Declaring custom completions to AUCTeX

Question

How do I declare custom completions for command arguments to AUCTeX?

I have a LaTeX package that defines a number of macros. I'm writing the Elisp style support manually as some of the TeX code is rather hairy. One of the macros is \ref-like, so in the style support file, I have

(TeX-add-symbols '("myref" TeX-arg-ref))

If I insert \ref or \myref with TeX-insert-macro, I get prompted for a label with completion. If I type \ref{ and press M-TAB (TeX-complete-symbol), I get completions of labels. But if I type \myref{ and press M-TAB, I only get the fallback to dictionary words.

How do I tell AUCTeX that the first argument of \myref should be completed as a label?

Answer 1

Add entries to TeX-complete-list. This isn't documented in the manual, but there are examples in the support files distributed with AUCTeX.

  (setq TeX-complete-list
        (append '(
                  ("\\\\myref{\\([^{}\n
\\%,]*\\)" 1 LaTeX-label-list "}")
                  ) TeX-complete-list))

Each element of TeX-complete-list is a list consisting of a regexp to complete after, e.g. the command name followed by an opening brace and the already-existing element content in a group, followed by either:

1. The number of the group that contains the text to be completed.
2. A function that is called with no arguments and returns a completion alist.
3. A string to add after a completion.

or:

1. A function of no arguments that is called to perform the completion.