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 org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.search.Query;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Set;
/**
*
*
**/
public abstract class SpanPositionCheckQuery extends SpanQuery implements Cloneable {
protected SpanQuery match;
public SpanPositionCheckQuery(SpanQuery match) {
this.match = match;
}
/**
* @return the SpanQuery whose matches are filtered.
*
* */
public SpanQuery getMatch() { return match; }
@Override
public String getField() { return match.getField(); }
@Override
public void extractTerms(Set<Term> terms) {
match.extractTerms(terms);
}
/** Return value if the match should be accepted {@code YES}, rejected {@code NO},
* or rejected and enumeration should advance to the next document {@code NO_AND_ADVANCE}.
* @see #acceptPosition(Spans)
*/
protected static enum AcceptStatus { YES, NO, NO_AND_ADVANCE };
/**
* Implementing classes are required to return whether the current position is a match for the passed in
* "match" {@link org.apache.lucene.search.spans.SpanQuery}.
*
* This is only called if the underlying {@link org.apache.lucene.search.spans.Spans#next()} for the
* match is successful
*
*
* @param spans The {@link org.apache.lucene.search.spans.Spans} instance, positioned at the spot to check
* @return whether the match is accepted, rejected, or rejected and should move to the next doc.
*
* @see org.apache.lucene.search.spans.Spans#next()
*
*/
protected abstract AcceptStatus acceptPosition(Spans spans) throws IOException;
@Override
public Spans getSpans(final IndexReader reader) throws IOException {
return new PositionCheckSpan(reader);
}
@Override
public Query rewrite(IndexReader reader) throws IOException {
SpanPositionCheckQuery clone = null;
SpanQuery rewritten = (SpanQuery) match.rewrite(reader);
if (rewritten != match) {
clone = (SpanPositionCheckQuery) this.clone();
clone.match = rewritten;
}
if (clone != null) {
return clone; // some clauses rewrote
} else {
return this; // no clauses rewrote
}
}
protected class PositionCheckSpan extends Spans {
private Spans spans;
public PositionCheckSpan(IndexReader reader) throws IOException {
spans = match.getSpans(reader);
}
@Override
public boolean next() throws IOException {
if (!spans.next())
return false;
return doNext();
}
@Override
public boolean skipTo(int target) throws IOException {
if (!spans.skipTo(target))
return false;
return doNext();
}
protected boolean doNext() throws IOException {
for (;;) {
switch(acceptPosition(this)) {
case YES: return true;
case NO:
if (!spans.next())
return false;
break;
case NO_AND_ADVANCE:
if (!spans.skipTo(spans.doc()+1))
return false;
break;
}
}
}
@Override
public int doc() { return spans.doc(); }
@Override
public int start() { return spans.start(); }
@Override
public int end() { return spans.end(); }
// TODO: Remove warning after API has been finalized
@Override
public Collection<byte[]> getPayload() throws IOException {
ArrayList<byte[]> result = null;
if (spans.isPayloadAvailable()) {
result = new ArrayList<byte[]>(spans.getPayload());
}
return result;//TODO: any way to avoid the new construction?
}
// TODO: Remove warning after API has been finalized
@Override
public boolean isPayloadAvailable() {
return spans.isPayloadAvailable();
}
@Override
public String toString() {
return "spans(" + SpanPositionCheckQuery.this.toString() + ")";
}
}
}