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    Length: 3143 (0xc47)
    Types: TextFile
    Names: »B«

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

TextFile

with Value, Scanner, Object, Message, Symbol,
     String_Class, Printer, Bug, Table, Block;
package body Expression is

    type Node_Structure is
        record
            Rule : Natural range 0 .. 1 := 0;
            Iden : Message.Tiny_String;  
            Val : Value.Node := Value.Empty_Node;  
            Line : Natural;
        end record;

    procedure Parse (N : in out Node) is
        use Scanner;  
        A_Object : Object.Reference;  
        Object_Exist : Boolean;
    begin  
        N := new Node_Structure;
        N.Line := Scanner.Get_Line_Number;
        if Scanner.Get_Token = Scanner.T_Pour then
            N.Rule := 0;
            Scanner.Next;
            N.Iden := Scanner.Get_Value;
            Table.Find (The_Table => Block.Symbol (Block.Current),
                        Name => N.Iden,
                        New_Reference => A_Object,
                        Success => Object_Exist);
            if not Object_Exist then
                Symbol.Insert (N.Iden, Object.Void_Reference);
            end if;
            Scanner.Next;
            if Scanner.Get_Token = T_Prendre then
                Scanner.Next;
                Value.Parse (N.Val);
            else
                raise Bug.Missing_Reserved_Word;
            end if;
        else
            N.Rule := 1;
            Value.Parse (N.Val);
        end if;
    end Parse;

    procedure Unparse (N : in Node) is
    begin
        Scanner.Set_Line_Number (N.Line);
        case N.Rule is
            when 0 =>
                Printer.Write ("pour");
                Printer.Write (N.Iden);
                Printer.Write ("prendre");
                Value.Unparse (N.Val);
            when 1 =>
                Value.Unparse (N.Val);
        end case;
    end Unparse;

    function Is_First (T : Scanner.Token) return Boolean is
        use Scanner;
    begin
        case T is
            when Scanner.T_Pour | Scanner.T_Integer |
                 Scanner.T_Identifier | Scanner.T_Parenthese_Open |
                 Scanner.T_Block_Open | Scanner.T_String =>
                return (Standard.True);
            when others =>
                return (Standard.False);
        end case;

    end Is_First;

    function Interpret (N : Node) return Object.Reference is
        Result, A_Object : Object.Reference;

    begin  
        Scanner.Set_Line_Number (N.Line);
        case N.Rule is
            when 0 =>
                Result := Value.Interpret (N.Val);
                A_Object := Symbol.Eval (N.Iden);
                case Object.Get_Class (A_Object) is
                    when Object.String_Class =>  
                        String_Class.Remove (A_Object);
                    when Object.Date_Class =>
                        raise Bug.Unexpected_Action_On_Date;
                    when others =>
                        null;
                end case;
                Object.Copy (Source => Result, Target => A_Object);
                Symbol.Insert (N.Iden, A_Object);
            when 1 =>  
                Result := Value.Interpret (N.Val);
        end case;
        return Result;
    end Interpret;
end Expression;