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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; } }





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