This moves the logic that sorts identifiers into sections into Sections
itself, and introduces XmleSections to allow for mocking for testing.
This then allows us to narrow the types significantly, eliminating some
runtime checks. The types can be narrowed further, but I'll be limiting the
work I'll be doing now; this'll be inevitably addressed as we use the ASG
for the compiler.
This also handles moving Sections tests, which was a TODO from the previous
commit.
DEV-10859
This is the appropriate place to be, now that we've begun narrowing the
types. We'll be able to do so further; this is just the first step.
This does not yet move the tests, but the code is still tested because it's
tightly coupled with `sort`. Those will move in the next commit(s).
DEV-10859
xmle sections will only ever contain an object of one type, so there is no
use in making this generic.
I think the original plan was to have this represent, generically, sections
of some object file (like ELF), but doing so would require a significant
redesign anyway, so it makes no sense. This is easier to reason about.
DEV-10859
This has always been a lowering operation, but it was not phrased in terms
of it, which made the process a bit more confusing to understand.
The implementation hasn't changed, but this is an incremental refactoring
and so exposes BaseAsg and its `graph` field temporarily.
DEV-10859
Mike Gerwitz