IgnoreBlocksAfterContentFromEndFilter.java

/**
 * Copyright (C) 2013 Christian Kohlschütter (ckkohl79@gmail.com)
 *
 * 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 de.l3s.boilerpipe.filters.english;

import java.util.List;
import java.util.ListIterator;

import de.l3s.boilerpipe.BoilerpipeFilter;
import de.l3s.boilerpipe.BoilerpipeProcessingException;
import de.l3s.boilerpipe.document.TextBlock;
import de.l3s.boilerpipe.document.TextDocument;
import de.l3s.boilerpipe.labels.DefaultLabels;

/**
 * Marks all blocks as "non-content" that occur after blocks that have been
 * marked {@link de.l3s.boilerpipe.labels.DefaultLabels#INDICATES_END_OF_TEXT}, and after any content block.
 * This filter can be used in conjunction with an upstream {@link de.l3s.boilerpipe.filters.english.TerminatingBlocksFinder}.
 * 
 * @author Christian Kohlschütter
 * @see de.l3s.boilerpipe.filters.english.TerminatingBlocksFinder
 */
public final class IgnoreBlocksAfterContentFromEndFilter extends HeuristicFilterBase implements BoilerpipeFilter {
    public static final IgnoreBlocksAfterContentFromEndFilter INSTANCE = new IgnoreBlocksAfterContentFromEndFilter(
            );

    private IgnoreBlocksAfterContentFromEndFilter() {
    }

    public boolean process(TextDocument doc)
            throws BoilerpipeProcessingException {
        boolean changes = false;
        
        
        int words = 0;

        List<TextBlock> blocks = doc.getTextBlocks();
        if (!blocks.isEmpty()) {
			ListIterator<TextBlock> it = blocks.listIterator(blocks.size());
			
			TextBlock tb;
			
			while(it.hasPrevious()) {
				tb = it.previous();
				if(tb.hasLabel(DefaultLabels.INDICATES_END_OF_TEXT)) {
					tb.addLabel(DefaultLabels.STRICTLY_NOT_CONTENT);
					tb.removeLabel(DefaultLabels.MIGHT_BE_CONTENT);
					tb.setIsContent(false);
					changes = true;
				} else if(tb.isContent()) {
					words += tb.getNumWords();
					if(words > 200) {
						break;
					}
				}

			}
		}        

        return changes;
    }    
}