Re: How to get syntax information in batch mode?

[martin rudalics]

> I have written an automatic code indentation function in ELisp and I
> want to be able to invoke this function from Emacs' batch mode so that
> it can be invoked from a Makefile, without needing to start Emacs
> interactively.
>
> However the function get-char-property always seems to return nil when
> noninteractive is set to t.  Am I correct about this deduction?
>
> I use get-char-property to tell the automatic indentation function
> whether or not we are currently inside a string or a comment.  Is
> there a different function for telling whether or not we are currently
> inside a string or a comment?

By default, Emacs doesn't fontify text that is not displayed.  Hence, in
general, your function might not work interactively either.

You have two basic ways to achieve what you want:

Use font-lock and text-properties: A brute force approach is to call
`font-lock-fontify-buffer' before doing the indentation.  More subtle is
`font-lock-fontify-syntactically-region (point-min) (point-max)' but you
might have to wrap this in something equivalent to font-lock's
`save-buffer-state' and you shouldn't want to set syntax-table text
properties in this case.  Also be careful when indenting to avoid that
text properties get inherited in some unpredictable way.

Use `parse-partial-sexp': To program this efficiently you should
intermittently save the parsing state to avoid rescanning from
point-min.  Emacs 22 has `syntax-ppss' which does this automatically.
`syntax-ppss' also guarantees that indenting won't mess up the parse
state.

Always bear in mind that font-lock uses the syntax parsing routines
anyway to find comments and strings.