From: Wojciech Meyer <wojciech.meyer@googlemail.com>
To: emacs-devel@gnu.org
Subject: Re: Problems with xml-parse-string
Date: Fri, 24 Sep 2010 18:34:05 +0100 [thread overview]
Message-ID: <AANLkTikpJ9Q+M8LwwDbj91kjugroJvA6zv6Wo+rs_MP2@mail.gmail.com> (raw)
In-Reply-To: <m31v8jgkdo.fsf@quimbies.gnus.org>
Sorry, I don't underdand your point at all. did you hear about
abstract data structures?
On 9/24/10, Lars Magne Ingebrigtsen <larsi@gnus.org> wrote:
> Chong Yidong <cyd@stupidchicken.com> writes:
>
>>> The main difference between sxml and xml.el output is that it has the
>>> weird an unnecessary "@" node for the attributes and that it wastes a
>>> cons in the attributes, isn't it?
>>
>> The xml.el output always has an alist for attributes after each tag; if
>> there are no attributes, the element after the tag name is nil. In
>> sxml, the `@' denotes an attribute list, which is omitted if no
>> attributes exist.
>
> Yes. So it's yet another irregularity you have to check for.
>
> To take a concrete example: You want the src of the img node you have.
>
> xml.el: (cdr (assq 'img (cadr node)))
> sxml.el: (if (and (consp (cadr node))
> (eq (caadr node) '@))
> (cadr (assq 'img node)))
>
> (And I'm not even sure that's correct. It's probably not. Which is my
> point.)
>
> libxml: (cdr (assq :img (cdr node)))
>
> (The difference between libxml and xml.c for attributes is minuscule.)
>
>>> Other than that it has the same problem that xml.el has, in that text
>>> nodes have to be special-cased, so you can't say assq or use simple
>>> descent without testing.
>>
>> It is illogical to criticize sxml for wasting conses, while arguing for
>> wrapping each text node in a cons.
>
> No, it is not. I'm sacrificing space for speed and regularity. sxml
> wasting cons cells, and adding slowdowns at the same time.
>
>> Anyway, it is difficult to see how real the problem is without a
>> concrete example. Could you provide one? I suspect that the real
>> problem, if one exists, is Elisp's relatively weak support for list
>> mapping and reduction; if that's the case, the correct solution is to
>> pull in some of the relevant functions from the CL package.
>
> Here's a pretty piece of code, chosen at random:
>
> (defun nnrss-find-el (tag data &optional found-list)
> "Find the all matching elements in the data.
> Careful with this on large documents!"
> (when (consp data)
> (dolist (bit data)
> (when (car-safe bit)
> (when (equal tag (car bit))
> ;; Old xml.el may return a list of string.
> (when (and (consp (caddr bit))
> (stringp (caaddr bit)))
> (setcar (cddr bit) (caaddr bit)))
> (setq found-list
> (append found-list
> (list bit))))
> (if (and (consp (car-safe (caddr bit)))
> (not (stringp (caddr bit))))
> (setq found-list
> (append found-list
> (nnrss-find-el
> tag (caddr bit))))
> (setq found-list
> (append found-list
> (nnrss-find-el
> tag (cddr bit))))))))
> found-list)
>
> The horror!
>
> --
> (domestic pets only, the antidote for overdose, milk.)
