This is intended to describe, to the user, the state that the parser is
in. This will be used to convey additional information for general parser
errors, but it should also probably be integrated into parsers' individual
errors as well when appropriate.
This is something I expected to add at some point, but I wanted to add them
because, when dealing with lowering errors, it can be difficult to tell
what parser the error originated from.
DEV-11864
A previous commit mentioned that there's not a place for `Dim`, and
duplicated it between `asg` and `xmlo`. Well, `Dtype` is also needed in
both, and so here's a home for now.
`Dtype` has always been an inappropriate detail for the system and will one
day be removed entirely in favor of higher-level types; the machine
representation is up to the compiler to decide.
DEV-11864
RSG (Ryan Specialty Group) recently announced a rename to Ryan Specialty (no
"Group"), but I'm not sure if the legal name has been changed yet or not, so
I'll wait on that.
These are no longer TODOs---they represent invalid tokens.
I'm going to put effort into providing further context with the diagnostic
system [right now] because these are internal errors caused by either
miscompilation or an incomplete reader.
DEV-10936
This is a working concept that will continue to evolve. I wanted to start
with some basic output before getting too carried away, since there's a lot
of potential here.
This is heavily influenced by Rust's helpful diagnostic messages, but will
take some time to realize a lot of the things that Rust does. The next step
will be to resolve line and column numbers, and then possibly include
snippets and underline spans, placing the labels alongside them. I need to
balance this work with everything else I have going on.
This is a large commit, but it converts the existing Error Display impls
into Diagnostic. This separation is a bit verbose, so I'll see how this
ends up evolving.
Diagnostics are tied to Error at the moment, but I imagine in the future
that any object would be able to describe itself, error or not, which would
be useful in the future both for the Summary Page and for query
functionality, to help developers understand the systems they are writing
using TAME.
Output is integrated into tameld only in this commit; I'll add tamec
next. Examples of what this outputs are available in the test cases in this
commit.
DEV-10935
This entirely removes the old XmloReader that has since been replaced with a
XIR-based reader.
I had been holding off on this because the new reader is slower, pending
performance optimizations (which I'll do a little later on), however the
performance loss is of no practical consideration and only affects the
linker, which is still fast.
Therefore, it's better to get this old code out of the way to simplify
refactoring going forward. In particular, I'm working on the diagnostic
system.
This is a little sad, in a way---this is some of my first Rust code that I'm
deleting.
DEV-10935
This resolves the performance issues caused by Rust's failure to elide the
ElementStack (ArrayVec) memcpys on move.
Since XIRF is invoked tens of millions of times in some cases for larger
systems, prior to this change, failure to optimize away moves for XIRF
resulted in tens of millions of memcpys. This resulted in linking of one
program going from 1s -> ~15s. This change reduces it to ~2.5s with the
wip-xmlo-xir-reader flag on, with the extra time coming from elsewhere (the
subject of future changes).
In particular, this change introduces a new mutable reference to
`ParseState::parse_token`, which is a reference to a `Context` owned by the
caller (e.g. `Parser`). In the case of XIRF, this means that
`Parser<flat::State, _>` will own the `ElementStack`/`ArrayVec` instead of
`flat::State`; this allows the latter to remain pure and benefit from Rust's
move optimizations, without sacrificing the otherwise-pure implementation.
ParseStates that do not need a mutable context can use `NoContext` and
remain pure.
DEV-12024
This makes the necessary tweaks to have the entire linker work end-to-end
and produce a compatible xmle file (that is, identical except for
nondeterministic topological ordering). That's good, and finally that can
get off of my plate.
What's disappointing, and what I'll have more information on in future
commits, is how slow it is.
The linking of our largest package goes from ~1s -> ~15s with this
change. The reason is because of tens of millions of `memcpy` calls. Why?
The ParseState abstraction is pure and passes an owned `self` around, and
Parser replaces its own reference using this:
let result;
TransitionResult(Transition(self.state), result) =
take(&mut self.state).parse_token(tok);
Naively, this would store a copy of the old state in `result`, allocate a
new ParseState for `self.state`, pass the original or a copy to
`parse_token`, and then overwrite `self.state` with the new ParseState that
is returned once it is all over.
Of course, that'd be devastating. What we want to happen is for Rust to
realize that it can just pass a reference to `self.state` and perform no
copying at all.
For certain parsers, this is exactly what happens. Great!
But for XIRF, it we have this:
/// Stack of element [`QName`] and [`Span`] pairs,
/// representing the current level of nesting.
