text: /*
  	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/>.
  */
  /**
   * @author Christian <c@ethdev.com>
   * @author Gav Wood <g@ethdev.com>
   * @date 2014
   * Solidity AST to EVM bytecode compiler for expressions.
   */
  
  #include <functional>
  #include <memory>
  #include <boost/noncopyable.hpp>
  #include <libdevcore/Common.h>
  #include <libevmasm/SourceLocation.h>
  #include <libsolidity/ast/ASTVisitor.h>
  #include <libsolidity/codegen/LValue.h>
  #include <libsolidity/interface/Exceptions.h>
  
  namespace dev {
  namespace eth
  {
  class AssemblyItem; // forward
  }
  namespace solidity {
  
  // forward declarations
  class CompilerContext;
  class CompilerUtils;
  class Type;
  class IntegerType;
  class ArrayType;
  
  /**
   * Compiler for expressions, i.e. converts an AST tree whose root is an Expression into a stream
   * of EVM instructions. It needs a compiler context that is the same for the whole compilation
   * unit.
   */
  class ExpressionCompiler: private ASTConstVisitor
  {
  public:
  	/// Appends code for a State Variable accessor function
  	static void appendStateVariableAccessor(CompilerContext& _context, VariableDeclaration const& _varDecl, bool _optimize = false);
  
  	explicit ExpressionCompiler(CompilerContext& _compilerContext, bool _optimize = false):
  		m_optimize(_optimize), m_context(_compilerContext) {}
  
  	/// Compile the given @a _expression and leave its value on the stack.
  	void compile(Expression const& _expression);
  
  	/// Appends code to set a state variable to its initial value/expression.
  	void appendStateVariableInitialization(VariableDeclaration const& _varDecl);
  
  	/// Appends code for a State Variable accessor function
  	void appendStateVariableAccessor(VariableDeclaration const& _varDecl);
  
  	/// Appends code for a Constant State Variable accessor function
  	void appendConstStateVariableAccessor(const VariableDeclaration& _varDecl);
  
  private:
  	virtual bool visit(Conditional const& _condition) override;
  	virtual bool visit(Assignment const& _assignment) override;
  	virtual bool visit(TupleExpression const& _tuple) override;
  	virtual bool visit(UnaryOperation const& _unaryOperation) override;
  	virtual bool visit(BinaryOperation const& _binaryOperation) override;
  	virtual bool visit(FunctionCall const& _functionCall) override;
  	virtual bool visit(NewExpression const& _newExpression) override;
  	virtual bool visit(MemberAccess const& _memberAccess) override;
  	virtual bool visit(IndexAccess const& _indexAccess) override;
  	virtual void endVisit(Identifier const& _identifier) override;
  	virtual void endVisit(Literal const& _literal) override;
  
  	///@{
  	///@name Append code for various operator types
  	void appendAndOrOperatorCode(BinaryOperation const& _binaryOperation);
  	void appendCompareOperatorCode(Token::Value _operator, Type const& _type);
  	void appendOrdinaryBinaryOperatorCode(Token::Value _operator, Type const& _type);
  
  	void appendArithmeticOperatorCode(Token::Value _operator, Type const& _type);
  	void appendBitOperatorCode(Token::Value _operator);
  	void appendShiftOperatorCode(Token::Value _operator, Type const& _valueType, Type const& _shiftAmountType);
  	/// @}
  
  	/// Appends code to call a function of the given type with the given arguments.
  	void appendExternalFunctionCall(
  		FunctionType const& _functionType,
  		std::vector<ASTPointer<Expression const>> const& _arguments
  	);
  	/// Appends code that evaluates a single expression and moves the result to memory. The memory offset is
  	/// expected to be on the stack and is updated by this call.
  	void appendExpressionCopyToMemory(Type const& _expectedType, Expression const& _expression);
  
  	/// Appends code for a variable that might be a constant or not
  	void appendVariable(VariableDeclaration const& _variable, Expression const& _expression);
  	/// Sets the current LValue to a new one (of the appropriate type) from the given declaration.
  	/// Also retrieves the value if it was not requested by @a _expression.
  	void setLValueFromDeclaration(Declaration const& _declaration, Expression const& _expression);
  	/// Sets the current LValue to a StorageItem holding the type of @a _expression. The reference is assumed
  	/// to be on the stack.
  	/// Also retrieves the value if it was not requested by @a _expression.
  	void setLValueToStorageItem(Expression const& _expression);
  	/// Sets the current LValue to a new LValue constructed from the arguments.
  	/// Also retrieves the value if it was not requested by @a _expression.
  	template <class _LValueType, class... _Arguments>
  	void setLValue(Expression const& _expression, _Arguments const&... _arguments);
  
  	/// @returns true if the operator applied to the given type requires a cleanup prior to the
  	/// operation.
  	static bool cleanupNeededForOp(Type::Category _type, Token::Value _op);
  
  	/// @returns the CompilerUtils object containing the current context.
  	CompilerUtils utils();
  
  	bool m_optimize;
  	CompilerContext& m_context;
  	std::unique_ptr<LValue> m_currentLValue;
  
  };
  
  template <class _LValueType, class... _Arguments>
  void ExpressionCompiler::setLValue(Expression const& _expression, _Arguments const&... _arguments)
  {
  	solAssert(!m_currentLValue, "Current LValue not reset before trying to set new one.");
  	std::unique_ptr<_LValueType> lvalue(new _LValueType(m_context, _arguments...));
  	if (_expression.annotation().lValueRequested)
  		m_currentLValue = move(lvalue);
  	else
  		lvalue->retrieveValue(_expression.location(), true);
  }
  
  }
  }
  