for the current position is not needed,
* this method may not be called at all for performance reasons. An ordered
* SpanQuery does not lazy load, so if you have payloads in your index and
* you do not want ordered SpanNearQuerys to collect payloads, you can
* disable collection with a constructor option.<br>
* <br>
* Note that the return type is a collection, thus the ordering should not be relied upon.
* <br/>
* @lucene.experimental
*
* @return a List of byte arrays containing the data of this payload, otherwise null if isPayloadAvailable is false
* @throws java.io.IOException
*/
// TODO: Remove warning after API has been finalized
public abstract Collection<byte[]> getPayload() throws IOException;
/**
* Checks if a payload can be loaded at this position.
* <p/>
* Payloads can only be loaded once per call to
* {@link #next()}.
*
* @return true if there is a payload available at this position that can be loaded
*/
public abstract boolean isPayloadAvailable();
}
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