From: Alan Mackenzie <acm@muc.de>
To: John Wiegley <johnw@gnu.org>
Cc: Stefan Monnier <monnier@IRO.UMontreal.CA>, emacs-devel@gnu.org
Subject: Re: [Emacs-diffs] master 9dcf599: Amend parse-partial-sexp correctly to handle two character comment delimiters
Date: Sun, 20 Mar 2016 14:40:18 +0000 [thread overview]
Message-ID: <20160320144018.GC3603@acm.fritz.box> (raw)
In-Reply-To: <jwvshzlz2f9.fsf-monnier+emacsdiffs@gnu.org>
Hello, John.
On Sun, Mar 20, 2016 at 09:47:58AM -0400, Stefan Monnier wrote:
> What was John's opinion on reusing nth 5?
> Stefan
Yes John, what is your opinion on reusing element 5 of the parser state?
Background:
The previous edition of `parse-partial-sexp' returned a ten-element list
which could be used for continuing that parse. Unfortunately, this list
was incomplete, leading to errors when the parse had stopped in the
middle of a two-character comment delimiter. This is bug #23019.
My patch, created with Stefan's help, has solved this bug, partly by
adding another element onto the parser state. But this new element
leaves element 5 ("t when just after an escape character") redundant.
Stefan is in favour of reusing position 5 for this new element, rather
than adding it at the end of the state (which has just been done). I am
against this, though not strongly. It might have some effects on
existing code, though this is not particularly likely.
What do you say?
--
Alan Mackenzie (Nuremberg, Germany).
> >>>>> "Alan" == Alan Mackenzie <acm@muc.de> writes:
> > branch: master
> > commit 9dcf5998935c8aaa846d7585b81f0dcfe1935b3d
> > Author: Alan Mackenzie <acm@muc.de>
> > Commit: Alan Mackenzie <acm@muc.de>
> > Amend parse-partial-sexp correctly to handle two character comment delimiters
> > Do this by adding a new field to the parser state: the syntax of the last
> > character scanned, should that be the first char of a (potential) two char
> > construct, nil otherwise.
> > This should make the parser state complete.
> > Also document element 9 of the parser state. Also refactor the code a bit.
> > * src/syntax.c (struct lisp_parse_state): Add a new field.
> > (SYNTAX_FLAGS_COMSTARTEND_FIRST): New function.
> > (internalize_parse_state): New function, extracted from scan_sexps_forward.
> > (back_comment): Call internalize_parse_state.
> > (forw_comment): Return the syntax of the last character scanned to the caller
> > when that character might be the first of a two character construct.
> > (Fforward_comment, scan_lists): New dummy variables, passed to forw_comment.
> > (scan_sexps_forward): Remove a redundant state parameter. Access all `state'
> > information via the address parameter `state'. Remove the code which converts
> > from external to internal form of `state'. Access buffer contents only from
> > `from' onwards. Reformulate code at the top of the main loop correctly to
> > recognize comment openers when starting in the middle of one. Call
> > forw_comment with extra argument (for return of syntax value of possible first
> > char of a two char construct).
> > (Fparse_partial_sexp): Document elements 9, 10 of the parser state in the
> > doc string. Clarify the doc string in general. Call
> > internalize_parse_state. Take account of the new elements when consing up the
> > output parser state.
> > * doc/lispref/syntax.texi: (Parser State): Document element 9 and the new
> > element 10. Minor wording corrections (remove reference to "trivial
> > cases").
> > (Low Level Parsing): Minor corrections.
> > * etc/NEWS: Note new element 10, and documentation of element 9 of parser
> > state.
next prev parent reply other threads:[~2016-03-20 14:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20160320132125.5713.70103@vcs.savannah.gnu.org>
[not found] ` <E1ahdIL-0001Ul-Uz@vcs.savannah.gnu.org>
2016-03-20 13:47 ` [Emacs-diffs] master 9dcf599: Amend parse-partial-sexp correctly to handle two character comment delimiters Stefan Monnier
2016-03-20 14:22 ` Alan Mackenzie
2016-03-20 14:40 ` Alan Mackenzie [this message]
2016-03-20 15:30 ` Stefan Monnier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160320144018.GC3603@acm.fritz.box \
--to=acm@muc.de \
--cc=emacs-devel@gnu.org \
--cc=johnw@gnu.org \
--cc=monnier@IRO.UMontreal.CA \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.