This introduces, but does not yet integrate, `CanonicalName`, which not only
represents canonicalized package names, but handles namespec resolution.
The term "namespec" is motivated by Git's use of *spec (e.g. refspec)
referring to various ways of specifying a particular object. Names look
like paths, and are derived from them, but they _are not paths_. Their
resolution is a purely lexical operation, and they include a number of
restrictions to simplify their clarity and handling. I expect them to
evolve more in the future, and I've had ideas to do so for quite some time.
In particular, resolving packages in this way and then loading the from the
filesystem relative to the project root will ensure that
traversing (conceptually) to a parent directory will not operate
unintuitively with symlinks. The path will always resolve unambigiously.
(With that said, if the symlink is to a shared directory with different
directory structures, that doesn't solve the compilation problem---we'll
have to move object files into a project-specific build directory to handle
that.)
Span Slicing
------------
Okay, it's worth commenting on the horridity of the path name slicing that
goes on here. Care has been taken to ensure that spans will be able to be
properly sliced in all relevant contexts, and there are plenty of words
devoted to that in the documentation committed here.
But there is a more fundamental problem here that I regret not having solved
earlier, because I don't have the time for it right now: while we do have
SPair, it makes no guarantees that the span associated with the corresponding
SymbolId is actually the span that matches the original source lexeme. In
fact, it's often not.
This is a problem when we want to slice up a symbol in an SPair and produce
a sensible span. If it _is_ a source lexeme with its original span, that's
no problem. But if it's _not_, then the two are not in sync, and slicing up
the span won't produce something that actually makes sense to the user. Or,
worse (or maybe it's not worse?), it may cause a panic if the slicing is out
of bounds.
The solution in the future might be to store explicitly the state of an
SPair, or call it Lexeme, or something, so that we know the conditions under
which slicing is safe. If I ever have time for that in this project.
But the result of the lack of a proper abstraction really shows here: this
is some of the most confusing code in TAMER, and it's really not doing
anything all that complicated. It is disproportionately confusing.
DEV-13162
NOTE: This temporarily breaks `tameld`. It is fixed in a future commit when
names are bound. This was an oversight when breaking apart changes into
separate commits, because the linker does not yet have system tests like
tamec does.
This is preparing for a full transition to requiring a canonical package
name. The previous `Unnamed` variant has been removed and `AirAggregate`
will provide a default `WS_EMPTY` name, as `Pkg` had done before.
The intent of this change is to allow for consulting the index before a
new `Pkg` object is created on the graph, but we're not quite ready for that
yet.
Well, that's not entirely true---the linker can be ready for that. But the
compiler needs to canonicalize import paths relative to the active package
canonical name, which it can't even do yet because tamec isn't generating a
name.
So maybe the linker will be first; it's useful to have that in a separate
commit anyway to emphasize the change.
DEV-13162
The previous commit introduced canonical names, and this uses them to index.
The next step will be to utilize those names to look up packages on
definition rather than creating a new package node, so that references to
yet-to-be-defined (or yet-to-be-imported) packages can be resolved on the
graph.
DEV-13162
This is already a concept in the XSLT-based compiler, where each package has
a `package/@name` generated from its path. The same will happen with tamec.
Before we can load packages into the graph, we need canonical identifiers so
that they can be indexed. The next commit will handle indexing using this
information.
DEV-13162
This may now index _any_ type of object, in preparation for indexing package
import paths. In practice, this only makes sense (at least currently) for
`Pkg` and `Ident`.
This generalization also applies to `Asg::lookup_or_missing`.
DEV-13162
This supports arbitrary documentation as sibling text (mixed content, in XML
terms). The motivation behind this change is to permit existing system
tests to succeed when `Todo | TodoAttr` are both rejected, rather than
having to ignore this.
TAME has always had a philosophy of literate documentation, however it was
never fully realized. This just maintains the status quo; the text is
unstructured, and maybe will be parsed in the future.
Unfortunately, this does _not_ include the output in the `xmli` file or the
system tests. The reason has nothing to do with TAMER---`xmllint` does not
format the output when there is mixed content, it seems, and I need to move
on for now; I'll consider my options in the future. But, it's available on
the graph and ready to go.
DEV-13708
These are used by virtually every `ObjectKind`; I've been meaning to do this
for a while, but now that I'm about to introduce a new one (`Doc`), let's
just get it out of the way.
DEV-13708
This doesn't do the actual hard work yet of resolving and loading a package,
but it does place it on the graph and re-derive it into the xmli output.
DEV-13708
This creates another trait and struct `ObjectIndexToTree` that assert a
stronger invariant than `ObjectIndexRelTo`---that not only does it uphold
the invariants of `ObjectIndexRelTo`, but also that it represents a _tree_
edge, which indicates _ownership_ rather than just a reference.
This will be used to statically infer what can serve as a scope boundary for
upcoming changes. Specifically, anything that can own an `Ident` introduces
a new level of scope.
