code: /*
   * Copyright 2015 recommenders.net.
   *
   * 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 net.recommenders.rival.split.parser;
  
  import java.io.BufferedReader;
  import java.io.File;
  import java.io.IOException;
  import java.util.Map;
  import net.recommenders.rival.core.SimpleParser;
  
  /**
   * Parser for the Last.fm dataset by O Celma.
   *
   * @author <a href="http://github.com/abellogin">Alejandro</a>
   */
  public class AbstractLastfmCelmaParser {
  
      /**
       * A flag that indicates if the artists should be considered as the items
       * (instead of tracks).
       */
      private boolean useArtists;
  
      /**
       * Default constructor.
       *
       * @param useTheArtists Flag to consider artists as the items (instead of
       * tracks).
       */
      public AbstractLastfmCelmaParser(final boolean useTheArtists) {
          this.useArtists = useTheArtists;
      }
  
      /**
       * Read a user/item mapping (user/item original value, user/item internal
       * id) from a file and return the maximum index number in that file.
       *
       * @param in The file with id mapping.
       * @param map The user/item mapping
       * @return The largest id number.
       * @throws IOException if file does not exist.
       */
      public static long getIndexMap(final File in, final Map<String, Long> map) throws IOException {
          long id = 0;
          if (in.exists()) {
              BufferedReader br = SimpleParser.getBufferedReader(in);
              String line;
              while ((line = br.readLine()) != null) {
                  String[] toks = line.split("\t");
                  long i = Long.parseLong(toks[1]);
                  map.put(toks[0], i);
                  id = Math.max(i, id);
              }
              br.close();
          }
          return id + 1;
      }
  
      /**
       * Gets the value of the flag indicating if the artists should be considered
       * as items (instead of tracks).
       *
       * @return the flag
       */
      protected boolean isUseArtists() {
          return useArtists;
      }
  }
  