aboutsummaryrefslogtreecommitdiff
path: root/crates/ra_hir/src/ty.rs
blob: 6a79af35b912e5a73979268d3affe6577bc9622e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
//! The type system. We currently use this to infer types for completion, hover
//! information and various assists.

mod autoderef;
pub(crate) mod primitive;
#[cfg(test)]
mod tests;
pub(crate) mod traits;
pub(crate) mod method_resolution;
mod op;
mod lower;
mod infer;
pub(crate) mod display;

use std::sync::Arc;
use std::ops::Deref;
use std::{fmt, mem};

use crate::{Name, AdtDef, type_ref::Mutability, db::HirDatabase, Trait, GenericParams};
use display::{HirDisplay, HirFormatter};

pub(crate) use lower::{TypableDef, type_for_def, type_for_field, callable_item_sig};
pub(crate) use infer::{infer, InferenceResult, InferTy};
pub use lower::CallableDef;

/// A type constructor or type name: this might be something like the primitive
/// type `bool`, a struct like `Vec`, or things like function pointers or
/// tuples.
#[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
pub enum TypeCtor {
    /// The primitive boolean type. Written as `bool`.
    Bool,

    /// The primitive character type; holds a Unicode scalar value
    /// (a non-surrogate code point). Written as `char`.
    Char,

    /// A primitive integer type. For example, `i32`.
    Int(primitive::UncertainIntTy),

    /// A primitive floating-point type. For example, `f64`.
    Float(primitive::UncertainFloatTy),

    /// Structures, enumerations and unions.
    Adt(AdtDef),

    /// The pointee of a string slice. Written as `str`.
    Str,

    /// The pointee of an array slice.  Written as `[T]`.
    Slice,

    /// An array with the given length. Written as `[T; n]`.
    Array,

    /// A raw pointer. Written as `*mut T` or `*const T`
    RawPtr(Mutability),

    /// A reference; a pointer with an associated lifetime. Written as
    /// `&'a mut T` or `&'a T`.
    Ref(Mutability),

    /// The anonymous type of a function declaration/definition. Each
    /// function has a unique type, which is output (for a function
    /// named `foo` returning an `i32`) as `fn() -> i32 {foo}`.
    ///
    /// This includes tuple struct / enum variant constructors as well.
    ///
    /// For example the type of `bar` here:
    ///
    /// ```rust
    /// fn foo() -> i32 { 1 }
    /// let bar = foo; // bar: fn() -> i32 {foo}
    /// ```
    FnDef(CallableDef),

    /// A pointer to a function.  Written as `fn() -> i32`.
    ///
    /// For example the type of `bar` here:
    ///
    /// ```rust
    /// fn foo() -> i32 { 1 }
    /// let bar: fn() -> i32 = foo;
    /// ```
    FnPtr,

    /// The never type `!`.
    Never,

    /// A tuple type.  For example, `(i32, bool)`.
    Tuple,
}

/// A nominal type with (maybe 0) type parameters. This might be a primitive
/// type like `bool`, a struct, tuple, function pointer, reference or
/// several other things.
#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub struct ApplicationTy {
    pub ctor: TypeCtor,
    pub parameters: Substs,
}

/// A type.
///
/// See also the `TyKind` enum in rustc (librustc/ty/sty.rs), which represents
/// the same thing (but in a different way).
///
/// This should be cheap to clone.
#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub enum Ty {
    /// A nominal type with (maybe 0) type parameters. This might be a primitive
    /// type like `bool`, a struct, tuple, function pointer, reference or
    /// several other things.
    Apply(ApplicationTy),

    /// A type parameter; for example, `T` in `fn f<T>(x: T) {}
    Param {
        /// The index of the parameter (starting with parameters from the
        /// surrounding impl, then the current function).
        idx: u32,
        /// The name of the parameter, for displaying.
        // FIXME get rid of this
        name: Name,
    },

    /// A bound type variable. Only used during trait resolution to represent
    /// Chalk variables.
    Bound(u32),

    /// A type variable used during type checking. Not to be confused with a
    /// type parameter.
    Infer(InferTy),

    /// A placeholder for a type which could not be computed; this is propagated
    /// to avoid useless error messages. Doubles as a placeholder where type
    /// variables are inserted before type checking, since we want to try to
    /// infer a better type here anyway -- for the IDE use case, we want to try
    /// to infer as much as possible even in the presence of type errors.
    Unknown,
}

