solidity/libsolidity/analysis/ConstantEvaluator.h

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/*
This file is part of solidity.
solidity is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
solidity is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with solidity. If not, see <http://www.gnu.org/licenses/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* @author Christian <c@ethdev.com>
* @date 2015
* Evaluator for types of constant expressions.
*/
#pragma once
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#include <libsolidity/ast/ASTVisitor.h>
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#include <utility>
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namespace solidity::langutil
{
class ErrorReporter;
}
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namespace solidity::frontend
{
class TypeChecker;
/**
* Small drop-in replacement for TypeChecker to evaluate simple expressions of integer constants.
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*
* Note: This always use "checked arithmetic" in the sense that any over- or underflow
* results in "unknown" value.
*/
class ConstantEvaluator: private ASTConstVisitor
{
public:
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struct TypedRational
{
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TypePointer type;
rational value;
};
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static std::optional<TypedRational> evaluate(
langutil::ErrorReporter& _errorReporter,
Expression const& _expr
);
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/// Performs arbitrary-precision evaluation of a binary operator. Returns nullopt on cases like
/// division by zero or e.g. bit operators applied to fractional values.
static std::optional<rational> evaluateBinaryOperator(Token _operator, rational const& _left, rational const& _right);
/// Performs arbitrary-precision evaluation of a unary operator. Returns nullopt on cases like
/// bit operators applied to fractional values.
static std::optional<rational> evaluateUnaryOperator(Token _operator, rational const& _input);
private:
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explicit ConstantEvaluator(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
std::optional<TypedRational> evaluate(ASTNode const& _node);
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void endVisit(BinaryOperation const& _operation) override;
void endVisit(UnaryOperation const& _operation) override;
void endVisit(Literal const& _literal) override;
void endVisit(Identifier const& _identifier) override;
void endVisit(TupleExpression const& _tuple) override;
langutil::ErrorReporter& m_errorReporter;
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/// Current recursion depth.
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size_t m_depth = 0;
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/// Values of sub-expressions and variable declarations.
std::map<ASTNode const*, std::optional<TypedRational>> m_values;
};
}