848 lines
27 KiB
Ada
848 lines
27 KiB
Ada
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separate (H2.Scheme)
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procedure Execute (Interp: in out Interpreter_Record) is
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LC: IO_Character_Record renames Interp.Input.Iochar;
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procedure Evaluate_Result is
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pragma Inline (Evaluate_Result);
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begin
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-- The result from the previous frame is stored in the current frame.
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-- This procedure takes the result and switch it to an operand and clears it.
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-- It is used to evaluate the result of Read_Object in principle.
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-- It takes only the head(car) element of the result chain.
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-- Calling this function to evaluate the result of any arbitrary frame
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-- other than 'Read_Object' is not recommended.
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Set_Frame_Operand (Interp.Stack, Get_Car(Get_Frame_Result(Interp.Stack)));
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Clear_Frame_Result (Interp.Stack);
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Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Object);
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end Evaluate_Result;
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procedure Evaluate_Group is
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pragma Inline (Evaluate_Group);
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Operand: aliased Object_Pointer;
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Car: aliased Object_Pointer;
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Cdr: aliased Object_Pointer;
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begin
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Push_Top (Interp, Operand'Unchecked_Access);
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Push_Top (Interp, Car'Unchecked_Access);
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Push_Top (Interp, Cdr'Unchecked_Access);
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Operand := Get_Frame_Operand(Interp.Stack);
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pragma Assert (Is_Normal_Pointer(Operand));
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case Operand.Tag is
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when Cons_Object =>
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Car := Get_Car(Operand);
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Cdr := Get_Cdr(Operand);
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if Is_Cons(Cdr) then
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-- Let the current frame remember the next expression list
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Set_Frame_Operand (Interp.Stack, Cdr);
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else
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if Cdr /= Nil_Pointer then
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-- The last CDR is not Nil.
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Ada.Text_IO.Put_Line ("$$$$..................FUCKING CDR. FOR GROUP....................$$$$");
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-- raise Syntax_Error;
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end if;
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-- Change the operand to a mark object so that the call to this
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-- procedure after the evaluation of the last car goes to the
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-- Mark_Object case.
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Set_Frame_Operand (Interp.Stack, Interp.Mark);
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end if;
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-- Clear the return value from the previous expression.
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Clear_Frame_Result (Interp.Stack);
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-- Arrange to evaluate the current expression
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Push_Frame (Interp, Opcode_Evaluate_Object, Car);
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when Mark_Object =>
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Operand := Get_Frame_Result (Interp.Stack);
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Pop_Frame (Interp); -- Done
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-- There must be only 1 return value chained in the Group frame.
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pragma Assert (Get_Cdr(Operand) = Nil_Pointer);
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-- Transfer the only return value to the upper chain
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Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
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when others =>
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raise Internal_Error;
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end case;
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Pop_Tops (Interp, 3);
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end Evaluate_Group;
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procedure Evaluate_Object is
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pragma Inline (Evaluate_Object);
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Operand: aliased Object_Pointer;
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Car: aliased Object_Pointer;
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Cdr: aliased Object_Pointer;
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begin
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Push_Top (Interp, Operand'Unchecked_Access);
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Push_Top (Interp, Car'Unchecked_Access);
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Push_Top (Interp, Cdr'Unchecked_Access);
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<<Start_Over>>
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Operand := Get_Frame_Operand(Interp.Stack);
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if not Is_Normal_Pointer(Operand) then
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-- integer, character, specal pointers
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-- TODO: some normal pointers may point to literal objects. e.g.) bignum
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goto Literal;
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end if;
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case Operand.Tag is
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when Symbol_Object => -- Is_Symbol(Operand)
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-- TODO: find it in the Environment hierarchy.. not in the current environemnt.
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Car := Get_Environment (Interp.Self, Operand);
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if Car = null then
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-- unbound
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Ada.Text_IO.Put_Line ("Unbound symbol....");
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Print (Interp, Operand);
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raise Evaluation_Error;
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else
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-- symbol found in the environment
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Operand := Car;
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goto Literal; -- In fact, this is not a literal, but can be handled in the same way
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end if;
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when Cons_Object => -- Is_Cons(Operand)
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Car := Get_Car(Operand);
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Cdr := Get_Cdr(Operand);
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if Is_Syntax(Car) then
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-- special syntax symbol. normal evaluate rule doesn't
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-- apply for special syntax objects.
