package org.apache.lucene.search;

/**
 * Copyright 2004 The Apache Software Foundation
 *
 * 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.
 */

import java.io.IOException;
import org.apache.lucene.index.*;

final class PhrasePositions {
  int doc;					  // current doc
  int position;					  // position in doc
  int count;					  // remaining pos in this doc
  int offset;					  // position in phrase
  TermPositions tp;				  // stream of positions
  PhrasePositions next;				  // used to make lists

  PhrasePositions(TermPositions t, int o) throws IOException {
    tp = t;
    offset = o;
  }

  final boolean next() throws IOException {	  // increments to next doc
    if (!tp.next()) {
      tp.close();				  // close stream
      doc = Integer.MAX_VALUE;			  // sentinel value
      return false;
    }
    doc = tp.doc();
    position = 0;
    return true;
  }

  final boolean skipTo(int target) throws IOException {
    if (!tp.skipTo(target)) {
      tp.close();				  // close stream
      doc = Integer.MAX_VALUE;			  // sentinel value
      return false;
    }
    doc = tp.doc();
    position = 0;
    return true;
  }


  final void firstPosition() throws IOException {
    count = tp.freq();				  // read first pos
    nextPosition();
  }

  final boolean nextPosition() throws IOException {
    if (count-- > 0) {				  // read subsequent pos's
      position = tp.nextPosition() - offset;
      return true;
    } else
      return false;
  }
}