MarkupTagAction.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.sax;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.regex.Pattern;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

import de.l3s.boilerpipe.document.TextBlock;
import de.l3s.boilerpipe.labels.DefaultLabels;
import de.l3s.boilerpipe.labels.LabelAction;

/**
 * Assigns labels for element CSS classes and ids to the corresponding
 * {@link TextBlock}. CSS classes are prefixed by
 * <code>{@link DefaultLabels#MARKUP_PREFIX}.</code>, and IDs are prefixed by
 * <code>{@link DefaultLabels#MARKUP_PREFIX}#</code>
 * 
 * @author Christian Kohlschütter
 */
public final class MarkupTagAction implements TagAction {

	private final boolean isBlockLevel;
	private LinkedList<List<String>> labelStack = new LinkedList<List<String>>();

	public MarkupTagAction(final boolean isBlockLevel) {
		this.isBlockLevel = isBlockLevel;
	}
	
	private static final Pattern PAT_NUM = Pattern.compile("[0-9]+");

	public boolean start(BoilerpipeHTMLContentHandler instance,
			String localName, String qName, Attributes atts)
			throws SAXException {
		List<String> labels = new ArrayList<String>(5);
		labels.add(DefaultLabels.MARKUP_PREFIX  + localName);

		String classVal = atts.getValue("class");

		if (classVal != null && classVal.length() > 0) {
			classVal = PAT_NUM.matcher(classVal).replaceAll("#");
			classVal = classVal.trim();
			String[] vals = classVal.split("[ ]+");
			labels.add(DefaultLabels.MARKUP_PREFIX + "."
					+ classVal.replace(' ', '.'));
			if (vals.length > 1) {
				for (String s : vals) {
					labels.add(DefaultLabels.MARKUP_PREFIX + "." + s);
				}
			}
		}

		String id = atts.getValue("id");
		if (id != null && id.length() > 0) {
			id = PAT_NUM.matcher(id).replaceAll("#");
			labels.add(DefaultLabels.MARKUP_PREFIX + "#" + id);
		}

		Set<String> ancestors = getAncestorLabels();
		List<String> labelsWithAncestors = new ArrayList<String>(
				(ancestors.size() + 1) * labels.size());

		for (String l : labels) {
			for (String an : ancestors) {
				labelsWithAncestors.add(an);
				labelsWithAncestors.add(an + " " + l);
			}
			labelsWithAncestors.add(l);
		}

		instance.addLabelAction(new LabelAction(labelsWithAncestors
				.toArray(new String[labelsWithAncestors.size()])));

		labelStack.add(labels);

		return isBlockLevel;
	}


	public boolean end(BoilerpipeHTMLContentHandler instance, String localName,
			String qName) throws SAXException {

		labelStack.removeLast();
		return isBlockLevel;
	}

    public boolean changesTagLevel() {
    	return isBlockLevel;
    }
    
	private Set<String> getAncestorLabels() {
		Set<String> set = new HashSet<String>();
		for (List<String> labels : labelStack) {
			if (labels == null) {
				continue;
			}
			set.addAll(labels);
		}
		return set;
	}
}