//   Copyright 2012 Georg-August-Universität Göttingen, Germany
//
//   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.ugoe.cs.autoquest.tasktrees.treeifc;

import java.io.Serializable;

/**
 * <p>
 * a task instance represents the execution of a specific task within a user session. A task
 * instance is always related to the task that was executed.
 * </p>
 * 
 * @author Patrick Harms
 */
public interface ITaskInstance extends Serializable, Cloneable {

    /**
     * <p>
     * returns the task related to the instance.
     * </p>
     * 
     * @return as described
     */
    public ITask getTask();

    /**
     * <p>
     * compares an instance to another one. Returns true if both instances are the same, i.e. not
     * only the related task is equal but also all children and further characteristics of the
     * task instance  
     * </p>
     * 
     * @param taskInstance the instance to compare to
     * 
     * @return as described
     */
    public boolean equals(ITaskInstance taskInstance);

    /**
     * <p>
     * returns a hash code for the task instance to be able to put it into hash maps
     * </p>
     * 
     * @return as described
     */
    public int hashCode();

    /**
     * <p>
     * clones a task instance by creating exact clones of each contained child instance as well
     * as the related task. Furthermore, all other non transient information of the task
     * instance must be cloned.
     * </p>
     * 
     * @return a clone of the task instance
     */
    public ITaskInstance clone();

    /**
     * <p>
     * implements the visitor pattern to be able to process task instances and their children.
     * </p>
     * 
     * @param visitor the visitor used to process the task
     */
    public void accept(ITaskInstanceVisitor visitor);
    
}
