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Commit | Line | Data |
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1b1a35ee XL |
1 | //! Defines the IR for types and logical predicates. |
2 | ||
f035d41b | 3 | #![deny(rust_2018_idioms)] |
1b1a35ee | 4 | #![warn(missing_docs)] |
f035d41b XL |
5 | |
6 | // Allows macros to refer to this crate as `::chalk_ir` | |
7 | extern crate self as chalk_ir; | |
8 | ||
1b1a35ee | 9 | use crate::cast::{Cast, CastTo, Caster}; |
f035d41b XL |
10 | use crate::fold::shift::Shift; |
11 | use crate::fold::{Fold, Folder, Subst, SuperFold}; | |
12 | use crate::visit::{SuperVisit, Visit, VisitExt, VisitResult, Visitor}; | |
13 | use chalk_derive::{Fold, HasInterner, SuperVisit, Visit, Zip}; | |
f035d41b XL |
14 | use std::marker::PhantomData; |
15 | ||
16 | pub use crate::debug::SeparatorTraitRef; | |
17 | ||
1b1a35ee | 18 | /// Uninhabited (empty) type, used in combination with `PhantomData`. |
f035d41b XL |
19 | #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
20 | pub enum Void {} | |
21 | ||
22 | /// Many of our internal operations (e.g., unification) are an attempt | |
23 | /// to perform some operation which may not complete. | |
24 | pub type Fallible<T> = Result<T, NoSolution>; | |
25 | ||
26 | /// Indicates that the attempted operation has "no solution" -- i.e., | |
27 | /// cannot be performed. | |
28 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
29 | pub struct NoSolution; | |
30 | ||
31 | /// Error type for the `UnificationOps::program_clauses` method -- | |
32 | /// indicates that the complete set of program clauses for this goal | |
33 | /// cannot be enumerated. | |
34 | pub struct Floundered; | |
35 | ||
36 | macro_rules! impl_debugs { | |
37 | ($($id:ident), *) => { | |
38 | $( | |
39 | impl<I: Interner> std::fmt::Debug for $id<I> { | |
40 | fn fmt(&self, fmt: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> { | |
41 | write!(fmt, "{}({:?})", stringify!($id), self.0) | |
42 | } | |
43 | } | |
44 | )* | |
45 | }; | |
46 | } | |
47 | ||
48 | #[macro_use] | |
49 | pub mod zip; | |
50 | ||
51 | #[macro_use] | |
52 | pub mod fold; | |
53 | ||
54 | #[macro_use] | |
55 | pub mod visit; | |
56 | ||
57 | pub mod cast; | |
58 | ||
59 | pub mod interner; | |
60 | use interner::{HasInterner, Interner}; | |
61 | ||
62 | pub mod could_match; | |
63 | pub mod debug; | |
64 | ||
65 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner)] | |
66 | /// The set of assumptions we've made so far, and the current number of | |
67 | /// universal (forall) quantifiers we're within. | |
68 | pub struct Environment<I: Interner> { | |
1b1a35ee | 69 | /// The clauses in the environment. |
f035d41b XL |
70 | pub clauses: ProgramClauses<I>, |
71 | } | |
72 | ||
1b1a35ee XL |
73 | impl<I: Interner> Copy for Environment<I> where I::InternedProgramClauses: Copy {} |
74 | ||
f035d41b | 75 | impl<I: Interner> Environment<I> { |
1b1a35ee | 76 | /// Creates a new environment. |
f035d41b XL |
77 | pub fn new(interner: &I) -> Self { |
78 | Environment { | |
1b1a35ee | 79 | clauses: ProgramClauses::empty(interner), |
f035d41b XL |
80 | } |
81 | } | |
82 | ||
1b1a35ee | 83 | /// Adds (an iterator of) clauses to the environment. |
f035d41b XL |
84 | pub fn add_clauses<II>(&self, interner: &I, clauses: II) -> Self |
85 | where | |
86 | II: IntoIterator<Item = ProgramClause<I>>, | |
87 | { | |
88 | let mut env = self.clone(); | |
89 | env.clauses = | |
1b1a35ee | 90 | ProgramClauses::from_iter(interner, env.clauses.iter(interner).cloned().chain(clauses)); |
f035d41b XL |
91 | env |
92 | } | |
1b1a35ee XL |
93 | |
94 | /// True if any of the clauses in the environment have a consequence of `Compatible`. | |
95 | /// Panics if the conditions or constraints of that clause are not empty. | |
96 | pub fn has_compatible_clause(&self, interner: &I) -> bool { | |
97 | self.clauses.as_slice(interner).iter().any(|c| { | |
98 | let ProgramClauseData(implication) = c.data(interner); | |
99 | match implication.skip_binders().consequence { | |
100 | DomainGoal::Compatible => { | |
101 | // We currently don't generate `Compatible` with any conditions or constraints | |
102 | // If this was needed, for whatever reason, then a third "yes, but must evaluate" | |
103 | // return value would have to be added. | |
104 | assert!(implication.skip_binders().conditions.is_empty(interner)); | |
105 | assert!(implication.skip_binders().constraints.is_empty(interner)); | |
106 | true | |
107 | } | |
108 | _ => false, | |
109 | } | |
110 | }) | |
111 | } | |
f035d41b XL |
112 | } |
113 | ||
1b1a35ee | 114 | /// A goal with an environment to solve it in. |
f035d41b | 115 | #[derive(Clone, Debug, PartialEq, Eq, Hash, Fold, Visit)] |
1b1a35ee | 116 | #[allow(missing_docs)] |
f035d41b XL |
117 | pub struct InEnvironment<G: HasInterner> { |
118 | pub environment: Environment<G::Interner>, | |
119 | pub goal: G, | |
120 | } | |
121 | ||
1b1a35ee XL |
122 | impl<G: HasInterner<Interner = I> + Copy, I: Interner> Copy for InEnvironment<G> where |
123 | I::InternedProgramClauses: Copy | |
124 | { | |
125 | } | |
126 | ||
f035d41b | 127 | impl<G: HasInterner> InEnvironment<G> { |
1b1a35ee | 128 | /// Creates a new environment/goal pair. |
f035d41b XL |
129 | pub fn new(environment: &Environment<G::Interner>, goal: G) -> Self { |
130 | InEnvironment { | |
131 | environment: environment.clone(), | |
132 | goal, | |
133 | } | |
134 | } | |
135 | ||
1b1a35ee | 136 | /// Maps the goal without touching the environment. |
f035d41b XL |
137 | pub fn map<OP, H>(self, op: OP) -> InEnvironment<H> |
138 | where | |
139 | OP: FnOnce(G) -> H, | |
140 | H: HasInterner<Interner = G::Interner>, | |
141 | { | |
142 | InEnvironment { | |
143 | environment: self.environment, | |
144 | goal: op(self.goal), | |
145 | } | |
146 | } | |
147 | } | |
148 | ||
149 | impl<G: HasInterner> HasInterner for InEnvironment<G> { | |
150 | type Interner = G::Interner; | |
151 | } | |
152 | ||
1b1a35ee | 153 | /// Different signed int types. |
f035d41b | 154 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] |
1b1a35ee | 155 | #[allow(missing_docs)] |
f035d41b XL |
156 | pub enum IntTy { |
157 | Isize, | |
158 | I8, | |
159 | I16, | |
160 | I32, | |
161 | I64, | |
162 | I128, | |
163 | } | |
164 | ||
1b1a35ee | 165 | /// Different unsigned int types. |
f035d41b | 166 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] |
1b1a35ee | 167 | #[allow(missing_docs)] |
f035d41b XL |
168 | pub enum UintTy { |
169 | Usize, | |
170 | U8, | |
171 | U16, | |
172 | U32, | |
173 | U64, | |
174 | U128, | |
175 | } | |
176 | ||
1b1a35ee | 177 | /// Different kinds of float types. |
f035d41b | 178 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] |
1b1a35ee | 179 | #[allow(missing_docs)] |
f035d41b XL |
180 | pub enum FloatTy { |
181 | F32, | |
182 | F64, | |
183 | } | |
184 | ||
1b1a35ee | 185 | /// Types of scalar values. |
f035d41b | 186 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] |
1b1a35ee | 187 | #[allow(missing_docs)] |
f035d41b XL |
188 | pub enum Scalar { |
189 | Bool, | |
190 | Char, | |
191 | Int(IntTy), | |
192 | Uint(UintTy), | |
193 | Float(FloatTy), | |
194 | } | |
195 | ||
1b1a35ee XL |
196 | /// Whether a function is safe or not. |
197 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
198 | pub enum Safety { | |
199 | /// Safe | |
200 | Safe, | |
201 | /// Unsafe | |
202 | Unsafe, | |
203 | } | |
204 | ||
205 | /// Whether a type is mutable or not. | |
f035d41b XL |
206 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] |
207 | pub enum Mutability { | |
1b1a35ee | 208 | /// Mutable |
f035d41b | 209 | Mut, |
1b1a35ee | 210 | /// Immutable |
f035d41b XL |
211 | Not, |
212 | } | |
213 | ||
1b1a35ee | 214 | /// Different kinds of Rust types. |
f035d41b XL |
215 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Fold, Visit)] |
216 | pub enum TypeName<I: Interner> { | |
217 | /// Abstract data types, i.e., structs, unions, or enumerations. | |
218 | /// For example, a type like `Vec<T>`. | |
219 | Adt(AdtId<I>), | |
220 | ||
221 | /// an associated type like `Iterator::Item`; see `AssociatedType` for details | |
222 | AssociatedType(AssocTypeId<I>), | |
223 | ||
224 | /// a scalar type like `bool` or `u32` | |
225 | Scalar(Scalar), | |
226 | ||
227 | /// a tuple of the given arity | |
228 | Tuple(usize), | |
229 | ||
230 | /// an array type like `[T; N]` | |
231 | Array, | |
232 | ||
233 | /// a slice type like `[T]` | |
234 | Slice, | |
235 | ||
236 | /// a raw pointer type like `*const T` or `*mut T` | |
237 | Raw(Mutability), | |
238 | ||
239 | /// a reference type like `&T` or `&mut T` | |
240 | Ref(Mutability), | |
241 | ||
242 | /// a placeholder for opaque types like `impl Trait` | |
243 | OpaqueType(OpaqueTyId<I>), | |
244 | ||
245 | /// a function definition | |
246 | FnDef(FnDefId<I>), | |
247 | ||
248 | /// the string primitive type | |
249 | Str, | |
250 | ||
251 | /// the never type `!` | |
252 | Never, | |
253 | ||
254 | /// A closure. | |
255 | Closure(ClosureId<I>), | |
256 | ||
257 | /// This can be used to represent an error, e.g. during name resolution of a type. | |
258 | /// Chalk itself will not produce this, just pass it through when given. | |
259 | Error, | |
260 | } | |
261 | ||
262 | impl<I: Interner> HasInterner for TypeName<I> { | |
263 | type Interner = I; | |
264 | } | |
265 | ||
266 | /// An universe index is how a universally quantified parameter is | |
267 | /// represented when it's binder is moved into the environment. | |
268 | /// An example chain of transformations would be: | |
269 | /// `forall<T> { Goal(T) }` (syntactical representation) | |
270 | /// `forall { Goal(?0) }` (used a DeBruijn index) | |
271 | /// `Goal(!U1)` (the quantifier was moved to the environment and replaced with a universe index) | |
272 | /// See https://rustc-dev-guide.rust-lang.org/borrow_check/region_inference.html#placeholders-and-universes for more. | |
273 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
274 | pub struct UniverseIndex { | |
1b1a35ee | 275 | /// The counter for the universe index, starts with 0. |
f035d41b XL |
276 | pub counter: usize, |
277 | } | |
278 | ||
279 | impl UniverseIndex { | |
1b1a35ee | 280 | /// Root universe index (0). |
f035d41b XL |
281 | pub const ROOT: UniverseIndex = UniverseIndex { counter: 0 }; |
282 | ||
1b1a35ee | 283 | /// Root universe index (0). |
f035d41b XL |
284 | pub fn root() -> UniverseIndex { |
285 | Self::ROOT | |
286 | } | |
287 | ||
1b1a35ee | 288 | /// Whether one universe can "see" another. |
f035d41b XL |
289 | pub fn can_see(self, ui: UniverseIndex) -> bool { |
290 | self.counter >= ui.counter | |
291 | } | |
292 | ||
1b1a35ee | 293 | /// Increases the index counter. |
f035d41b XL |
294 | pub fn next(self) -> UniverseIndex { |
295 | UniverseIndex { | |
296 | counter: self.counter + 1, | |
297 | } | |
298 | } | |
299 | } | |
300 | ||
301 | /// Maps the universes found in the `u_canonicalize` result (the | |
302 | /// "canonical" universes) to the universes found in the original | |
303 | /// value (and vice versa). When used as a folder -- i.e., from | |
304 | /// outside this module -- converts from "canonical" universes to the | |
305 | /// original (but see the `UMapToCanonical` folder). | |
306 | #[derive(Clone, Debug)] | |
307 | pub struct UniverseMap { | |
308 | /// A reverse map -- for each universe Ux that appears in | |
309 | /// `quantified`, the corresponding universe in the original was | |
310 | /// `universes[x]`. | |
311 | pub universes: Vec<UniverseIndex>, | |
312 | } | |
313 | ||
314 | impl UniverseMap { | |
1b1a35ee | 315 | /// Creates a new universe map. |
f035d41b XL |
316 | pub fn new() -> Self { |
317 | UniverseMap { | |
318 | universes: vec![UniverseIndex::root()], | |
319 | } | |
320 | } | |
321 | ||
322 | /// Number of canonical universes. | |
323 | pub fn num_canonical_universes(&self) -> usize { | |
324 | self.universes.len() | |
325 | } | |
326 | } | |
1b1a35ee XL |
327 | |
328 | /// The id for an Abstract Data Type (i.e. structs, unions and enums). | |
f035d41b XL |
329 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
330 | pub struct AdtId<I: Interner>(pub I::InternedAdtId); | |
331 | ||
332 | /// The id of a trait definition; could be used to load the trait datum by | |
333 | /// invoking the [`trait_datum`] method. | |
334 | /// | |
335 | /// [`trait_datum`]: ../chalk_solve/trait.RustIrDatabase.html#tymethod.trait_datum | |
336 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
337 | pub struct TraitId<I: Interner>(pub I::DefId); | |
338 | ||
1b1a35ee | 339 | /// The id for an impl. |
f035d41b XL |
340 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
341 | pub struct ImplId<I: Interner>(pub I::DefId); | |
342 | ||
1b1a35ee | 343 | /// Id for a specific clause. |
f035d41b XL |
344 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
345 | pub struct ClauseId<I: Interner>(pub I::DefId); | |
346 | ||
347 | /// The id for the associated type member of a trait. The details of the type | |
348 | /// can be found by invoking the [`associated_ty_data`] method. | |
349 | /// | |
350 | /// [`associated_ty_data`]: ../chalk_solve/trait.RustIrDatabase.html#tymethod.associated_ty_data | |
351 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
352 | pub struct AssocTypeId<I: Interner>(pub I::DefId); | |
353 | ||
1b1a35ee | 354 | /// Id for an opaque type. |
f035d41b XL |
355 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
356 | pub struct OpaqueTyId<I: Interner>(pub I::DefId); | |
357 | ||
1b1a35ee | 358 | /// Function definition id. |
f035d41b XL |
359 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
360 | pub struct FnDefId<I: Interner>(pub I::DefId); | |
361 | ||
1b1a35ee | 362 | /// Id for Rust closures. |
