content: package org.apache.lucene.index;
  
  /**
   * 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;
  
  /**
   * TermPositions provides an interface for enumerating the &lt;document,
   * frequency, &lt;position&gt;* &gt; tuples for a term.  <p> The document and
   * frequency are the same as for a TermDocs.  The positions portion lists the ordinal
   * positions of each occurrence of a term in a document.
   *
   * @see IndexReader#termPositions()
   */
  
  public interface TermPositions
      extends TermDocs
  {
      /** Returns next position in the current document.  It is an error to call
      this more than {@link #freq()} times
      without calling {@link #next()}<p> This is
      invalid until {@link #next()} is called for
      the first time.
      */
      int nextPosition() throws IOException;
      
      /** 
       * Returns the length of the payload at the current term position.
       * This is invalid until {@link #nextPosition()} is called for
       * the first time.<br>
       * @return length of the current payload in number of bytes
       */
      int getPayloadLength();
      
      /** 
       * Returns the payload data at the current term position.
       * This is invalid until {@link #nextPosition()} is called for
       * the first time.
       * This method must not be called more than once after each call
       * of {@link #nextPosition()}. However, 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.<br>
       * 
       * @param data the array into which the data of this payload is to be
       *             stored, if it is big enough; otherwise, a new byte[] array
       *             is allocated for this purpose. 
       * @param offset the offset in the array into which the data of this payload
       *               is to be stored.
       * @return a byte[] array containing the data of this payload
       * @throws IOException
       */
      byte[] getPayload(byte[] data, int offset) throws IOException;
  
    /**
     * Checks if a payload can be loaded at this position.
     * <p>
     * Payloads can only be loaded once per call to 
     * {@link #nextPosition()}.
     * 
     * @return true if there is a payload available at this position that can be loaded
     */
      public boolean isPayloadAvailable();
  
  }
  