mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
87 lines
2.6 KiB
C++
87 lines
2.6 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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// SPDX-License-Identifier: GPL-3.0
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/**
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* @author Christian <c@ethdev.com>
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* @date 2015
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* Evaluator for types of constant expressions.
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*/
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#pragma once
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#include <libsolidity/ast/ASTVisitor.h>
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#include <utility>
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namespace solidity::langutil
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{
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class ErrorReporter;
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}
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namespace solidity::frontend
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{
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class TypeChecker;
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/**
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* Small drop-in replacement for TypeChecker to evaluate simple expressions of integer constants.
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*
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* Note: This always use "checked arithmetic" in the sense that any over- or underflow
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* results in "unknown" value.
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*/
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class ConstantEvaluator: private ASTConstVisitor
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{
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public:
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struct TypedRational
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{
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Type const* type;
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rational value;
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};
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static std::optional<TypedRational> evaluate(
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langutil::ErrorReporter& _errorReporter,
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Expression const& _expr
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);
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/// Performs arbitrary-precision evaluation of a binary operator. Returns nullopt on cases like
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/// division by zero or e.g. bit operators applied to fractional values.
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static std::optional<rational> evaluateBinaryOperator(Token _operator, rational const& _left, rational const& _right);
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/// Performs arbitrary-precision evaluation of a unary operator. Returns nullopt on cases like
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/// bit operators applied to fractional values.
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static std::optional<rational> evaluateUnaryOperator(Token _operator, rational const& _input);
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private:
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explicit ConstantEvaluator(langutil::ErrorReporter& _errorReporter): m_errorReporter(_errorReporter) {}
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std::optional<TypedRational> evaluate(ASTNode const& _node);
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void endVisit(BinaryOperation const& _operation) override;
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void endVisit(UnaryOperation const& _operation) override;
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void endVisit(Literal const& _literal) override;
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void endVisit(Identifier const& _identifier) override;
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void endVisit(TupleExpression const& _tuple) override;
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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.
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std::map<ASTNode const*, std::optional<TypedRational>> m_values;
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};
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}
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