f035d41b XL |
363 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] |
364 | pub struct ClosureId<I: Interner>(pub I::DefId); | |
365 | ||
366 | impl_debugs!(ImplId, ClauseId); | |
367 | ||
1b1a35ee | 368 | /// A Rust type. The actual type data is stored in `TyData`. |
f035d41b XL |
369 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
370 | pub struct Ty<I: Interner> { | |
371 | interned: I::InternedType, | |
372 | } | |
373 | ||
374 | impl<I: Interner> Ty<I> { | |
1b1a35ee | 375 | /// Creates a type from `TyData`. |
f035d41b XL |
376 | pub fn new(interner: &I, data: impl CastTo<TyData<I>>) -> Self { |
377 | Ty { | |
378 | interned: I::intern_ty(interner, data.cast(interner)), | |
379 | } | |
380 | } | |
381 | ||
1b1a35ee | 382 | /// Gets the interned type. |
f035d41b XL |
383 | pub fn interned(&self) -> &I::InternedType { |
384 | &self.interned | |
385 | } | |
386 | ||
1b1a35ee | 387 | /// Gets the underlying type data. |
f035d41b XL |
388 | pub fn data(&self, interner: &I) -> &TyData<I> { |
389 | I::ty_data(interner, &self.interned) | |
390 | } | |
391 | ||
1b1a35ee | 392 | /// Creates a `FromEnv` constraint using this type. |
f035d41b XL |
393 | pub fn from_env(&self) -> FromEnv<I> { |
394 | FromEnv::Ty(self.clone()) | |
395 | } | |
396 | ||
1b1a35ee | 397 | /// Creates a WF-constraint for this type. |
f035d41b XL |
398 | pub fn well_formed(&self) -> WellFormed<I> { |
399 | WellFormed::Ty(self.clone()) | |
400 | } | |
401 | ||
402 | /// Creates a domain goal `FromEnv(T)` where `T` is this type. | |
403 | pub fn into_from_env_goal(self, interner: &I) -> DomainGoal<I> { | |
404 | self.from_env().cast(interner) | |
405 | } | |
406 | ||
407 | /// If this is a `TyData::BoundVar(d)`, returns `Some(d)` else `None`. | |
408 | pub fn bound_var(&self, interner: &I) -> Option<BoundVar> { | |
409 | if let TyData::BoundVar(bv) = self.data(interner) { | |
410 | Some(*bv) | |
411 | } else { | |
412 | None | |
413 | } | |
414 | } | |
415 | ||
416 | /// If this is a `TyData::InferenceVar(d)`, returns `Some(d)` else `None`. | |
417 | pub fn inference_var(&self, interner: &I) -> Option<InferenceVar> { | |
418 | if let TyData::InferenceVar(depth, _) = self.data(interner) { | |
419 | Some(*depth) | |
420 | } else { | |
421 | None | |
422 | } | |
423 | } | |
424 | ||
1b1a35ee XL |
425 | /// Returns true if this is a `BoundVar` or an `InferenceVar` of `TyKind::General`. |
426 | pub fn is_general_var(&self, interner: &I, binders: &CanonicalVarKinds<I>) -> bool { | |
f035d41b | 427 | match self.data(interner) { |
1b1a35ee XL |
428 | TyData::BoundVar(bv) |
429 | if bv.debruijn == DebruijnIndex::INNERMOST | |
430 | && binders.at(interner, bv.index).kind == VariableKind::Ty(TyKind::General) => | |
431 | { | |
432 | true | |
433 | } | |
434 | TyData::InferenceVar(_, TyKind::General) => true, | |
f035d41b XL |
435 | _ => false, |
436 | } | |
437 | } | |
438 | ||
1b1a35ee | 439 | /// Returns true if this is an `Alias`. |
f035d41b XL |
440 | pub fn is_alias(&self, interner: &I) -> bool { |
441 | match self.data(interner) { | |
442 | TyData::Alias(..) => true, | |
443 | _ => false, | |
444 | } | |
445 | } | |
446 | ||
1b1a35ee | 447 | /// Returns true if this is an `IntTy` or `UintTy`. |
f035d41b XL |
448 | pub fn is_integer(&self, interner: &I) -> bool { |
449 | match self.data(interner) { | |
450 | TyData::Apply(ApplicationTy { | |
451 | name: TypeName::Scalar(Scalar::Int(_)), | |
452 | .. | |
453 | }) | |
454 | | TyData::Apply(ApplicationTy { | |
455 | name: TypeName::Scalar(Scalar::Uint(_)), | |
456 | .. | |
457 | }) => true, | |
458 | _ => false, | |
459 | } | |
460 | } | |
461 | ||
1b1a35ee | 462 | /// Returns true if this is a `FloatTy`. |
f035d41b XL |
463 | pub fn is_float(&self, interner: &I) -> bool { |
464 | match self.data(interner) { | |
465 | TyData::Apply(ApplicationTy { | |
466 | name: TypeName::Scalar(Scalar::Float(_)), | |
467 | .. | |
468 | }) => true, | |
469 | _ => false, | |
470 | } | |
471 | } | |
472 | ||
473 | /// True if this type contains "bound" types/lifetimes, and hence | |
474 | /// needs to be shifted across binders. This is a very inefficient | |
475 | /// check, intended only for debug assertions, because I am lazy. | |
476 | pub fn needs_shift(&self, interner: &I) -> bool { | |
477 | self.has_free_vars(interner) | |
478 | } | |
479 | } | |
480 | ||
1b1a35ee | 481 | /// Type data, which holds the actual type information. |
f035d41b XL |
482 | #[derive(Clone, PartialEq, Eq, Hash, HasInterner)] |
483 | pub enum TyData<I: Interner> { | |
484 | /// An "application" type is one that applies the set of type | |
485 | /// arguments to some base type. For example, `Vec<u32>` would be | |
486 | /// "applying" the parameters `[u32]` to the code type `Vec`. | |
487 | /// This type is also used for base types like `u32` (which just apply | |
488 | /// an empty list). | |
489 | Apply(ApplicationTy<I>), | |
490 | ||
1b1a35ee | 491 | /// instantiated from a universally quantified type, e.g., from |
f035d41b XL |
492 | /// `forall<T> { .. }`. Stands in as a representative of "some |
493 | /// unknown type". | |
494 | Placeholder(PlaceholderIndex), | |
495 | ||
496 | /// A "dyn" type is a trait object type created via the "dyn Trait" syntax. | |
497 | /// In the chalk parser, the traits that the object represents is parsed as | |
498 | /// a QuantifiedInlineBound, and is then changed to a list of where clauses | |
499 | /// during lowering. | |
500 | /// | |
501 | /// See the `Opaque` variant for a discussion about the use of | |
502 | /// binders here. | |
503 | Dyn(DynTy<I>), | |
504 | ||
505 | /// An "alias" type represents some form of type alias, such as: | |
506 | /// - An associated type projection like `<T as Iterator>::Item` | |
507 | /// - `impl Trait` types | |
508 | /// - Named type aliases like `type Foo<X> = Vec<X>` | |
509 | Alias(AliasTy<I>), | |
510 | ||
511 | /// A function type such as `for<'a> fn(&'a u32)`. | |
512 | /// Note that "higher-ranked" types (starting with `for<>`) are either | |
513 | /// function types or dyn types, and do not appear otherwise in Rust | |
514 | /// surface syntax. | |
1b1a35ee | 515 | Function(FnPointer<I>), |
f035d41b XL |
516 | |
517 | /// References the binding at the given depth. The index is a [de | |
518 | /// Bruijn index], so it counts back through the in-scope binders. | |
519 | BoundVar(BoundVar), | |
520 | ||
521 | /// Inference variable defined in the current inference context. | |
522 | InferenceVar(InferenceVar, TyKind), | |
523 | } | |
524 | ||
1b1a35ee XL |
525 | impl<I: Interner> Copy for TyData<I> |
526 | where | |
527 | I::InternedLifetime: Copy, | |
528 | I::InternedSubstitution: Copy, | |
529 | I::InternedVariableKinds: Copy, | |
530 | I::InternedQuantifiedWhereClauses: Copy, | |
531 | { | |
532 | } | |
533 | ||
f035d41b | 534 | impl<I: Interner> TyData<I> { |
1b1a35ee | 535 | /// Casts the type data to a type. |
f035d41b XL |
536 | pub fn intern(self, interner: &I) -> Ty<I> { |
537 | Ty::new(interner, self) | |
538 | } | |
539 | } | |
540 | ||
541 | /// Identifies a particular bound variable within a binder. | |
542 | /// Variables are identified by the combination of a [`DebruijnIndex`], | |
543 | /// which identifies the *binder*, and an index within that binder. | |
544 | /// | |
545 | /// Consider this case: | |
546 | /// | |
547 | /// ```ignore | |
548 | /// forall<'a, 'b> { forall<'c, 'd> { ... } } | |
549 | /// ``` | |
550 | /// | |
551 | /// Within the `...` term: | |
552 | /// | |
553 | /// * the variable `'a` have a debruijn index of 1 and index 0 | |
554 | /// * the variable `'b` have a debruijn index of 1 and index 1 | |
555 | /// * the variable `'c` have a debruijn index of 0 and index 0 | |
556 | /// * the variable `'d` have a debruijn index of 0 and index 1 | |
557 | /// | |
558 | /// The variables `'a` and `'b` both have debruijn index of 1 because, | |
559 | /// counting out, they are the 2nd binder enclosing `...`. The indices | |
560 | /// identify the location *within* that binder. | |
561 | /// | |
562 | /// The variables `'c` and `'d` both have debruijn index of 0 because | |
563 | /// they appear in the *innermost* binder enclosing the `...`. The | |
564 | /// indices identify the location *within* that binder. | |
565 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] | |
566 | pub struct BoundVar { | |
1b1a35ee | 567 | /// Debruijn index, which identifies the binder. |
f035d41b | 568 | pub debruijn: DebruijnIndex, |
1b1a35ee | 569 | /// Index within the binder. |
f035d41b XL |
570 | pub index: usize, |
571 | } | |
572 | ||
573 | impl BoundVar { | |
1b1a35ee | 574 | /// Creates a new bound variable. |
f035d41b XL |
575 | pub fn new(debruijn: DebruijnIndex, index: usize) -> Self { |
576 | Self { debruijn, index } | |
577 | } | |
578 | ||
1b1a35ee | 579 | /// Casts the bound variable to a type. |
f035d41b XL |
580 | pub fn to_ty<I: Interner>(self, interner: &I) -> Ty<I> { |
581 | TyData::<I>::BoundVar(self).intern(interner) | |
582 | } | |
583 | ||
1b1a35ee | 584 | /// Wrap the bound variable in a lifetime. |
f035d41b XL |
585 | pub fn to_lifetime<I: Interner>(self, interner: &I) -> Lifetime<I> { |
586 | LifetimeData::<I>::BoundVar(self).intern(interner) | |
587 | } | |
588 | ||
1b1a35ee | 589 | /// Wraps the bound variable in a constant. |
f035d41b XL |
590 | pub fn to_const<I: Interner>(self, interner: &I, ty: Ty<I>) -> Const<I> { |
591 | ConstData { | |
592 | ty, | |
593 | value: ConstValue::<I>::BoundVar(self), | |
594 | } | |
595 | .intern(interner) | |
596 | } | |
597 | ||
598 | /// True if this variable is bound within the `amount` innermost binders. | |
599 | pub fn bound_within(self, outer_binder: DebruijnIndex) -> bool { | |
600 | self.debruijn.within(outer_binder) | |
601 | } | |
602 | ||
603 | /// Adjusts the debruijn index (see [`DebruijnIndex::shifted_in`]). | |
604 | #[must_use] | |
605 | pub fn shifted_in(self) -> Self { | |
606 | BoundVar::new(self.debruijn.shifted_in(), self.index) | |
607 | } | |
608 | ||
609 | /// Adjusts the debruijn index (see [`DebruijnIndex::shifted_in`]). | |
610 | #[must_use] | |
611 | pub fn shifted_in_from(self, outer_binder: DebruijnIndex) -> Self { | |
612 | BoundVar::new(self.debruijn.shifted_in_from(outer_binder), self.index) | |
613 | } | |
614 | ||
615 | /// Adjusts the debruijn index (see [`DebruijnIndex::shifted_in`]). | |
616 | #[must_use] | |
617 | pub fn shifted_out(self) -> Option<Self> { | |
618 | self.debruijn | |
619 | .shifted_out() | |
620 | .map(|db| BoundVar::new(db, self.index)) | |
621 | } | |
622 | ||
623 | /// Adjusts the debruijn index (see [`DebruijnIndex::shifted_in`]). | |
624 | #[must_use] | |
625 | pub fn shifted_out_to(self, outer_binder: DebruijnIndex) -> Option<Self> { | |
626 | self.debruijn | |
627 | .shifted_out_to(outer_binder) | |
628 | .map(|db| BoundVar::new(db, self.index)) | |
629 | } | |
630 | ||
631 | /// Return the index of the bound variable, but only if it is bound | |
632 | /// at the innermost binder. Otherwise, returns `None`. | |
633 | pub fn index_if_innermost(self) -> Option<usize> { | |
634 | self.index_if_bound_at(DebruijnIndex::INNERMOST) | |
635 | } | |
636 | ||
637 | /// Return the index of the bound variable, but only if it is bound | |
638 | /// at the innermost binder. Otherwise, returns `None`. | |
639 | pub fn index_if_bound_at(self, debruijn: DebruijnIndex) -> Option<usize> { | |
640 | if self.debruijn == debruijn { | |
641 | Some(self.index) | |
642 | } else { | |
643 | None | |
644 | } | |
645 | } | |
646 | } | |
647 | ||
648 | /// References the binder at the given depth. The index is a [de | |
649 | /// Bruijn index], so it counts back through the in-scope binders, | |
650 | /// with 0 being the innermost binder. This is used in impls and | |
651 | /// the like. For example, if we had a rule like `for<T> { (T: | |
652 | /// Clone) :- (T: Copy) }`, then `T` would be represented as a | |
653 | /// `BoundVar(0)` (as the `for` is the innermost binder). | |
654 | /// | |
655 | /// [de Bruijn index]: https://en.wikipedia.org/wiki/De_Bruijn_index | |
656 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] | |
657 | pub struct DebruijnIndex { | |
658 | depth: u32, | |
659 | } | |
660 | ||
661 | impl DebruijnIndex { | |
1b1a35ee | 662 | /// Innermost index. |
f035d41b | 663 | pub const INNERMOST: DebruijnIndex = DebruijnIndex { depth: 0 }; |
1b1a35ee | 664 | /// One level higher than the innermost index. |
f035d41b XL |
665 | pub const ONE: DebruijnIndex = DebruijnIndex { depth: 1 }; |
666 | ||
1b1a35ee | 667 | /// Creates a new de Bruijn index with a given depth. |
f035d41b XL |
668 | pub fn new(depth: u32) -> Self { |
669 | DebruijnIndex { depth } | |
670 | } | |
671 | ||
1b1a35ee XL |
672 | /// Depth of the De Bruijn index, counting from 0 starting with |
673 | /// the innermost binder. | |
f035d41b XL |
674 | pub fn depth(self) -> u32 { |
675 | self.depth | |
676 | } | |
677 | ||
678 | /// True if the binder identified by this index is within the | |
679 | /// binder identified by the index `outer_binder`. | |
680 | /// | |
681 | /// # Example | |
682 | /// | |
683 | /// Imagine you have the following binders in scope | |
684 | /// | |
685 | /// ```ignore | |
686 | /// forall<a> forall<b> forall<c> | |
687 | /// ``` | |
688 | /// | |
689 | /// then the Debruijn index for `c` would be `0`, the index for | |
690 | /// `b` would be 1, and so on. Now consider the following calls: | |
691 | /// | |
692 | /// * `c.within(a) = true` | |
693 | /// * `b.within(a) = true` | |
694 | /// * `a.within(a) = false` | |
695 | /// * `a.within(c) = false` | |
696 | pub fn within(self, outer_binder: DebruijnIndex) -> bool { | |
697 | self < outer_binder | |
698 | } | |
699 | ||
700 | /// Returns the resulting index when this value is moved into | |
