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    Length: 3884 (0xf2c)
    Types: TextFile
    Names: »B«

└─⟦a7d1ea751⟧ Bits:30000550 8mm tape, Rational 1000, !users!projects 94_04_11
    └─⟦129cab021⟧ »DATA« 
        └─⟦this⟧ 

TextFile

with Block_Class;
with Bounded_String;
with Custom;
with Errors;
with Trace;
with Unparser;
with Value;

package body Expression is

    type Node_Structure is
        record
            Line : Natural;
            Rule : Natural range 1 .. 2;
            Ident : Scanner.Lexeme;
            Val : Value.Node := Value.Empty_Node;
        end record;

    procedure Parse (N : in out Node) is
    begin
        Trace.Display ("parsing Expression");
        N := new Node_Structure;
        N.Line := Scanner.Get_Line_Number;
        if Value.Is_First (Scanner.Get_Token) then
            N.Rule := 1;
            Value.Parse (N.Val);
        else
            case Scanner.Get_Token is
                when Scanner.L_Pour =>
                    Scanner.Next_Token;
                    case Scanner.Get_Token is
                        when Scanner.L_Id =>
                            N.Rule := 2;
                            N.Ident := Scanner.Get_Value;
                            Scanner.Next_Token;
                            case Scanner.Get_Token is
                                when Scanner.L_Pren =>
                                    Scanner.Next_Token;
                                    if Value.Is_First (Scanner.Get_Token) then
                                        if not Custom.Is_Predefined_Id
                                                  (Bounded_String.Image
                                                      (N.Ident)) then
                                            if not Block_Class.
                                                   Table_Created then
                Block_Class.New_Symbols_Table;  
                                            end if;
                                            Block_Class.Init_Symbol (N.Ident);
                                        end if;
                                        Value.Parse (N.Val);
                                    else
                                        raise Errors.
                                                 Expecting_Value_After_Prendre;
                                    end if;
                                when others =>
                                    raise Errors.Expecting_Prendre_After_Id;
                            end case;
                        when others =>
                            raise Errors.Expecting_Id_After_Pour;
                    end case;
                when others =>
                    raise Errors.Expecting_Pour_Or_Value;
            end case;
        end if;
    end Parse;

    procedure Unparse (N : Node) is
    begin
        case N.Rule is
            when 1 =>
                Value.Unparse (N.Val);
            when 2 =>
                Unparser.Put ("Pour ");
                Unparser.Put (N.Ident);
                Unparser.Put (" prendre ");
                Value.Unparse (N.Val);
        end case;
        Trace.Display ("fin unparse Expression");
    end Unparse;

    function Is_First (T : Scanner.Token) return Boolean is
        use Scanner;
    begin
        return T = Scanner.L_Pour or else Value.Is_First (T);
    end Is_First;

    function Interpret (N : Node) return Object.Reference is
        Result : Object.Reference;
    begin
        Errors.Save_Interpret_Line (N.Line);
        case N.Rule is
            when 1 =>
                Result := Value.Interpret (N.Val);
            when 2 =>
                if not Custom.Is_Predefined_Id
                          (Bounded_String.Image (N.Ident)) then
                    Result := Value.Interpret (N.Val);
                    Block_Class.Set_Value (N.Ident, Result);
                else
                    raise Errors.Affectation_To_Predefined_Id;
                end if;
        end case;
        Trace.Display ("fin interpretation Expression");
        Trace.Display (Result);
        return Result;
    end Interpret;

end Expression;