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.simple;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Set;
  
  import com.kohlschutter.boilerpipe.BoilerpipeFilter;
  import com.kohlschutter.boilerpipe.BoilerpipeProcessingException;
  import com.kohlschutter.boilerpipe.document.TextBlock;
  import com.kohlschutter.boilerpipe.document.TextDocument;
  
  /**
   * Splits TextBlocks at paragraph boundaries.
   * 
   * NOTE: This is not fully supported (i.e., it will break highlighting support via
   * #getContainedTextElements()), but this one probably is necessary for some other filters.
   * 
   * @see MinClauseWordsFilter
   */
  public final class SplitParagraphBlocksFilter implements BoilerpipeFilter {
    public static final SplitParagraphBlocksFilter INSTANCE = new SplitParagraphBlocksFilter();
  
    /**
     * Returns the singleton instance for TerminatingBlocksFinder.
     */
    public static SplitParagraphBlocksFilter getInstance() {
      return INSTANCE;
    }
  
    public boolean process(TextDocument doc) throws BoilerpipeProcessingException {
      boolean changes = false;
  
      final List<TextBlock> blocks = doc.getTextBlocks();
      final List<TextBlock> blocksNew = new ArrayList<TextBlock>();
  
      for (TextBlock tb : blocks) {
        final String text = tb.getText();
        final String[] paragraphs = text.split("[\n\r]+");
        if (paragraphs.length < 2) {
          blocksNew.add(tb);
          continue;
        }
        final boolean isContent = tb.isContent();
        final Set<String> labels = tb.getLabels();
        for (String p : paragraphs) {
          final TextBlock tbP = new TextBlock(p);
          tbP.setIsContent(isContent);
          tbP.addLabels(labels);
          blocksNew.add(tbP);
          changes = true;
        }
      }
  
      if (changes) {
        blocks.clear();
        blocks.addAll(blocksNew);
      }
  
      return changes;
    }
  
  }
  