From: Eli Zaretskii <eliz@gnu.org>
To: "Stephen J. Turnbull" <stephen@xemacs.org>
Cc: dak@gnu.org, emacs-devel@gnu.org
Subject: Re: Compiling Elisp to a native code with a GCC plugin
Date: Fri, 17 Sep 2010 22:57:13 +0200 [thread overview]
Message-ID: <83wrqkytp2.fsf@gnu.org> (raw)
In-Reply-To: <87hbhoxkuw.fsf@uwakimon.sk.tsukuba.ac.jp>
> From: "Stephen J. Turnbull" <stephen@xemacs.org>
> Date: Sat, 18 Sep 2010 03:53:27 +0900
> Cc: emacs-devel@gnu.org
>
> Actually, there's an exceptional case: if both strings are pure ASCII.
> In that case it might be possible that one string is multibyte and the
> other unibyte, while the numbers of characters and of bytes are equal.
A unibyte string in Emacs has its `size_byte' member set to a negative
value:
/* Mark STR as a unibyte string. */
#define STRING_SET_UNIBYTE(STR) \
do { if (EQ (STR, empty_multibyte_string)) \
(STR) = empty_unibyte_string; \
else XSTRING (STR)->size_byte = -1; } while (0)
By contrast, a multibyte string holds there the number of bytes in its
internal representation. So a pure ASCII string could be unibyte or
multibyte, and the `size_byte' member will be negative in the former
case and positive in the latter case.
However, AFAIK Emacs always makes a unibyte string if all the
characters are pure ASCII. So this does not matter in practice.
> The example you gave proves nothing, however. In fact, when that
> string is presented by `string-as-multibyte', ?\351 will be converted
> to a private space character in Unicode and therefore will have more
> than one byte in its representation. Thus the length in bytes of the
> string (as multibyte) will be 7 (or maybe more, I forget which private
> space naked bytes live in). Here's one way to get byte length of a
> string:
>
> (defun string-byte-count (s)
> (length (if (string-multibyte-p s) (encode-coding-string s 'utf-8) s)))
See above: this is not accurate.
next prev parent reply other threads:[~2010-09-17 20:57 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-14 19:12 Compiling Elisp to a native code with a GCC plugin Wojciech Meyer
2010-09-14 19:32 ` Tom Tromey
2010-09-14 19:45 ` Wojciech Meyer
2010-09-14 20:17 ` Lars Magne Ingebrigtsen
2010-09-14 20:52 ` Wojciech Meyer
2010-09-14 20:55 ` Tom Tromey
2010-09-14 21:05 ` Wojciech Meyer
2010-09-14 20:44 ` Tom Tromey
2010-09-14 21:00 ` Wojciech Meyer
2010-09-14 21:16 ` Tom Tromey
2010-09-14 21:29 ` Wojciech Meyer
2010-09-14 21:59 ` Tom Tromey
2010-09-14 22:37 ` Wojciech Meyer
2010-09-14 22:55 ` Tom Tromey
2010-09-14 23:33 ` Wojciech Meyer
2010-09-15 1:38 ` Tom Tromey
2010-09-14 22:49 ` Wojciech Meyer
2010-09-14 23:13 ` Thomas Lord
2010-09-14 23:42 ` Wojciech Meyer
2010-09-15 10:47 ` Leo
2010-09-15 11:41 ` Andreas Schwab
2010-09-15 12:10 ` Wojciech Meyer
2010-09-15 14:07 ` Stefan Monnier
