+ virtual void visit(ProgramSyntax::Literal &);
+ virtual void visit(ProgramSyntax::ParenthesizedExpression &);
+ virtual void visit(ProgramSyntax::VariableReference &);
+ virtual void visit(ProgramSyntax::MemberAccess &);
+ virtual void visit(ProgramSyntax::UnaryExpression &);
+ virtual void visit(ProgramSyntax::BinaryExpression &);
+ virtual void visit(ProgramSyntax::FunctionCall &);