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top - downloadIndex: ┃ B T ┃
Length: 2588 (0xa1c)
Types: TextFile
Names: »B«
└─⟦2f6cfab89⟧ Bits:30000547 8mm tape, Rational 1000, !projects 94-01-04
└─ ⟦d65440be7⟧ »DATA«
└─⟦this⟧
with Object;
with Scanner;
with Value;
package body Expression is
type Node_Structure is
record
Rule : Natural range 1 .. 2;
Ident : Scanner.Lexeme := Scanner.Empty_Lexeme;
Value : Value.Node := Value.Empty_Node;
end record;
procedure Parse (N : in out Node; Error : out Boolean) is
Failed : Boolean := False;
begin
if Value.Is_First (Scanner.Get_Token) then
N := new Node_Structure;
N.Rule := 1;
Value.Parse (N.Value, Failed);
else
case Scanner.Get_Token is
when Scanner.L_Pour =>
Scanner.Next_Token;
case Scanner.Get_Token is
when Scanner.L_Id =>
N := new Node_Structure;
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
Value.Parse (N.Value, Failed);
else
Failed := True;
end if;
when others =>
Failed := True;
end case;
when others =>
Failed := True;
end case;
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 = Scanner.L_Pour or else Value.Is_First (T);
end Is_First;
function Interpret (N : Node;
Inherited : Object.Reference := Object.Void_Reference)
return Object.Reference is
Result : Object.Reference;
begin
case N.Rule is
when 0 =>
Result := Inherited;
when 1 =>
Result := Expression.Interpret (N.Expr);
Result := More_Statements.Interpret (N.More, Result);
when 2 =>
Result := Expression.Interpret (N.Expr);
end case;
return Result;
end Interpret;
end Expression;