/// A list of substitutions for generic parameters.
#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub struct Substs(Arc<[Ty]>);

impl Substs {
    pub fn empty() -> Substs {
        Substs(Arc::new([]))
    }

    pub fn single(ty: Ty) -> Substs {
        Substs(Arc::new([ty]))
    }

    pub fn prefix(&self, n: usize) -> Substs {
        Substs(self.0.iter().cloned().take(n).collect::<Vec<_>>().into())
    }

    pub fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
        // Without an Arc::make_mut_slice, we can't avoid the clone here:
        let mut v: Vec<_> = self.0.iter().cloned().collect();
        for t in &mut v {
            t.walk_mut(f);
        }
        self.0 = v.into();
    }

    pub fn as_single(&self) -> &Ty {
        if self.0.len() != 1 {
            panic!("expected substs of len 1, got {:?}", self);
        }
        &self.0[0]
    }

    /// Return Substs that replace each parameter by itself (i.e. `Ty::Param`).
    pub fn identity(generic_params: &GenericParams) -> Substs {
        Substs(
            generic_params
                .params_including_parent()
                .into_iter()
                .map(|p| Ty::Param { idx: p.idx, name: p.name.clone() })
                .collect::<Vec<_>>()
                .into(),
        )
    }

    /// Return Substs that replace each parameter by a bound variable.
    pub fn bound_vars(generic_params: &GenericParams) -> Substs {
        Substs(
            generic_params
                .params_including_parent()
                .into_iter()
                .map(|p| Ty::Bound(p.idx))
                .collect::<Vec<_>>()
                .into(),
        )
    }
}

impl From<Vec<Ty>> for Substs {
    fn from(v: Vec<Ty>) -> Self {
        Substs(v.into())
    }
}

impl Deref for Substs {
    type Target = [Ty];

    fn deref(&self) -> &[Ty] {
        &self.0
    }
}

/// A trait with type parameters. This includes the `Self`, so this represents a concrete type implementing the trait.
/// Name to be bikeshedded: TraitBound? TraitImplements?
#[derive(Clone, PartialEq, Eq, Debug, Hash)]
pub struct TraitRef {
    /// FIXME name?
    trait_: Trait,
    substs: Substs,
}

impl TraitRef {
    pub fn self_ty(&self) -> &Ty {
        &self.substs[0]
    }

    pub fn subst(mut self, substs: &Substs) -> TraitRef {
        self.substs.walk_mut(&mut |ty_mut| {
            let ty = mem::replace(ty_mut, Ty::Unknown);
            *ty_mut = ty.subst(substs);
        });
        self
    }
}

/// Basically a claim (currently not validated / checked) that the contained
/// type / trait ref contains no inference variables; any inference variables it
/// contained have been replaced by bound variables, and `num_vars` tells us how
/// many there are. This is used to erase irrelevant differences between types
/// before using them in queries.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub(crate) struct Canonical<T> {
    pub value: T,
    pub num_vars: usize,
}

/// A function signature as seen by type inference: Several parameter types and
/// one return type.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct FnSig {
    params_and_return: Arc<[Ty]>,
}

impl FnSig {
    pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty) -> FnSig {
        params.push(ret);
        FnSig { params_and_return: params.into() }
    }

    pub fn from_fn_ptr_substs(substs: &Substs) -> FnSig {
        FnSig { params_and_return: Arc::clone(&substs.0) }
    }

    pub fn params(&self) -> &[Ty] {
        &self.params_and_return[0..self.params_and_return.len() - 1]
    }

    pub fn ret(&self) -> &Ty {
        &self.params_and_return[self.params_and_return.len() - 1]
    }

    /// Applies the given substitutions to all types in this signature and
    /// returns the result.
    pub fn subst(&self, substs: &Substs) -> FnSig {
        let result: Vec<_> =
            self.params_and_return.iter().map(|ty| ty.clone().subst(substs)).collect();
        FnSig { params_and_return: result.into() }
    }

    pub fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
        // Without an Arc::make_mut_slice, we can't avoid the clone here:
        let mut v: Vec<_> = self.params_and_return.iter().cloned().collect();
        for t in &mut v {
            t.walk_mut(f);
        }
        self.params_and_return = v.into();
    }
}

