DataMuseum.dk

top - download

    Length: 1795 (0x703)
    Types: TextFile
    Names: »B«

└─⟦f64eaa120⟧ Bits:30000752 8mm tape, Rational 1000, !projects 93 02 16
    └─ ⟦6f12a12be⟧ »DATA« 
        └─⟦this⟧ 

TextFile

with Expression, More_Statements, Scanner, Objects;
package body Statements is

    type Node_Structure is
        record
            Rule : Natural range 0 .. 2 := 0;
            Expr : Expression.Node := Expression.Empty_Node;
            More : More_Statements.Node := More_Statements.Empty_Node;
        end record;

    procedure Parse (N : in out Node; Error : out Boolean) is
        Failed : Boolean := True;
    begin
        N := new Node_Structure;
        if Expression.Is_First (Scanner.Symbol) then
            N.Rule := 1;
            Expression.Parse (N.Expr, Failed);
            if not Failed then
                More_Statements.Parse (N.More, Failed);
            end if;
        else
            N.Rule := 2;
            case Scanner.Symbol is
                when Scanner.Renvoyer =>
                    Expression.Parse (N.Expr, Failed);
                when others =>
                    Failed := True;
            end case;
        end if;
        Error := Failed;
    end Parse;


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


    function Interpret (N : Node) return Objects.Reference is
        Result : Objects.Reference := Objects.Void_Reference;
        use More_Statements;
    begin
        case N.Rule is
            when 0 =>
                null;
            when 1 =>
                Result := Expression.Interpret (N.Expr);
                if N.More /= More_Statements.Empty_Node then
                    Result := More_Statements.Interpret (N.More);
                end if;
            when 2 =>
                Result := Expression.Interpret (N.Expr);
        end case;
        return Result;
    end Interpret;

end Statements;