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case Car.Scode is
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when Begin_Syntax =>
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Operand := Cdr; -- Skip "begin"
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if not Is_Cons(Operand) then
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-- e.g) (begin)
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-- (begin . 10)
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Ada.Text_IO.Put_LINE ("FUCKNING CDR FOR BEGIN");
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raise Syntax_Error;
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--Pop_Frame (Interp); -- Done
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else
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Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Group);
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Set_Frame_Operand (Interp.Stack, Operand);
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if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
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-- I call Evaluate_Group for optimization here.
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Evaluate_Group; -- for optimization only. not really needed.
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-- I can jump to Start_Over because Evaluate_Group called
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-- above pushes an Opcode_Evaluate_Object frame.
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pragma Assert (Get_Frame_Opcode(Interp.Stack) = Opcode_Evaluate_Object);
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goto Start_Over; -- for optimization only. not really needed.
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end if;
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end if;
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when Define_Syntax =>
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-- (define x 10)
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-- (define (add x y) (+ x y)) -> (define add (lambda (x y) (+ x y)))
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Operand := Cdr; -- Skip "define"
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if not Is_Cons(Operand) then
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-- e.g) (define)
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-- (define . 10)
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Ada.Text_IO.Put_LINE ("FUCKNING CDR FOR DEFINE");
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raise Syntax_Error;
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elsif Get_Cdr(Operand) /= Nil_Pointer then
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-- TODO: IMPLEMENT OTHER CHECK
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null;
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end if;
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--Pop_Frame (Interp); -- Done
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--Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
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-- TODO: IMPLEMENT DEFINE.
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when Lambda_Syntax =>
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-- (lambda (x y) (+ x y));
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Operand := Cdr; -- Skip "lambda"
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if not Is_Cons(Operand) then
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-- e.g) (lambda)
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-- (lambda . 10)
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Ada.Text_IO.Put_LINE ("FUCKNING CDR FOR BEGIN");
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raise Syntax_Error;
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--Pop_Frame (Interp); -- Done
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else
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if not Is_Cons(Get_Car(Operand)) then
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Ada.Text_IO.Put_Line ("INVALID PARRAMETER LIST");
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raise Syntax_Error;
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--Pop_Frame (Interp); -- Done
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end if;
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--Print (Interp, Get_Cdr(Operand));
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if not Is_Cons(Get_Cdr(Operand)) then
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Ada.Text_IO.Put_Line ("NO BODY");
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raise Syntax_Error;
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--Pop_Frame (Interp); -- Done
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end if;
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declare
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Closure: Object_Pointer;
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begin
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Closure := Make_Closure (Interp.Self, Operand, Interp.Environment);
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Pop_Frame (Interp); -- Done
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Chain_Frame_Result (Interp, Interp.Stack, Closure);
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end;
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end if;
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when Quote_Syntax =>
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Operand := Cdr; -- Skip "quote"
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if not Is_Cons(Operand) then
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-- e.g) (quote)
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-- (quote . 10)
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Ada.Text_IO.Put_LINE ("FUCKNING CDR FOR QUOTE");
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raise Syntax_Error;
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elsif Get_Cdr(Operand) /= Nil_Pointer then
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Ada.Text_IO.Put_LINE ("WRONG NUMBER OF ARGUMENTS FOR QUOTE");
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raise Syntax_Error;
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end if;
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Pop_Frame (Interp); -- Done
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Chain_Frame_Result (Interp, Interp.Stack, Get_Car(Operand));
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when others =>
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Ada.Text_IO.Put_Line ("Unknown syntax");
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--Set_Frame_Opcode (Interp.Stack, Opcode_Evaluate_Syntax); -- Switch to syntax evaluation
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raise Internal_Error;
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end case;
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else
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if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
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while not Is_Normal_Pointer(Car) loop
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-- This while block is for optimization only. It's not really needed.
