org.semanticweb.elk.reasoner.taxonomy.NonBottomClassNode Maven / Gradle / Ivy

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ELK consequence-based reasoning engine
There is a newer version: 0.4.3
/*
 * #%L
 * elk-reasoner
 * 
 * $Id$
 * $HeadURL$
 * %%
 * Copyright (C) 2011 Oxford University Computing Laboratory
 * %%
 * 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.
 * #L%
 */
/**
 * @author Yevgeny Kazakov, May 15, 2011
 */
package org.semanticweb.elk.reasoner.taxonomy;

import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.log4j.Logger;
import org.semanticweb.elk.owl.interfaces.ElkClass;
import org.semanticweb.elk.owl.util.Comparators;
import org.semanticweb.elk.reasoner.taxonomy.model.TaxonomyNode;
import org.semanticweb.elk.reasoner.taxonomy.model.TaxonomyNodeUtils;
import org.semanticweb.elk.reasoner.taxonomy.model.UpdateableTaxonomyNode;
import org.semanticweb.elk.util.collections.ArrayHashSet;
import org.semanticweb.elk.util.hashing.HashGenerator;

/**
 * Class for storing information about a class in the context of classification.
 * It is the main data container for ClassTaxonomy objects. Like most such data
 * containers in ELK, it is read-only for public access but provides
 * package-private ways of modifying it. Modifications of this class happen in
 * implementations of ClassTaxonomy only.
 * 
 * @author Yevgeny Kazakov
 * @author Markus Kroetzsch
 * @author Pavel Klinov
 */
class NonBottomClassNode implements UpdateableTaxonomyNode {

	// logger for events
	private static final Logger LOGGER_ = Logger
			.getLogger(NonBottomClassNode.class);

	/**
	 * The link to the taxonomy to which this node belongs
	 */
	private final ConcurrentClassTaxonomy taxonomy_;

	/**
	 * Equivalent ElkClass objects that are representatives of this node.
	 */
	private final List members_;
	/**
	 * ElkClass nodes whose members are direct super-classes of the members of
	 * this node.
	 */
	private final Set> directSuperNodes_;
	/**
	 * ElkClass nodes, except for the bottom node, whose members are direct
	 * sub-classes of the members of this node.
	 */
	private final Set> directSubNodes_;
	/**
	 * true if the direct super-nodes of this node need to be
	 * recomputed
	 */
	private final AtomicBoolean modified_ = new AtomicBoolean(true);

	/**
	 * Constructing the class node for a given taxonomy and the set of
	 * equivalent classes.
	 * 
	 * @param taxonomy
	 *            the taxonomy to which this node belongs
	 * @param members
	 *            non-empty list of equivalent ElkClass objects
	 */
	protected NonBottomClassNode(ConcurrentClassTaxonomy taxonomy,
			Collection members) {
		this.taxonomy_ = taxonomy;
		this.members_ = new ArrayList(members);
		this.directSubNodes_ = new ArrayHashSet>();
		this.directSuperNodes_ = new ArrayHashSet>();
		Collections.sort(this.members_, Comparators.ELK_CLASS_COMPARATOR);
	}

	/**
	 * Add a direct super-class node. This method is not thread safe.
	 * 
	 * @param superNode
	 *            node to add
	 */
	@Override
	public synchronized void addDirectSuperNode(UpdateableTaxonomyNode superNode) {
		
		if (LOGGER_.isTraceEnabled()) {
			LOGGER_.trace(this + ": new direct super-node " + superNode);
		}
		
		directSuperNodes_.add(superNode);
	}

	/**
	 * Add a direct sub-class node. This method is not thread safe.
	 * 
	 * @param subNode
	 *            node to add
	 */
	@Override
	public synchronized void addDirectSubNode(UpdateableTaxonomyNode subNode) {
		if (LOGGER_.isTraceEnabled()) {
			LOGGER_.trace(this + ": new direct sub-node " + subNode);
		}

		if (directSubNodes_.isEmpty()) {
			this.taxonomy_.countNodesWithSubClasses.incrementAndGet();
		}

		directSubNodes_.add(subNode);
	}

	// TODO: change the type of the output to SortedSet
	@Override
	public Set getMembers() {
		// create an unmodifiable set view of the members; alternatively, one
		// could have created a TreeSet, but it consumes more memory
		return new AbstractSet() {

			@Override
			public boolean contains(Object arg) {
				if (arg instanceof ElkClass)
					return (Collections.binarySearch(members_, (ElkClass) arg,
							Comparators.ELK_CLASS_COMPARATOR) >= 0);
				return false;
			}

			@Override
			public boolean isEmpty() {
				return members_.isEmpty();
			}

			@Override
			public Iterator iterator() {
				return members_.iterator();
			}

			@Override
			public int size() {
				return members_.size();
			}

		};
	}

	@Override
	public ElkClass getCanonicalMember() {
		return members_.get(0);
	}

	@Override
	public Set> getDirectSuperNodes() {
		return getDirectUpdateableSuperNodes();
	}

	@Override
	public Set> getDirectUpdateableSuperNodes() {
		return Collections.unmodifiableSet(directSuperNodes_);
	}

	@Override
	public Set> getAllSuperNodes() {
		return TaxonomyNodeUtils.getAllSuperNodes(this);
	}

	@Override
	public Set> getDirectSubNodes() {
		if (!directSubNodes_.isEmpty()) {
			return Collections.>unmodifiableSet(directSubNodes_);
		} else {
			return Collections.singleton(this.taxonomy_.getBottomNode());
		}
	}

	@Override
	public Set> getDirectUpdateableSubNodes() {
		return Collections.unmodifiableSet(directSubNodes_);
	}

	@Override
	public Set> getAllSubNodes() {
		return TaxonomyNodeUtils.getAllSubNodes(this);
	}

	private final int hashCode_ = HashGenerator.generateNextHashCode();

	@Override
	public final int hashCode() {
		return hashCode_;
	}

	@Override
	public String toString() {
		return members_.toString();
	}

	public void setMembers(Collection members) {
		if (LOGGER_.isTraceEnabled())
			LOGGER_.trace(this + ": updating members to " + members);
		members_.clear();
		members_.addAll(members);
		Collections.sort(this.members_, Comparators.ELK_CLASS_COMPARATOR);
	}

	@Override
	public boolean trySetModified(boolean modified) {
		boolean result = modified_.compareAndSet(!modified, modified);
		if (result && LOGGER_.isTraceEnabled())
			LOGGER_.trace("node " + this + ": set "
					+ (modified ? "modified" : "not modifiled"));
		return result;
	}

	@Override
	public boolean isModified() {
		return modified_.get();
	}

	@Override
	public /*synchronized*/ boolean removeDirectSubNode(
			UpdateableTaxonomyNode subNode) {
		boolean changed = directSubNodes_.remove(subNode);

		if (changed && LOGGER_.isTraceEnabled())
			if (LOGGER_.isTraceEnabled())
				LOGGER_.trace(this + ": removed direct sub-node " + subNode);

		if (directSubNodes_.isEmpty()) {
			taxonomy_.countNodesWithSubClasses.decrementAndGet();
		}

		return changed;
	}

	@Override
	public /*synchronized*/ boolean removeDirectSuperNode(
			UpdateableTaxonomyNode superNode) {
		boolean changed = directSuperNodes_.remove(superNode);

		if (LOGGER_.isTraceEnabled())
			LOGGER_.trace(this + ": removed direct super-node " + superNode);

		return changed;
	}
}