This helps to clarify the situations under which these errors can occur, and
the generality also helps to show why the inner types are as they
are (e.g. use of `String`).
But more importantly, this allows for an error type in `finalize` that is
detached from the `ParseState`, which will be able to be utilized in the
lowering pipeline as a more general error distinguishable from other
lowering errors. At the moment I'm maintaining BC, but a following commit
will demonstrate the use case to introduce recoverable vs. non-recoverable
errors.
DEV-13158
This newtype allows a caller to prove (using types) that a parser of a given
type (`ParseState`) has been finalized.
This will be used by the lowering pipeline to ensure that all parsers in the
pipeline end up getting finalized (as you can see from a TODO added in the
code, one of them is missing). The lack of such a type was an oversight
during the (rather stressed) development of the parsing system, and I
shouldn't need to resort to unit tests to verify that parsers have been
finalized.
DEV-13158
This reverts commit 85ec626fcd804eb2fac3fd6f0339182554f72cfd.
This revert had to be modified to work alongside other changes. Interior
mutability is fortunately no longer needed after the previous commit which
allows reporting to occur in a single place in the lowering pipeline (at the
terminal parser).
DEV-13158
The term "terminal parser" isn't formalized yet in the system, but is meant
to refer to the innermost parser that is responsible for pulling tokens
through the lowering pipeline.
This approach is more of what one would expect when dealing with
`Result`-like monads---we are effectively chaining the inner operation while
propagating errors to short-circuit lowering and let the caller decide
whether recovery ought to be permitted with diagnostic messages. This will
become more clear as it is further refactored.
This also means that the previous changes for introducing interior
mutability for a shared mutable `Reporter` can be reverted, which is great,
since that approach was antithetical to how the streaming pipeline
operates (and introduces awkward mutable state into an
otherwise-mostly-immutable system).
DEV-13158
This extracts error tracking into the Reporter itself, which is already
shared between lowering operations. This can then be used to display the
number of errors.
A new formatter (in tamer::fmt) will be added to handle the singular/plural
conversion in place of "error(s)" in the future; I have more important
things to work on right now.
DEV-13158
Previously these errors would immediately abort.
This results in some duplicate code, but it's beginning to derive a common
implementation. Check out the commits that follow; this is really an
intermediate refactoring state.
DEV-13158
Another baby step. The small commits are intended to allow comprehension of
what changes when looking at the diffs.
This also removes a comment stating that errors do not fail compilation,
since they most certainly do.
DEV-13158
This begins refactoring the lowering pipeline to begin to obviate
abstraction boundaries. The lowering pipeline is the backbone of the
system, and so it needs to become clear and self-documenting, which will
take a little bit of work.
DEV-13158
This always annoys me when I add a dependency and I don't know where I ought
to put it.
Anyway, I was originally going to add the `regex` crate, but with further
planning, I may not end up having use for it. Nonetheless, at least this is
consistent.
Just preparing to actually define NIR itself. The _grammar_ has been
represented (derived from our internal systems, using them as a test case),
but the IR itself has not yet received a definition.
DEV-7145
This is a quick-and-dirty change. The lowering pipeline needs a proper
abstraction, but I'm about to be on vacation at the end of the week and
would like to get NIR->AIR lowering started before I consider that
abstraction further, so this will do for now.
NIR parsing has been tested in production without failing for over a week.
DEV-7145
This was originally the "noramlized" IR, but that's not possible to do
without template expansion, which is going to happen at a later point. So,
this is just "NIR", pronounced "near", which is an IR that is "near" to the
source code. You can define it was "Near IR" if you want, but it's just a
homonym with a not-quite-defined acronym to me.
DEV-7145
A type alias was added for BC before errors were hoisted out in a previous
commit, but they are unnecessary because of the associated type on
`ParseState`.
This also corrects the long-existing issue of using generated identifiers in
tests.
DEV-7145
This moves `paste::paste!` up a line and reduces a level of indentation,
since it's so squished. Aside from docblock reformatting, there are no
other changes.