///
/// This storage is statically allocated,
/// allowing XIRF's parser to avoid memory allocation entirely.
type ElementStack<const MAX_DEPTH: usize> = ArrayVec<(QName, Span), MAX_DEPTH>;
/// XIRF document parser state.
///
/// This parser is a pushdown automaton that parses a single XML document.
#[derive(Debug, Default, PartialEq, Eq)]
pub enum State<const MAX_DEPTH: usize, SA = AttrParseState>
where
SA: FlatAttrParseState,
{
/// Document parsing has not yet begun.
#[default]
PreRoot,
/// Parsing nodes.
NodeExpected(ElementStack<MAX_DEPTH>),
/// Delegating to attribute parser.
AttrExpected(ElementStack<MAX_DEPTH>, SA),
/// End of document has been reached.
Done,
}
ParseState contains an ArrayVec, and its implementation details are causes
LLVM _not_ to elide the `memcpy`. And there's a lot of them.
Considering that ParseState is supposed to use only statically allocated
memory and be zero-copy, this is rather ironic.
Now, this _could_ be potentially fixed by not using ArrayVec; removing
it (and the corresponding checks for balanced tags) gets us down to
2s (which still needs improvement), but we can't have a core abstraction in
our system resting on a house of cards. What if the optimization changes
between releases and suddenly linking / building becomes shit slow? That's
too much of a risk.
Further, having to limit what abstractions we use just to appease the
compiler to optimize away moves is very restrictive.
The better option seems like to go back to what I used to do: pass around
`&mut self`. I had moved to an owned `self` to force consideration of _all_
state transitions, but I can try to do the same thing in a different type of
way using mutable references, and then we avoid this problem. The
abstraction isn't pure (in the functional sense) anymore, but it's safe and
isn't relying on delicate inlining and optimizer implementation details to
have a performant system.
More information to come.
DEV-10863
This concludes the bulk of the header parsing, though there are surely going
to be other issues when I try to read a real xmlo file, such as
whitespace. That is something I expect that I'd rather handle as part of
XIRF, but maybe I'll initially ignore it here just to get it working. We'll
see.
DEV-10863
This parses the symbol dependency list (adjacency list).
I'm noticing some glaring issues in error handling, particularly that the
token being parsed while an error occurs is not returned and so recovery is
impossible. I'll have to address that later on, after I get this parser
completed.
Another previous question that I had a hard time answering in prior months
was how I was going to compose boilerplate parsers, e.g. handling the
parsing of single-attribute elements and such. A pattern is clearly taking
shape, and with the composition of parsers more formalized, that'll be able
to be abstracted away. But again, that's going to wait until after this
parser is actually functioning. Too many delays so far.
DEV-10863
Ideally this would just be an attribute, but I guess I never got around to
making that change in the compiler and I don't want a detour right now.
DEV-10863
I clearly was not paying attention to what was correct behavior here, since
the tests also verified the wrong behavior: rather than taking the last
processed attribute span, we should be taking the span of the opening
tag for the `preproc:sym` node.
DEV-10863
This simply removes boilerplate.
This will receive concrete examples once I come up with docs for the entire
module; there's boilerplate involved in testing and documenting this in
isolation and the time investment is not worth it yet until I'm certain that
this will not be changed.
DEV-10863
This integrates much of the work done so far to parse into a
`XmloEvent::SymDecl`. The attribute parsing _is_ verbose, and I do intend
to abstract it away later on, but I'm going to wait on that for now.
The new reader should be finishing up soon, which is really exciting, since
I started working on this months ago (before having to take a break on
TAMER); I'm anticipating strong performance gains in the reader, and this is
a test that will tell us how the compiler will perform moving forward with
the abstractions that I've spent so much time on.
DEV-10863
This introduces a new method similar to the previous `delegate`, but with
another closure that allows for handling lookahead tokens from the child
parser.
Admittedly, this isn't exactly what I was going for---a list of arguments
isn't exactly self-documenting, especially with the brevity when the
arguments line up---but this was easy to do and so I'll run with this for
now.
This also modified `delegate` to accept a context, even though it wasn't
necessary, both for consistency with its lookup counterpart and for brevity
with the `into` argument (allowing, in our case, to just pass the name of
the variant, rather than a closure).
I'm not going to handle the actual starting and accepting state stitching
abstraction for now; I'd like to observe future boilerplate more before I
consider the best way to handle it, though I do have some ideas.
DEV-10863
This is the delegation portion of what I've come to call "state
stitching"---wiring together two state machines that recognize the same
input tokens.