> larsi@gnus.org * Lars Magne Ingebrigtsen
>
>
>
--
Sent from my mobile device
next prev parent reply other threads:[~2010-09-24 17:34 UTC|newest]
Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 18:11 Problems with xml-parse-string Leo
2010-09-14 18:24 ` Lars Magne Ingebrigtsen
2010-09-14 21:18 ` Stefan Monnier
2010-09-15 8:06 ` Lars Magne Ingebrigtsen
2010-09-15 8:51 ` Stefan Monnier
2010-09-15 9:21 ` Lars Magne Ingebrigtsen
2010-09-15 9:54 ` Leo
2010-09-15 10:16 ` Julien Danjou
2010-09-15 15:58 ` Chad Brown
2010-09-21 23:00 ` Chong Yidong
2010-09-21 23:24 ` Leo
2010-09-22 2:26 ` Chong Yidong
2010-09-22 3:15 ` Chong Yidong
2010-09-22 7:14 ` Stefan Monnier
2010-09-22 10:35 ` Lars Magne Ingebrigtsen
2010-09-22 10:58 ` Lars Magne Ingebrigtsen
2010-09-22 11:00 ` Leo
2010-09-22 11:09 ` Lars Magne Ingebrigtsen
2010-09-22 11:41 ` Lars Magne Ingebrigtsen
2010-09-22 11:55 ` Wojciech Meyer
2010-09-22 12:09 ` Lars Magne Ingebrigtsen
2010-09-22 12:17 ` Wojciech Meyer
2010-09-22 12:18 ` Lars Magne Ingebrigtsen
2010-09-22 12:20 ` Wojciech Meyer
2010-09-22 12:26 ` Lars Magne Ingebrigtsen
2010-09-22 12:34 ` Wojciech Meyer
2010-09-22 12:46 ` Lars Magne Ingebrigtsen
2010-09-22 12:45 ` Leo
2010-09-22 13:14 ` Lars Magne Ingebrigtsen
2010-09-22 14:07 ` Chong Yidong
2010-09-22 15:04 ` Eli Zaretskii
2010-09-22 23:59 ` Stefan Monnier
2010-09-23 5:53 ` Leo
2010-09-23 15:43 ` Chong Yidong
2010-09-23 16:53 ` Leo
2010-09-23 21:58 ` Wojciech Meyer
2010-09-23 22:21 ` Lars Magne Ingebrigtsen
2010-09-24 0:04 ` Stefan Monnier
2010-09-24 0:06 ` Lars Magne Ingebrigtsen
2010-09-24 1:09 ` Chong Yidong
2010-09-24 2:46 ` David De La Harpe Golden
2010-09-24 5:38 ` David Kastrup
2010-09-24 8:02 ` Eli Zaretskii
2010-09-24 10:47 ` Wojciech Meyer
2010-09-24 10:44 ` Wojciech Meyer
2010-09-24 10:49 ` Lars Magne Ingebrigtsen
2010-09-24 15:25 ` Chong Yidong
2010-09-24 15:53 ` Lars Magne Ingebrigtsen
2010-09-24 16:26 ` Chong Yidong
2010-09-24 16:46 ` Lars Magne Ingebrigtsen
2010-09-24 17:34 ` Wojciech Meyer [this message]
2010-09-24 18:09 ` Frank Schmitt
2010-09-24 18:21 ` Ted Zlatanov
2010-09-24 18:31 ` Wojciech Meyer
2010-09-24 18:47 ` Chong Yidong
2010-09-24 18:53 ` Chong Yidong
2010-09-24 18:58 ` Wojciech Meyer
2010-09-24 19:06 ` Lars Magne Ingebrigtsen
2010-09-24 19:25 ` Chong Yidong
2010-09-24 19:34 ` Lars Magne Ingebrigtsen
2010-09-24 21:57 ` Chong Yidong
2010-09-25 13:11 ` Lars Magne Ingebrigtsen
2010-09-25 13:31 ` Eli Zaretskii
2010-09-25 13:56 ` David Kastrup
2010-09-25 13:59 ` Wojciech Meyer
2010-09-25 16:13 ` Eli Zaretskii
2010-09-25 16:46 ` Wojciech Meyer
2010-09-25 22:29 ` Juanma Barranquero
2010-09-25 15:00 ` Chong Yidong
2010-09-24 22:01 ` Stefan Monnier
2010-09-24 22:17 ` Chong Yidong
2010-09-25 0:25 ` Wojciech Meyer
2010-09-25 14:42 ` Andy Wingo
2010-09-25 15:12 ` Leo
2010-09-25 15:21 ` Leo
2010-09-25 15:42 ` Wojciech Meyer
2010-09-25 20:02 ` Stefan Monnier
2010-09-25 20:32 ` Leo
2010-09-25 23:08 ` Leo
2010-09-26 21:55 ` Stefan Monnier
2010-09-26 23:34 ` Leo
2010-09-26 3:48 ` pcase.el (was: Problems with xml-parse-string) Ted Zlatanov
2010-09-26 22:06 ` pcase.el Stefan Monnier
2010-09-27 16:59 ` pcase.el Leo
2010-09-27 22:51 ` pcase.el Stefan Monnier
2010-09-28 18:17 ` pcase.el Ted Zlatanov
2010-09-24 23:43 ` Problems with xml-parse-string Andrew W. Nosenko
2010-09-23 2:16 ` Kevin Rodgers
2010-09-22 14:05 ` Chong Yidong
2010-09-22 14:32 ` Lars Magne Ingebrigtsen
2010-09-22 15:46 ` Chong Yidong
2010-09-22 16:12 ` Lars Magne Ingebrigtsen
2010-09-22 16:51 ` Wojciech Meyer
2010-09-22 18:06 ` Chong Yidong
2010-09-22 18:14 ` Edward O'Connor
2010-09-22 18:34 ` Leo
2010-09-22 18:41 ` Chong Yidong
2010-09-22 19:57 ` Wojciech Meyer
2010-09-22 18:06 ` Andy Wingo
2010-09-22 23:48 ` Stefan Monnier
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