This begins generating parsers that are capable of parsing elements. I need
to move on, so this abstraction isn't going to go as far as it could, but
let's see where it takes me.
This was the work that required the recent lookahead changes, which has been
detailed in previous commits.
This initial support is basic, but robust. It supports parsing elements
with attributes and children, but it does not yet support the equivalent of
the Kleene star (`*`). Such support will likely be added by supporting
parsers that are able to recurse on their own definition in tail position,
which will also require supporting parsers that do not add to the stack.
This generates parsers that, like all the other parsers, use enums to
provide a typed stack. Stitched parsers produce a nested stack that is
always bounded in size. Fortunately, expressions---which can nest
deeply---do not need to maintain ancestor context on the stack, and so this
should work fine; we can get away with this because XIRF ensures proper
nesting for us. Statements that _do_ need to maintain such context are not
nested.
This also does not yet support emitting an object on closing tag, which
will be necessary for NIR, which will be a streaming IR that is "near" to
the source XML in structure. This will then be used to lower into AIR for
the ASG, which gives structure needed for further analysis.
More information to come; I just want to get this committed to serve as a
mental synchronization point and clear my head, since I've been sitting on
these changes for so long and have to keep stashing them as I tumble down
rabbit holes covered in yak hair.
DEV-7145
This is partly an experiment, but is designed to simplify producing English
sentences in various contexts. It makes use of a not only unstable, but
incomplete, Rust feature---adt_const_params, for a static str const type
parameter. Hopefully that ends up being stabalized.
This uses types, but it's the same as function composition due to Rust's
monomorphization.
DEV-7145
Mike Gerwitz