Possible to use _arguments with _regex_arguments?

["Ronan Pigott" <rpigott314@gmail.com>]

Hello,

I've written a number of zsh completions recently and I find that
generally there are two patterns that work well, with _arguments using
->state to dispatch completions and _regex_arguments to build a regex
state machine.

Often I find that I'd like to use both _arguments and _regex_arguments
together, using _arguments to parse the opt_args and _regex_arguments to
handle the rest. I think it would have some advantages over building the
whole completion in _regex_arguments. _arguments already closely resembles
the behavior of getopt, consuming arguments it recognizes and leaving
the remainder in $line for dispatched functions to consider. It also
easily supports behavior where it ignores flags following a '--'
argument, which is not trivial to replicate with _regex_arguments.
Ideally, I think it would be possible to use _arguments to
define the flagged arguments I want to check and keep their values in
opt_args, but use a _regex_arguments function as an action for
_arguments acting on $line, like so:

```
_regex_arguments _myfunc ...
_arguments -S -s \
	{-o+,--option}'[An option]:tag:(some values)'
	'*:positional arguments:_myfunc'
```

However, in the above case, if _myfunc was not carefully crafted to ignore
'--option' it will fail to match and provide no completions because _myfunc
operates exclusively on $words. Is it possible to use _regex_arguments
functions on anything else, or in any other context?

One thing I thought to try was set '{words=("$line[@]"); _myfunc}' for
the action, but it did not seem to work.

If it cannot be done, is there another way that I can transform the line
to be completed before running (or re-running) the completion to make
this idea possible?