2010-09-15 14:27 ` Helmut Eller
2010-09-15 14:59 ` Stefan Monnier
2010-09-15 15:09 ` Lars Magne Ingebrigtsen
2010-09-15 15:31 ` Andreas Schwab
2010-09-15 15:35 ` Lars Magne Ingebrigtsen
2010-09-15 16:28 ` Andreas Schwab
2010-09-16 16:57 ` Lars Magne Ingebrigtsen
2010-09-15 15:42 ` Stefan Monnier
2010-09-15 15:51 ` Lars Magne Ingebrigtsen
2010-09-15 15:57 ` Leo
2010-09-15 16:01 ` Lars Magne Ingebrigtsen
2010-09-15 16:05 ` David Kastrup
2010-09-15 16:23 ` Leo
2010-09-15 16:37 ` David Kastrup
2010-09-16 16:58 ` Lars Magne Ingebrigtsen
2010-09-16 21:11 ` Andreas Schwab
2010-09-16 23:17 ` Lars Magne Ingebrigtsen
2010-09-17 8:13 ` Eli Zaretskii
2010-09-17 13:17 ` Lars Magne Ingebrigtsen
2010-09-17 13:30 ` Eli Zaretskii
2010-09-17 13:34 ` Lars Magne Ingebrigtsen
2010-09-16 17:35 ` Lars Magne Ingebrigtsen
2010-09-16 2:57 ` Stephen J. Turnbull
2010-09-16 6:54 ` David Kastrup
2010-09-16 8:10 ` Stephen J. Turnbull
2010-09-16 8:31 ` David Kastrup
2010-09-16 17:01 ` Lars Magne Ingebrigtsen
2010-09-17 6:52 ` Stephen J. Turnbull
2010-09-17 13:09 ` Lars Magne Ingebrigtsen
2010-09-17 13:31 ` David Kastrup
2010-09-17 13:39 ` Lars Magne Ingebrigtsen
2010-09-17 13:55 ` David Kastrup
2010-09-17 14:18 ` Lars Magne Ingebrigtsen
2010-09-17 14:57 ` David Kastrup
2010-09-17 15:06 ` Lars Magne Ingebrigtsen
2010-09-17 15:24 ` Lars Magne Ingebrigtsen
2010-09-17 16:11 ` Eli Zaretskii
2010-09-17 16:33 ` David Kastrup
2010-09-17 16:41 ` Andreas Schwab
2010-09-17 17:17 ` David Kastrup
2010-09-17 18:24 ` David Kastrup
2010-09-17 20:30 ` David Kastrup
2010-09-17 20:49 ` Lars Magne Ingebrigtsen
2010-09-18 4:31 ` David Kastrup
2010-09-17 18:53 ` Stephen J. Turnbull
2010-09-17 20:57 ` Eli Zaretskii [this message]
2010-09-18 14:19 ` Stephen J. Turnbull
2010-09-18 15:46 ` Eli Zaretskii
2010-09-18 15:58 ` Stefan Monnier
2010-09-17 17:24 ` Lars Magne Ingebrigtsen
2010-09-17 16:11 ` David Kastrup
2010-09-17 16:18 ` Eli Zaretskii
2010-09-17 16:24 ` Lars Magne Ingebrigtsen
2010-09-17 16:39 ` Eli Zaretskii
2010-09-17 17:30 ` Lars Magne Ingebrigtsen
2010-09-17 18:49 ` Eli Zaretskii
2010-09-17 16:39 ` Eli Zaretskii
2010-09-17 13:49 ` Andreas Schwab
2010-09-17 13:55 ` Lars Magne Ingebrigtsen
2010-09-17 14:31 ` Wojciech Meyer
2010-09-17 14:40 ` Andreas Schwab
2010-09-17 14:47 ` Lars Magne Ingebrigtsen
2010-09-17 15:10 ` Andreas Schwab
2010-09-17 15:16 ` Lars Magne Ingebrigtsen
2010-09-17 15:39 ` Andreas Schwab
2010-09-17 15:42 ` Lars Magne Ingebrigtsen
2010-09-17 16:04 ` Andreas Schwab
2010-09-17 16:14 ` Eli Zaretskii
2010-09-17 19:22 ` James Cloos
2010-09-17 17:40 ` Stephen J. Turnbull
2010-09-17 19:40 ` Lars Magne Ingebrigtsen
2010-09-15 15:46 ` Helmut Eller
2010-09-15 16:28 ` Thomas Lord
2010-09-15 21:04 ` Leo
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