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Re: [Emacs-diffs] master 9dcf599: Amend parse-partial-sexp correctly to
From: |
Stefan Monnier |
Subject: |
Re: [Emacs-diffs] master 9dcf599: Amend parse-partial-sexp correctly to handle two character comment delimiters |
Date: |
Sun, 20 Mar 2016 11:30:51 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.1.50 (gnu/linux) |
What he says,
Stefan
>>>>> "Alan" == Alan Mackenzie <address@hidden> writes:
> 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.