Merge pull request #3279 from ethereum/function_hoister

Function hoister

2 files changed, 111 insertions, 0 deletions

diff --git a/libjulia/optimiser/FunctionHoister.cpp b/libjulia/optimiser/FunctionHoister.cpp
new file mode 100644
index 00000000..9cf67f23
--- /dev/null
+++ b/libjulia/optimiser/FunctionHoister.cpp
@@ -0,0 +1,59 @@
+/*
+	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/>.
+*/
+/**
+ * Optimiser component that changes the code so that it consists of a block starting with
+ * a single block followed only by function definitions and with no functions defined
+ * anywhere else.
+ */
+
+#include <libjulia/optimiser/FunctionHoister.h>
+
+#include <libsolidity/inlineasm/AsmData.h>
+
+#include <libsolidity/interface/Exceptions.h>
+
+#include <libdevcore/CommonData.h>
+
+#include <boost/range/algorithm_ext/erase.hpp>
+
+using namespace std;
+using namespace dev;
+using namespace dev::julia;
+using namespace dev::solidity;
+
+
+void FunctionHoister::operator()(Block& _block)
+{
+	bool topLevel = m_isTopLevel;
+	m_isTopLevel = false;
+	for (auto&& statement: _block.statements)
+	{
+		boost::apply_visitor(*this, statement);
+		if (statement.type() == typeid(FunctionDefinition))
+		{
+			m_functions.emplace_back(std::move(statement));
+			statement = Block{_block.location, {}};
+		}
+	}
+	auto isEmptyBlock = [](Statement const& _st) -> bool {
+		return _st.type() == typeid(Block) && boost::get<Block>(_st).statements.empty();
+	};
+	// Remove empty blocks
+	boost::range::remove_erase_if(_block.statements, isEmptyBlock);
+	if (topLevel)
+		_block.statements += std::move(m_functions);
+}
diff --git a/libjulia/optimiser/FunctionHoister.h b/libjulia/optimiser/FunctionHoister.h
new file mode 100644
index 00000000..f9f8bce0
--- /dev/null
+++ b/libjulia/optimiser/FunctionHoister.h
@@ -0,0 +1,52 @@
+/*
+	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/>.
+*/
+/**
+ * Optimiser component that changes the code so that all function definitions are at the top
+ * level block.
+ */
+
+#pragma once
+
+#include <libjulia/ASTDataForward.h>
+
+#include <libjulia/optimiser/ASTWalker.h>
+
+namespace dev
+{
+namespace julia
+{
+
+/**
+ * Moves all functions to the top-level scope.
+ * Applying this transformation to source code that has ambiguous identifiers might
+ * lead to invalid code.
+ *
+ * Prerequisites: Disambiguator
+ */
+class FunctionHoister: public ASTModifier
+{
+public:
+	using ASTModifier::operator();
+	virtual void operator()(Block& _block);
+
+private:
+	bool m_isTopLevel = true;
+	std::vector<Statement> m_functions;
+};
+
+}
+}