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.Iterator;
  import java.util.List;
  
  import com.kohlschutter.boilerpipe.BoilerpipeFilter;
  import com.kohlschutter.boilerpipe.BoilerpipeProcessingException;
  import com.kohlschutter.boilerpipe.conditions.TextBlockCondition;
  import com.kohlschutter.boilerpipe.document.TextBlock;
  import com.kohlschutter.boilerpipe.document.TextDocument;
  
  /**
   * Marks blocks as "content" if their preceding and following blocks are both already marked
   * "content", and the given {@link TextBlockCondition} is met.
   */
  public class SurroundingToContentFilter implements BoilerpipeFilter {
    public static final SurroundingToContentFilter INSTANCE_TEXT = new SurroundingToContentFilter(
        new TextBlockCondition() {
  
          @Override
          public boolean meetsCondition(TextBlock tb) {
            return tb.getLinkDensity() == 0 && tb.getNumWords() > 6;
          }
        });
  
    private final TextBlockCondition cond;
  
    public SurroundingToContentFilter(final TextBlockCondition cond) {
      this.cond = cond;
    }
  
    public boolean process(TextDocument doc) throws BoilerpipeProcessingException {
  
      List<TextBlock> tbs = doc.getTextBlocks();
      if (tbs.size() < 3) {
        return false;
      }
  
      TextBlock a = tbs.get(0);
      TextBlock b = tbs.get(1);
      TextBlock c;
      boolean hasChanges = false;
      for (Iterator<TextBlock> it = tbs.listIterator(2); it.hasNext();) {
        c = it.next();
        if (!b.isContent() && a.isContent() && c.isContent() && cond.meetsCondition(b)) {
          b.setIsContent(true);
          hasChanges = true;
        }
  
        a = c;
        if (!it.hasNext()) {
          break;
        }
        b = it.next();
      }
  
      return hasChanges;
    }
  
  }
  