DEV-7145
This slims out the macro even further. It does result in an
awkwardly-placed `PhantomData` because I don't want to add another variant
that isn't actually used (since they represent states).
DEV-7145
This is in preparation for hoisting out the common states, as was done with
the Sum NT in a previous commit.
I also think that organizing states in this way is more clear. The previous
embedding of the variants named after the NTs themselves was because the
parser was storing the child state within it, before the introduction of the
superstate trampoline.
DEV-7145
Everything except for one state was already accounted for. We can now have
confidence that the parser will never panic due to state transitions (beyond
legitimate error conditions).
There are some `unreachable!`s to contend with still.
DEV-7145
This is the same as the previous commits, but for non-sum NTs.
This also extracts errors into a separate module, which I had hoped to do in
a separate commit, but it's not worth separating them. My _original_ reason
for doing so was debugging (I'll get into that below), but I had wanted to
trim down `ele.rs` anyway, since that mess is large and a lot to grok.
My debugging was trying to figure out why Rust was failing to derive
`PartialEq` on `NtError` because of `AttrParseError`. As it turns out,
`AttrParseError::InvalidValue` was failing, thus the introduction of the
`PartialEq` trait bound on `AttrParseState::ValueError`. Figuring this out
required implementing `PartialEq` myself without `derive` (well, using LSP,
which did all the work for me).
I'm not sure why this was not failing previously, which is a bit of a
concern, though perhaps in the context of the macro-expanded code, Rust was
able to properly resolve the types.
DEV-7145
The `ele_parse!` macro is a monstrosity, and expands into many different
identifiers. The hope is that chipping away at things like this will not
only make the template easier to understand by framing portions of the
problem in terms of more traditional Rust code, but will also hopefully
reduce compile times by reducing the amount of code that is expanded by the
macro.
DEV-7145
This introduces an order-only prerequisite `bootstrap-if-necessary` for the
generation of `suppliers.mk`. Projects utilizing TAME as a dependency may
include a `bootstrap.mk` that overrides this target to trigger any
bootstrapping scripts that may be necessary due to toolchain updates.
DEV-7145
This was a relic of the old bootstrap system, where bootstrapping was in the
context of a parent project that utilized TAME (and so TAME needed to be
built). But that doesn't make sense in the context of TAME itself, and what
_part_ of TAME should be built should be controlled by the project utilizing
it.
This is especially important now that TAMER builds are getting much longer
with the introduction of NIR and its parser-generator.
DEV-7145
This introduces NIR, but only as an accepting grammar; it doesn't yet emit
the NIR IR, beyond TODOs.
This modifies `tamec` to, while copying XIR, also attempt to lower NIR to
produce parser errors, if any. It does not yet fail compilation, as I just
want to be cautious and observe that everything's working properly for a
little while as people use it, before I potentially break builds.
This is the culmination of months of supporting effort. The NIR grammar is
derived from our existing TAME sources internally, which I use for now as a
test case until I introduce test cases directly into TAMER later on (I'd do
it now, if I hadn't spent so much time on this; I'll start introducing tests
as I begin emitting NIR tokens). This is capable of fully parsing our
largest system with >900 packages, as well as `core`.
`tamec`'s lowering is a mess; that'll be cleaned up in future commits. The
same can be said about `tameld`.
NIR's grammar has some initial documentation, but this will improve over
time as well.
The generated docs still need some improvement, too, especially with
generated identifiers; I just want to get this out here for testing.
DEV-7145
This includes when on the last state / expecting a close.
Previously, there were a couple major issues:
1. After parsing an NT, we can't allow preemption because we must emit a
dead state so that we can remove the NT from the stack, otherwise
they'll never close (until the parent does) and that results in
unbounded stack growth for a lot of siblings. Therefore, we cannot
preempt on `Text`, which causes the NT to receive it, emit a dead
state, transition away from the NT, and not accept another NT of the
same type after `Text`.