impl Ty {
    pub fn simple(ctor: TypeCtor) -> Ty {
        Ty::Apply(ApplicationTy { ctor, parameters: Substs::empty() })
    }
    pub fn apply_one(ctor: TypeCtor, param: Ty) -> Ty {
        Ty::Apply(ApplicationTy { ctor, parameters: Substs::single(param) })
    }
    pub fn apply(ctor: TypeCtor, parameters: Substs) -> Ty {
        Ty::Apply(ApplicationTy { ctor, parameters })
    }
    pub fn unit() -> Self {
        Ty::apply(TypeCtor::Tuple, Substs::empty())
    }

    pub fn walk(&self, f: &mut impl FnMut(&Ty)) {
        match self {
            Ty::Apply(a_ty) => {
                for t in a_ty.parameters.iter() {
                    t.walk(f);
                }
            }
            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
        }
        f(self);
    }

    fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
        match self {
            Ty::Apply(a_ty) => {
                a_ty.parameters.walk_mut(f);
            }
            Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
        }
        f(self);
    }

    fn fold(mut self, f: &mut impl FnMut(Ty) -> Ty) -> Ty {
        self.walk_mut(&mut |ty_mut| {
            let ty = mem::replace(ty_mut, Ty::Unknown);
            *ty_mut = f(ty);
        });
        self
    }

    pub fn as_reference(&self) -> Option<(&Ty, Mutability)> {
        match self {
            Ty::Apply(ApplicationTy { ctor: TypeCtor::Ref(mutability), parameters }) => {
                Some((parameters.as_single(), *mutability))
            }
            _ => None,
        }
    }

    pub fn as_adt(&self) -> Option<(AdtDef, &Substs)> {
        match self {
            Ty::Apply(ApplicationTy { ctor: TypeCtor::Adt(adt_def), parameters }) => {
                Some((*adt_def, parameters))
            }
            _ => None,
        }
    }

    pub fn as_tuple(&self) -> Option<&Substs> {
        match self {
            Ty::Apply(ApplicationTy { ctor: TypeCtor::Tuple, parameters }) => Some(parameters),
            _ => None,
        }
    }

    pub fn as_callable(&self) -> Option<(CallableDef, &Substs)> {
        match self {
            Ty::Apply(ApplicationTy { ctor: TypeCtor::FnDef(callable_def), parameters }) => {
                Some((*callable_def, parameters))
            }
            _ => None,
        }
    }

    fn builtin_deref(&self) -> Option<Ty> {
        match self {
            Ty::Apply(a_ty) => match a_ty.ctor {
                TypeCtor::Ref(..) => Some(Ty::clone(a_ty.parameters.as_single())),
                TypeCtor::RawPtr(..) => Some(Ty::clone(a_ty.parameters.as_single())),
                _ => None,
            },
            _ => None,
        }
    }

    fn callable_sig(&self, db: &impl HirDatabase) -> Option<FnSig> {
        match self {
            Ty::Apply(a_ty) => match a_ty.ctor {
                TypeCtor::FnPtr => Some(FnSig::from_fn_ptr_substs(&a_ty.parameters)),
                TypeCtor::FnDef(def) => {
                    let sig = db.callable_item_signature(def);
                    Some(sig.subst(&a_ty.parameters))
                }
                _ => None,
            },
            _ => None,
        }
    }

    /// If this is a type with type parameters (an ADT or function), replaces
    /// the `Substs` for these type parameters with the given ones. (So e.g. if
    /// `self` is `Option<_>` and the substs contain `u32`, we'll have
    /// `Option<u32>` afterwards.)
    pub fn apply_substs(self, substs: Substs) -> Ty {
        match self {
            Ty::Apply(ApplicationTy { ctor, parameters: previous_substs }) => {
                assert_eq!(previous_substs.len(), substs.len());
                Ty::Apply(ApplicationTy { ctor, parameters: substs })
            }
            _ => self,
        }
    }

    /// Replaces type parameters in this type using the given `Substs`. (So e.g.
    /// if `self` is `&[T]`, where type parameter T has index 0, and the
    /// `Substs` contain `u32` at index 0, we'll have `&[u32]` afterwards.)
    pub fn subst(self, substs: &Substs) -> Ty {
        self.fold(&mut |ty| match ty {
            Ty::Param { idx, name } => {
                if (idx as usize) < substs.len() {
                    substs[idx as usize].clone()
                } else {
                    Ty::Param { idx, name }
                }
            }
            ty => ty,
        })
    }

