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.document.TextBlock;
  import com.kohlschutter.boilerpipe.document.TextDocument;
  import com.kohlschutter.boilerpipe.labels.DefaultLabels;
  
  /**
   * Removes {@link TextBlock}s which have explicitly been marked as "not content".
   */
  public final class BoilerplateBlockFilter implements BoilerpipeFilter {
    public static final BoilerplateBlockFilter INSTANCE = new BoilerplateBlockFilter(null);
    public static final BoilerplateBlockFilter INSTANCE_KEEP_TITLE = new BoilerplateBlockFilter(
        DefaultLabels.TITLE);
    private final String labelToKeep;
  
    /**
     * Returns the singleton instance for BoilerplateBlockFilter.
     */
    public static BoilerplateBlockFilter getInstance() {
      return INSTANCE;
    }
  
    public BoilerplateBlockFilter(final String labelToKeep) {
      this.labelToKeep = labelToKeep;
    }
  
    public boolean process(TextDocument doc) throws BoilerpipeProcessingException {
      List<TextBlock> textBlocks = doc.getTextBlocks();
      boolean hasChanges = false;
  
      for (Iterator<TextBlock> it = textBlocks.iterator(); it.hasNext();) {
        TextBlock tb = it.next();
        if (!tb.isContent() && (labelToKeep == null || !tb.hasLabel(DefaultLabels.TITLE))) {
          it.remove();
          hasChanges = true;
        }
      }
  
      return hasChanges;
    }
  
  }
  