2. When encountering an unknown element, the error message stated that a
closing tag was expected rather than one of the elements accepted by the
final NT.
For #1, this was solved by allowing the parent to transition back to the NT
if it would have been matched by the previous NT. A future change may
therefore allow us to remove repetition handling entirely and allow the
parent to deal with it (maybe).
For #2, the trouble is with the parser generator macro---we don't have a
good way of knowing the last NT, and the last NT may not even exist if none
was provided. This solution is a compromise, after having tried and failed
at many others; I desperately need to move on, and this results in the
correct behavior and doesn't sacrifice performance. But it can be done
better in the future.
It's also worth noting for #2 that the behavior isn't _entirely_ desirable,
but in practice it is mostly correct. Specifically, if we encounter an
unknown token, we're going to blow through all NTs until the last one, which
will be forced to handle it. After that, we cannot return to a previous NT,
and so we've forefitted the ability to parse anything that came before it.
NIR's grammar is such that sequences are rare and, if present, there's
really only ever two NTs, and so this awkward behavior will rarely cause
practical issues. With that said, it ought to be improved in the future,
but let's wait to see if other parts of the lowering pipeline provide more
appropriate places to handle some of these things (even though it really
ought to be handled at the grammar level).
But I'm well out of time to spend on this. I have to move on.
DEV-7145
This removes the deprecated `@const@` argument in favor of shorthand
`@value@` constants, which were introduced long ago precisely to avoid
having to define separate `@const@` parameters for all of these templates.
DEV-7145
"keep" is an old feature that forced the linker to retain symbols that were
unused. This was removed long ago in favor of having all linker roots
defined by the return map.
This also removes an old `@always`, which seems like a typo for
`when="always"` or something...not entirely sure.
DEV-7145
Accumulators were an ancient TAME feature removed long ago during The Great
Refactoring (...okay, that part didn't fit the definition of a "refactor",
but that's technically what that's referring to).
TAMER will not accept it.
DEV-7145
This has not been in use for years and it's time to go away---it is the only
thing in TAME that causes nondeterminism, at least that I'm immediately
aware of. Perhaps I'll find something else while reimplementing TAME in
TAMER.
_This does not remove the compiler code to produce this._ If something
still needs `__DATE_YEAR__` (because it's really old), it can define this
value itself, and still utilize it until TAMER (which will not include it).
DEV-7145
`ele_parse!` was recently converted to accept zero-or-more for every NT to
simplify the parser-generator, since NIR isn't going to be able to
accurately determine whether child requirements are met anyway (because of
the template system).
This ensures that `Close` can be accepted when we're expecting an
element. It also adds a test for a scenario that's causing me some trouble
in stashed code so that I can ensure that it doesn't break.
DEV-7145
This sets the maximum depth to 64, which is still arbitrary, but
unfortunately the sum types introduce multiple levels of nesting, in
particular for template applications, so nested applications can result in a
fairly large stack.
I have various ideas to improve upon that---limited a bit in that repetition
as it is current implemented inhibits tail calls---but they're not worth
doing just yet relative to other priorities. The impact of this change is
not significant.
DEV-7145
This removes support for configurable repetition.
What? Why?
As it turns out, the complexity that repetition adds is quite significant
and is not worth the effort. The truth is that NIR is going to have to
allow zero-or-more matches on virtually everything _anyway_ because template
application is allowed virtually anywhere---it is not possible to fully
statically analyze TAME's sources because templates can expand into just
about anything. Given that, AIR (or something down the line) is going to
have to supply the necessary invariants instead.
It does suck, though, that this removes a lot of code that I fairly recently
wrote, and spent a decent amount of time on. But it's important to know
when to cut your losses.
Perhaps I could have planned better, but deriving this whole system as been
quite the experiment.
DEV-7145
If attributes fail to parse (e.g. missing required attribute) and parsing
reaches a dead state, this will recover by ignoring the entire element. It
previously panicked with a TODO.
DEV-7145
Mike Gerwitz
Brandon Ellis