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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/>.
*/
/**
 * Analysis part of inline assembly.
 */

#pragma once

#include <libsolidity/interface/Exceptions.h>

#include <boost/variant.hpp>

#include <functional>
#include <memory>

namespace dev
{
namespace solidity
{
namespace assembly
{

struct Literal;
struct Block;
struct Label;
struct FunctionalInstruction;
struct FunctionalAssignment;
struct VariableDeclaration;
struct Instruction;
struct Identifier;
struct Assignment;
struct FunctionDefinition;
struct FunctionCall;

template <class...>
struct GenericVisitor{};

template <class Visitable, class... Others>
struct GenericVisitor<Visitable, Others...>: public GenericVisitor<Others...>
{
    using GenericVisitor<Others...>::operator ();
    explicit GenericVisitor(
        std::function<void(Visitable&)> _visitor,
        std::function<void(Others&)>... _otherVisitors
    ):
        GenericVisitor<Others...>(_otherVisitors...),
        m_visitor(_visitor)
    {}

    void operator()(Visitable& _v) const { m_visitor(_v); }

    std::function<void(Visitable&)> m_visitor;
};
template <>
struct GenericVisitor<>: public boost::static_visitor<> {
    void operator()() const {}
};


struct Scope
{
    struct Variable
    {
        int stackHeight = 0;
        bool active = false;
    };

    struct Label
    {
        size_t id = unassignedLabelId;
        int stackAdjustment = 0;
        bool resetStackHeight = false;
        static const size_t errorLabelId = -1;
        static const size_t unassignedLabelId = 0;
    };

    struct Function
    {
        Function(size_t _arguments, size_t _returns): arguments(_arguments), returns(_returns) {}
        size_t arguments = 0;
        size_t returns = 0;
    };

    using Identifier = boost::variant<Variable, Label, Function>;
    using Visitor = GenericVisitor<Variable const, Label const, Function const>;
    using NonconstVisitor = GenericVisitor<Variable, Label, Function>;

    bool registerVariable(std::string const& _name);
    bool registerLabel(std::string const& _name);
    bool registerFunction(std::string const& _name, size_t _arguments, size_t _returns);

    /// Looks up the identifier in this or super scopes (stops and function and assembly boundaries)
    /// and returns a valid pointer if found or a nullptr if not found.
    /// The pointer will be invalidated if the scope is modified.
    Identifier* lookup(std::string const& _name);
    /// Looks up the identifier in this and super scopes (stops and function and assembly boundaries)
    /// and calls the visitor, returns false if not found.
    template <class V>
    bool lookup(std::string const& _name, V const& _visitor)
    {
        if (Identifier* id = lookup(_name))
        {
            boost::apply_visitor(_visitor, *id);
            return true;
        }
        else
            return false;
    }
    /// @returns true if the name exists in this scope or in super scopes (also searches
    /// across function and assembly boundaries).
    bool exists(std::string const& _name);
    Scope* superScope = nullptr;
    /// If true, identifiers from the super scope are not visible here, but they are still
    /// taken into account to prevent shadowing.
    bool closedScope = false;
    std::map<std::string, Identifier> identifiers;
};


class AsmAnalyzer: public boost::static_visitor<bool>
{
public:
    using Scopes = std::map<assembly::Block const*, std::shared_ptr<Scope>>;
    AsmAnalyzer(Scopes& _scopes, ErrorList& _errors);

    bool operator()(assembly::Instruction const&) { return true; }
    bool operator()(assembly::Literal const& _literal);
    bool operator()(assembly::Identifier const&) { return true; }
    bool operator()(assembly::FunctionalInstruction const& _functionalInstruction);
    bool operator()(assembly::Label const& _label);
    bool operator()(assembly::Assignment const&) { return true; }
    bool operator()(assembly::FunctionalAssignment const& _functionalAssignment);
    bool operator()(assembly::VariableDeclaration const& _variableDeclaration);
    bool operator()(assembly::FunctionDefinition const& _functionDefinition);
    bool operator()(assembly::FunctionCall const& _functionCall);
    bool operator()(assembly::Block const& _block);

private:
    Scope* m_currentScope = nullptr;
    Scopes& m_scopes;
    ErrorList& m_errors;
};

}
}
}