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-- If I know that the next object to evaluate is a literal object,
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-- I can simply reverse-chain it to the return field of the current
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-- frame without pushing another frame dedicated for it.
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-- TODO: some normal pointers may point to a literal object. e.g.) bignum
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Chain_Frame_Result (Interp, Interp.Stack, Car);
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if Is_Cons(Cdr) then
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Operand := Cdr;
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Car := Get_Car(Operand);
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Cdr := Get_Cdr(Operand);
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else
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-- last cons
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Operand := Reverse_Cons(Get_Frame_Result(Interp.Stack));
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Clear_Frame_Result (Interp.Stack);
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Set_Frame_Opcode (Interp.Stack, Opcode_Apply);
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Set_Frame_Operand (Interp.Stack, Operand);
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goto Done;
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end if;
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end loop;
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end if;
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if Is_Cons(Cdr) then
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-- Not the last cons cell yet
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Set_Frame_Operand (Interp.Stack, Cdr); -- change the operand for the next call
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else
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-- Reached the last cons cell
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if Cdr /= Nil_Pointer then
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-- The last CDR is not Nil.
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Ada.Text_IO.Put_Line ("$$$$..................FUCKING CDR.....................$$$$");
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-- raise Syntax_Error;
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end if;
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-- Change the operand to a mark object so that the call to this
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-- procedure after the evaluation of the last car goes to the
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-- Mark_Object case.
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Set_Frame_Operand (Interp.Stack, Interp.Mark);
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end if;
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-- Arrange to evaluate the car object
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if (Interp.Trait.Trait_Bits and No_Optimization) = 0 then
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Push_Frame (Interp, Opcode_Evaluate_Object, Car);
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goto Start_Over; -- for optimization only. not really needed.
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end if;
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end if;
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when Mark_Object =>
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-- TODO: you can use the mark context to differentiate context
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-- Get the evaluation result stored in the current stack frame by
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-- various sub-Opcode_Evaluate_Object frames. the return value
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-- chain must be reversed Chain_Frame_Result reverse-chains values.
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Operand := Reverse_Cons(Get_Frame_Result(Interp.Stack));
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-- Refresh the current stack frame to Opcode_Apply.
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-- This should be faster than Popping the current frame and pushing
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-- a new frame.
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-- Envir := Get_Frame_Environment(Interp.Stack);
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-- Pop_Frame (Interp); -- done
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-- Push_Frame (Interp, Opcode_Apply, Operand, Envir);
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Clear_Frame_Result (Interp.Stack);
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Set_Frame_Opcode (Interp.Stack, Opcode_Apply);
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Set_Frame_Operand (Interp.Stack, Operand);
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when others =>
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-- normal literal object
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goto Literal;
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end case;
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goto Done;
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<<Literal>>
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Pop_Frame (Interp); -- done
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Ada.Text_IO.Put ("Return => ");
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Print (Interp, Operand);
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Chain_Frame_Result (Interp, Interp.Stack, Operand);
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goto Done;
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<<Done>>
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Pop_Tops (Interp, 3);
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end Evaluate_Object;
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procedure Evaluate_Procedure is
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pragma Inline (Evaluate_Procedure);
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begin
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null;
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end Evaluate_Procedure;
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procedure Apply is separate;
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procedure Fetch_Character is
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begin
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-- TODO: calculate Interp.Input.Row, Interp.Input.Column
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if Interp.Input.Pos >= Interp.Input.Last then
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if Interp.Input.Flags /= 0 then
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-- An error has occurred or EOF has been reached previously.
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-- Note calling this procedure after EOF results in an error.
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Interp.Input.Iochar := (Error_Character, Object_Character'First);
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--return;
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raise IO_Error;
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end if;
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Interp.Input.Pos := Interp.Input.Data'First - 1;
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begin
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Read (Interp.Input.Stream.all, Interp.Input.Data, Interp.Input.Last);
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exception
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when others =>
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-- The callee can raise an exception upon errors.
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-- If an exception is raised, data read into the buffer
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-- is also ignored.
