Ludovic Courtès escreveu:
> Hello,
>
> This is a followup to this discussion:
>
> http://thread.gmane.org/gmane.lisp.guile.devel/7194
>
> The attached patch changes several list-related functions so that they
> don't validate their input with `SCM_VALIDATE_LIST ()' since it's O(n).
>
> A side-effect (besides performance improvements) is that all these
> functions will now happily traverse circular lists, and will silently
> deal with dotted lists. This is acceptable behavior IMO.
>
> Nevertheless, the second patch below implements the "tortoise and the
> hare" in `list-copy' so that it detects circular list; it seems
> worthwhile to check that here since `list-copy' would otherwise exhaust
> memory.
>
> (Note that SRFI-1's `list-copy' *does* accept improper lists, including
> circular lists, although SRFI-1 does not explicitly mention that it
> should handle improper list.)
>
> Also, in some cases, the `wrong-type-arg' message is different (but the
> exception key is the same).
>
> OK to apply to both branches?
- return scm_c_memq (x, lst);
+ for (; !SCM_NULL_OR_NIL_P (lst); lst = SCM_CDR (lst))
+ {
+ SCM_VALIDATE_CONS (2, lst);
Looks cleaner to use SCM_CONS_P (or whatever it is called) as loop guard,
so it is obviously correct, and crash if the lst is not properly terminated
after the loop (- perhaps only if we're not compiling in optimizing mode).
On a tangent, is anyone still seriously considering to run Emacs atop GUILE?
(It looks a bit like a travesty if we're trying to accomodate elisp while
also trying to follow standards like SRFI-x and RxRS)
- SCM from_here;
+ SCM from_here, hare;
you could do the init to lst right here. IMO it's neater not to have
uninitialized
memory locations during program execution.
;;;; list.test --- tests guile's lists -*- scheme -*-
-;;;; Copyright (C) 2000, 2001, 2006 Free Software Foundation, Inc.
+;;;; Copyright (C) 2000, 2001, 2006, 2008 Free Software Foundation, Inc.
Can we do this in one fell swoop, adding 2008 to all files? After all
publishing
a commit is a release in some sense. Then, we don't have to worry about the
file
headers anymore.
--
Han-Wen Nienhuys - [EMAIL PROTECTED] - http://www.xs4all.nl/~hanwen
