/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.samoa.moa.classifiers.core.conditionaltests;

import org.apache.samoa.instances.Instance;
import org.apache.samoa.instances.InstancesHeader;
import org.apache.samoa.moa.AbstractMOAObject;

/**
 * Abstract conditional test for instances to use to split nodes in Hoeffding trees.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public abstract class InstanceConditionalTest extends AbstractMOAObject {

  /**
   * Returns the number of the branch for an instance, -1 if unknown.
   * 
   * @param inst
   *          the instance to be used
   * @return the number of the branch for an instance, -1 if unknown.
   */
  public abstract int branchForInstance(Instance inst);

  /**
   * Gets whether the number of the branch for an instance is known.
   * 
   * @param inst
   * @return true if the number of the branch for an instance is known
   */
  public boolean resultKnownForInstance(Instance inst) {
    return branchForInstance(inst) >= 0;
  }

  /**
   * Gets the number of maximum branches, -1 if unknown.
   * 
   * @return the number of maximum branches, -1 if unknown..
   */
  public abstract int maxBranches();

  /**
   * Gets the text that describes the condition of a branch. It is used to describe the branch.
   * 
   * @param branch
   *          the number of the branch to describe
   * @param context
   *          the context or header of the data stream
   * @return the text that describes the condition of the branch
   */
  public abstract String describeConditionForBranch(int branch,
      InstancesHeader context);

  /**
   * Returns an array with the attributes that the test depends on.
   * 
   * @return an array with the attributes that the test depends on
   */
  public abstract int[] getAttsTestDependsOn();
}