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Interp.Input.Flags := Interp.Input.Flags and IO_Error_Occurred;
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Interp.Input.Iochar := (Error_Character, Object_Character'First);
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--return;
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raise IO_Error;
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end;
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if Interp.Input.Last < Interp.Input.Data'First then
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-- The callee must read 0 bytes on EOF
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Interp.Input.Flags := Interp.Input.Flags and IO_End_Reached;
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Interp.Input.Iochar := (End_Character, Object_Character'First);
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return;
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end if;
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end if;
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Interp.Input.Pos := Interp.Input.Pos + 1;
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Interp.Input.Iochar := (Normal_Character, Interp.Input.Data(Interp.Input.Pos));
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end Fetch_Character;
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function Is_White_Space (X: in Object_Character) return Standard.Boolean is
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begin
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return X = Ch.Space or else X = Ch.HT or else X = Ch.VT or else
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X = Ch.CR or else X = Ch.LF or else X = Ch.FF;
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end Is_White_Space;
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function Is_Identifier_Stopper (X: in Object_Character) return Standard.Boolean is
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begin
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return X = Ch.Left_Parenthesis or else X = Ch.Right_Parenthesis or else
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X = Ch.Apostrophe or else LC.Value = Ch.Quotation or else
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X = Ch.Number_Sign or else LC.Value = Ch.Semicolon or else
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Is_White_Space(X);
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end Is_Identifier_Stopper;
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procedure Skip_Spaces_And_Comments is
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begin
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loop
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exit when LC.Kind /= Normal_Character;
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-- Normal character
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if Is_White_Space(LC.Value) then
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Fetch_Character;
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elsif LC.Value = Ch.Semicolon then
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-- Comment.
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loop
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Fetch_Character;
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exit when LC.Kind = End_Character; -- EOF before LF
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if LC.Kind = Normal_Character and then LC.Value = Ch.LF then -- TODO: handle different line ending convention
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Fetch_Character; -- Read the next character after LF
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exit;
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end if;
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end loop;
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else
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exit;
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end if;
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end loop;
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end Skip_Spaces_And_Comments;
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procedure Fetch_Token is
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Tmp: Object_Character_Array(1..10); -- large enough???
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begin
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if not Interp.LC_Unfetched then
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Fetch_Character;
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else
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-- Reuse the last character unfetched
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Interp.LC_Unfetched := Standard.False;
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end if;
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Skip_Spaces_And_Comments;
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if LC.Kind /= Normal_Character then
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Token.Set (Interp, End_Token);
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return;
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end if;
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-- TODO: Pass Token Location when calling Token.Set
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-- Use Ch.Pos.XXX values instead of Ch.XXX values as gnat complained that
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-- Ch.XXX values are not static. For this reason, "case LC.Value is ..."
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-- changed to use Object_Character'Pos(LC.Value).
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case Object_Character'Pos(LC.Value) is
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when Ch.Pos.Left_Parenthesis =>
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Token.Set (Interp, Left_Parenthesis_Token, LC.Value);
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when Ch.Pos.Right_Parenthesis =>
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Token.Set (Interp, Right_Parenthesis_Token, LC.Value);
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when Ch.Pos.Period =>
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Token.Set (Interp, Period_Token, LC.Value);
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when Ch.Pos.Apostrophe =>
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Token.Set (Interp, Single_Quote_Token, LC.Value);
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when Ch.Pos.Quotation =>
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Fetch_Character;
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Token.Set (Interp, String_Token);
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loop
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if LC.Kind /= Normal_Character then
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-- String ended prematurely.
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-- TODO: Set Error code, Error Number.... Error location
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raise Syntax_Error;
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end if;
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if LC.Value = Ch.Backslash then
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Fetch_Character;
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if LC.Kind /= Normal_Character then
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-- String ended prematurely.
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-- TODO: Set Error code, Error Number.... Error location
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raise Syntax_Error;
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end if;
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-- TODO: escape letters??? \n \r \\ etc....
