(unknown charset) [BLACKBOX] Question about Meta.LookupPath

From: (unknown charset) unknown charset <no email>
Date: Thu, 11 Jul 2013 20:05:20 +0400

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Hi there.

Some time ago I started a small project, that included SQL routines via
SqlDB services.
Among other features, my project includes some interaction of SqlDB module
and global record variable field, that can be addressed by usage of symbol
":"
For example: SELECT * FROM divisions WHERE id = :PrivMod.rec.id

The point is that PrivMod.rec is ANYPTR that is dynamically initialized
during system work.
But I am always sure that if rec#NIL real object contains exported .id
field.

Unfortunatly, magic is broken :( because of strange limitation of
Meta.LookupPath procedure, used in SqlDB.Compile.

I've performed some tests and found than LookupPath cannot actually find
the "PrivMod.rec.id" if rec: ANYPTR, rec#NIL and rec(MyMod.MyType).id
exists.
Obviously, Meta mechanisms itself finds this field easily, trouble in the
LookupPath procedure.

I've prepared some demo fix:

Original:
> PROCEDURE LookupPath* (IN path: ARRAY OF CHAR; OUT i: Item);
> VAR j, n: INTEGER; name: Name; ch: CHAR; done: BOOLEAN; filter:
> FilterHook;
> BEGIN
> done := FALSE; filter := filterHook;
> WHILE ~done & (filter # NIL) DO filter.filter(path, i, done); filter :=
> filter.next END;
> IF ~done THEN
> j := 0;
> GetName(path, name, j);
> Lookup(name, i);
> IF (i.obj = modObj) & (path[j] = ".") THEN
> INC(j); GetName(path, name, j);
> i.Lookup(name, i); ch := path[j]; INC(j);
> WHILE (i.obj = varObj) & (ch # 0X) DO
> IF i.typ = ptrTyp THEN i.Deref(i) END;
> IF ch = "." THEN
> GetName(path, name, j);
> IF i.typ = recTyp THEN i.Lookup(name, i) ELSE SetUndef(i) END
> ELSIF ch = "[" THEN
> n := 0; ch := path[j]; INC(j);
> WHILE (ch >= "0") & (ch <= "9") DO n := 10 * n + ORD(ch) -
> ORD("0"); ch := path[j]; INC(j) END;
> IF (ch = "]") & (i.typ = arrTyp) THEN i.Index(n, i) ELSE
> SetUndef(i) END
> END;
> ch := path[j]; INC(j)
> END
> END
> END
> END LookupPath;

My fix:
> PROCEDURE LookupPath* (IN path: ARRAY OF CHAR; OUT i: Item);
> VAR j, n: INTEGER; name: Name; ch: CHAR; done: BOOLEAN; filter:
> FilterHook;
> BEGIN
> done := FALSE; filter := filterHook;
> WHILE ~done & (filter # NIL) DO filter.filter(path, i, done); filter :=
> filter.next END;
> IF ~done THEN
> j := 0;
> GetName(path, name, j);
> Lookup(name, i);
> IF (i.obj = modObj) & (path[j] = ".") THEN
> INC(j); GetName(path, name, j);
> i.Lookup(name, i); ch := path[j]; INC(j);
> WHILE (i.obj = varObj) & (ch # 0X) DO
> IF i.typ = ptrTyp THEN i.Deref(i) END;
> IF ch = "." THEN
> GetName(path, name, j);
> CASE i.typ OF
> recTyp: i.Lookup(name, i)
> |ptrTyp, anyPtrTyp: i.Deref(i);
> ASSERT(i.obj=varObj, 40);
> i.Lookup(name, i)
> ELSE SetUndef(i) END
> ELSIF ch = "[" THEN
> n := 0; ch := path[j]; INC(j);
> WHILE (ch >= "0") & (ch <= "9") DO n := 10 * n + ORD(ch) -
> ORD("0"); ch := path[j]; INC(j) END;
> IF (ch = "]") & (i.typ = arrTyp) THEN i.Index(n, i) ELSE
> SetUndef(i) END
> END;
> ch := path[j]; INC(j)
> END
> END
> END
> END LookupPath;

So, i wonder if someone knows what was the reason of such limitation and
is it possible to accumulate such fix in further versions of BB (rc7,
maybe :D )

Best regards.

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Received on Thu Jul 11 2013 - 18:05:20 UTC