701 | /// through one binder. | |
702 | #[must_use] | |
703 | pub fn shifted_in(self) -> DebruijnIndex { | |
704 | self.shifted_in_from(DebruijnIndex::ONE) | |
705 | } | |
706 | ||
707 | /// Update this index in place by shifting it "in" through | |
708 | /// `amount` number of binders. | |
709 | pub fn shift_in(&mut self) { | |
710 | *self = self.shifted_in(); | |
711 | } | |
712 | ||
713 | /// Adds `outer_binder` levels to the `self` index. Intuitively, this | |
714 | /// shifts the `self` index, which was valid at the outer binder, | |
715 | /// so that it is valid at the innermost binder. | |
716 | /// | |
717 | /// Example: Assume that the following binders are in scope: | |
718 | /// | |
719 | /// ```ignore | |
720 | /// for<A> for<B> for<C> for<D> | |
721 | /// ^ outer binder | |
722 | /// ``` | |
723 | /// | |
724 | /// Assume further that the `outer_binder` argument is 2, | |
725 | /// which means that it is referring to the `for<B>` binder | |
726 | /// (since `D` would be the innermost binder). | |
727 | /// | |
728 | /// This means that `self` is relative to the binder `B` -- so | |
729 | /// if `self` is 0 (`INNERMOST`), then it refers to `B`, | |
730 | /// and if `self` is 1, then it refers to `A`. | |
731 | /// | |
732 | /// We will return as follows: | |
733 | /// | |
734 | /// * `0.shifted_in_from(2) = 2` -- i.e., `B`, when shifted in to the binding level `D`, has index 2 | |
735 | /// * `1.shifted_in_from(2) = 3` -- i.e., `A`, when shifted in to the binding level `D`, has index 3 | |
736 | /// * `2.shifted_in_from(1) = 3` -- here, we changed the `outer_binder` to refer to `C`. | |
737 | /// Therefore `2` (relative to `C`) refers to `A`, so the result is still 3 (since `A`, relative to the | |
738 | /// innermost binder, has index 3). | |
739 | #[must_use] | |
740 | pub fn shifted_in_from(self, outer_binder: DebruijnIndex) -> DebruijnIndex { | |
741 | DebruijnIndex::new(self.depth() + outer_binder.depth()) | |
742 | } | |
743 | ||
744 | /// Returns the resulting index when this value is moved out from | |
745 | /// `amount` number of new binders. | |
746 | #[must_use] | |
747 | pub fn shifted_out(self) -> Option<DebruijnIndex> { | |
748 | self.shifted_out_to(DebruijnIndex::ONE) | |
749 | } | |
750 | ||
751 | /// Update in place by shifting out from `amount` binders. | |
752 | pub fn shift_out(&mut self) { | |
753 | *self = self.shifted_out().unwrap(); | |
754 | } | |
755 | ||
756 | /// Subtracts `outer_binder` levels from the `self` index. Intuitively, this | |
757 | /// shifts the `self` index, which was valid at the innermost | |
758 | /// binder, to one that is valid at the binder `outer_binder`. | |
759 | /// | |
760 | /// This will return `None` if the `self` index is internal to the | |
761 | /// outer binder (i.e., if `self < outer_binder`). | |
762 | /// | |
763 | /// Example: Assume that the following binders are in scope: | |
764 | /// | |
765 | /// ```ignore | |
766 | /// for<A> for<B> for<C> for<D> | |
767 | /// ^ outer binder | |
768 | /// ``` | |
769 | /// | |
770 | /// Assume further that the `outer_binder` argument is 2, | |
771 | /// which means that it is referring to the `for<B>` binder | |
772 | /// (since `D` would be the innermost binder). | |
773 | /// | |
774 | /// This means that the result is relative to the binder `B` -- so | |
775 | /// if `self` is 0 (`INNERMOST`), then it refers to `B`, | |
776 | /// and if `self` is 1, then it refers to `A`. | |
777 | /// | |
778 | /// We will return as follows: | |
779 | /// | |
780 | /// * `1.shifted_out_to(2) = None` -- i.e., the binder for `C` can't be named from the binding level `B` | |
781 | /// * `3.shifted_out_to(2) = Some(1)` -- i.e., `A`, when shifted out to the binding level `B`, has index 1 | |
782 | pub fn shifted_out_to(self, outer_binder: DebruijnIndex) -> Option<DebruijnIndex> { | |
783 | if self.within(outer_binder) { | |
784 | None | |
785 | } else { | |
786 | Some(DebruijnIndex::new(self.depth() - outer_binder.depth())) | |
787 | } | |
788 | } | |
789 | } | |
790 | ||
791 | /// A "DynTy" represents a trait object (`dyn Trait`). Trait objects | |
792 | /// are conceptually very related to an "existential type" of the form | |
1b1a35ee | 793 | /// `exists<T> { T: Trait }` (another example of such type is `impl Trait`). |
f035d41b XL |
794 | /// `DynTy` represents the bounds on that type. |
795 | /// | |
1b1a35ee | 796 | /// The "bounds" here represents the unknown self type. So, a type like |
f035d41b XL |
797 | /// `dyn for<'a> Fn(&'a u32)` would be represented with two-levels of |
798 | /// binder, as "depicted" here: | |
799 | /// | |
800 | /// ```notrust | |
801 | /// exists<type> { | |
802 | /// vec![ | |
803 | /// // A QuantifiedWhereClause: | |
804 | /// forall<region> { ^1.0: Fn(&^0.0 u32) } | |
805 | /// ] | |
806 | /// } | |
807 | /// ``` | |
808 | /// | |
809 | /// The outer `exists<type>` binder indicates that there exists | |
810 | /// some type that meets the criteria within, but that type is not | |
811 | /// known. It is referenced within the type using `^1.0`, indicating | |
812 | /// a bound type with debruijn index 1 (i.e., skipping through one | |
813 | /// level of binder). | |
814 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] | |
815 | pub struct DynTy<I: Interner> { | |
1b1a35ee | 816 | /// The unknown self type. |
f035d41b | 817 | pub bounds: Binders<QuantifiedWhereClauses<I>>, |
1b1a35ee | 818 | /// Lifetime of the `DynTy`. |
f035d41b XL |
819 | pub lifetime: Lifetime<I>, |
820 | } | |
821 | ||
1b1a35ee XL |
822 | impl<I: Interner> Copy for DynTy<I> |
823 | where | |
824 | I::InternedLifetime: Copy, | |
825 | I::InternedQuantifiedWhereClauses: Copy, | |
826 | I::InternedVariableKinds: Copy, | |
827 | { | |
828 | } | |
829 | ||
830 | /// A type, lifetime or constant whose value is being inferred. | |
f035d41b XL |
831 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)] |
832 | pub struct InferenceVar { | |
833 | index: u32, | |
834 | } | |
835 | ||
836 | impl From<u32> for InferenceVar { | |
837 | fn from(index: u32) -> InferenceVar { | |
838 | InferenceVar { index } | |
839 | } | |
840 | } | |
841 | ||
842 | impl InferenceVar { | |
1b1a35ee | 843 | /// Gets the underlying index value. |
f035d41b XL |
844 | pub fn index(self) -> u32 { |
845 | self.index | |
846 | } | |
847 | ||
1b1a35ee | 848 | /// Wraps the inference variable in a type. |
f035d41b XL |
849 | pub fn to_ty<I: Interner>(self, interner: &I, kind: TyKind) -> Ty<I> { |
850 | TyData::<I>::InferenceVar(self, kind).intern(interner) | |
851 | } | |
852 | ||
1b1a35ee | 853 | /// Wraps the inference variable in a lifetime. |
f035d41b XL |
854 | pub fn to_lifetime<I: Interner>(self, interner: &I) -> Lifetime<I> { |
855 | LifetimeData::<I>::InferenceVar(self).intern(interner) | |
856 | } | |
857 | ||
1b1a35ee | 858 | /// Wraps the inference variable in a constant. |
f035d41b XL |
859 | pub fn to_const<I: Interner>(self, interner: &I, ty: Ty<I>) -> Const<I> { |
860 | ConstData { | |
861 | ty, | |
862 | value: ConstValue::<I>::InferenceVar(self), | |
863 | } | |
864 | .intern(interner) | |
865 | } | |
866 | } | |
867 | ||
868 | /// for<'a...'z> X -- all binders are instantiated at once, | |
869 | /// and we use deBruijn indices within `self.ty` | |
870 | #[derive(Clone, PartialEq, Eq, Hash, HasInterner)] | |
1b1a35ee XL |
871 | #[allow(missing_docs)] |
872 | pub struct FnPointer<I: Interner> { | |
f035d41b | 873 | pub num_binders: usize, |
1b1a35ee XL |
874 | pub abi: I::FnAbi, |
875 | pub safety: Safety, | |
876 | pub variadic: bool, | |
f035d41b XL |
877 | pub substitution: Substitution<I>, |
878 | } | |
879 | ||
1b1a35ee XL |
880 | impl<I: Interner> Copy for FnPointer<I> where I::InternedSubstitution: Copy {} |
881 | ||
882 | /// Constants. | |
883 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] | |
f035d41b XL |
884 | pub struct Const<I: Interner> { |
885 | interned: I::InternedConst, | |
886 | } | |
887 | ||
888 | impl<I: Interner> Const<I> { | |
1b1a35ee | 889 | /// Create a `Const` using something that can be cast to const data. |
f035d41b XL |
890 | pub fn new(interner: &I, data: impl CastTo<ConstData<I>>) -> Self { |
891 | Const { | |
892 | interned: I::intern_const(interner, data.cast(interner)), | |
893 | } | |
894 | } | |
895 | ||
1b1a35ee | 896 | /// Gets the interned constant. |
f035d41b XL |
897 | pub fn interned(&self) -> &I::InternedConst { |
898 | &self.interned | |
899 | } | |
900 | ||
1b1a35ee | 901 | /// Gets the constant data from the interner. |
f035d41b XL |
902 | pub fn data(&self, interner: &I) -> &ConstData<I> { |
903 | I::const_data(interner, &self.interned) | |
904 | } | |
905 | ||
906 | /// If this is a `ConstData::BoundVar(d)`, returns `Some(d)` else `None`. | |
907 | pub fn bound_var(&self, interner: &I) -> Option<BoundVar> { | |
908 | if let ConstValue::BoundVar(bv) = &self.data(interner).value { | |
909 | Some(*bv) | |
910 | } else { | |
911 | None | |
912 | } | |
913 | } | |
914 | ||
915 | /// If this is a `ConstData::InferenceVar(d)`, returns `Some(d)` else `None`. | |
916 | pub fn inference_var(&self, interner: &I) -> Option<InferenceVar> { | |
917 | if let ConstValue::InferenceVar(iv) = &self.data(interner).value { | |
918 | Some(*iv) | |
919 | } else { | |
920 | None | |
921 | } | |
922 | } | |
923 | ||
924 | /// True if this const is a "bound" const, and hence | |
925 | /// needs to be shifted across binders. Meant for debug assertions. | |
926 | pub fn needs_shift(&self, interner: &I) -> bool { | |
927 | match &self.data(interner).value { | |
928 | ConstValue::BoundVar(_) => true, | |
929 | ConstValue::InferenceVar(_) => false, | |
930 | ConstValue::Placeholder(_) => false, | |
931 | ConstValue::Concrete(_) => false, | |
932 | } | |
933 | } | |
934 | } | |
935 | ||
1b1a35ee | 936 | /// Constant data, containing the constant's type and value. |
f035d41b XL |
937 | #[derive(Clone, PartialEq, Eq, Hash, HasInterner)] |
938 | pub struct ConstData<I: Interner> { | |
1b1a35ee | 939 | /// Type that holds the constant. |
f035d41b | 940 | pub ty: Ty<I>, |
1b1a35ee | 941 | /// The value of the constant. |
f035d41b XL |
942 | pub value: ConstValue<I>, |
943 | } | |
944 | ||
1b1a35ee | 945 | /// A constant value, not necessarily concrete. |
f035d41b XL |
946 | #[derive(Clone, PartialEq, Eq, Hash, HasInterner)] |
947 | pub enum ConstValue<I: Interner> { | |
1b1a35ee | 948 | /// Bound var (e.g. a parameter). |
f035d41b | 949 | BoundVar(BoundVar), |
1b1a35ee | 950 | /// Constant whose value is being inferred. |
f035d41b | 951 | InferenceVar(InferenceVar), |
1b1a35ee | 952 | /// Lifetime on some yet-unknown placeholder. |
f035d41b | 953 | Placeholder(PlaceholderIndex), |
1b1a35ee | 954 | /// Concrete constant value. |
f035d41b XL |
955 | Concrete(ConcreteConst<I>), |
956 | } | |
957 | ||
1b1a35ee XL |
958 | impl<I: Interner> Copy for ConstValue<I> where I::InternedConcreteConst: Copy {} |
959 | ||
f035d41b | 960 | impl<I: Interner> ConstData<I> { |
1b1a35ee | 961 | /// Wraps the constant data in a `Const`. |
f035d41b XL |
962 | pub fn intern(self, interner: &I) -> Const<I> { |
963 | Const::new(interner, self) | |
964 | } | |
965 | } | |
966 | ||
1b1a35ee XL |
967 | /// Concrete constant, whose value is known (as opposed to |
968 | /// inferred constants and placeholders). | |
969 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] | |
f035d41b | 970 | pub struct ConcreteConst<I: Interner> { |
1b1a35ee | 971 | /// The interned constant. |
f035d41b XL |
972 | pub interned: I::InternedConcreteConst, |
973 | } | |
974 | ||
975 | impl<I: Interner> ConcreteConst<I> { | |
1b1a35ee | 976 | /// Checks whether two concrete constants are equal. |
f035d41b XL |
977 | pub fn const_eq(&self, ty: &Ty<I>, other: &ConcreteConst<I>, interner: &I) -> bool { |
978 | interner.const_eq(&ty.interned, &self.interned, &other.interned) | |
979 | } | |
980 | } | |
981 | ||
1b1a35ee | 982 | /// A Rust lifetime. |
f035d41b XL |
983 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
984 | pub struct Lifetime<I: Interner> { | |
985 | interned: I::InternedLifetime, | |
986 | } | |
987 | ||
988 | impl<I: Interner> Lifetime<I> { | |
1b1a35ee XL |
989 | /// Create a lifetime from lifetime data |
990 | /// (or something that can be cast to lifetime data). | |
f035d41b XL |
991 | pub fn new(interner: &I, data: impl CastTo<LifetimeData<I>>) -> Self { |
992 | Lifetime { | |
993 | interned: I::intern_lifetime(interner, data.cast(interner)), | |
994 | } | |
995 | } | |
996 | ||
1b1a35ee | 997 | /// Gets the interned value. |
f035d41b XL |
998 | pub fn interned(&self) -> &I::InternedLifetime { |
999 | &self.interned | |
1000 | } | |
1001 | ||
1b1a35ee | 1002 | /// Gets the lifetime data. |
f035d41b XL |
1003 | pub fn data(&self, interner: &I) -> &LifetimeData<I> { |
1004 | I::lifetime_data(interner, &self.interned) | |
1005 | } | |
1006 | ||
1007 | /// If this is a `Lifetime::BoundVar(d)`, returns `Some(d)` else `None`. | |
1008 | pub fn bound_var(&self, interner: &I) -> Option<BoundVar> { | |
1009 | if let LifetimeData::BoundVar(bv) = self.data(interner) { | |
1010 | Some(*bv) | |
1011 | } else { | |
1012 | None | |
1013 | } | |
1014 | } | |
1015 | ||
1016 | /// If this is a `Lifetime::InferenceVar(d)`, returns `Some(d)` else `None`. | |
1017 | pub fn inference_var(&self, interner: &I) -> Option<InferenceVar> { | |
1018 | if let LifetimeData::InferenceVar(depth) = self.data(interner) { | |
1019 | Some(*depth) | |
1020 | } else { | |
1021 | None | |
1022 | } | |
1023 | } | |
1024 | ||
1025 | /// True if this lifetime is a "bound" lifetime, and hence | |
1026 | /// needs to be shifted across binders. Meant for debug assertions. | |
1027 | pub fn needs_shift(&self, interner: &I) -> bool { | |
1028 | match self.data(interner) { | |
