/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* Licensed 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.sindice.siren.search.node;
import java.io.IOException;
import org.sindice.siren.index.DocsNodesAndPositionsEnum;
import org.sindice.siren.index.PositionsIterator;
/**
* Maps the current position of a {@link DocsNodesAndPositionsEnum} to a
* position relative to the offset of the term in the phrase.
*/
class NodePhrasePosition {
/**
* Current position
* <p>
* Sentinel value is equal to {@link Integer.MIN_VALUE} since a position can
* be negative.
*/
int pos = Integer.MIN_VALUE;
final int offset; // position in phrase
private final DocsNodesAndPositionsEnum docsEnum; // stream of positions
protected NodePhrasePosition next; // used to make lists
NodePhrasePosition(final DocsNodesAndPositionsEnum docsEnum, final int offset) {
this.docsEnum = docsEnum;
this.offset = offset;
}
void init() throws IOException {
pos = Integer.MIN_VALUE;
}
/**
* Go to next location of this term current document, and set
* <code>position</code> as <code>location - offset</code>, so that a
* matching exact phrase is easily identified when all NodePhrasePositions
* have exactly the same <code>position</code>.
*/
public final boolean nextPosition() throws IOException {
if (docsEnum.nextPosition()) { // read subsequent pos's
pos = docsEnum.pos() - offset;
return true;
}
else {
pos = PositionsIterator.NO_MORE_POS;
return false;
}
}
@Override
public String toString() {
return "NodePhrasePositions(d:"+docsEnum.doc()+" n:"+docsEnum.node()+" o:"+offset+" p:"+pos+")";
}
}