Track usage of variables.

1 files changed, 80 insertions, 0 deletions

diff --git a/libsolidity/formal/VariableUsage.cpp b/libsolidity/formal/VariableUsage.cpp
new file mode 100644
index 00000000..4e96059d
--- /dev/null
+++ b/libsolidity/formal/VariableUsage.cpp
@@ -0,0 +1,80 @@
+/*
+	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 <libsolidity/formal/VariableUsage.h>
+
+#include <libsolidity/ast/ASTVisitor.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::solidity;
+
+VariableUsage::VariableUsage(ASTNode const& _node)
+{
+	auto nodeFun = [&](ASTNode const& n) -> bool
+	{
+		if (Identifier const* identifier = dynamic_cast<decltype(identifier)>(&n))
+		{
+			Declaration const* declaration = identifier->annotation().referencedDeclaration;
+			solAssert(declaration, "");
+			if (VariableDeclaration const* varDecl = dynamic_cast<VariableDeclaration const*>(declaration))
+				if (
+					varDecl->isLocalVariable() &&
+					identifier->annotation().lValueRequested &&
+					varDecl->annotation().type->isValueType()
+				)
+					m_touchedVariable[&n] = varDecl;
+		}
+		return true;
+	};
+	auto edgeFun = [&](ASTNode const& _parent, ASTNode const& _child)
+	{
+		if (m_touchedVariable.count(&_child) || m_children.count(&_child))
+			m_children[&_parent].push_back(&_child);
+	};
+
+	ASTReduce reducer(nodeFun, edgeFun);
+	_node.accept(reducer);
+}
+
+vector<Declaration const*> VariableUsage::touchedVariables(ASTNode const& _node) const
+{
+	if (!m_children.count(&_node) && !m_touchedVariable.count(&_node))
+		return {};
+
+	set<Declaration const*> touched;
+	vector<ASTNode const*> toVisit;
+	toVisit.push_back(&_node);
+
+	while (!toVisit.empty())
+	{
+		ASTNode const* n = toVisit.back();
+		toVisit.pop_back();
+		if (m_children.count(n))
+		{
+			solAssert(!m_touchedVariable.count(n), "");
+			toVisit += m_children.at(n);
+		}
+		else
+		{
+			solAssert(m_touchedVariable.count(n), "");
+			touched.insert(m_touchedVariable.at(n));
+		}
+	}
+
+	return {touched.begin(), touched.end()};
+}