1029 | LifetimeData::BoundVar(_) => true, | |
1030 | LifetimeData::InferenceVar(_) => false, | |
1031 | LifetimeData::Placeholder(_) => false, | |
1032 | LifetimeData::Phantom(..) => unreachable!(), | |
1033 | } | |
1034 | } | |
1035 | } | |
1036 | ||
1b1a35ee | 1037 | /// Lifetime data, including what kind of lifetime it is and what it points to. |
f035d41b XL |
1038 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
1039 | pub enum LifetimeData<I: Interner> { | |
1b1a35ee | 1040 | /// See TyData::BoundVar. |
f035d41b | 1041 | BoundVar(BoundVar), |
1b1a35ee | 1042 | /// Lifetime whose value is being inferred. |
f035d41b | 1043 | InferenceVar(InferenceVar), |
1b1a35ee | 1044 | /// Lifetime on some yet-unknown placeholder. |
f035d41b | 1045 | Placeholder(PlaceholderIndex), |
1b1a35ee | 1046 | /// Lifetime on phantom data. |
f035d41b XL |
1047 | Phantom(Void, PhantomData<I>), |
1048 | } | |
1049 | ||
1050 | impl<I: Interner> LifetimeData<I> { | |
1b1a35ee | 1051 | /// Wrap the lifetime data in a lifetime. |
f035d41b XL |
1052 | pub fn intern(self, interner: &I) -> Lifetime<I> { |
1053 | Lifetime::new(interner, self) | |
1054 | } | |
1055 | } | |
1056 | ||
1057 | /// Index of an universally quantified parameter in the environment. | |
1058 | /// Two indexes are required, the one of the universe itself | |
1059 | /// and the relative index inside the universe. | |
1060 | #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)] | |
1061 | pub struct PlaceholderIndex { | |
1062 | /// Index *of* the universe. | |
1063 | pub ui: UniverseIndex, | |
1064 | /// Index *in* the universe. | |
1065 | pub idx: usize, | |
1066 | } | |
1067 | ||
1068 | impl PlaceholderIndex { | |
1b1a35ee | 1069 | /// Wrap the placeholder instance in a lifetime. |
f035d41b XL |
1070 | pub fn to_lifetime<I: Interner>(self, interner: &I) -> Lifetime<I> { |
1071 | LifetimeData::<I>::Placeholder(self).intern(interner) | |
1072 | } | |
1073 | ||
1b1a35ee | 1074 | /// Create an interned type. |
f035d41b XL |
1075 | pub fn to_ty<I: Interner>(self, interner: &I) -> Ty<I> { |
1076 | TyData::Placeholder(self).intern(interner) | |
1077 | } | |
1078 | ||
1b1a35ee | 1079 | /// Wrap the placeholder index in a constant. |
f035d41b XL |
1080 | pub fn to_const<I: Interner>(self, interner: &I, ty: Ty<I>) -> Const<I> { |
1081 | ConstData { | |
1082 | ty, | |
1083 | value: ConstValue::Placeholder(self), | |
1084 | } | |
1085 | .intern(interner) | |
1086 | } | |
1087 | } | |
1088 | ||
1b1a35ee XL |
1089 | /// Normal Rust types, containing the type name and zero or more generic arguments. |
1090 | /// For example, in `Vec<u32>` those would be `Vec` and `[u32]` respectively. | |
f035d41b XL |
1091 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1092 | pub struct ApplicationTy<I: Interner> { | |
1b1a35ee | 1093 | /// The type name. |
f035d41b | 1094 | pub name: TypeName<I>, |
1b1a35ee | 1095 | /// The substitution containing the generic arguments. |
f035d41b XL |
1096 | pub substitution: Substitution<I>, |
1097 | } | |
1098 | ||
1b1a35ee XL |
1099 | impl<I: Interner> Copy for ApplicationTy<I> where I::InternedSubstitution: Copy {} |
1100 | ||
f035d41b | 1101 | impl<I: Interner> ApplicationTy<I> { |
1b1a35ee | 1102 | /// Create an interned type from this application type. |
f035d41b XL |
1103 | pub fn intern(self, interner: &I) -> Ty<I> { |
1104 | Ty::new(interner, self) | |
1105 | } | |
1106 | ||
1b1a35ee | 1107 | /// Gets an iterator of all type parameters. |
f035d41b XL |
1108 | pub fn type_parameters<'a>(&'a self, interner: &'a I) -> impl Iterator<Item = Ty<I>> + 'a { |
1109 | self.substitution | |
1110 | .iter(interner) | |
1111 | .filter_map(move |p| p.ty(interner)) | |
1112 | .cloned() | |
1113 | } | |
1114 | ||
1b1a35ee | 1115 | /// Gets the first type parameter. |
f035d41b XL |
1116 | pub fn first_type_parameter(&self, interner: &I) -> Option<Ty<I>> { |
1117 | self.type_parameters(interner).next() | |
1118 | } | |
1119 | ||
1b1a35ee | 1120 | /// Gets the number of type parameters. |
f035d41b XL |
1121 | pub fn len_type_parameters(&self, interner: &I) -> usize { |
1122 | self.type_parameters(interner).count() | |
1123 | } | |
1124 | } | |
1125 | ||
1126 | /// Represents some extra knowledge we may have about the type variable. | |
1127 | /// ```ignore | |
1128 | /// let x: &[u32]; | |
1129 | /// let i = 1; | |
1130 | /// x[i] | |
1131 | /// ``` | |
1132 | /// In this example, `i` is known to be some type of integer. We can infer that | |
1133 | /// it is `usize` because that is the only integer type that slices have an | |
1134 | /// `Index` impl for. `i` would have a `TyKind` of `Integer` to guide the | |
1135 | /// inference process. | |
1136 | #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)] | |
1b1a35ee | 1137 | #[allow(missing_docs)] |
f035d41b XL |
1138 | pub enum TyKind { |
1139 | General, | |
1140 | Integer, | |
1141 | Float, | |
1142 | } | |
1143 | ||
1b1a35ee | 1144 | /// The "kind" of variable. Type, lifetime or constant. |
f035d41b | 1145 | #[derive(Clone, PartialEq, Eq, Hash)] |
1b1a35ee | 1146 | #[allow(missing_docs)] |
f035d41b XL |
1147 | pub enum VariableKind<I: Interner> { |
1148 | Ty(TyKind), | |
1149 | Lifetime, | |
1150 | Const(Ty<I>), | |
1151 | } | |
1152 | ||
1b1a35ee XL |
1153 | impl<I: Interner> interner::HasInterner for VariableKind<I> { |
1154 | type Interner = I; | |
1155 | } | |
1156 | ||
1157 | impl<I: Interner> Copy for VariableKind<I> where I::InternedType: Copy {} | |
1158 | ||
f035d41b XL |
1159 | impl<I: Interner> VariableKind<I> { |
1160 | fn to_bound_variable(&self, interner: &I, bound_var: BoundVar) -> GenericArg<I> { | |
1161 | match self { | |
1162 | VariableKind::Ty(_) => { | |
1163 | GenericArgData::Ty(TyData::BoundVar(bound_var).intern(interner)).intern(interner) | |
1164 | } | |
1165 | VariableKind::Lifetime => { | |
1166 | GenericArgData::Lifetime(LifetimeData::BoundVar(bound_var).intern(interner)) | |
1167 | .intern(interner) | |
1168 | } | |
1169 | VariableKind::Const(ty) => GenericArgData::Const( | |
1170 | ConstData { | |
1171 | ty: ty.clone(), | |
1172 | value: ConstValue::BoundVar(bound_var), | |
1173 | } | |
1174 | .intern(interner), | |
1175 | ) | |
1176 | .intern(interner), | |
1177 | } | |
1178 | } | |
1179 | } | |
1180 | ||
1b1a35ee | 1181 | /// A generic argument, see `GenericArgData` for more information. |
f035d41b XL |
1182 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
1183 | pub struct GenericArg<I: Interner> { | |
1184 | interned: I::InternedGenericArg, | |
1185 | } | |
1186 | ||
1187 | impl<I: Interner> GenericArg<I> { | |
1b1a35ee | 1188 | /// Constructs a generic argument using `GenericArgData`. |
f035d41b XL |
1189 | pub fn new(interner: &I, data: GenericArgData<I>) -> Self { |
1190 | let interned = I::intern_generic_arg(interner, data); | |
1191 | GenericArg { interned } | |
1192 | } | |
1193 | ||
1b1a35ee | 1194 | /// Gets the interned value. |
f035d41b XL |
1195 | pub fn interned(&self) -> &I::InternedGenericArg { |
1196 | &self.interned | |
1197 | } | |
1198 | ||
1b1a35ee | 1199 | /// Gets the underlying data. |
f035d41b XL |
1200 | pub fn data(&self, interner: &I) -> &GenericArgData<I> { |
1201 | I::generic_arg_data(interner, &self.interned) | |
1202 | } | |
1203 | ||
1b1a35ee | 1204 | /// Asserts that this is a type argument. |
f035d41b XL |
1205 | pub fn assert_ty_ref(&self, interner: &I) -> &Ty<I> { |
1206 | self.ty(interner).unwrap() | |
1207 | } | |
1208 | ||
1b1a35ee | 1209 | /// Asserts that this is a lifetime argument. |
f035d41b XL |
1210 | pub fn assert_lifetime_ref(&self, interner: &I) -> &Lifetime<I> { |
1211 | self.lifetime(interner).unwrap() | |
1212 | } | |
1213 | ||
1b1a35ee | 1214 | /// Asserts that this is a constant argument. |
f035d41b XL |
1215 | pub fn assert_const_ref(&self, interner: &I) -> &Const<I> { |
1216 | self.constant(interner).unwrap() | |
1217 | } | |
1218 | ||
1b1a35ee | 1219 | /// Checks whether the generic argument is a type. |
f035d41b XL |
1220 | pub fn is_ty(&self, interner: &I) -> bool { |
1221 | match self.data(interner) { | |
1222 | GenericArgData::Ty(_) => true, | |
1223 | GenericArgData::Lifetime(_) => false, | |
1224 | GenericArgData::Const(_) => false, | |
1225 | } | |
1226 | } | |
1227 | ||
1b1a35ee | 1228 | /// Returns the type if it is one, `None` otherwise. |
f035d41b XL |
1229 | pub fn ty(&self, interner: &I) -> Option<&Ty<I>> { |
1230 | match self.data(interner) { | |
1231 | GenericArgData::Ty(t) => Some(t), | |
1232 | _ => None, | |
1233 | } | |
1234 | } | |
1235 | ||
1b1a35ee | 1236 | /// Returns the lifetime if it is one, `None` otherwise. |
f035d41b XL |
1237 | pub fn lifetime(&self, interner: &I) -> Option<&Lifetime<I>> { |
1238 | match self.data(interner) { | |
1239 | GenericArgData::Lifetime(t) => Some(t), | |
1240 | _ => None, | |
1241 | } | |
1242 | } | |
1243 | ||
1b1a35ee | 1244 | /// Returns the constant if it is one, `None` otherwise. |
f035d41b XL |
1245 | pub fn constant(&self, interner: &I) -> Option<&Const<I>> { |
1246 | match self.data(interner) { | |
1247 | GenericArgData::Const(c) => Some(c), | |
1248 | _ => None, | |
1249 | } | |
1250 | } | |
1251 | } | |
1252 | ||
1b1a35ee | 1253 | /// Generic arguments data. |
f035d41b XL |
1254 | #[derive(Clone, PartialEq, Eq, Hash, Visit, Fold, Zip)] |
1255 | pub enum GenericArgData<I: Interner> { | |
1b1a35ee | 1256 | /// Type argument |
f035d41b | 1257 | Ty(Ty<I>), |
1b1a35ee | 1258 | /// Lifetime argument |
f035d41b | 1259 | Lifetime(Lifetime<I>), |
1b1a35ee | 1260 | /// Constant argument |
f035d41b XL |
1261 | Const(Const<I>), |
1262 | } | |
1263 | ||
1b1a35ee XL |
1264 | impl<I: Interner> Copy for GenericArgData<I> |
1265 | where | |
1266 | I::InternedType: Copy, | |
1267 | I::InternedLifetime: Copy, | |
1268 | I::InternedConst: Copy, | |
1269 | { | |
1270 | } | |
1271 | ||
f035d41b | 1272 | impl<I: Interner> GenericArgData<I> { |
1b1a35ee | 1273 | /// Create an interned type. |
f035d41b XL |
1274 | pub fn intern(self, interner: &I) -> GenericArg<I> { |
1275 | GenericArg::new(interner, self) | |
1276 | } | |
1277 | } | |
1278 | ||
1b1a35ee | 1279 | /// A value with an associated variable kind. |
f035d41b XL |
1280 | #[derive(Clone, PartialEq, Eq, Hash)] |
1281 | pub struct WithKind<I: Interner, T> { | |
1b1a35ee | 1282 | /// The associated variable kind. |
f035d41b | 1283 | pub kind: VariableKind<I>, |
1b1a35ee | 1284 | /// The wrapped value. |
f035d41b XL |
1285 | value: T, |
1286 | } | |
1287 | ||
1b1a35ee XL |
1288 | impl<I: Interner, T: Copy> Copy for WithKind<I, T> where I::InternedType: Copy {} |
1289 | ||
f035d41b XL |
1290 | impl<I: Interner, T> HasInterner for WithKind<I, T> { |
1291 | type Interner = I; | |
1292 | } | |
1293 | ||
1294 | impl<I: Interner, T> From<WithKind<I, T>> for (VariableKind<I>, T) { | |
1295 | fn from(with_kind: WithKind<I, T>) -> Self { | |
1296 | (with_kind.kind, with_kind.value) | |
1297 | } | |
1298 | } | |
1299 | ||
1300 | impl<I: Interner, T> WithKind<I, T> { | |
1b1a35ee | 1301 | /// Creates a `WithKind` from a variable kind and a value. |
f035d41b XL |
1302 | pub fn new(kind: VariableKind<I>, value: T) -> Self { |
1303 | Self { kind, value } | |
1304 | } | |
1305 | ||
1b1a35ee | 1306 | /// Maps the value in `WithKind`. |
f035d41b XL |
1307 | pub fn map<U, OP>(self, op: OP) -> WithKind<I, U> |
1308 | where | |
1309 | OP: FnOnce(T) -> U, | |
1310 | { | |
1311 | WithKind { | |
1312 | kind: self.kind, | |
1313 | value: op(self.value), | |
1314 | } | |
1315 | } | |
1316 | ||
1b1a35ee | 1317 | /// Maps a function taking `WithKind<I, &T>` over `&WithKind<I, T>`. |
f035d41b XL |
1318 | pub fn map_ref<U, OP>(&self, op: OP) -> WithKind<I, U> |
1319 | where | |
1320 | OP: FnOnce(&T) -> U, | |
1321 | { | |
1322 | WithKind { | |
1323 | kind: self.kind.clone(), | |
1324 | value: op(&self.value), | |
1325 | } | |
1326 | } | |
1327 | ||
1b1a35ee | 1328 | /// Extract the value, ignoring the variable kind. |
f035d41b XL |
1329 | pub fn skip_kind(&self) -> &T { |
1330 | &self.value | |
1331 | } | |
1332 | } | |
1333 | ||
1b1a35ee | 1334 | /// A variable kind with universe index. |
f035d41b XL |
1335 | #[allow(type_alias_bounds)] |
1336 | pub type CanonicalVarKind<I: Interner> = WithKind<I, UniverseIndex>; | |
1337 | ||
1b1a35ee | 1338 | /// An alias, which is a trait indirection such as a projection or opaque type. |
f035d41b XL |
1339 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1340 | pub enum AliasTy<I: Interner> { | |
1b1a35ee | 1341 | /// An associated type projection. |
f035d41b | 1342 | Projection(ProjectionTy<I>), |
1b1a35ee | 1343 | /// An opaque type. |
f035d41b XL |
1344 | Opaque(OpaqueTy<I>), |
1345 | } | |
1346 | ||
1b1a35ee XL |
1347 | impl<I: Interner> Copy for AliasTy<I> where I::InternedSubstitution: Copy {} |
1348 | ||
f035d41b | 1349 | impl<I: Interner> AliasTy<I> { |
1b1a35ee | 1350 | /// Create an interned type for this alias. |
f035d41b XL |
1351 | pub fn intern(self, interner: &I) -> Ty<I> { |
1352 | Ty::new(interner, self) | |
1353 | } | |
1354 | ||
1b1a35ee | 1355 | /// Gets the type parameters of the `Self` type in this alias type. |
f035d41b XL |
1356 | pub fn self_type_parameter(&self, interner: &I) -> Ty<I> { |
1357 | match self { | |
1358 | AliasTy::Projection(projection_ty) => projection_ty | |
1359 | .substitution | |
1360 | .iter(interner) | |
1361 | .find_map(move |p| p.ty(interner)) | |
1362 | .unwrap() | |
1363 | .clone(), | |
1364 | _ => todo!(), | |
1365 | } | |
1366 | } | |
1367 | } | |
1368 | ||
1b1a35ee | 1369 | /// A projection `<P0 as TraitName<P1..Pn>>::AssocItem<Pn+1..Pm>`. |
f035d41b XL |
1370 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1371 | pub struct ProjectionTy<I: Interner> { | |
1b1a35ee | 1372 | /// The id for the associated type member. |
f035d41b | 1373 | pub associated_ty_id: AssocTypeId<I>, |