    /// Substitutes `Ty::Bound` vars (as opposed to type parameters).
    pub fn subst_bound_vars(self, substs: &Substs) -> Ty {
        self.fold(&mut |ty| match ty {
            Ty::Bound(idx) => {
                if (idx as usize) < substs.len() {
                    substs[idx as usize].clone()
                } else {
                    Ty::Bound(idx)
                }
            }
            ty => ty,
        })
    }

    /// Returns the type parameters of this type if it has some (i.e. is an ADT
    /// or function); so if `self` is `Option<u32>`, this returns the `u32`.
    fn substs(&self) -> Option<Substs> {
        match self {
            Ty::Apply(ApplicationTy { parameters, .. }) => Some(parameters.clone()),
            _ => None,
        }
    }
}

impl HirDisplay for &Ty {
    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
        HirDisplay::hir_fmt(*self, f)
    }
}

impl HirDisplay for ApplicationTy {
    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
        match self.ctor {
            TypeCtor::Bool => write!(f, "bool")?,
            TypeCtor::Char => write!(f, "char")?,
            TypeCtor::Int(t) => write!(f, "{}", t)?,
            TypeCtor::Float(t) => write!(f, "{}", t)?,
            TypeCtor::Str => write!(f, "str")?,
            TypeCtor::Slice => {
                let t = self.parameters.as_single();
                write!(f, "[{}]", t.display(f.db))?;
            }
            TypeCtor::Array => {
                let t = self.parameters.as_single();
                write!(f, "[{};_]", t.display(f.db))?;
            }
            TypeCtor::RawPtr(m) => {
                let t = self.parameters.as_single();
                write!(f, "*{}{}", m.as_keyword_for_ptr(), t.display(f.db))?;
            }
            TypeCtor::Ref(m) => {
                let t = self.parameters.as_single();
                write!(f, "&{}{}", m.as_keyword_for_ref(), t.display(f.db))?;
            }
            TypeCtor::Never => write!(f, "!")?,
            TypeCtor::Tuple => {
                let ts = &self.parameters;
                if ts.len() == 1 {
                    write!(f, "({},)", ts[0].display(f.db))?;
                } else {
                    write!(f, "(")?;
                    f.write_joined(&*ts.0, ", ")?;
                    write!(f, ")")?;
                }
            }
            TypeCtor::FnPtr => {
                let sig = FnSig::from_fn_ptr_substs(&self.parameters);
                write!(f, "fn(")?;
                f.write_joined(sig.params(), ", ")?;
                write!(f, ") -> {}", sig.ret().display(f.db))?;
            }
            TypeCtor::FnDef(def) => {
                let sig = f.db.callable_item_signature(def);
                let name = match def {
                    CallableDef::Function(ff) => ff.name(f.db),
                    CallableDef::Struct(s) => s.name(f.db).unwrap_or_else(Name::missing),
                    CallableDef::EnumVariant(e) => e.name(f.db).unwrap_or_else(Name::missing),
                };
                match def {
                    CallableDef::Function(_) => write!(f, "fn {}", name)?,
                    CallableDef::Struct(_) | CallableDef::EnumVariant(_) => write!(f, "{}", name)?,
                }
                if self.parameters.len() > 0 {
                    write!(f, "<")?;
                    f.write_joined(&*self.parameters.0, ", ")?;
                    write!(f, ">")?;
                }
                write!(f, "(")?;
                f.write_joined(sig.params(), ", ")?;
                write!(f, ") -> {}", sig.ret().display(f.db))?;
            }
            TypeCtor::Adt(def_id) => {
                let name = match def_id {
                    AdtDef::Struct(s) => s.name(f.db),
                    AdtDef::Enum(e) => e.name(f.db),
                }
                .unwrap_or_else(Name::missing);
                write!(f, "{}", name)?;
                if self.parameters.len() > 0 {
                    write!(f, "<")?;
                    f.write_joined(&*self.parameters.0, ", ")?;
                    write!(f, ">")?;
                }
            }
        }
        Ok(())
    }
}

impl HirDisplay for Ty {
    fn hir_fmt(&self, f: &mut HirFormatter<impl HirDatabase>) -> fmt::Result {
        match self {
            Ty::Apply(a_ty) => a_ty.hir_fmt(f)?,
            Ty::Param { name, .. } => write!(f, "{}", name)?,
            Ty::Bound(idx) => write!(f, "?{}", idx)?,
            Ty::Unknown => write!(f, "{{unknown}}")?,
            Ty::Infer(..) => write!(f, "_")?,
        }
        Ok(())
    }
}