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/*
 * Copyright (c) 2013, SRI International
 * All rights reserved.
 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 * 
 * http://opensource.org/licenses/BSD-3-Clause
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of the aic-expresso nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
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package com.sri.ai.grinder.sgdpllt.theory.differencearithmetic;

import static com.sri.ai.util.Util.getFirst;

import com.google.common.annotations.Beta;
import com.sri.ai.expresso.api.Expression;
import com.sri.ai.grinder.sgdpllt.api.Context;

/**
 * A step solver computing the possible values of the variable of
 * a single-variable difference arithmetic constraint.
 * @author braz
 *
 */
@Beta
public class ValuesOfSingleVariableDifferenceArithmeticConstraintStepSolver extends AbstractSingleVariableDifferenceArithmeticConstraintFeasibilityRegionStepSolver {

	public ValuesOfSingleVariableDifferenceArithmeticConstraintStepSolver(SingleVariableDifferenceArithmeticConstraint constraint) {
		super(constraint);
	}
	
	@Override
	public ValuesOfSingleVariableDifferenceArithmeticConstraintStepSolver clone() {
		return (ValuesOfSingleVariableDifferenceArithmeticConstraintStepSolver) super.clone();
	}

	@Override
	public boolean unboundedVariableProducesShortCircuitSolution() {
		return false;
	}

	@Override
	public Expression getSolutionExpressionForUnboundedVariables() {
		return null; // not used because just knowing that the variable is unbounded is not enought to determine solution
	}

	@Override
	protected Expression getSolutionExpressionGivenContradiction() {
		return RangeAndExceptionsSet.EMPTY;
	}

	@Override
	public Expression getSolutionExpressionForBoundVariable() {
		Expression solutionExpression = new RangeAndExceptionsSet.Singleton(getFirst(getEquals()));
		return solutionExpression;
	}

	@Override
	public Expression getSolutionExpressionGivenBoundsAndDistinctDisequals(Expression greatestStrictLowerBound, Expression leastNonStrictUpperBound, Expression boundsDifference, Expression distinctDisequalsSet, Context context) {
		Expression solutionExpression;
		solutionExpression = 
				new RangeAndExceptionsSet.DefaultRangeAndExceptionsSet(
						greatestStrictLowerBound,
						leastNonStrictUpperBound,
						distinctDisequalsSet.getArguments()
						);
		return solutionExpression;
	}
}