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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, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.sri.ai.expresso.api;

import com.google.common.annotations.Beta;
import com.sri.ai.expresso.core.DefaultIntensionalMultiSet;
import com.sri.ai.expresso.core.DefaultIntensionalUniSet;
import com.sri.ai.grinder.sgdpllt.library.set.Sets;

/**
 * An {@link Expression} that represents an intensionally defined set.
 * 
 * An object E belongs to an intensionally defined set { (on I) H | C }
 * if and only if there is a value I' for the index expressions I such that I'
 * satisfies C and E = H(I'), where H(I') is the result of
 * replacing I by I' in H.
 *  
 * 
 * @author braz
 */
@Beta
public interface IntensionalSet extends QuantifiedExpression {
	
	String SYNTACTIC_FORM_TYPE = "Intensional set";
	//
	String UNI_SET_LABEL          = "{ . . . }";
	String MULTI_SET_LABEL        = "{{ . . . }}";
	String CONDITION_LABEL        = ":";
	String SCOPED_VARIABLES_LABEL = "( on . )";

	/**
	 * Indicates whether the set is a uniset.
	 */
	boolean isUniSet();
	
	/**
	 * Indicates whether the set is a multiset.
	 */
	boolean isMultiSet();

	/**
	 * Returns the head H of the set { (on I) H | C }
	 */
	Expression getHead();

	/**
	 * Returns the condition C of the set { (on I) H | C }
	 */
	Expression getCondition();

	/**
	 * Returns a new instance with the head replaced by given new one.
	 */
	Expression setHead(Expression newHead);

	/**
	 * Returns a new instance with the condition replaced by given new one.
	 */
	IntensionalSet setCondition(Expression newCondition);

	/**
	 * Returns a new instance with the head and condition replaced by given new ones.
	 */
	IntensionalSet setHeadAndCondition(Expression newHead, Expression newCondition);

	@Override
	IntensionalSet setIndexExpressions(IndexExpressionsSet newIndexExpressions);
	
	/**
	 * Make another intensional set of the same kind (uni/multi) as a given intensional set.
	 * @param intensionalSet
	 * @param indexExpressions
	 * @param head
	 * @param condition
	 * @return
	 */
	public static Expression intensionalSetOfSameKindAs(IntensionalSet intensionalSet, IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		return make(Sets.isMultiSet(intensionalSet) ? MULTI_SET_LABEL : UNI_SET_LABEL, indexExpressions, head, condition);
	}

	/**
	 * Makes an intensional multi-set.
	 * @param indexExpressions
	 * @param head
	 * @param condition
	 * @return
	 */
	public static Expression intensionalMultiSet(IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		return make(MULTI_SET_LABEL, indexExpressions, head, condition);
	}

	/**
	 * Makes an intensional uni-set.
	 * @param indexExpressions
	 * @param head
	 * @param condition
	 * @return
	 */
	public static Expression intensionalUniSet(IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		return make(UNI_SET_LABEL, indexExpressions, head, condition);
	}
	
	/**
	 * Makes an intensional multi-set.
	 * @param indexExpressions
	 * @param head
	 * @param condition
	 * @return
	 */
	public static Expression makeMultiSet(IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		return make(MULTI_SET_LABEL, indexExpressions, head, condition);
	}

	/**
	 * Makes an intensional uni-set.
	 * @param indexExpressions
	 * @param head
	 * @param condition
	 * @return
	 */
	public static Expression makeUniSet(IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		return make(UNI_SET_LABEL, indexExpressions, head, condition);
	}
	
	public static IntensionalSet make(Object label, IndexExpressionsSet indexExpressions, Expression head, Expression condition) {
		IntensionalSet result;
		if (label.equals(UNI_SET_LABEL)) {
			result = new DefaultIntensionalUniSet(indexExpressions, head, condition);
		}
		else if (label.equals(MULTI_SET_LABEL)) {
			result = new DefaultIntensionalMultiSet(indexExpressions, head, condition);
		}
		else {
			throw new Error("makeSetFromIndexExpressions requires UNI_SET_LABEL or MULTI_SET_LABEL");
		}
		return result;
	}
}