path: root/libsolidity/codegen/ExpressionCompiler.h

/*
    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>
 * @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/Utils.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);
    /// @}

    /// 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 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);
}

}
}