From: luigi scarso <luigi.scarso@gmail.com>
To: mailing list for ConTeXt users <ntg-context@ntg.nl>
Subject: Re: Bug: Segmentation fault
Date: Wed, 11 Dec 2019 09:48:57 +0100 [thread overview]
Message-ID: <CAG5iGsCPjo2C2xmO9DJUYyyhmMn0u7WhsVRJ1uo+N8LMk6bF=g@mail.gmail.com> (raw)
In-Reply-To: <6bf2d70c-b606-3833-8b91-6c84607c0f53@gmail.com>
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On Wed, Dec 11, 2019 at 1:28 AM Henri Menke <henrimenke@gmail.com> wrote:
> In this case I wanted to generate the thin space (\,). My expectation
> (which worked elsewhere) was that full expansion will turn "\string\\,"
> into "\\," where the two backslashes have catcode 12 and will not be
> expanded further. Then the Lua string will turn the escape sequence \\
> into a single backslash, therefore ending up with \, in the Lua string.
>
>
\directlua{token.set_macro("foo","\relax")}
(gdb) x/7c str
0x555559376c18: 13 '\r' 101 'e' 108 'l' 97 'a' 120 'x' 32 ' ' 0 '\000'
(gdb) p lstr
$24 = 6
where \foo is
\foo=macro:
->#!.
vs
\directlua{token.set_macro("foo",[==[\relax]==])}
(gdb) x/8c str
0x555559376ea8: 92 '\\' 114 'r' 101 'e' 108 'l' 97 'a' 120 'x' 32 ' ' 0
'\000'
(gdb) p lstr
$25 = 7
\foo=macro:
->\relax .
Another example is
\directlua{token.set_macro("foo","\medskip")}\show\foo
which gives the error: invalid escape sequence near '"^^Kskip \m'.
vs
\directlua{token.set_macro("foo",[==[\medskip]==])}\show\foo
which gives
\foo=macro:
->\vskip \medskipamount .
Your example:
\directlua{token.set_macro("foo","\string\\,")}\show\foo
gives
(gdb) x/3c str
0x5555593765a8: 92 '\\' 44 ',' 0 '\000'
(gdb) p lstr
$29 = 2
\foo=macro:
->BAD,.
vs
\directlua{token.set_macro("foo",[==[\,]==])}\show\foo
(gdb) x/20c str
0x555559376908: 92 '\\' 109 'm' 115 's' 107 'k' 105 'i' 112 'p' 32 ' ' 92
'\\'
0x555559376910: 116 't' 104 'h' 105 'i' 110 'n' 109 'm' 117 'u' 115 's' 107
'k'
0x555559376918: 105 'i' 112 'p' 32 ' ' 0 '\000'
(gdb) p lstr
$31 = 19
\foo=macro:
->\mskip \thinmuskip .
--
luigi
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next prev parent reply other threads:[~2019-12-11 8:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 20:26 Henri Menke
2019-12-10 20:36 ` luigi scarso
2019-12-10 22:36 ` Hans Hagen
2019-12-10 23:03 ` luigi scarso
2019-12-10 23:10 ` Hans Hagen
2019-12-10 23:23 ` luigi scarso
2019-12-11 0:28 ` Henri Menke
2019-12-11 8:48 ` luigi scarso [this message]
2019-12-11 9:11 ` Hans Hagen
2019-12-11 10:57 ` luigi scarso
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