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Token.Append_Character (Interp, LC.Value);
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elsif LC.Value = Ch.Quotation then
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exit;
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else
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Token.Append_Character (Interp, LC.Value);
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Fetch_Character;
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end if;
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end loop;
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when Ch.Pos.Number_Sign =>
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Fetch_Character;
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-- TODO: t, false, etc
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when Ch.Pos.Zero .. Ch.Pos.Nine =>
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-- TODO; negative number, floating-point number, bignum, hexdecimal, etc
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Token.Set (Interp, Integer_Token);
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loop
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Token.Append_Character (Interp, LC.Value);
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Fetch_Character;
|
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if LC.Kind /= Normal_Character or else
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LC.Value not in Ch.Zero .. Ch.Nine then
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-- Unfetch the last character
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Interp.LC_Unfetched := Standard.True;
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exit;
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end if;
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end loop;
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when Ch.Pos.Plus_Sign | Ch.Pos.Minus_Sign =>
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Tmp(1) := LC.Value;
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Fetch_Character;
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if LC.Kind = Normal_Character and then
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LC.Value in Ch.Zero .. Ch.Nine then
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Token.Set (Interp, Integer_Token, Tmp(1..1));
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loop
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Token.Append_Character (Interp, LC.Value);
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Fetch_Character;
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if LC.Kind /= Normal_Character or else
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LC.Value not in Ch.Zero .. Ch.Nine then
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-- Unfetch the last character
|
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Interp.LC_Unfetched := Standard.True;
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exit;
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end if;
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end loop;
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else
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Token.Set (Interp, Identifier_Token, Tmp(1..1));
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loop
|
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-- TODO: more characters
|
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if LC.Kind /= Normal_Character or else
|
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Is_Identifier_Stopper(LC.Value) then
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-- Unfetch the last character
|
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Interp.LC_Unfetched := Standard.True;
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exit;
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end if;
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|
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Token.Append_Character (Interp, LC.Value);
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Fetch_Character;
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end loop;
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end if;
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|
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when others =>
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Token.Set (Interp, Identifier_Token);
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loop
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Token.Append_Character (Interp, LC.Value);
|
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Fetch_Character;
|
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--exit when not Is_Ident_Char(C.Value);
|
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-- TODO: more characters
|
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if LC.Kind /= Normal_Character or else
|
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Is_Identifier_Stopper(LC.Value) then
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-- Unfetch the last character
|
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Interp.LC_Unfetched := Standard.True;
|
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exit;
|
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end if;
|
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end loop;
|
|
end case;
|
|
|
|
--Ada.Text_IO.Put (">>>>>>>>>>>>>>>>>>>>>>> Token: " & Interp.Token.Value.Ptr(1..Interp.Token.Value.Last));
|
|
end Fetch_Token;
|
|
|
|
procedure Read_List is
|
|
pragma Inline (Read_List);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
-- This procedure reads each token in a list.
|
|
-- If the list contains no period, this procedure reads up to the
|
|
-- closing right paranthesis; If a period is contained, it transfers
|
|
-- the control over to Read_List_Cdr.
|
|
|
|
Fetch_Token;
|
|
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
case Interp.Token.Kind is
|
|
when End_Token =>
|
|
Ada.Text_IO.Put_Line ("ERROR: PREMATURE LIST END");
|
|
raise Syntax_Error;
|
|
|
|
when Left_Parenthesis_Token =>
|
|
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
|
|
|
|
when Right_Parenthesis_Token =>
|
|
V := Get_Frame_Result(Interp.Stack);
|
|
if V /= Nil_Pointer then
|
|
V := Reverse_Cons(V);
|
|
end if;
|
|
Pop_Frame (Interp);
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when Period_Token =>
|
|
V := Get_Frame_Result(Interp.Stack);
|
|
if V = Nil_Pointer then
|
|
-- . immediately after (
|
|
raise Syntax_Error;
|
|
else
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_Cdr);
|
|
end if;
|
|
|
|
when Single_Quote_Token =>
|
|
Push_Frame (Interp, Opcode_Close_Quote, Nil_Pointer);
|
|
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
|
|
|
|
when Integer_Token =>
|
|
-- TODO: bignum
|
|
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when String_Token =>
|
|
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when Identifier_Token =>
|
|
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when others =>
|
|
-- TODO: set various error info
|
|
raise Syntax_Error;
|
|
end case;
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Read_List;
|
|
|
|
procedure Read_List_Cdr is
|
|
pragma Inline (Read_List_Cdr);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
-- This procedure reads the first token after a period has been read.
