/**
* 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.heuristics;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
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;
/**
* Fuses adjacent blocks if their labels are equal.
*
* @author Christian Kohlschütter
*/
public final class LabelFusion implements BoilerpipeFilter {
public static final LabelFusion INSTANCE = new LabelFusion();
/**
* Creates a new {@link de.l3s.boilerpipe.filters.heuristics.LabelFusion} instance.
*/
private LabelFusion() {
}
public boolean process(TextDocument doc)
throws BoilerpipeProcessingException {
List<TextBlock> textBlocks = doc.getTextBlocks();
if (textBlocks.size() < 2) {
return false;
}
boolean changes = false;
TextBlock prevBlock = textBlocks.get(0);
int offset = 1;
for (Iterator<TextBlock> it = textBlocks.listIterator(offset); it
.hasNext();) {
TextBlock block = it.next();
if(equalLabels(prevBlock.getLabels(), block.getLabels())) {
prevBlock.mergeNext(block);
it.remove();
changes = true;
} else {
prevBlock = block;
}
}
return changes;
}
private boolean equalLabels(Set<String> labels, Set<String> labels2) {
if(labels == null || labels2 == null) {
return false;
}
return markupLabelsOnly(labels).equals(markupLabelsOnly(labels2));
}
private Set<String> markupLabelsOnly(final Set<String> set1) {
Set<String> set = new HashSet<String>(set1);
for(Iterator<String> it = set.iterator(); it.hasNext(); ) {
final String label = it.next();
if(!label.startsWith(DefaultLabels.MARKUP_PREFIX)) {
it.remove();
}
}
return set;
}
}