content: 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() + ")";
        }
  
    }
  }