1b1a35ee | 1374 | /// The substitution for the projection. |
f035d41b XL |
1375 | pub substitution: Substitution<I>, |
1376 | } | |
1377 | ||
1b1a35ee XL |
1378 | impl<I: Interner> Copy for ProjectionTy<I> where I::InternedSubstitution: Copy {} |
1379 | ||
1380 | /// An opaque type `opaque type T<..>: Trait = HiddenTy`. | |
f035d41b XL |
1381 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1382 | pub struct OpaqueTy<I: Interner> { | |
1b1a35ee | 1383 | /// The id for the opaque type. |
f035d41b | 1384 | pub opaque_ty_id: OpaqueTyId<I>, |
1b1a35ee | 1385 | /// The substitution for the opaque type. |
f035d41b XL |
1386 | pub substitution: Substitution<I>, |
1387 | } | |
1388 | ||
1b1a35ee XL |
1389 | impl<I: Interner> Copy for OpaqueTy<I> where I::InternedSubstitution: Copy {} |
1390 | ||
1391 | /// A trait reference describes the relationship between a type and a trait. | |
1392 | /// This can be used in two forms: | |
1393 | /// - `P0: Trait<P1..Pn>` (e.g. `i32: Copy`), which mentions that the type | |
1394 | /// implements the trait. | |
1395 | /// - `<P0 as Trait<P1..Pn>>` (e.g. `i32 as Copy`), which casts the type to | |
1396 | /// that specific trait. | |
f035d41b XL |
1397 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1398 | pub struct TraitRef<I: Interner> { | |
1b1a35ee | 1399 | /// The trait id. |
f035d41b | 1400 | pub trait_id: TraitId<I>, |
1b1a35ee | 1401 | /// The substitution, containing both the `Self` type and the parameters. |
f035d41b XL |
1402 | pub substitution: Substitution<I>, |
1403 | } | |
1404 | ||
1b1a35ee XL |
1405 | impl<I: Interner> Copy for TraitRef<I> where I::InternedSubstitution: Copy {} |
1406 | ||
f035d41b | 1407 | impl<I: Interner> TraitRef<I> { |
1b1a35ee | 1408 | /// Gets all type parameters in this trait ref, including `Self`. |
f035d41b XL |
1409 | pub fn type_parameters<'a>(&'a self, interner: &'a I) -> impl Iterator<Item = Ty<I>> + 'a { |
1410 | self.substitution | |
1411 | .iter(interner) | |
1412 | .filter_map(move |p| p.ty(interner)) | |
1413 | .cloned() | |
1414 | } | |
1415 | ||
1b1a35ee | 1416 | /// Gets the type parameters of the `Self` type in this trait ref. |
f035d41b XL |
1417 | pub fn self_type_parameter(&self, interner: &I) -> Ty<I> { |
1418 | self.type_parameters(interner).next().unwrap() | |
1419 | } | |
1420 | ||
1b1a35ee | 1421 | /// Construct a `FromEnv` using this trait ref. |
f035d41b XL |
1422 | pub fn from_env(self) -> FromEnv<I> { |
1423 | FromEnv::Trait(self) | |
1424 | } | |
1425 | ||
1b1a35ee | 1426 | /// Construct a `WellFormed` using this trait ref. |
f035d41b XL |
1427 | pub fn well_formed(self) -> WellFormed<I> { |
1428 | WellFormed::Trait(self) | |
1429 | } | |
1430 | } | |
1431 | ||
1b1a35ee XL |
1432 | /// Lifetime outlives, which for `'a: 'b`` checks that the lifetime `'a` |
1433 | /// is a superset of the value of `'b`. | |
f035d41b | 1434 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1b1a35ee | 1435 | #[allow(missing_docs)] |
f035d41b XL |
1436 | pub struct LifetimeOutlives<I: Interner> { |
1437 | pub a: Lifetime<I>, | |
1438 | pub b: Lifetime<I>, | |
1439 | } | |
1b1a35ee XL |
1440 | |
1441 | impl<I: Interner> Copy for LifetimeOutlives<I> where I::InternedLifetime: Copy {} | |
1442 | ||
1443 | /// Type outlives, which for `T: 'a` checks that the type `T` | |
1444 | /// lives at least as long as the lifetime `'a` | |
1445 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] | |
1446 | pub struct TypeOutlives<I: Interner> { | |
1447 | /// The type which must outlive the given lifetime. | |
1448 | pub ty: Ty<I>, | |
1449 | /// The lifetime which the type must outlive. | |
1450 | pub lifetime: Lifetime<I>, | |
1451 | } | |
1452 | ||
1453 | impl<I: Interner> Copy for TypeOutlives<I> | |
1454 | where | |
1455 | I::InternedLifetime: Copy, | |
1456 | I::InternedType: Copy, | |
1457 | { | |
1458 | } | |
1459 | ||
f035d41b XL |
1460 | /// Where clauses that can be written by a Rust programmer. |
1461 | #[derive(Clone, PartialEq, Eq, Hash, Fold, SuperVisit, HasInterner, Zip)] | |
1462 | pub enum WhereClause<I: Interner> { | |
1b1a35ee | 1463 | /// Type implements a trait. |
f035d41b | 1464 | Implemented(TraitRef<I>), |
1b1a35ee | 1465 | /// Type is equal to an alias. |
f035d41b | 1466 | AliasEq(AliasEq<I>), |
1b1a35ee | 1467 | /// One lifetime outlives another. |
f035d41b | 1468 | LifetimeOutlives(LifetimeOutlives<I>), |
1b1a35ee XL |
1469 | /// Type outlives a lifetime. |
1470 | TypeOutlives(TypeOutlives<I>), | |
f035d41b XL |
1471 | } |
1472 | ||
1b1a35ee XL |
1473 | impl<I: Interner> Copy for WhereClause<I> |
1474 | where | |
1475 | I::InternedSubstitution: Copy, | |
1476 | I::InternedLifetime: Copy, | |
1477 | I::InternedType: Copy, | |
1478 | { | |
1479 | } | |
1480 | ||
1481 | /// Checks whether a type or trait ref is well-formed. | |
f035d41b XL |
1482 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1483 | pub enum WellFormed<I: Interner> { | |
1484 | /// A predicate which is true when some trait ref is well-formed. | |
1485 | /// For example, given the following trait definitions: | |
1486 | /// | |
1487 | /// ```notrust | |
1488 | /// trait Clone { ... } | |
1489 | /// trait Copy where Self: Clone { ... } | |
1490 | /// ``` | |
1491 | /// | |
1492 | /// then we have the following rule: | |
1493 | /// | |
1494 | /// ```notrust | |
1495 | /// WellFormed(?Self: Copy) :- ?Self: Copy, WellFormed(?Self: Clone) | |
1496 | /// ``` | |
1497 | Trait(TraitRef<I>), | |
1498 | ||
1499 | /// A predicate which is true when some type is well-formed. | |
1500 | /// For example, given the following type definition: | |
1501 | /// | |
1502 | /// ```notrust | |
1503 | /// struct Set<K> where K: Hash { | |
1504 | /// ... | |
1505 | /// } | |
1506 | /// ``` | |
1507 | /// | |
1508 | /// then we have the following rule: `WellFormedTy(Set<K>) :- Implemented(K: Hash)`. | |
1509 | Ty(Ty<I>), | |
1510 | } | |
1511 | ||
1b1a35ee XL |
1512 | impl<I: Interner> Copy for WellFormed<I> |
1513 | where | |
1514 | I::InternedType: Copy, | |
1515 | I::InternedSubstitution: Copy, | |
1516 | { | |
1517 | } | |
1518 | ||
1519 | /// Checks whether a type or trait ref can be derived from the contents of the environment. | |
f035d41b XL |
1520 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
1521 | pub enum FromEnv<I: Interner> { | |
1522 | /// A predicate which enables deriving everything which should be true if we *know* that | |
1523 | /// some trait ref is well-formed. For example given the above trait definitions, we can use | |
1524 | /// `FromEnv(T: Copy)` to derive that `T: Clone`, like in: | |
1525 | /// | |
1526 | /// ```notrust | |
1527 | /// forall<T> { | |
1528 | /// if (FromEnv(T: Copy)) { | |
1529 | /// T: Clone | |
1530 | /// } | |
1531 | /// } | |
1532 | /// ``` | |
1533 | Trait(TraitRef<I>), | |
1534 | ||
1535 | /// A predicate which enables deriving everything which should be true if we *know* that | |
1536 | /// some type is well-formed. For example given the above type definition, we can use | |
1537 | /// `FromEnv(Set<K>)` to derive that `K: Hash`, like in: | |
1538 | /// | |
1539 | /// ```notrust | |
1540 | /// forall<K> { | |
1541 | /// if (FromEnv(Set<K>)) { | |
1542 | /// K: Hash | |
1543 | /// } | |
1544 | /// } | |
1545 | /// ``` | |
1546 | Ty(Ty<I>), | |
1547 | } | |
1548 | ||
1b1a35ee XL |
1549 | impl<I: Interner> Copy for FromEnv<I> |
1550 | where | |
1551 | I::InternedType: Copy, | |
1552 | I::InternedSubstitution: Copy, | |
1553 | { | |
1554 | } | |
1555 | ||
f035d41b XL |
1556 | /// A "domain goal" is a goal that is directly about Rust, rather than a pure |
1557 | /// logical statement. As much as possible, the Chalk solver should avoid | |
1558 | /// decomposing this enum, and instead treat its values opaquely. | |
1559 | #[derive(Clone, PartialEq, Eq, Hash, Fold, SuperVisit, HasInterner, Zip)] | |
1560 | pub enum DomainGoal<I: Interner> { | |
1b1a35ee | 1561 | /// Simple goal that is true if the where clause is true. |
f035d41b XL |
1562 | Holds(WhereClause<I>), |
1563 | ||
1b1a35ee | 1564 | /// True if the type or trait ref is well-formed. |
f035d41b XL |
1565 | WellFormed(WellFormed<I>), |
1566 | ||
1b1a35ee | 1567 | /// True if the trait ref can be derived from in-scope where clauses. |
f035d41b XL |
1568 | FromEnv(FromEnv<I>), |
1569 | ||
1b1a35ee | 1570 | /// True if the alias type can be normalized to some other type |
f035d41b XL |
1571 | Normalize(Normalize<I>), |
1572 | ||
1573 | /// True if a type is considered to have been "defined" by the current crate. This is true for | |
1574 | /// a `struct Foo { }` but false for a `#[upstream] struct Foo { }`. However, for fundamental types | |
1575 | /// like `Box<T>`, it is true if `T` is local. | |
1576 | IsLocal(Ty<I>), | |
1577 | ||
1578 | /// True if a type is *not* considered to have been "defined" by the current crate. This is | |
1579 | /// false for a `struct Foo { }` but true for a `#[upstream] struct Foo { }`. However, for | |
1580 | /// fundamental types like `Box<T>`, it is true if `T` is upstream. | |
1581 | IsUpstream(Ty<I>), | |
1582 | ||
1583 | /// True if a type and its input types are fully visible, known types. That is, there are no | |
1584 | /// unknown type parameters anywhere in this type. | |
1585 | /// | |
1586 | /// More formally, for each struct S<P0..Pn>: | |
1587 | /// forall<P0..Pn> { | |
1588 | /// IsFullyVisible(S<P0...Pn>) :- | |
1589 | /// IsFullyVisible(P0), | |
1590 | /// ... | |
1591 | /// IsFullyVisible(Pn) | |
1592 | /// } | |
1593 | /// | |
1594 | /// Note that any of these types can have lifetimes in their parameters too, but we only | |
1595 | /// consider type parameters. | |
1596 | IsFullyVisible(Ty<I>), | |
1597 | ||
1598 | /// Used to dictate when trait impls are allowed in the current (local) crate based on the | |
1599 | /// orphan rules. | |
1600 | /// | |
1601 | /// `LocalImplAllowed(T: Trait)` is true if the type T is allowed to impl trait Trait in | |
1602 | /// the current crate. Under the current rules, this is unconditionally true for all types if | |
1603 | /// the Trait is considered to be "defined" in the current crate. If that is not the case, then | |
1604 | /// `LocalImplAllowed(T: Trait)` can still be true if `IsLocal(T)` is true. | |
1605 | LocalImplAllowed(TraitRef<I>), | |
1606 | ||
1607 | /// Used to activate the "compatible modality" rules. Rules that introduce predicates that have | |
1608 | /// to do with "all compatible universes" should depend on this clause so that they only apply | |
1609 | /// if this is present. | |
1b1a35ee | 1610 | Compatible, |
f035d41b XL |
1611 | |
1612 | /// Used to indicate that a given type is in a downstream crate. Downstream crates contain the | |
1613 | /// current crate at some level of their dependencies. | |
1614 | /// | |
1615 | /// Since chalk does not actually see downstream types, this is usually introduced with | |
1616 | /// implication on a fresh, universally quantified type. | |
1617 | /// | |
1618 | /// forall<T> { if (DownstreamType(T)) { /* ... */ } } | |
1619 | /// | |
1620 | /// This makes a new type `T` available and makes `DownstreamType(T)` provable for that type. | |
1621 | DownstreamType(Ty<I>), | |
1622 | ||
1623 | /// Used to activate the "reveal mode", in which opaque (`impl Trait`) types can be equated | |
1624 | /// to their actual type. | |
1b1a35ee | 1625 | Reveal, |
f035d41b XL |
1626 | |
1627 | /// Used to indicate that a trait is object safe. | |
1628 | ObjectSafe(TraitId<I>), | |
1629 | } | |
1630 | ||
1b1a35ee XL |
1631 | impl<I: Interner> Copy for DomainGoal<I> |
1632 | where | |
1633 | I::InternedSubstitution: Copy, | |
1634 | I::InternedLifetime: Copy, | |
1635 | I::InternedType: Copy, | |
1636 | { | |
1637 | } | |
1638 | ||
1639 | /// A where clause that can contain `forall<>` or `exists<>` quantifiers. | |
f035d41b XL |
1640 | pub type QuantifiedWhereClause<I> = Binders<WhereClause<I>>; |
1641 | ||
1642 | impl<I: Interner> WhereClause<I> { | |
1643 | /// Turn a where clause into the WF version of it i.e.: | |
1644 | /// * `Implemented(T: Trait)` maps to `WellFormed(T: Trait)` | |
1645 | /// * `ProjectionEq(<T as Trait>::Item = Foo)` maps to `WellFormed(<T as Trait>::Item = Foo)` | |
1646 | /// * any other clause maps to itself | |
1647 | pub fn into_well_formed_goal(self, interner: &I) -> DomainGoal<I> { | |
1648 | match self { | |
1649 | WhereClause::Implemented(trait_ref) => WellFormed::Trait(trait_ref).cast(interner), | |
1650 | wc => wc.cast(interner), | |
1651 | } | |
1652 | } | |
1653 | ||
1654 | /// Same as `into_well_formed_goal` but with the `FromEnv` predicate instead of `WellFormed`. | |
1655 | pub fn into_from_env_goal(self, interner: &I) -> DomainGoal<I> { | |
1656 | match self { | |
1657 | WhereClause::Implemented(trait_ref) => FromEnv::Trait(trait_ref).cast(interner), | |
1658 | wc => wc.cast(interner), | |
1659 | } | |
1660 | } | |
1661 | ||
1b1a35ee | 1662 | /// If where clause is a `TraitRef`, returns its trait id. |
f035d41b XL |
1663 | pub fn trait_id(&self) -> Option<TraitId<I>> { |
1664 | match self { | |
1665 | WhereClause::Implemented(trait_ref) => Some(trait_ref.trait_id), | |
1666 | WhereClause::AliasEq(_) => None, | |
1667 | WhereClause::LifetimeOutlives(_) => None, | |
1b1a35ee | 1668 | WhereClause::TypeOutlives(_) => None, |
f035d41b XL |
1669 | } |
1670 | } | |
1671 | } | |
1672 | ||
1673 | impl<I: Interner> QuantifiedWhereClause<I> { | |
1674 | /// As with `WhereClause::into_well_formed_goal`, but for a | |
1675 | /// quantified where clause. For example, `forall<T> { | |
1676 | /// Implemented(T: Trait)}` would map to `forall<T> { | |
1677 | /// WellFormed(T: Trait) }`. | |
1678 | pub fn into_well_formed_goal(self, interner: &I) -> Binders<DomainGoal<I>> { | |
1679 | self.map(|wc| wc.into_well_formed_goal(interner)) | |
