Help with GNU Emacs syntax.el and XEmacs buffer-syntactic-context et al?

[Aidan Kehoe]

 Ar an ceathrú lá de mí Meitheamh, scríobh Mats Lidell: 

 > Been looking again at the task of getting the mode for go work with
 > XEmacs and need some help.
 > 
 > It uses functions from syntax.el[1] which in GNU Emacs contains
 > "helper functions to find syntactic context". Oddly(!?) this file
 > contains at the bottom commented out XEmacs(!) compatibility functions
 > for "buffer-syntactic-contex" and "buffer-syntactic-context-dept"
 > which are found in font-lock.c. This could indicate that we have
 > overlapping functionality which in its turn might be better handled by
 > just using our APIs instead!?
 > 
 > I ask myself what is the proper thing to do here:
 >   1. Ignore that we have these overlap and just get the functions in
 >      syntax.el into XEmacs as is.

My feeling is that this is the right way to go. In your position I’d create
a new file in XEmacs, call it syntax-ppss.el (notice that #'syntax-ppss is the
main function exported by their syntax.el), and move GNU’s syntax.el into
that file.

Note when testing that #'syntax-ppss relies on #'parse-partial-sexp, and I
don’t know how compatible ours is with theirs.

 > [...] [2] The actual offending function used by go-mode is this:
 > (syntax-ppss (&optional pos)
 >   "Parse-Partial-Sexp State at POS, defaulting to point.
 > The returned value is the same as `parse-partial-sexp' except that
 > the 2nd and 6th values of the returned state cannot be relied upon.
 > Point is at POS when this function returns."
 > 
 > What would be the XEmacs way to implement that?

According to the docstring, a wrapper around #'parse-partial-sexp would do
it. But is #'syntax-ppss faster? Does it not modify some global state? Does
it cache things that #'parse-partial-sexp doesn’t? It’s just about possible
that there’s no point to it, in which case a wrapper would be the way to go.

-- 
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