com.sri.ai.grinder.sgdpllt.rewriter.api.Simplifier 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
* 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.grinder.sgdpllt.rewriter.api;
import com.sri.ai.expresso.api.Expression;
import com.sri.ai.grinder.sgdpllt.api.Context;
import com.sri.ai.grinder.sgdpllt.api.ExpressionLiteralSplitterStepSolver;
import com.sri.ai.grinder.sgdpllt.api.ExpressionLiteralSplitterStepSolver.Solution;
import com.sri.ai.grinder.sgdpllt.api.ExpressionLiteralSplitterStepSolver.Step;
import com.sri.ai.grinder.sgdpllt.theory.base.FunctionOnContextExpressionStepSolver;
/**
* A Simplifier knows just enough about the symbols in a language to simplify it in a shallow way,
* that is, to replace function applications by a simpler equivalent expression, if that expression is determined by their immediate arguments.
* Shallow simplifications are required to take polynomial time in the size of expressions (preferably linear time).
*
* Examples of shallow simplifications are x + 0
to x
, x or true
to true
, and x + 1 + 3
to x + 4
.
* Simplifications that are not shallow include those requiring case analysis (inference), such as (p and q) or (p and not q)
leading to p
.
*
* A simplifier can be used as a rewriter that always returns unconditional steps, that is, solutions.
* @author braz
*
*/
@FunctionalInterface
public interface Simplifier extends TopRewriter {
/**
* We define this method to make this a functional interface again,
* so that simplifiers can be easily defined with lambda expressions.
* @param expression
* @param context
* @return
*/
Expression applySimplifier(Expression expression, Context context);
default Expression apply(Expression expression, Context context) { // more efficient
return applySimplifier(expression, context);
}
default ExpressionLiteralSplitterStepSolver makeStepSolver(Expression expression) {
return new FunctionOnContextExpressionStepSolver(c -> apply(expression, c));
}
default Step step(Expression expression, Context context) { // optimized version
Expression simplifiedExpression = apply(expression, context);
Solution result = new Solution(simplifiedExpression);
return result;
}
}