This handles the delegation of tokens once the parser has been entered, but
does not yet handle the actual stitching part of it: wiring the start and
accepting states of the child parser to the parent.
This is indirectly tested by the XmloReader, but it will receive its own
tests once I further finalize this concept. I'm playing around with some
ideas. With that said, a quick visual inspection together with the
guarantees provided by the type system should convince any familiar reader
of its correctness.
DEV-10863
This wasn't the simplest thing to start with, but I wanted to explore
something with a higher level of complexity. There is some boilerplate to
observe here, including:
1. The state stitching (as I guess I'm calling it now) of SymtableState
with XmloReaderState is all boilerplate and requires no lookahead,
presenting an abstraction opportunity that I was holding off on
previously (attr parsing for XIRF requires lookahead).
2. This is simply collecting attributes into a struct. This can be
abstracted away in the future.
3. Creating stub parsers to verify that generics are stitched rather than
being tightly coupled with another state is boilerplate that maybe can
be abstracted away after a pattern is observed in future tests.
DEV-10863
This does some cleanup and adds `parse::Object` for use in disambiguating
`From` for `ParseStatus`, allowing the `Transition` API to be much more
flexible in the data it accepts and automatically converts. This allows us
to concisely provide raw output data to be wrapped, or provide `ParseStatus`
directly when more convenient.
There aren't yet examples in the docs; I'll do so once I make sure this API
is actually utilized as intended.
DEV-10863
Since this is the object produced by this parser, this is likely the most
useful first thing to present as a summary of what `XmloReader` actually
does.
DEV-10863
This removes the flag from most of the code, which also resolves the
indentation. Not only was it bothering me, but I don't want (a) every line
modified when the module body is hoisted and (b) `rustfmt` to reformat
everything when that happens.
This means that everything will be built, even though it's not used, when
the flag is off, but I see that as a good thing.
DEV-10863
Finally we get to do some actual parsing with all of the preparatory work!
This means that we're finally ready to fully replace the old XmloReader,
provided that I'm okay with some boilerplate / lack of abstractions for
now (and I am, because all I've been doing is working on abstractions to
prepare lowering operations).
DEV-10863
This introduces a WIP lowering operation, abstracting away quite a bit of
the manual wiring work, which is really important to providing an API that
provides the proper level of abstraction for actually understanding what the
system is doing.
This does not yet have tests associated with it---I had started, but it's a
lot of work and boilerplate for something that is going to
evolve. Generally, I wouldn't use that as an excuse, but the robust type
definitions in play, combined with the tiny amount of actual logic, provide
a pretty high level of confidence. It's very difficult to wire these types
together and produce something incorrect without doing something obviously
bad.
Similarly, I'm holding off on proper docs too, though I did write some
information here.
More to come, after I actually get to work on the XmloReader.
On a side note: I'm happy to have made progress on this, since this wiring
is something I've been dreading and wondering about since before the Parser
abstraction even existed.
Note also that this makes parser::feed_toks private again---I don't intend
to support push parsers yet, since they're only needed internally. Maybe
for error recovery, but I'll wait to decide until it's actually needed.
DEV-10863
This begins to transition XmloReader into a ParseState. Unlike previous
changes where ParseStates were composed into a single ParseState, this is
instead a lowering operation that will take the output of one Parser and
provide it to another.
The mess in ld::poc (...which still needs to be refactored and removed)
shows the concept, which will be abstracted away. This won't actually get
to the ASG in order to test that that this works with the
wip-xmlo-xir-reader flag on (development hasn't gotten that far yet), but
since it type-checks, it should conceptually work.
Wiring lowering operations together is something that I've been dreading for
months, but my approach of only abstracting after-the-fact has helped to
guide a sane approach for this. For some definition of "sane".
It's also worth noting that AsgBuilder will too become a ParseState
implemented as another lowering operation, so:
XIR -> XIRF -> XMLO -> ASG
These steps will all be streaming, with iteration happening only at the
topmost level. For this reason, it's important that ASG not be responsible
for doing that pull, and further we should propagate Parsed::Incomplete
rather than filtering it out and looping an indeterminate number of times
outside of the toplevel.
One final note: the choice of 64 for the maximum depth is entirely
arbitrary and should be more than generous; it'll be finalized at some point
in the future once I actually evaluate what maximum depth is reasonable
based on how the system is used, with some added growing room.
DEV-10863
The Options here are awkward and will be able to go away in the new reader
and in AsgBuilder once it has a proper state machine.
