solidity/libyul/optimiser/VarDeclInitializer.cpp

/*
	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/>.
*/

#include <libyul/optimiser/VarDeclInitializer.h>
#include <libyul/AsmData.h>

#include <libdevcore/CommonData.h>
#include <libdevcore/Visitor.h>

using namespace std;
using namespace dev;
using namespace yul;

void VarDeclInitializer::operator()(Block& _block)
{
	ASTModifier::operator()(_block);

	static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};

	using OptionalStatements = boost::optional<vector<Statement>>;
	GenericFallbackReturnsVisitor<OptionalStatements, VariableDeclaration> visitor{
		[](VariableDeclaration& _varDecl) -> OptionalStatements
		{
			if (_varDecl.value)
				return {};
			else if (_varDecl.variables.size() == 1)
			{
				_varDecl.value = make_shared<Expression>(zero);
				return {};
			}
			else
			{
				OptionalStatements ret{vector<Statement>{}};
				langutil::SourceLocation loc{std::move(_varDecl.location)};
				for (auto& var: _varDecl.variables)
					ret->push_back(VariableDeclaration{loc, {std::move(var)}, make_shared<Expression>(zero)});
				return ret;
			}
		}
	};
	iterateReplacing(_block.statements, boost::apply_visitor(visitor));
}