LValue refactoring.

1 files changed, 112 insertions, 0 deletions

diff --git a/LValue.h b/LValue.h
new file mode 100644
index 00000000..35ddc451
--- /dev/null
+++ b/LValue.h
@@ -0,0 +1,112 @@
+/*
+	This file is part of cpp-ethereum.
+
+	cpp-ethereum 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.
+
+	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/**
+ * @author Christian <c@ethdev.com>
+ * @date 2015
+ * LValues for use in the expresison compiler.
+ */
+
+#pragma once
+
+#include <memory>
+#include <libevmcore/SourceLocation.h>
+
+namespace dev
+{
+namespace solidity
+{
+
+class Declaration;
+class Type;
+class CompilerContext;
+
+/**
+ * Abstract class used to retrieve, delete and store data in lvalues/variables.
+ */
+class LValue
+{
+protected:
+	LValue(CompilerContext& _compilerContext, std::shared_ptr<Type const> const& _dataType):
+		m_context(_compilerContext), m_dataType(_dataType) {}
+
+public:
+	/// @returns true if this lvalue reference type occupies a slot on the stack.
+	virtual bool storesReferenceOnStack() const = 0;
+	/// Copies the value of the current lvalue to the top of the stack and, if @a _remove is true,
+	/// also removes the reference from the stack.
+	/// @a _location source location of the current expression, used for error reporting.
+	virtual void retrieveValue(SourceLocation const& _location, bool _remove = false) const = 0;
+	/// Moves a value from the stack to the lvalue. Removes the value if @a _move is true.
+	/// @a _location is the source location of the expression that caused this operation.
+	/// Stack pre: value [lvalue_ref]
+	/// Stack post if !_move: value_of(lvalue_ref)
+	virtual void storeValue(Type const& _sourceType,
+		SourceLocation const& _location = SourceLocation(), bool _move = false) const = 0;
+	/// Stores zero in the lvalue.
+	/// @a _location is the source location of the requested operation
+	virtual void setToZero(SourceLocation const& _location = SourceLocation()) const = 0;
+
+protected:
+	CompilerContext& m_context;
+	std::shared_ptr<Type const> m_dataType;
+};
+
+/**
+ * Local variable that is completely stored on the stack.
+ */
+class StackVariable: public LValue
+{
+public:
+	explicit StackVariable(CompilerContext& _compilerContext, Declaration const& _declaration);
+
+	virtual bool storesReferenceOnStack() const { return false; }
+	virtual void retrieveValue(SourceLocation const& _location, bool _remove = false) const override;
+	virtual void storeValue(Type const& _sourceType,
+		SourceLocation const& _location = SourceLocation(), bool _move = false) const override;
+	virtual void setToZero(SourceLocation const& _location = SourceLocation()) const override;
+
+private:
+	/// Base stack offset (@see CompilerContext::getBaseStackOffsetOfVariable) of the local variable.
+	unsigned m_baseStackOffset;
+	/// Number of stack elements occupied by the value (not the reference).
+	unsigned m_size;
+};
+
+/**
+ * Reference to some item in storage. The (starting) position of the item is stored on the stack.
+ */
+class StorageItem: public LValue
+{
+public:
+	/// Constructs the LValue and pushes the location of @a _declaration onto the stack.
+	explicit StorageItem(CompilerContext& _compilerContext, Declaration const& _declaration);
+	/// Constructs the LValue and assumes that the storage reference is already on the stack.
+	explicit StorageItem(CompilerContext& _compilerContext, std::shared_ptr<Type const> const& _type);
+	virtual bool storesReferenceOnStack() const { return true; }
+	virtual void retrieveValue(SourceLocation const& _location, bool _remove = false) const override;
+	virtual void storeValue(Type const& _sourceType,
+		SourceLocation const& _location = SourceLocation(), bool _move = false) const override;
+	virtual void setToZero(SourceLocation const& _location = SourceLocation()) const override;
+
+private:
+	/// Number of stack elements occupied by the value (not the reference).
+	/// Only used for value types.
+	unsigned m_size;
+};
+
+}
+}