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/*
 * Copyright (c) 2017, 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
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package com.sri.ai.grinder.sgdpllt.library.set;

import com.sri.ai.expresso.api.Expression;
import com.sri.ai.expresso.api.IndexExpressionsSet;
import com.sri.ai.expresso.api.IntensionalSet;
import com.sri.ai.expresso.helper.Expressions;
import com.sri.ai.grinder.helper.GrinderUtil;
import com.sri.ai.grinder.sgdpllt.api.Context;
import com.sri.ai.grinder.sgdpllt.rewriter.api.Simplifier;

/**
 *  * {{ (on I) Alpha | Beta }} 
 * ---> 
 * {{ (on I) Alpha | evaluate(Beta, context extended with the indices) }}
 * 
 * 
 * @author oreilly
 *
 */
public class IntensionalSetConditionSimplifier implements Simplifier {
	@Override
	public Expression applySimplifier(Expression expression, Context context) {
		return simplify(expression, context);
	}
	
	public static Expression simplify(Expression expression, Context context) {
		Expression result = expression;
		
		if (Sets.isIntensionalSet(expression)) {
			IntensionalSet intensionalSet = (IntensionalSet) expression;
			
			Expression condition = intensionalSet.getCondition();
			if (!(condition.equals(Expressions.TRUE) || condition.equals(Expressions.FALSE))) {
				IndexExpressionsSet indexExpressionsSet = intensionalSet.getIndexExpressions();
				Context extendedContext = context.extendWith(indexExpressionsSet);
				
				Expression evaluatedCondition = context.getTheory().evaluate(condition, extendedContext);
				if (!evaluatedCondition.equals(condition)) {
					result = IntensionalSet.make(
								Sets.isIntensionalMultiSet(expression) ? IntensionalSet.MULTI_SET_LABEL : IntensionalSet.UNI_SET_LABEL, 
										indexExpressionsSet, 
										intensionalSet.getHead(), 
										evaluatedCondition);
				}
			}
		}
		
		return result;
	}
}