code: /**
   * boilerpipe
   *
   * Copyright (c) 2009, 2014 Christian Kohlschütter
   *
   * The author 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.
   */
  package com.kohlschutter.boilerpipe.filters.heuristics;
  
  import java.util.Iterator;
  import java.util.List;
  
  import com.kohlschutter.boilerpipe.BoilerpipeFilter;
  import com.kohlschutter.boilerpipe.BoilerpipeProcessingException;
  import com.kohlschutter.boilerpipe.document.TextBlock;
  import com.kohlschutter.boilerpipe.document.TextDocument;
  
  /**
   * Merges two subsequent blocks if their text densities are equal.
   */
  public class SimpleBlockFusionProcessor implements BoilerpipeFilter {
    public static final SimpleBlockFusionProcessor INSTANCE = new SimpleBlockFusionProcessor();
  
    /**
     * Returns the singleton instance for BlockFusionProcessor.
     */
    public static SimpleBlockFusionProcessor getInstance() {
      return INSTANCE;
    }
  
    public boolean process(TextDocument doc) throws BoilerpipeProcessingException {
      List<TextBlock> textBlocks = doc.getTextBlocks();
      boolean changes = false;
  
      if (textBlocks.size() < 2) {
        return false;
      }
  
      TextBlock b1 = textBlocks.get(0);
      for (Iterator<TextBlock> it = textBlocks.listIterator(1); it.hasNext();) {
        TextBlock b2 = it.next();
  
        final boolean similar = (b1.getTextDensity() == b2.getTextDensity());
  
        if (similar) {
          b1.mergeNext(b2);
          it.remove();
          changes = true;
        } else {
          b1 = b2;
        }
      }
  
      return changes;
    }
  
  }
  