path: root/libyul/optimiser/Semantics.h

/*
    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/>.
*/
/**
 * Specific AST walkers that collect semantical facts.
 */

#pragma once

#include <libyul/optimiser/ASTWalker.h>

#include <set>

namespace yul
{

/**
 * Specific AST walker that determines whether an expression is movable.
 */
class MovableChecker: public ASTWalker
{
public:
    MovableChecker() = default;
    explicit MovableChecker(Expression const& _expression);

    void operator()(Identifier const& _identifier) override;
    void operator()(FunctionalInstruction const& _functionalInstruction) override;
    void operator()(FunctionCall const& _functionCall) override;

    /// Disallow visiting anything apart from Expressions (this throws).
    void visit(Statement const&) override;
    using ASTWalker::visit;

    bool movable() const { return m_movable; }
    std::set<YulString> const& referencedVariables() const { return m_variableReferences; }

private:
    /// Which variables the current expression references.
    std::set<YulString> m_variableReferences;
    /// Is the current expression movable or not.
    bool m_movable = true;
};

}