1680 | } | |
1681 | ||
1682 | /// As with `WhereClause::into_from_env_goal`, but mapped over any | |
1683 | /// binders. For example, `forall<T> { | |
1684 | /// Implemented(T: Trait)}` would map to `forall<T> { | |
1685 | /// FromEnv(T: Trait) }`. | |
1686 | pub fn into_from_env_goal(self, interner: &I) -> Binders<DomainGoal<I>> { | |
1687 | self.map(|wc| wc.into_from_env_goal(interner)) | |
1688 | } | |
1689 | ||
1b1a35ee | 1690 | /// If the underlying where clause is a `TraitRef`, returns its trait id. |
f035d41b XL |
1691 | pub fn trait_id(&self) -> Option<TraitId<I>> { |
1692 | self.skip_binders().trait_id() | |
1693 | } | |
1694 | } | |
1695 | ||
f035d41b XL |
1696 | impl<I: Interner> DomainGoal<I> { |
1697 | /// Convert `Implemented(...)` into `FromEnv(...)`, but leave other | |
1698 | /// goals unchanged. | |
1699 | pub fn into_from_env_goal(self, interner: &I) -> DomainGoal<I> { | |
1700 | match self { | |
1701 | DomainGoal::Holds(wc) => wc.into_from_env_goal(interner), | |
1702 | goal => goal, | |
1703 | } | |
1704 | } | |
1705 | ||
1b1a35ee | 1706 | /// Lists generic arguments that are inputs to this domain goal. |
f035d41b XL |
1707 | pub fn inputs(&self, interner: &I) -> Vec<GenericArg<I>> { |
1708 | match self { | |
1709 | DomainGoal::Holds(WhereClause::AliasEq(alias_eq)) => { | |
1710 | vec![GenericArgData::Ty(alias_eq.alias.clone().intern(interner)).intern(interner)] | |
1711 | } | |
1712 | _ => Vec::new(), | |
1713 | } | |
1714 | } | |
1715 | } | |
1716 | ||
1b1a35ee | 1717 | /// Equality goal: tries to prove that two values are equal. |
f035d41b | 1718 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, Zip)] |
1b1a35ee | 1719 | #[allow(missing_docs)] |
f035d41b XL |
1720 | pub struct EqGoal<I: Interner> { |
1721 | pub a: GenericArg<I>, | |
1722 | pub b: GenericArg<I>, | |
1723 | } | |
1724 | ||
1b1a35ee XL |
1725 | impl<I: Interner> Copy for EqGoal<I> where I::InternedGenericArg: Copy {} |
1726 | ||
f035d41b XL |
1727 | /// Proves that the given type alias **normalizes** to the given |
1728 | /// type. A projection `T::Foo` normalizes to the type `U` if we can | |
1729 | /// **match it to an impl** and that impl has a `type Foo = V` where | |
1730 | /// `U = V`. | |
1731 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, Zip)] | |
1b1a35ee | 1732 | #[allow(missing_docs)] |
f035d41b XL |
1733 | pub struct Normalize<I: Interner> { |
1734 | pub alias: AliasTy<I>, | |
1735 | pub ty: Ty<I>, | |
1736 | } | |
1737 | ||
1b1a35ee XL |
1738 | impl<I: Interner> Copy for Normalize<I> |
1739 | where | |
1740 | I::InternedSubstitution: Copy, | |
1741 | I::InternedType: Copy, | |
1742 | { | |
1743 | } | |
1744 | ||
f035d41b XL |
1745 | /// Proves **equality** between an alias and a type. |
1746 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, Zip)] | |
1b1a35ee | 1747 | #[allow(missing_docs)] |
f035d41b XL |
1748 | pub struct AliasEq<I: Interner> { |
1749 | pub alias: AliasTy<I>, | |
1750 | pub ty: Ty<I>, | |
1751 | } | |
1752 | ||
1b1a35ee XL |
1753 | impl<I: Interner> Copy for AliasEq<I> |
1754 | where | |
1755 | I::InternedSubstitution: Copy, | |
1756 | I::InternedType: Copy, | |
1757 | { | |
1758 | } | |
1759 | ||
f035d41b XL |
1760 | impl<I: Interner> HasInterner for AliasEq<I> { |
1761 | type Interner = I; | |
1762 | } | |
1763 | ||
1764 | /// Indicates that the `value` is universally quantified over `N` | |
1765 | /// parameters of the given kinds, where `N == self.binders.len()`. A | |
1766 | /// variable with depth `i < N` refers to the value at | |
1767 | /// `self.binders[i]`. Variables with depth `>= N` are free. | |
1768 | /// | |
1769 | /// (IOW, we use deBruijn indices, where binders are introduced in reverse order | |
1770 | /// of `self.binders`.) | |
1771 | #[derive(Clone, PartialEq, Eq, Hash)] | |
1772 | pub struct Binders<T: HasInterner> { | |
1b1a35ee | 1773 | /// The binders that quantify over the value. |
f035d41b | 1774 | pub binders: VariableKinds<T::Interner>, |
1b1a35ee XL |
1775 | |
1776 | /// The value being quantified over. | |
f035d41b XL |
1777 | value: T, |
1778 | } | |
1779 | ||
1b1a35ee XL |
1780 | impl<T: HasInterner + Copy> Copy for Binders<T> where |
1781 | <T::Interner as Interner>::InternedVariableKinds: Copy | |
1782 | { | |
1783 | } | |
1784 | ||
f035d41b XL |
1785 | impl<T: HasInterner> HasInterner for Binders<T> { |
1786 | type Interner = T::Interner; | |
1787 | } | |
1788 | ||
1789 | impl<T: HasInterner> Binders<T> { | |
1b1a35ee | 1790 | /// Create new binders. |
f035d41b XL |
1791 | pub fn new(binders: VariableKinds<T::Interner>, value: T) -> Self { |
1792 | Self { binders, value } | |
1793 | } | |
1794 | ||
1795 | /// Wraps the given value in a binder without variables, i.e. `for<> | |
1796 | /// (value)`. Since our deBruijn indices count binders, not variables, this | |
1797 | /// is sometimes useful. | |
1798 | pub fn empty(interner: &T::Interner, value: T) -> Self { | |
1b1a35ee | 1799 | let binders = VariableKinds::empty(interner); |
f035d41b XL |
1800 | Self { binders, value } |
1801 | } | |
1802 | ||
1803 | /// Skips the binder and returns the "bound" value. This is a | |
1804 | /// risky thing to do because it's easy to get confused about | |
1805 | /// De Bruijn indices and the like. `skip_binder` is only valid | |
1806 | /// when you are either extracting data that has nothing to | |
1807 | /// do with bound vars, or you are being very careful about | |
1808 | /// your depth accounting. | |
1809 | /// | |
1810 | /// Some examples where `skip_binder` is reasonable: | |
1811 | /// | |
1812 | /// - extracting the `TraitId` from a TraitRef; | |
1813 | /// - checking if there are any fields in a StructDatum | |
1814 | pub fn skip_binders(&self) -> &T { | |
1815 | &self.value | |
1816 | } | |
1817 | ||
1818 | /// Converts `&Binders<T>` to `Binders<&T>`. Produces new `Binders` | |
1819 | /// with cloned quantifiers containing a reference to the original | |
1820 | /// value, leaving the original in place. | |
1821 | pub fn as_ref(&self) -> Binders<&T> { | |
1822 | Binders { | |
1823 | binders: self.binders.clone(), | |
1824 | value: &self.value, | |
1825 | } | |
1826 | } | |
1827 | ||
1b1a35ee | 1828 | /// Maps the binders by applying a function. |
f035d41b XL |
1829 | pub fn map<U, OP>(self, op: OP) -> Binders<U> |
1830 | where | |
1831 | OP: FnOnce(T) -> U, | |
1832 | U: HasInterner<Interner = T::Interner>, | |
1833 | { | |
1834 | let value = op(self.value); | |
1835 | Binders { | |
1836 | binders: self.binders, | |
1837 | value, | |
1838 | } | |
1839 | } | |
1840 | ||
1841 | /// Transforms the inner value according to the given function; returns | |
1842 | /// `None` if the function returns `None`. | |
1843 | pub fn filter_map<U, OP>(self, op: OP) -> Option<Binders<U>> | |
1844 | where | |
1845 | OP: FnOnce(T) -> Option<U>, | |
1846 | U: HasInterner<Interner = T::Interner>, | |
1847 | { | |
1848 | let value = op(self.value)?; | |
1849 | Some(Binders { | |
1850 | binders: self.binders, | |
1851 | value, | |
1852 | }) | |
1853 | } | |
1854 | ||
1b1a35ee | 1855 | /// Maps a function taking `Binders<&T>` over `&Binders<T>`. |
f035d41b XL |
1856 | pub fn map_ref<'a, U, OP>(&'a self, op: OP) -> Binders<U> |
1857 | where | |
1858 | OP: FnOnce(&'a T) -> U, | |
1859 | U: HasInterner<Interner = T::Interner>, | |
1860 | { | |
1861 | self.as_ref().map(op) | |
1862 | } | |
1863 | ||
1864 | /// Creates a `Substitution` containing bound vars such that applying this | |
1865 | /// substitution will not change the value, i.e. `^0.0, ^0.1, ^0.2` and so | |
1866 | /// on. | |
1867 | pub fn identity_substitution(&self, interner: &T::Interner) -> Substitution<T::Interner> { | |
1b1a35ee | 1868 | Substitution::from_iter( |
f035d41b XL |
1869 | interner, |
1870 | self.binders | |
1871 | .iter(interner) | |
1872 | .enumerate() | |
1b1a35ee | 1873 | .map(|p| p.to_generic_arg(interner)), |
f035d41b XL |
1874 | ) |
1875 | } | |
1876 | ||
1877 | /// Creates a fresh binders that contains a single type | |
1878 | /// variable. The result of the closure will be embedded in this | |
1879 | /// binder. Note that you should be careful with what you return | |
1880 | /// from the closure to account for the binder that will be added. | |
1881 | /// | |
1882 | /// XXX FIXME -- this is potentially a pretty footgun-y function. | |
1883 | pub fn with_fresh_type_var( | |
1884 | interner: &T::Interner, | |
1885 | op: impl FnOnce(Ty<T::Interner>) -> T, | |
1886 | ) -> Binders<T> { | |
1887 | // The new variable is at the front and everything afterwards is shifted up by 1 | |
1888 | let new_var = TyData::BoundVar(BoundVar::new(DebruijnIndex::INNERMOST, 0)).intern(interner); | |
1889 | let value = op(new_var); | |
1b1a35ee | 1890 | let binders = VariableKinds::from1(interner, VariableKind::Ty(TyKind::General)); |
f035d41b XL |
1891 | Binders { binders, value } |
1892 | } | |
1893 | ||
1b1a35ee | 1894 | /// Returns the number of binders. |
f035d41b XL |
1895 | pub fn len(&self, interner: &T::Interner) -> usize { |
1896 | self.binders.len(interner) | |
1897 | } | |
1898 | } | |
1899 | ||
1900 | impl<T, I> Binders<Binders<T>> | |
1901 | where | |
1902 | T: Fold<I, I> + HasInterner<Interner = I>, | |
1903 | T::Result: HasInterner<Interner = I>, | |
1904 | I: Interner, | |
1905 | { | |
1906 | /// This turns two levels of binders (`for<A> for<B>`) into one level (`for<A, B>`). | |
1907 | pub fn fuse_binders(self, interner: &T::Interner) -> Binders<T::Result> { | |
1908 | let num_binders = self.len(interner); | |
1909 | // generate a substitution to shift the indexes of the inner binder: | |
1b1a35ee | 1910 | let subst = Substitution::from_iter( |
f035d41b XL |
1911 | interner, |
1912 | self.value | |
1913 | .binders | |
1914 | .iter(interner) | |
1915 | .enumerate() | |
1b1a35ee | 1916 | .map(|(i, pk)| (i + num_binders, pk).to_generic_arg(interner)), |
f035d41b XL |
1917 | ); |
1918 | let value = self.value.substitute(interner, &subst); | |
1b1a35ee | 1919 | let binders = VariableKinds::from_iter( |
f035d41b XL |
1920 | interner, |
1921 | self.binders | |
1922 | .iter(interner) | |
1923 | .chain(self.value.binders.iter(interner)) | |
1924 | .cloned(), | |
1925 | ); | |
1926 | Binders { binders, value } | |
1927 | } | |
1928 | } | |
1929 | ||
1930 | impl<T: HasInterner> From<Binders<T>> for (VariableKinds<T::Interner>, T) { | |
1931 | fn from(binders: Binders<T>) -> Self { | |
1932 | (binders.binders, binders.value) | |
1933 | } | |
1934 | } | |
1935 | ||
1936 | impl<T, I> Binders<T> | |
1937 | where | |
1938 | T: Fold<I, I> + HasInterner<Interner = I>, | |
1939 | I: Interner, | |
1940 | { | |
1941 | /// Substitute `parameters` for the variables introduced by these | |
1942 | /// binders. So if the binders represent (e.g.) `<X, Y> { T }` and | |
1943 | /// parameters is the slice `[A, B]`, then returns `[X => A, Y => | |
1944 | /// B] T`. | |
1945 | pub fn substitute( | |
1946 | &self, | |
1947 | interner: &I, | |
1948 | parameters: &(impl AsParameters<I> + ?Sized), | |
1949 | ) -> T::Result { | |
1950 | let parameters = parameters.as_parameters(interner); | |
1951 | assert_eq!(self.binders.len(interner), parameters.len()); | |
1952 | Subst::apply(interner, parameters, &self.value) | |
1953 | } | |
1954 | } | |
1955 | ||
1956 | /// Allows iterating over a Binders<Vec<T>>, for instance. | |
1957 | /// Each element will include the same set of parameter bounds. | |
1958 | impl<V, U> IntoIterator for Binders<V> | |
1959 | where | |
1960 | V: HasInterner + IntoIterator<Item = U>, | |
1961 | U: HasInterner<Interner = V::Interner>, | |
1962 | { | |
1963 | type Item = Binders<U>; | |
1964 | type IntoIter = BindersIntoIterator<V>; | |
1965 | ||
1966 | fn into_iter(self) -> Self::IntoIter { | |
1967 | BindersIntoIterator { | |
1968 | iter: self.value.into_iter(), | |
1969 | binders: self.binders, | |
1970 | } | |
1971 | } | |
1972 | } | |
1973 | ||
1b1a35ee | 1974 | /// `IntoIterator` for binders. |
f035d41b XL |
1975 | pub struct BindersIntoIterator<V: HasInterner + IntoIterator> { |
1976 | iter: <V as IntoIterator>::IntoIter, | |
1977 | binders: VariableKinds<V::Interner>, | |
1978 | } | |
1979 | ||
1980 | impl<V> Iterator for BindersIntoIterator<V> | |
1981 | where | |
1982 | V: HasInterner + IntoIterator, | |
1983 | <V as IntoIterator>::Item: HasInterner<Interner = V::Interner>, | |
1984 | { | |
1985 | type Item = Binders<<V as IntoIterator>::Item>; | |
1986 | fn next(&mut self) -> Option<Self::Item> { | |
1987 | self.iter | |
1988 | .next() | |
1989 | .map(|v| Binders::new(self.binders.clone(), v)) | |
1990 | } | |
1991 | } | |
1992 | ||
1993 | /// Represents one clause of the form `consequence :- conditions` where | |
1994 | /// `conditions = cond_1 && cond_2 && ...` is the conjunction of the individual | |
1995 | /// conditions. | |
1996 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] | |
1997 | pub struct ProgramClauseImplication<I: Interner> { | |
1b1a35ee | 1998 | /// The consequence of the clause, which holds if the conditions holds. |
f035d41b | 1999 | pub consequence: DomainGoal<I>, |
1b1a35ee XL |
2000 | |
2001 | /// The condition goals that should hold. | |
f035d41b | 2002 | pub conditions: Goals<I>, |
1b1a35ee XL |
2003 | |
2004 | /// The lifetime constraints that should be proven. | |
2005 | pub constraints: Constraints<I>, | |
2006 | ||
2007 | /// The relative priority of the implication. | |
f035d41b XL |
2008 | pub priority: ClausePriority, |
2009 | } | |
2010 | ||
1b1a35ee | 2011 | /// Specifies how important an implication is. |
f035d41b XL |
2012 | #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)] |
2013 | pub enum ClausePriority { | |
1b1a35ee | 2014 | /// High priority, the solver should prioritize this. |
f035d41b | 2015 | High, |
1b1a35ee XL |
2016 | |