|
|
-- It transfers the control over to Read_List_End once it has read
|
|
-- and processed the token. It chains the value made of the token
|
|
-- to the front of the frame's return value list expecting Read_List_End
|
|
-- to handle the head item specially.
|
|
Fetch_Token;
|
|
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
case Interp.Token.Kind is
|
|
when End_Token =>
|
|
Ada.Text_IO.Put_Line ("ERROR: PREMATURE LIST END");
|
|
raise Syntax_Error;
|
|
|
|
when Left_Parenthesis_Token =>
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
|
|
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
|
|
|
|
when Single_Quote_Token =>
|
|
Ada.Text_IO.Put_Line ("ERROR: CDR QUOT LIST END");
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
|
|
Push_Frame (Interp, Opcode_Close_Quote, Nil_Pointer);
|
|
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
|
|
|
|
when Integer_Token =>
|
|
-- TODO: bignum
|
|
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when String_Token =>
|
|
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when Identifier_Token =>
|
|
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Read_List_End);
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when others =>
|
|
-- TODO: set various error info
|
|
raise Syntax_Error;
|
|
end case;
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Read_List_Cdr;
|
|
|
|
procedure Read_List_End is
|
|
pragma Inline (Read_List_End);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
Fetch_Token;
|
|
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
case Interp.Token.Kind is
|
|
when Right_Parenthesis_Token =>
|
|
V := Get_Frame_Result(Interp.Stack);
|
|
pragma Assert (V /= Nil_Pointer);
|
|
-- The first item in the chain is actually Cdr of the last cell.
|
|
V := Reverse_Cons(Get_Cdr(V), Get_Car(V));
|
|
Pop_Frame (Interp);
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
when others =>
|
|
raise Syntax_Error;
|
|
end case;
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Read_List_End;
|
|
|
|
procedure Close_List is
|
|
pragma Inline (Close_List);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
V := Get_Frame_Result(Interp.Stack);
|
|
pragma Assert (Get_Cdr(V) = Nil_Pointer);
|
|
Pop_Frame (Interp); -- Done with the current frame
|
|
Chain_Frame_Result (Interp, Interp.Stack, Get_Car(V));
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Close_List;
|
|
|
|
procedure Close_Quote is
|
|
pragma Inline (Close_Quote);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
-- TODO: use Interp.Quote_Syntax instead of Make_Symbol("quote")
|
|
Chain_Frame_Result (Interp, Interp.Stack, Make_Symbol(Interp.Self, Label_Quote));
|
|
V := Get_Frame_Result(Interp.Stack);
|
|
Pop_Frame (Interp); -- Done with the current frame
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Close_Quote;
|
|
|
|
procedure Read_Object is
|
|
pragma Inline (Read_Object);
|
|
V: aliased Object_Pointer;
|
|
begin
|
|
Fetch_Token;
|
|
|
|
--Push_Top (Interp, V'Unchecked_Access);
|
|
|
|
case Interp.Token.Kind is
|
|
when End_Token =>
|
|
Ada.Text_IO.Put_Line ("INFO: NO MORE TOKEN ");
|
|
raise Stream_End_Error;
|
|
|
|
when Left_Parenthesis_Token =>
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Close_List);
|
|
Push_Frame (Interp, Opcode_Read_List, Nil_Pointer);
|
|
|
|
when Single_Quote_Token =>
|
|
Set_Frame_Opcode (Interp.Stack, Opcode_Close_Quote);
|
|
Push_Frame (Interp, Opcode_Read_Object, Nil_Pointer);
|
|
|
|
when Integer_Token =>
|
|
-- TODO: bignum
|
|
V := String_To_Integer_Pointer(Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Pop_Frame (Interp); -- Done with the current frame
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when String_Token =>
|
|
V := Make_String (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Pop_Frame (Interp); -- Done with the current frame
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when Identifier_Token =>
|
|
V := Make_Symbol (Interp.Self, Interp.Token.Value.Ptr.all(1..Interp.Token.Value.Last));
|
|
Pop_Frame (Interp); -- Done with the current frame
|
|
Chain_Frame_Result (Interp, Interp.Stack, V);
|
|
|
|
when others =>
|
|
-- TODO: set various error info
|
|
raise Syntax_Error;
|
|
end case;
|
|
|
|
--Pop_Tops (Interp, 1);
|
|
end Read_Object;
|
|
|
|
begin
|
|
|
|
-- Stack frames looks like this upon initialization
|
|
--
|
|
-- | Opcode | Operand | Result
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | Source | Nil
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- For a source (+ 1 2), it should look like this.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | Source | Nil
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The operand changes to the cdr of the source.
