This removes special cases, but it does complicate the parent `AirAggregate`
parser. A pattern of delegation is forming, though abstracting it may be an
interesting challenge, given Rust's limitation on macro invocations as match
arms. But, I think I can manage by generating the entire match using a
macro with a match-compatible syntax, augmenting where
needed...maybe. This'll be messy.
...but if I can write the nightmare that is `ele_parse!`, I'm sure I can
manage this. I just prefer to avoid complex macros unless I really need
them.
DEV-13708
And finally we have tokens aggregated onto the ASG in the context of a
template. I expected to arrive here much more quickly, but there was a lot
of necessary refactoring. There's a lot more that could be done, but I need
to continue; I had wanted this done a week ago.
It is worth noting, though, that this finally achieves something I had been
wondering about since the inception of this project---how I'd represent
templates on the graph. I think this worked out rather nicely. It wasn't
even until a few months ago that I decided to use AIR instead of NIR for
that purpose (NIR wouldn't have worked).
And note how I didn't have to touch the program derivation at all---the
system test just works with the AIR change, because of the consistent
construction of the graph. Beautiful.
DEV-13708
This sets us up to be able to determine how `Dangling` expressions will be
rooted into templates.
This new strategy isn't yet handling `Dangling`; I wanted to get this
committed first so that the `Dangling` refactoring is more clear.
DEV-13708
Expressions were previously tied to packages. This prepares for using a
`Tpl` as a container for expressions.
This does not yet handle the situation of auto-rooting dangling expressions
within the container.
DEV-13708
Mike Gerwitz