2017 | /// Low priority, this implication has lower chance to be relevant to the goal. | |
f035d41b XL |
2018 | Low, |
2019 | } | |
2020 | ||
2021 | impl std::ops::BitAnd for ClausePriority { | |
2022 | type Output = ClausePriority; | |
2023 | fn bitand(self, rhs: ClausePriority) -> Self::Output { | |
2024 | match (self, rhs) { | |
2025 | (ClausePriority::High, ClausePriority::High) => ClausePriority::High, | |
2026 | _ => ClausePriority::Low, | |
2027 | } | |
2028 | } | |
2029 | } | |
2030 | ||
1b1a35ee | 2031 | /// Contains the data for a program clause. |
f035d41b XL |
2032 | #[derive(Clone, PartialEq, Eq, Hash, Fold, HasInterner, Zip)] |
2033 | pub struct ProgramClauseData<I: Interner>(pub Binders<ProgramClauseImplication<I>>); | |
2034 | ||
2035 | impl<I: Interner> ProgramClauseImplication<I> { | |
1b1a35ee | 2036 | /// Change the implication into an application holding a `FromEnv` goal. |
f035d41b XL |
2037 | pub fn into_from_env_clause(self, interner: &I) -> ProgramClauseImplication<I> { |
2038 | if self.conditions.is_empty(interner) { | |
2039 | ProgramClauseImplication { | |
2040 | consequence: self.consequence.into_from_env_goal(interner), | |
2041 | conditions: self.conditions.clone(), | |
1b1a35ee | 2042 | constraints: self.constraints.clone(), |
f035d41b XL |
2043 | priority: self.priority, |
2044 | } | |
2045 | } else { | |
2046 | self | |
2047 | } | |
2048 | } | |
2049 | } | |
2050 | ||
2051 | impl<I: Interner> ProgramClauseData<I> { | |
1b1a35ee | 2052 | /// Change the program clause data into a `FromEnv` program clause. |
f035d41b XL |
2053 | pub fn into_from_env_clause(self, interner: &I) -> ProgramClauseData<I> { |
2054 | ProgramClauseData(self.0.map(|i| i.into_from_env_clause(interner))) | |
2055 | } | |
2056 | ||
1b1a35ee | 2057 | /// Intern the program clause data. |
f035d41b XL |
2058 | pub fn intern(self, interner: &I) -> ProgramClause<I> { |
2059 | ProgramClause { | |
2060 | interned: interner.intern_program_clause(self), | |
2061 | } | |
2062 | } | |
2063 | } | |
2064 | ||
1b1a35ee | 2065 | /// A program clause is a logic expression used to describe a part of the program. |
f035d41b XL |
2066 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
2067 | pub struct ProgramClause<I: Interner> { | |
2068 | interned: I::InternedProgramClause, | |
2069 | } | |
2070 | ||
2071 | impl<I: Interner> ProgramClause<I> { | |
1b1a35ee | 2072 | /// Create a new program clause using `ProgramClauseData`. |
f035d41b XL |
2073 | pub fn new(interner: &I, clause: ProgramClauseData<I>) -> Self { |
2074 | let interned = interner.intern_program_clause(clause); | |
2075 | Self { interned } | |
2076 | } | |
2077 | ||
1b1a35ee | 2078 | /// Change the clause into a `FromEnv` clause. |
f035d41b XL |
2079 | pub fn into_from_env_clause(self, interner: &I) -> ProgramClause<I> { |
2080 | let program_clause_data = self.data(interner); | |
2081 | let new_clause = program_clause_data.clone().into_from_env_clause(interner); | |
2082 | Self::new(interner, new_clause) | |
2083 | } | |
2084 | ||
1b1a35ee | 2085 | /// Get the interned program clause. |
f035d41b XL |
2086 | pub fn interned(&self) -> &I::InternedProgramClause { |
2087 | &self.interned | |
2088 | } | |
2089 | ||
1b1a35ee | 2090 | /// Get the program clause data. |
f035d41b XL |
2091 | pub fn data(&self, interner: &I) -> &ProgramClauseData<I> { |
2092 | interner.program_clause_data(&self.interned) | |
2093 | } | |
2094 | } | |
2095 | ||
f035d41b XL |
2096 | /// Wraps a "canonicalized item". Items are canonicalized as follows: |
2097 | /// | |
2098 | /// All unresolved existential variables are "renumbered" according to their | |
2099 | /// first appearance; the kind/universe of the variable is recorded in the | |
2100 | /// `binders` field. | |
2101 | #[derive(Clone, Debug, PartialEq, Eq, Hash)] | |
2102 | pub struct Canonical<T: HasInterner> { | |
1b1a35ee | 2103 | /// The item that is canonicalized. |
f035d41b | 2104 | pub value: T, |
1b1a35ee XL |
2105 | |
2106 | /// The kind/universe of the variable. | |
f035d41b XL |
2107 | pub binders: CanonicalVarKinds<T::Interner>, |
2108 | } | |
2109 | ||
2110 | impl<T: HasInterner> HasInterner for Canonical<T> { | |
2111 | type Interner = T::Interner; | |
2112 | } | |
2113 | ||
2114 | /// A "universe canonical" value. This is a wrapper around a | |
2115 | /// `Canonical`, indicating that the universes within have been | |
2116 | /// "renumbered" to start from 0 and collapse unimportant | |
2117 | /// distinctions. | |
2118 | /// | |
2119 | /// To produce one of these values, use the `u_canonicalize` method. | |
2120 | #[derive(Clone, Debug, PartialEq, Eq, Hash)] | |
2121 | pub struct UCanonical<T: HasInterner> { | |
1b1a35ee | 2122 | /// The wrapped `Canonical`. |
f035d41b | 2123 | pub canonical: Canonical<T>, |
1b1a35ee XL |
2124 | |
2125 | /// The number of universes that have been collapsed. | |
f035d41b XL |
2126 | pub universes: usize, |
2127 | } | |
2128 | ||
2129 | impl<T: HasInterner> UCanonical<T> { | |
1b1a35ee XL |
2130 | /// Checks whether the universe canonical value is a trivial |
2131 | /// substitution (e.g. an identity substitution). | |
f035d41b XL |
2132 | pub fn is_trivial_substitution( |
2133 | &self, | |
2134 | interner: &T::Interner, | |
2135 | canonical_subst: &Canonical<AnswerSubst<T::Interner>>, | |
2136 | ) -> bool { | |
2137 | let subst = &canonical_subst.value.subst; | |
2138 | assert_eq!( | |
2139 | self.canonical.binders.len(interner), | |
1b1a35ee | 2140 | subst.as_slice(interner).len() |
f035d41b XL |
2141 | ); |
2142 | subst.is_identity_subst(interner) | |
2143 | } | |
2144 | ||
1b1a35ee | 2145 | /// Creates an identity substitution. |
f035d41b XL |
2146 | pub fn trivial_substitution(&self, interner: &T::Interner) -> Substitution<T::Interner> { |
2147 | let binders = &self.canonical.binders; | |
1b1a35ee | 2148 | Substitution::from_iter( |
f035d41b XL |
2149 | interner, |
2150 | binders | |
2151 | .iter(interner) | |
2152 | .enumerate() | |
2153 | .map(|(index, pk)| { | |
2154 | let bound_var = BoundVar::new(DebruijnIndex::INNERMOST, index); | |
2155 | match &pk.kind { | |
2156 | VariableKind::Ty(_) => { | |
2157 | GenericArgData::Ty(TyData::BoundVar(bound_var).intern(interner)) | |
2158 | .intern(interner) | |
2159 | } | |
2160 | VariableKind::Lifetime => GenericArgData::Lifetime( | |
2161 | LifetimeData::BoundVar(bound_var).intern(interner), | |
2162 | ) | |
2163 | .intern(interner), | |
2164 | VariableKind::Const(ty) => GenericArgData::Const( | |
2165 | ConstData { | |
2166 | ty: ty.clone(), | |
2167 | value: ConstValue::BoundVar(bound_var), | |
2168 | } | |
2169 | .intern(interner), | |
2170 | ) | |
2171 | .intern(interner), | |
2172 | } | |
2173 | }) | |
2174 | .collect::<Vec<_>>(), | |
2175 | ) | |
2176 | } | |
2177 | } | |
2178 | ||
f035d41b XL |
2179 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] |
2180 | /// A general goal; this is the full range of questions you can pose to Chalk. | |
2181 | pub struct Goal<I: Interner> { | |
2182 | interned: I::InternedGoal, | |
2183 | } | |
2184 | ||
2185 | impl<I: Interner> Goal<I> { | |
1b1a35ee | 2186 | /// Create a new goal using `GoalData`. |
f035d41b XL |
2187 | pub fn new(interner: &I, interned: GoalData<I>) -> Self { |
2188 | let interned = I::intern_goal(interner, interned); | |
2189 | Self { interned } | |
2190 | } | |
2191 | ||
1b1a35ee | 2192 | /// Gets the interned goal. |
f035d41b XL |
2193 | pub fn interned(&self) -> &I::InternedGoal { |
2194 | &self.interned | |
2195 | } | |
2196 | ||
1b1a35ee | 2197 | /// Gets the interned goal data. |
f035d41b XL |
2198 | pub fn data(&self, interner: &I) -> &GoalData<I> { |
2199 | interner.goal_data(&self.interned) | |
2200 | } | |
2201 | ||
1b1a35ee | 2202 | /// Create a goal using a `forall` or `exists` quantifier. |
f035d41b XL |
2203 | pub fn quantify( |
2204 | self, | |
2205 | interner: &I, | |
2206 | kind: QuantifierKind, | |
2207 | binders: VariableKinds<I>, | |
2208 | ) -> Goal<I> { | |
2209 | GoalData::Quantified(kind, Binders::new(binders, self)).intern(interner) | |
2210 | } | |
2211 | ||
1b1a35ee | 2212 | /// Takes a goal `G` and turns it into `not { G }`. |
f035d41b XL |
2213 | pub fn negate(self, interner: &I) -> Self { |
2214 | GoalData::Not(self).intern(interner) | |
2215 | } | |
2216 | ||
2217 | /// Takes a goal `G` and turns it into `compatible { G }`. | |
2218 | pub fn compatible(self, interner: &I) -> Self { | |
2219 | // compatible { G } desugars into: forall<T> { if (Compatible, DownstreamType(T)) { G } } | |
2220 | // This activates the compatible modality rules and introduces an anonymous downstream type | |
2221 | GoalData::Quantified( | |
2222 | QuantifierKind::ForAll, | |
2223 | Binders::with_fresh_type_var(interner, |ty| { | |
2224 | GoalData::Implies( | |
1b1a35ee | 2225 | ProgramClauses::from_iter( |
f035d41b | 2226 | interner, |
1b1a35ee | 2227 | vec![DomainGoal::Compatible, DomainGoal::DownstreamType(ty)], |
f035d41b XL |
2228 | ), |
2229 | self.shifted_in(interner), | |
2230 | ) | |
2231 | .intern(interner) | |
2232 | }), | |
2233 | ) | |
2234 | .intern(interner) | |
2235 | } | |
2236 | ||
1b1a35ee | 2237 | /// Create an implication goal that holds if the predicates are true. |
f035d41b XL |
2238 | pub fn implied_by(self, interner: &I, predicates: ProgramClauses<I>) -> Goal<I> { |
2239 | GoalData::Implies(predicates, self).intern(interner) | |
2240 | } | |
2241 | ||
2242 | /// True if this goal is "trivially true" -- i.e., no work is | |
2243 | /// required to prove it. | |
2244 | pub fn is_trivially_true(&self, interner: &I) -> bool { | |
2245 | match self.data(interner) { | |
2246 | GoalData::All(goals) => goals.is_empty(interner), | |
2247 | _ => false, | |
2248 | } | |
2249 | } | |
2250 | } | |
2251 | ||
2252 | impl<I> Goal<I> | |
2253 | where | |
2254 | I: Interner, | |
2255 | { | |
1b1a35ee | 2256 | /// Creates a single goal that only holds if a list of goals holds. |
f035d41b XL |
2257 | pub fn all<II>(interner: &I, iter: II) -> Self |
2258 | where | |
2259 | II: IntoIterator<Item = Goal<I>>, | |
2260 | { | |
2261 | let mut iter = iter.into_iter(); | |
2262 | if let Some(goal0) = iter.next() { | |
2263 | if let Some(goal1) = iter.next() { | |
2264 | // More than one goal to prove | |
1b1a35ee | 2265 | let goals = Goals::from_iter( |
f035d41b XL |
2266 | interner, |
2267 | Some(goal0).into_iter().chain(Some(goal1)).chain(iter), | |
2268 | ); | |
2269 | GoalData::All(goals).intern(interner) | |
2270 | } else { | |
2271 | // One goal to prove | |
2272 | goal0 | |
2273 | } | |
2274 | } else { | |
2275 | // No goals to prove, always true | |
1b1a35ee | 2276 | GoalData::All(Goals::empty(interner)).intern(interner) |
f035d41b XL |
2277 | } |
2278 | } | |
2279 | } | |
2280 | ||
2281 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] | |
2282 | /// A general goal; this is the full range of questions you can pose to Chalk. | |
2283 | pub enum GoalData<I: Interner> { | |
2284 | /// Introduces a binding at depth 0, shifting other bindings up | |
2285 | /// (deBruijn index). | |
2286 | Quantified(QuantifierKind, Binders<Goal<I>>), | |
1b1a35ee XL |
2287 | |
2288 | /// A goal that holds given some clauses (like an if-statement). | |
f035d41b | 2289 | Implies(ProgramClauses<I>, Goal<I>), |
1b1a35ee XL |
2290 | |
2291 | /// List of goals that all should hold. | |
f035d41b | 2292 | All(Goals<I>), |
1b1a35ee XL |
2293 | |
2294 | /// Negation: the inner goal should not hold. | |
f035d41b XL |
2295 | Not(Goal<I>), |
2296 | ||
2297 | /// Make two things equal; the rules for doing so are well known to the logic | |
2298 | EqGoal(EqGoal<I>), | |
2299 | ||
2300 | /// A "domain goal" indicates some base sort of goal that can be | |
2301 | /// proven via program clauses | |
2302 | DomainGoal(DomainGoal<I>), | |
2303 | ||
2304 | /// Indicates something that cannot be proven to be true or false | |
2305 | /// definitively. This can occur with overflow but also with | |
2306 | /// unifications of skolemized variables like `forall<X,Y> { X = Y | |
2307 | /// }`. Of course, that statement is false, as there exist types | |
2308 | /// X, Y where `X = Y` is not true. But we treat it as "cannot | |
2309 | /// prove" so that `forall<X,Y> { not { X = Y } }` also winds up | |
2310 | /// as cannot prove. | |
1b1a35ee XL |
2311 | CannotProve, |
2312 | } | |
2313 | ||
2314 | impl<I: Interner> Copy for GoalData<I> | |
2315 | where | |
2316 | I::InternedType: Copy, | |
2317 | I::InternedLifetime: Copy, | |
2318 | I::InternedGenericArg: Copy, | |
2319 | I::InternedSubstitution: Copy, | |
2320 | I::InternedGoal: Copy, | |
2321 | I::InternedGoals: Copy, | |
2322 | I::InternedProgramClauses: Copy, | |
2323 | I::InternedVariableKinds: Copy, | |
2324 | { | |
f035d41b XL |
2325 | } |
2326 | ||
2327 | impl<I: Interner> GoalData<I> { | |
1b1a35ee | 2328 | /// Create an interned goal. |
f035d41b XL |
2329 | pub fn intern(self, interner: &I) -> Goal<I> { |
2330 | Goal::new(interner, self) | |
2331 | } | |
2332 | } | |
2333 | ||
1b1a35ee | 2334 | /// Kinds of quantifiers in the logic, such as `forall` and `exists`. |
f035d41b XL |
2335 | #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)] |
2336 | pub enum QuantifierKind { | |
1b1a35ee XL |
2337 | /// Universal quantifier `ForAll`. |
2338 | /// | |
2339 | /// A formula with the universal quantifier `forall(x). P(x)` is satisfiable | |
2340 | /// if and only if the subformula `P(x)` is true for all possible values for x. | |
f035d41b | 2341 | ForAll, |
1b1a35ee XL |
2342 | |
2343 | /// Existential quantifier `Exists`. | |
2344 | /// | |
2345 | /// A formula with the existential quantifier `exists(x). P(x)` is satisfiable | |
2346 | /// if and only if there exists at least one value for all possible values of x | |
2347 | /// which satisfies the subformula `P(x)`. | |