|
|
-- The symbol '+' is pushed to the stack with Opcode_Evaluate_Object.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | + | Nil
|
|
-- | Opcode_Evaluate_Object | (1 2) | Nil
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- After the evaluation of the symbol, the pushed frame is removed
|
|
-- and the result is set to the return field.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | (1 2) | (#Proc+)
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The same action is taken to evaluate the literal 1.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | 1 | Nil
|
|
-- | Opcode_Evaluate_Object | (2) | (#Proc+)
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The result of the valuation is reverse-chained to the return field.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | (2) | (1 #Proc+)
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The same action is taken to evaluate the literal 2.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | 2 | Nil
|
|
-- | Opcode_Evaluate_Object | Mark | (1 #Proc+)
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The result of the valuation is reverse-chained to the return field.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Opcode_Evaluate_Object | Mark | (2 1 #Proc+)
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- Once evluation of each cons cell is complete, switch the top frame
|
|
-- to 'Apply' reversing the result field into the operand field and
|
|
-- nullifying the result field afterwards.
|
|
-- -----------------------------------------------------------------
|
|
-- top | Apply | (#Proc+ 1 2) | Nil
|
|
-- bottom | Opcode_Exit | Nil | Nil
|
|
--
|
|
-- The apply operation produces the final result and sets it to the
|
|
-- parent frame while removing the apply frame.
|
|
-- -----------------------------------------------------------------
|
|
-- top/bottom| Opcode_Exit | Nil | (3)
|
|
|
|
-- The caller must push some frames before calling this procedure
|
|
pragma Assert (Interp.Stack /= Nil_Pointer);
|
|
|
|
-- The caller must ensure there are no temporary object pointers.
|
|
pragma Assert (Interp.Top.Last < Interp.Top.Data'First);
|
|
|
|
loop
|
|
case Get_Frame_Opcode(Interp.Stack) is
|
|
when Opcode_Exit =>
|
|
exit;
|
|
|
|
when Opcode_Evaluate_Result =>
|
|
Evaluate_Result;
|
|
|
|
when Opcode_Evaluate_Object =>
|
|
Evaluate_Object;
|
|
|
|
when Opcode_Evaluate_Group =>
|
|
Evaluate_Group;
|
|
|
|
when Opcode_Evaluate_Procedure =>
|
|
Evaluate_Procedure;
|
|
|
|
when Opcode_Apply =>
|
|
Apply;
|
|
|
|
when Opcode_Read_Object =>
|
|
Read_Object;
|
|
|
|
when Opcode_Read_List =>
|
|
Read_List;
|
|
|
|
when Opcode_Read_List_Cdr =>
|
|
Read_List_Cdr;
|
|
|
|
when Opcode_Read_List_End =>
|
|
Read_List_End;
|
|
|
|
when Opcode_Close_List =>
|
|
Close_List;
|
|
|
|
when Opcode_Close_Quote =>
|
|
Close_Quote;
|
|
|
|
end case;
|
|
end loop;
|
|
|
|
exception
|
|
when Stream_End_Error =>
|
|
Ada.Text_IO.Put_Line ("INFO: NO MORE TOKEN .............");
|
|
raise;
|
|
|
|
when others =>
|
|
Ada.Text_IO.Put_Line ("EXCEPTION OCCURRED");
|
|
-- TODO: restore stack frame???
|
|
-- TODO: restore envirronemtn frame???
|
|
raise;
|
|
end Execute;
|