From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Bart Schaefer <schaefer@brasslantern.com>
Cc: Peter Stephenson <p.stephenson@samsung.com>,
Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: bufferwords() lexes a subshell in a shortloop repeat as a string
Date: Wed, 20 Jan 2016 07:47:54 +0000 [thread overview]
Message-ID: <20160120074754.GC29602@tarsus.local2> (raw)
In-Reply-To: <CAH+w=7Z7d9Xc2ro9F1cMoyT_TeqmVNYzZc0vOnrCchtRi_4VDQ@mail.gmail.com>
Bart Schaefer wrote on Mon, Jan 18, 2016 at 20:56:04 -0800:
> [Returning to the original topic of this thread ...]
>
> On Sun, Jan 17, 2016 at 6:25 PM, Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
> > What confuses me is that 'repeat 3 (x)' and 'repeat 3; do (x); done' are
> > split differently. ;-)
> >
> > Shouldn't both of them treat the "(x)" the same way [either both of
> > them considering it one unit, or both of them considering it three units]?
>
> As Peter said earlier, the (z) flag does nothing but break the string
> into syntactic shell words. With the exception of "for" loops, which
> are a weird special case because of "for ((...))", It does NOT
> interpret shell keywords to parse any corresponding loop structures.
> It knows a little about assignments and redirections but otherwise
> reads lexical tokens in their most generic possible context; you can
> think of it as having "lex" without "yacc" to drive it.
>
Okay; so what I was seeing was that bufferwords() knew that a DOLOOP token
is followed by a command position, but not that a REPEAT token is
followed by a token that's followed by a command position.
I think REPEAT is the only place where that happens: other reserved
words are followed immediately by a command position with no intervening
words. (Which is why get_comp_string() sets 'ins' to '2' only for
REPEAT tokens.)
Aside: bufferwords(), get_comp_string(), and z-sy-h's main loop have
something in common: they all drive the lexer and keep track of a little
bit of syntax. E.g., with this patch all of them keep track of "if the
command word is 'repeat', the word-after-next is a command word".
> (z) also does not expand aliases, which means that even if it did
> interpret keywords you could trivially break it by aliasing something
> else to expand as "repeat" or vice-versa. (In fact you can already
> break the magic "for" parsing the same way.)
Don't do that, then :-)
Cheers,
Daniel
prev parent reply other threads:[~2016-01-20 7:48 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 6:26 Daniel Shahaf
2016-01-15 9:41 ` Peter Stephenson
2016-01-15 19:25 ` Bart Schaefer
2016-01-17 18:16 ` Peter Stephenson
2016-01-17 22:46 ` Bart Schaefer
2016-01-18 9:41 ` Peter Stephenson
2016-01-18 16:36 ` Bart Schaefer
2016-01-18 16:52 ` Peter Stephenson
2016-01-19 0:32 ` Bart Schaefer
2016-01-19 3:29 ` Bart Schaefer
2016-01-19 4:07 ` kshglob + noglob (was Re: bufferwords() lexes ....) Bart Schaefer
2016-01-19 9:36 ` bufferwords() lexes a subshell in a shortloop repeat as a string Peter Stephenson
2016-01-19 18:59 ` Bart Schaefer
2016-01-18 2:25 ` Daniel Shahaf
2016-01-18 10:45 ` Peter Stephenson
2016-01-20 7:47 ` Daniel Shahaf
2016-01-20 15:59 ` Bart Schaefer
2016-01-21 6:50 ` Bart Schaefer
2016-01-23 23:53 ` Daniel Shahaf
2016-01-24 5:56 ` Bart Schaefer
2016-01-19 4:56 ` Bart Schaefer
2016-01-20 7:47 ` Daniel Shahaf [this message]
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