2348 | ||
2349 | /// In the context of chalk, the existential quantifier usually demands the | |
2350 | /// existence of exactly one instance (i.e. type) that satisfies the formula | |
2351 | /// (i.e. type constraints). More than one instance means that the result is ambiguous. | |
f035d41b XL |
2352 | Exists, |
2353 | } | |
2354 | ||
2355 | /// A constraint on lifetimes. | |
2356 | /// | |
2357 | /// When we search for solutions within the trait system, we essentially ignore | |
2358 | /// lifetime constraints, instead gathering them up to return with our solution | |
2359 | /// for later checking. This allows for decoupling between type and region | |
2360 | /// checking in the compiler. | |
1b1a35ee | 2361 | #[derive(Clone, PartialEq, Eq, Hash, Fold, Visit, HasInterner, Zip)] |
f035d41b | 2362 | pub enum Constraint<I: Interner> { |
1b1a35ee XL |
2363 | /// Outlives constraint `'a: 'b`, indicating that the value of `'a` must be |
2364 | /// a superset of the value of `'b`. | |
2365 | LifetimeOutlives(Lifetime<I>, Lifetime<I>), | |
2366 | ||
2367 | /// Type outlives constraint `T: 'a`, indicating that the type `T` must live | |
2368 | /// at least as long as the value of `'a`. | |
2369 | TypeOutlives(Ty<I>, Lifetime<I>), | |
f035d41b XL |
2370 | } |
2371 | ||
1b1a35ee XL |
2372 | impl<I: Interner> Copy for Constraint<I> |
2373 | where | |
2374 | I::InternedLifetime: Copy, | |
2375 | I::InternedType: Copy, | |
2376 | { | |
f035d41b XL |
2377 | } |
2378 | ||
2379 | impl<I: Interner> Substitution<I> { | |
f035d41b XL |
2380 | /// A substitution is an **identity substitution** if it looks |
2381 | /// like this | |
2382 | /// | |
2383 | /// ```text | |
2384 | /// ?0 := ?0 | |
2385 | /// ?1 := ?1 | |
2386 | /// ?2 := ?2 | |
2387 | /// ... | |
2388 | /// ``` | |
2389 | /// | |
2390 | /// Basically, each value is mapped to a type or lifetime with its | |
2391 | /// same index. | |
2392 | pub fn is_identity_subst(&self, interner: &I) -> bool { | |
2393 | self.iter(interner).zip(0..).all(|(generic_arg, index)| { | |
2394 | let index_db = BoundVar::new(DebruijnIndex::INNERMOST, index); | |
2395 | match generic_arg.data(interner) { | |
2396 | GenericArgData::Ty(ty) => match ty.data(interner) { | |
2397 | TyData::BoundVar(depth) => index_db == *depth, | |
2398 | _ => false, | |
2399 | }, | |
2400 | GenericArgData::Lifetime(lifetime) => match lifetime.data(interner) { | |
2401 | LifetimeData::BoundVar(depth) => index_db == *depth, | |
2402 | _ => false, | |
2403 | }, | |
2404 | GenericArgData::Const(constant) => match &constant.data(interner).value { | |
2405 | ConstValue::BoundVar(depth) => index_db == *depth, | |
2406 | _ => false, | |
2407 | }, | |
2408 | } | |
2409 | }) | |
2410 | } | |
2411 | ||
1b1a35ee | 2412 | /// Apply the substitution to a value. |
f035d41b XL |
2413 | pub fn apply<T>(&self, value: &T, interner: &I) -> T::Result |
2414 | where | |
2415 | T: Fold<I, I>, | |
2416 | { | |
2417 | value | |
2418 | .fold_with( | |
2419 | &mut &SubstFolder { | |
2420 | interner, | |
2421 | subst: self, | |
2422 | }, | |
2423 | DebruijnIndex::INNERMOST, | |
2424 | ) | |
2425 | .unwrap() | |
2426 | } | |
2427 | } | |
2428 | ||
2429 | struct SubstFolder<'i, I: Interner> { | |
2430 | interner: &'i I, | |
2431 | subst: &'i Substitution<I>, | |
2432 | } | |
2433 | ||
2434 | impl<I: Interner> SubstFolder<'_, I> { | |
1b1a35ee | 2435 | /// Index into the list of parameters. |
f035d41b XL |
2436 | pub fn at(&self, index: usize) -> &GenericArg<I> { |
2437 | let interner = self.interner; | |
1b1a35ee | 2438 | &self.subst.as_slice(interner)[index] |
f035d41b XL |
2439 | } |
2440 | } | |
2441 | ||
1b1a35ee | 2442 | /// Convert a value to a list of parameters. |
f035d41b | 2443 | pub trait AsParameters<I: Interner> { |
1b1a35ee | 2444 | /// Convert the current value to parameters. |
f035d41b XL |
2445 | fn as_parameters(&self, interner: &I) -> &[GenericArg<I>]; |
2446 | } | |
2447 | ||
2448 | impl<I: Interner> AsParameters<I> for Substitution<I> { | |
2449 | #[allow(unreachable_code, unused_variables)] | |
2450 | fn as_parameters(&self, interner: &I) -> &[GenericArg<I>] { | |
1b1a35ee | 2451 | self.as_slice(interner) |
f035d41b XL |
2452 | } |
2453 | } | |
2454 | ||
2455 | impl<I: Interner> AsParameters<I> for [GenericArg<I>] { | |
2456 | fn as_parameters(&self, _interner: &I) -> &[GenericArg<I>] { | |
2457 | self | |
2458 | } | |
2459 | } | |
2460 | ||
2461 | impl<I: Interner> AsParameters<I> for [GenericArg<I>; 1] { | |
2462 | fn as_parameters(&self, _interner: &I) -> &[GenericArg<I>] { | |
2463 | self | |
2464 | } | |
2465 | } | |
2466 | ||
2467 | impl<I: Interner> AsParameters<I> for Vec<GenericArg<I>> { | |
2468 | fn as_parameters(&self, _interner: &I) -> &[GenericArg<I>] { | |
2469 | self | |
2470 | } | |
2471 | } | |
2472 | ||
2473 | impl<T, I: Interner> AsParameters<I> for &T | |
2474 | where | |
2475 | T: ?Sized + AsParameters<I>, | |
2476 | { | |
2477 | fn as_parameters(&self, interner: &I) -> &[GenericArg<I>] { | |
2478 | T::as_parameters(self, interner) | |
2479 | } | |
2480 | } | |
2481 | ||
1b1a35ee XL |
2482 | /// Utility for converting a list of all the binders into scope |
2483 | /// into references to those binders. Simply pair the binders with | |
2484 | /// the indices, and invoke `to_generic_arg()` on the `(binder, | |
2485 | /// index)` pair. The result will be a reference to a bound | |
2486 | /// variable of appropriate kind at the corresponding index. | |
f035d41b | 2487 | pub trait ToGenericArg<I: Interner> { |
1b1a35ee | 2488 | /// Converts the binders in scope to references to those binders. |
f035d41b XL |
2489 | fn to_generic_arg(&self, interner: &I) -> GenericArg<I> { |
2490 | self.to_generic_arg_at_depth(interner, DebruijnIndex::INNERMOST) | |
2491 | } | |
2492 | ||
1b1a35ee | 2493 | /// Converts the binders at the specified depth to references to those binders. |
f035d41b XL |
2494 | fn to_generic_arg_at_depth(&self, interner: &I, debruijn: DebruijnIndex) -> GenericArg<I>; |
2495 | } | |
2496 | ||
1b1a35ee | 2497 | impl<'a, I: Interner> ToGenericArg<I> for (usize, &'a VariableKind<I>) { |
f035d41b | 2498 | fn to_generic_arg_at_depth(&self, interner: &I, debruijn: DebruijnIndex) -> GenericArg<I> { |
1b1a35ee | 2499 | let &(index, binder) = self; |
f035d41b XL |
2500 | let bound_var = BoundVar::new(debruijn, index); |
2501 | binder.to_bound_variable(interner, bound_var) | |
2502 | } | |
2503 | } | |
2504 | ||
2505 | impl<'i, I: Interner> Folder<'i, I> for &SubstFolder<'i, I> { | |
2506 | fn as_dyn(&mut self) -> &mut dyn Folder<'i, I> { | |
2507 | self | |
2508 | } | |
2509 | ||
2510 | fn fold_free_var_ty( | |
2511 | &mut self, | |
2512 | bound_var: BoundVar, | |
2513 | outer_binder: DebruijnIndex, | |
2514 | ) -> Fallible<Ty<I>> { | |
2515 | assert_eq!(bound_var.debruijn, DebruijnIndex::INNERMOST); | |
2516 | let ty = self.at(bound_var.index); | |
2517 | let ty = ty.assert_ty_ref(self.interner()); | |
2518 | Ok(ty.shifted_in_from(self.interner(), outer_binder)) | |
2519 | } | |
2520 | ||
2521 | fn fold_free_var_lifetime( | |
2522 | &mut self, | |
2523 | bound_var: BoundVar, | |
2524 | outer_binder: DebruijnIndex, | |
2525 | ) -> Fallible<Lifetime<I>> { | |
2526 | assert_eq!(bound_var.debruijn, DebruijnIndex::INNERMOST); | |
2527 | let l = self.at(bound_var.index); | |
2528 | let l = l.assert_lifetime_ref(self.interner()); | |
2529 | Ok(l.shifted_in_from(self.interner(), outer_binder)) | |
2530 | } | |
2531 | ||
2532 | fn fold_free_var_const( | |
2533 | &mut self, | |
2534 | _ty: &Ty<I>, | |
2535 | bound_var: BoundVar, | |
2536 | outer_binder: DebruijnIndex, | |
2537 | ) -> Fallible<Const<I>> { | |
2538 | assert_eq!(bound_var.debruijn, DebruijnIndex::INNERMOST); | |
2539 | let c = self.at(bound_var.index); | |
2540 | let c = c.assert_const_ref(self.interner()); | |
2541 | Ok(c.shifted_in_from(self.interner(), outer_binder)) | |
2542 | } | |
2543 | ||
2544 | fn interner(&self) -> &'i I { | |
2545 | self.interner | |
2546 | } | |
2547 | ||
2548 | fn target_interner(&self) -> &'i I { | |
2549 | self.interner() | |
2550 | } | |
2551 | } | |
2552 | ||
1b1a35ee XL |
2553 | macro_rules! interned_slice { |
2554 | ($seq:ident, $data:ident => $elem:ty, $intern:ident => $interned:ident) => { | |
2555 | /// List of interned elements. | |
2556 | #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, HasInterner)] | |
2557 | pub struct $seq<I: Interner> { | |
2558 | interned: I::$interned, | |
2559 | } | |
2560 | ||
2561 | impl<I: Interner> $seq<I> { | |
2562 | /// Get the interned elements. | |
2563 | pub fn interned(&self) -> &I::$interned { | |
2564 | &self.interned | |
2565 | } | |
2566 | } | |
2567 | ||
2568 | impl<I: Interner> $seq<I> { | |
2569 | /// Tries to create a sequence using an iterator of element-like things. | |
2570 | pub fn from_fallible<E>( | |
2571 | interner: &I, | |
2572 | elements: impl IntoIterator<Item = Result<impl CastTo<$elem>, E>>, | |
2573 | ) -> Result<Self, E> { | |
2574 | Ok(Self { | |
2575 | interned: I::$intern(interner, elements.into_iter().casted(interner))?, | |
2576 | }) | |
2577 | } | |
2578 | ||
2579 | /// Returns a slice containing the elements. | |
2580 | pub fn as_slice(&self, interner: &I) -> &[$elem] { | |
2581 | Interner::$data(interner, &self.interned) | |
2582 | } | |
2583 | ||
2584 | /// Create a sequence from elements | |
2585 | pub fn from_iter( | |
2586 | interner: &I, | |
2587 | elements: impl IntoIterator<Item = impl CastTo<$elem>>, | |
2588 | ) -> Self { | |
2589 | Self::from_fallible( | |
2590 | interner, | |
2591 | elements | |
2592 | .into_iter() | |
2593 | .map(|el| -> Result<$elem, ()> { Ok(el.cast(interner)) }), | |
2594 | ) | |
2595 | .unwrap() | |
2596 | } | |
2597 | ||
2598 | /// Index into the sequence. | |
2599 | pub fn at(&self, interner: &I, index: usize) -> &$elem { | |
2600 | &self.as_slice(interner)[index] | |
2601 | } | |
2602 | ||
2603 | /// Create a sequence from a single element. | |
2604 | pub fn from1(interner: &I, element: impl CastTo<$elem>) -> Self { | |
2605 | Self::from_iter(interner, Some(element)) | |
2606 | } | |
2607 | ||
2608 | /// Create an empty sequence. | |
2609 | pub fn empty(interner: &I) -> Self { | |
2610 | Self::from_iter(interner, None::<$elem>) | |
2611 | } | |
2612 | ||
2613 | /// Check whether this is an empty sequence. | |
2614 | pub fn is_empty(&self, interner: &I) -> bool { | |
2615 | self.as_slice(interner).is_empty() | |
2616 | } | |
2617 | ||
2618 | /// Get an iterator over the elements of the sequence. | |
2619 | pub fn iter(&self, interner: &I) -> std::slice::Iter<'_, $elem> { | |
2620 | self.as_slice(interner).iter() | |
2621 | } | |
2622 | ||
2623 | /// Get the length of the sequence. | |
2624 | pub fn len(&self, interner: &I) -> usize { | |
2625 | self.as_slice(interner).len() | |
2626 | } | |
2627 | } | |
2628 | }; | |
2629 | } | |
2630 | ||
2631 | interned_slice!( | |
2632 | QuantifiedWhereClauses, | |
2633 | quantified_where_clauses_data => QuantifiedWhereClause<I>, | |
2634 | intern_quantified_where_clauses => InternedQuantifiedWhereClauses | |
2635 | ); | |
2636 | ||
2637 | interned_slice!( | |
2638 | ProgramClauses, | |
2639 | program_clauses_data => ProgramClause<I>, | |
2640 | intern_program_clauses => InternedProgramClauses | |
2641 | ); | |
2642 | ||
2643 | interned_slice!( | |
2644 | VariableKinds, | |
2645 | variable_kinds_data => VariableKind<I>, | |
2646 | intern_generic_arg_kinds => InternedVariableKinds | |
2647 | ); | |
2648 | ||
2649 | interned_slice!( | |
2650 | CanonicalVarKinds, | |
2651 | canonical_var_kinds_data => CanonicalVarKind<I>, | |
2652 | intern_canonical_var_kinds => InternedCanonicalVarKinds | |
2653 | ); | |
2654 | ||
2655 | interned_slice!(Goals, goals_data => Goal<I>, intern_goals => InternedGoals); | |
2656 | ||
2657 | interned_slice!( | |
2658 | Constraints, | |
2659 | constraints_data => InEnvironment<Constraint<I>>, | |
2660 | intern_constraints => InternedConstraints | |
2661 | ); | |
2662 | ||
2663 | interned_slice!( | |
2664 | Substitution, | |
2665 | substitution_data => GenericArg<I>, | |
2666 | intern_substitution => InternedSubstitution | |
2667 | ); | |
2668 | ||
f035d41b XL |
2669 | /// Combines a substitution (`subst`) with a set of region constraints |
2670 | /// (`constraints`). This represents the result of a query; the | |
2671 | /// substitution stores the values for the query's unknown variables, | |
2672 | /// and the constraints represents any region constraints that must | |
2673 | /// additionally be solved. | |
2674 | #[derive(Clone, Debug, PartialEq, Eq, Hash, Fold, Visit, HasInterner)] | |
2675 | pub struct ConstrainedSubst<I: Interner> { | |
1b1a35ee XL |
2676 | /// The substitution that is being constrained. |
2677 | /// | |
2678 | /// NB: The `is_trivial` routine relies on the fact that `subst` is folded first. | |
2679 | pub subst: Substitution<I>, | |
2680 | ||
2681 | /// Region constraints that constrain the substitution. | |
2682 | pub constraints: Constraints<I>, | |
f035d41b XL |
2683 | } |
2684 | ||
1b1a35ee | 2685 | /// The resulting substitution after solving a goal. |
f035d41b XL |
2686 | #[derive(Clone, Debug, PartialEq, Eq, Hash, Fold, Visit, HasInterner)] |
2687 | pub struct AnswerSubst<I: Interner> { | |
1b1a35ee XL |
2688 | /// The substitution result. |
2689 | /// | |
2690 | /// NB: The `is_trivial` routine relies on the fact that `subst` is folded first. | |
2691 | pub subst: Substitution<I>, | |
2692 | ||
2693 | /// List of constraints that are part of the answer. | |
2694 | pub constraints: Constraints<I>, | |
2695 | ||
2696 | /// Delayed subgoals, used when the solver answered with an (incomplete) `Answer` (instead of a `CompleteAnswer`). | |
f035d41b XL |
2697 | pub delayed_subgoals: Vec<InEnvironment<Goal<I>>>, |
2698 | } |