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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 - 2012 Department of Computer Science, University of Oxford
 * %%
 * 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%
 */
package org.semanticweb.elk.reasoner.saturation.rulesystem;

import java.util.Queue;

import org.semanticweb.elk.reasoner.indexing.hierarchy.IndexedClassExpression;

public interface Context {

	/**
	 * @return the root expression of this context
	 */
	public IndexedClassExpression getRoot();

	/**
	 * Get the queue of items scheduled to be processed in this context.
	 * 
	 * @return queue
	 */
	public Queue> getToDo();

	/**
	 * Ensure that the context is active, and return true if the activation
	 * state has been changed from false to true. This method is thread safe:
	 * for two concurrent executions only one succeeds.
	 * 
	 * @return true if the context was not active; returns false otherwise
	 */
	public boolean tryActivate();

	/**
	 * Ensure that the context is not active, and return true if the activation
	 * state has been changed from true to false. This method is thread safe:
	 * for two concurrent executions only one succeeds.
	 * 
	 * @return true if the context was active; returns false otherwise
	 */
	public boolean tryDeactivate();
}