This gets rid of some of the initial migratory work for the new reader,
because PackageAttrs is gone. I'm going to wait to update this to the new
way until I get further into this.
DEV-11449
I'm finally back to TAMER development.
The original plan, some time ago, was to gate an entirely new XmloReader
behind a feature flag (wip-xmlo-xir-reader), and go from there, leaving the
existing implementation untouched. Unfortunately, it became too difficult
and confusing to marry the old aggregate API with the new streaming one.
AsgBuilder is the only system interacting with XmloReader, so I decided (see
previous commits) to just go the route of refactoring the existing
one. I'm not yet sure if I'll continue to progressively refactor this one
and eliminate the two separate implementations behind the flag, or if I'll
get this API similar and then keep the flag and reimplement it. But I'll
know soon.
DEV-11449
This removes XIRT support for attribute fragments. The reason is that
because this is a write-only operation---fragments are used to concatenate
SymbolIds without reallocation, which can only happen if we are generating
XIR internally.
Given that this cannot happen during read, it was a mistake to complicate
the parsers. But it makes sense why I did originally, given that the XIRT
parser was written for simplifying test cases. But now that we want parsers
for real, and are writing production-quality parsers, this extra complexity
is very undesirable.
As a bonus, we also avoid any potential for heap allocations related to
attributes. Granted, they didn't _really_ exist to begin with, but it was
part of XIRT, and was ugly.
DEV-11268
Well, parse to the extent that it was being parsed before, anyway.
The core of this change demonstrates how well TAMER's abstractions work well
together. (As long as you have an e.g. LSP to help you make sense of all of
the inference, I suppose.)
Token::Open(QN_LV_PACKAGE | QN_PACKAGE, _) => {
return Ok(XmloEvent::Package(
attr_parser_from(&mut self.reader)
.try_collect_ok()??,
));
}
This finally makes use of `attr_parser_from` and `try_collect_ok`. All of
the types are inferred---from the iterator transformations, to the error
conversions, to the destination PackageAttrs type.
DEV-10863
See the previous commit. There is no sense in some common "IR" namespace,
since those IRs should live close to whatever system whose data they
represent.
In the case of these, they are general IRs that can apply to many different
parts of the system. If that proves to be a false statement, they'll be
moved.
DEV-10863
The IRs really ought to live where they are owned, especially given that
"IR" is so generic that it makes no sense for there to be a single location
for them; they're just data structures coupled with different phases of
compilation.
This will be renamed next commit; see that for details.
This also removes some documentation describing the lowering process,
because it's undergone a number of changes and needs to be accurately
re-summarized in another location. That will come at a later time after the
work is further along so that I don't have to keep spending the time
rewriting it.
DEV-10863
This was previous gated behind the negation of the wip-xmlo-xir-reader flag,
which meant that it was not being compiled or picked up by LSP. Both of
those things are inconvenient and unideal.
DEV-10863
There isn't a whole lot here, but there is additional work needed in various
places to support upcoming changes and so I want to get this commited to
ease the cognitive burden of what I have thusfar. And to stop stashing. We
have a feature flag for a reason.
DEV-10863
This moves the Iterator impl and From<B> back into `quickxml`. The type of
the new reader is different, taking an iterator instead of a BufRead. This
will allow us to easily mock for unit tests, without the clustfuckery that
has ensued previously with quick-xml mocking.
DEV-10863
The original plan was to modify the existing reader to use the new
XmlXirReader, but that's going to be a lot of ongoing uncommitted work, with
both tests and implementation. The better option seems to be to reimplement
it, since so many things are changing.
This flag will be short-lived and removed as soon as the implementation is
complete.
DEV-10863
This is a union (sum type) of three other errors types, plus errors specific
to this builder.
This commit does a good job demonstrating the boilerplate, as well as a need
for additional context (in the case of `IdentKindError`), that we'll want to
work on abstracting away.
This flips the API from using XmloWriter as the context to using Asg and
consuming anything that can produce XmloResults. This not only makes more
sense, but avoids having to create a trait for XmloReader, and simplifies
the trait bounds we have to concern ourselves with.
This serves as a constructor for the time being, decoupling from POC. We
may do something better once we have a better idea of how the various
abstractions around this will evolve.
If we cannot set a fragment, we need to display the error to the user.
We are currently ignoring "___head", "___tail", and objects that are
both virtual and overridden. Those will be corrected in with future
changes.
Mike Gerwitz
Joseph Frazer