/*******************************************************************************
*   Copyright 2012 Analog Devices, Inc.
*
*   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 com.analog.lyric.dimple.factorfunctions;

import com.analog.lyric.dimple.factorfunctions.core.FactorFunction;
import com.analog.lyric.dimple.model.values.Value;


/**
 * Deterministic logical OR. This is a deterministic directed factor.
 * 
 * The variables are ordered as follows in the argument list:
 * 
 * 1) Output (Logical OR of inputs)
 * 2...) An arbitrary number of inputs (inputs may be boolean, double 0.0/1.0 or integer 0/1)
 * 
 */
public class Or extends FactorFunction
{
    @Override
    public final double evalEnergy(Value[] arguments)
    {
    	final boolean outValue = arguments[0].getBoolean();
    	
    	boolean orValue = false;
    	for(int i = 1; i < arguments.length; ++i)
    		orValue |= arguments[i].getBoolean();

    	return (orValue == outValue) ? 0 : Double.POSITIVE_INFINITY;
    }
    
    
    @Override
    public final boolean isDirected() {return true;}
    @Override
	public final int[] getDirectedToIndices() {return new int[]{0};}
    @Override
	public final boolean isDeterministicDirected() {return true;}
    @Override
	public final void evalDeterministic(Value[] arguments)
    {
    	boolean orValue = false;
    	for(int i = 1; i < arguments.length; ++i)
    		orValue |= arguments[i].getBoolean();
    	
    	// Replace the output value
    	arguments[0].setBoolean(orValue);
    }
}