com.sri.ai.grinder.sgdpllt.library.boole.Not Maven / Gradle / Ivy
/*
* 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
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.sri.ai.grinder.sgdpllt.library.boole;
import static com.sri.ai.grinder.sgdpllt.library.FunctorConstants.NOT;
import com.google.common.annotations.Beta;
import com.sri.ai.expresso.api.Expression;
import com.sri.ai.expresso.helper.Expressions;
import com.sri.ai.grinder.sgdpllt.api.Context;
import com.sri.ai.grinder.sgdpllt.library.FunctorConstants;
import com.sri.ai.grinder.sgdpllt.rewriter.api.Simplifier;
/**
* @author braz
*
*/
@Beta
public class Not implements Simplifier {
@Override
public Expression applySimplifier(Expression expression, Context context) {
return simplify(expression);
}
public static Expression simplify(Expression formula) {
Expression result;
if (formula.get(0).equals(Expressions.TRUE)) {
result = Expressions.FALSE;
}
else if (formula.get(0).equals(Expressions.FALSE)) {
result = Expressions.TRUE;
}
else if (formula.get(0).hasFunctor(FunctorConstants.NOT)) {
result = formula.get(0).get(0);
}
else {
result = formula;
}
return result;
}
public static boolean isNegation(Expression expression) {
return expression.hasFunctor(NOT);
}
/** Make a "not" application on given expression. */
public static Expression make(Expression expression) {
if (expression.equals(Expressions.TRUE)) {
return Expressions.FALSE;
}
if (expression.equals(Expressions.FALSE)) {
return Expressions.TRUE;
}
return Expressions.apply("not", expression);
}
/**
* Another name for {@link #makeRewritingProcess(Expression)}.
* @param expression
* @return
*/
public static Expression not(Expression expression) {
return make(expression);
}
}