/*

  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

#include <libyul/optimiser/VarDeclInitializer.h>

#include <libyul/AST.h>

#include <libsolutil/CommonData.h>

#include <libsolutil/Visitor.h>

#include <libyul/Dialect.h>

using namespace std;

using namespace solidity;

using namespace solidity::yul;

void VarDeclInitializer::operator()(Block& _block)

{

  ASTModifier::operator()(_block);

  using OptionalStatements = std::optional<vector<Statement>>;

  util::GenericVisitor visitor{

    util::VisitorFallback<OptionalStatements>{},

    [this](VariableDeclaration& _varDecl) -> OptionalStatements

    {

      if (_varDecl.value)

        return {};

      if (_varDecl.variables.size() == 1)

      {

        _varDecl.value = make_unique<Expression>(m_dialect.zeroLiteralForType(_varDecl.variables.front().type));

        return {};

      }

      else

      {

        OptionalStatements ret{vector<Statement>{}};

        for (auto& var: _varDecl.variables)

        {

          unique_ptr<Expression> expr = make_unique<Expression >(m_dialect.zeroLiteralForType(var.type));

          ret->emplace_back(VariableDeclaration{std::move(_varDecl.debugData), {std::move(var)}, std::move(expr)});

        }

        return ret;

      }

    }

  };

  util::iterateReplacing(_block.statements, [&](auto&& _statement) { return std::visit(visitor, _statement); });

}