/*
* Copyright (c) 2011 Salzburg Research.
*
* 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 at.newmedialab.ldpath.model.functions;
import at.newmedialab.ldpath.api.backend.RDFBackend;
import at.newmedialab.ldpath.api.functions.SelectorFunction;
import at.newmedialab.ldpath.model.transformers.StringTransformer;
import at.newmedialab.ldpath.util.Collections;
import org.htmlcleaner.CleanerProperties;
import org.htmlcleaner.CompactXmlSerializer;
import org.htmlcleaner.HtmlCleaner;
import org.htmlcleaner.TagNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
/**
* Function to clean up HTML and remove all script and style elements from the content.
* <p/>
* Author: Sebastian Schaffert
*/
public class CleanHtmlFunction<Node> implements SelectorFunction<Node> {
private HtmlCleaner cleaner;
private final StringTransformer<Node> transformer = new StringTransformer<Node>();
private Logger log = LoggerFactory.getLogger(CleanHtmlFunction.class);
public CleanHtmlFunction() {
this.cleaner = new HtmlCleaner();
CleanerProperties p = cleaner.getProperties();
p.setOmitComments(true);
p.setTranslateSpecialEntities(true);
p.setTransResCharsToNCR(true);
// remove all tags that contain uninteresting content
p.setPruneTags("style,script,form,object,audio,video");
}
/**
* Apply the function to the list of nodes passed as arguments and return the result as type T.
* Throws IllegalArgumentException if the function cannot be applied to the nodes passed as argument
* or the number of arguments is not correct.
*
* @param args a list of KiWiNodes
* @return
*/
@Override
public Collection<Node> apply(RDFBackend<Node> backend, Collection<Node>... args) throws IllegalArgumentException {
List<Node> result = new ArrayList<Node>();
for(Iterator<Node> it = Collections.iterator(args);it.hasNext();) {
Node node = it.next();
TagNode tagNode = cleaner.clean(transformer.transform(backend,node));
try {
result.add(backend.createLiteral(new CompactXmlSerializer(cleaner.getProperties()).getAsString(tagNode)));
} catch (IOException e) {
log.warn("I/O error while serializing to string",e);
}
}
return result;
}
/**
* Return the name of the NodeFunction for registration in the function registry
*
* @return
* @param backend
*/
@Override
public String getPathExpression(RDFBackend<Node> backend) {
return "cleanHtml";
}
}