DEV-13708
Previously, `AirTplAggregate` worked only in a `Pkg` context, being able to
root `Tpl` `Ident`s in `Pkg` and expand only into `Pkg`. This still does
the same, but generalizes to allow for different roots and expansion
targets.
This will be utilized to parse nested templates.
DEV-13708
This this a big change that's difficult to break up, and I don't have the
energy after it.
This introduces nullary template application, short- and long-form. Note
that a body of the short form is a `@values@` argument, so that's not
supported yet.
This continues to formalize the idea of what "template application" and
"template expansion" mean in TAMER. It makes a separate `TplApply`
unnecessary, because now application is simply a reference to a
template. Expansion and application are one and the same: when a template
expands, it'll re-bind metavariables to the parent context. So in a
template context, this amounts to application.
But applying a closed template will have nothing to bind, and so is
equivalent to expansion. And since `Meta` objects are not valid outside of
a `Tpl` context, applying a non-closed template outside of another template
will be invalid.
So we get all of this with a single primitive (getting the "value" of a
template).
The expansion is conceptually like `,@` in Lisp, where we're splicing trees.
It's a mess in some spots, but I want to get this committed before I do a
little bit of cleanup.
The previous commit demonstrated the amount of boilerplate necessary for
introducing new `ObjectKind`s; this abstracts away a lot of that
boilerplate, and allows for declarative relationship definition for the
ASG's ontology.
DEV-13708
There's quite a bit of boilerplate here that'll eventually need factoring
out. But it's also clear that it is somewhat onerous to add new object
types.
Note that a good chunk of this burden is _intentional_, via exhaustiveness
checks---adding a new type of object is an exceptional occurrence (well, in
principle, but we haven't added them all yet, so it'll be more common
initially), and we'd rather be safe to ensure that everything is properly
considering how that new type of object interacts with it.
Let's not confuse coupling with safety---the latter causes a burden because
of the former, not because of itself; it provides a service to us.
But, nonetheless, we'll want to reduce this burden somewhat since there are
a number more to add.
DEV-13708
The `TreePreOrderDfs` iterator needed to expose additional edge context to
the caller (specifically, the `Span`). This was getting a bit messy, so
this consolodates everything into a new `DynObjectRel`, which also
emphasizes that it is in need of narrowing.
Packing everything up like that also allows us to return more information to
the caller without complicating the API, since the caller does not need to
be concerned with all of those values individually.
Depth is kept separate, since that is a property of the traversal and is not
stored on the graph. (Rather, it _is_ a property of the graph, but it's not
calculated until traversal. But, depth will also vary for a given node
because of cross edges, and so we cannot store any concrete depth on the
graph for a given node. Not even a canonical one, because once we start
doing inlining and common subexpression elimination, there will be shared
edges that are _not_ cross edges (the node is conceptually part of _both_
trees). Okay, enough of this rambling parenthetical.)
DEV-13708
The `Pkg` span will now properly reflect the entire definition of the
package including the opening and closing tags.
This was found while I was working on a graph traversal.
DEV-13597
This introduces the concept of ontological cross edges.
The term "cross edge" is most often seen in the context of graph traversals,
e.g. the trees formed by a depth-first search. This, however, refers to the
trees that are inherent in the ontology of the graph.
For example, an `ExprRef` will produce a cross edge to the referenced
`Ident`, that that is a different tree than the current expression. (Well,
I suppose technically it _could_ be a back edge, but then that'd be a cycle
which would fail the process once we get to preventing it. So let's ignore
that for now.)
DEV-13708
This causes a package definition to be rooted (so that it can be easily
accessed for a graph walk). This keeps consistent with the new
`ObjectIndex`-based API by introducing a unit `Root` `ObjectKind` and the
boilerplate that goes with it.
This boilerplate, now glaringly obvious, will be refactored at some point,
since its repetition is onerous and distracting.
DEV-13159
Included in this diff are the corresponding changes to the graph to support
the change. Adding the edge was easy, but we also need a way to get the
package for an identifier. The easiest way to do that is to modify the edge
weight to include not just the target node type, but also the source.
DEV-13159
This does not yet create edges from identifiers to the package; just getting
this introduced was quite a bit of work, so I want to get this committed.
Note that this also includes a change to NIR so that `Close` contains the
entity so that we can pattern-match for AIR transformations rather than
retaining yet another stack with checks that are already going to be done by
AIR. This makes NIR stand less on its own from a self-validation point, but
that's okay, given that it's the language that the user entered and,
conceptually, they could enter invalid NIR the same as they enter invalid
XML (e.g. from a REPL).
In _practice_, of course, NIR is lowered from XML and the schema is enforced
during that lowering and so the validation does exist as part of that
parsing.
These concessions speak more to the verbosity of the language (Rust) than
anything.
DEV-13159
Mike Gerwitz