[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Emacs-diffs] master 9dcf599: Amend parse-partial-sexp correctly to
From: |
Alan Mackenzie |
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 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
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 <address@hidden> writes:
> > branch: master
> > commit 9dcf5998935c8aaa846d7585b81f0dcfe1935b3d
> > Author: Alan Mackenzie <address@hidden>
> > Commit: Alan Mackenzie <address@hidden>
> > 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.