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1 | // Copyright 2012 The Rust Project Developers. See the COPYRIGHT |
2 | // file at the top-level directory of this distribution and at | |
3 | // http://rust-lang.org/COPYRIGHT. | |
4 | // | |
5 | // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | |
6 | // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | |
7 | // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | |
8 | // option. This file may not be copied, modified, or distributed | |
9 | // except according to those terms. | |
10 | ||
c1a9b12d | 11 | use super::{InferCtxt, FixupError, FixupResult}; |
54a0048b | 12 | use ty::{self, Ty, TyCtxt, TypeFoldable}; |
3b2f2976 | 13 | use ty::fold::{TypeFolder, TypeVisitor}; |
1a4d82fc JJ |
14 | |
15 | /////////////////////////////////////////////////////////////////////////// | |
16 | // OPPORTUNISTIC TYPE RESOLVER | |
17 | ||
18 | /// The opportunistic type resolver can be used at any time. It simply replaces | |
19 | /// type variables that have been unified with the things they have | |
20 | /// been unified with (similar to `shallow_resolve`, but deep). This is | |
21 | /// useful for printing messages etc but also required at various | |
22 | /// points for correctness. | |
a7813a04 XL |
23 | pub struct OpportunisticTypeResolver<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
24 | infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, | |
1a4d82fc JJ |
25 | } |
26 | ||
a7813a04 XL |
27 | impl<'a, 'gcx, 'tcx> OpportunisticTypeResolver<'a, 'gcx, 'tcx> { |
28 | pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self { | |
1a4d82fc JJ |
29 | OpportunisticTypeResolver { infcx: infcx } |
30 | } | |
31 | } | |
32 | ||
a7813a04 XL |
33 | impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for OpportunisticTypeResolver<'a, 'gcx, 'tcx> { |
34 | fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { | |
1a4d82fc JJ |
35 | self.infcx.tcx |
36 | } | |
37 | ||
38 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
c1a9b12d | 39 | if !t.has_infer_types() { |
1a4d82fc JJ |
40 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
41 | } else { | |
42 | let t0 = self.infcx.shallow_resolve(t); | |
9cc50fc6 SL |
43 | t0.super_fold_with(self) |
44 | } | |
45 | } | |
46 | } | |
47 | ||
48 | /// The opportunistic type and region resolver is similar to the | |
3b2f2976 | 49 | /// opportunistic type resolver, but also opportunistically resolves |
9cc50fc6 | 50 | /// regions. It is useful for canonicalization. |
a7813a04 XL |
51 | pub struct OpportunisticTypeAndRegionResolver<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
52 | infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, | |
9cc50fc6 SL |
53 | } |
54 | ||
a7813a04 XL |
55 | impl<'a, 'gcx, 'tcx> OpportunisticTypeAndRegionResolver<'a, 'gcx, 'tcx> { |
56 | pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self { | |
9cc50fc6 SL |
57 | OpportunisticTypeAndRegionResolver { infcx: infcx } |
58 | } | |
59 | } | |
60 | ||
a7813a04 XL |
61 | impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for OpportunisticTypeAndRegionResolver<'a, 'gcx, 'tcx> { |
62 | fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { | |
9cc50fc6 SL |
63 | self.infcx.tcx |
64 | } | |
65 | ||
66 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
67 | if !t.needs_infer() { | |
68 | t // micro-optimize -- if there is nothing in this type that this fold affects... | |
69 | } else { | |
70 | let t0 = self.infcx.shallow_resolve(t); | |
71 | t0.super_fold_with(self) | |
72 | } | |
73 | } | |
74 | ||
7cac9316 | 75 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 76 | match *r { |
abe05a73 XL |
77 | ty::ReVar(rid) => |
78 | self.infcx.borrow_region_constraints() | |
79 | .opportunistic_resolve_var(self.tcx(), rid), | |
80 | _ => | |
81 | r, | |
1a4d82fc JJ |
82 | } |
83 | } | |
84 | } | |
85 | ||
3b2f2976 XL |
86 | /////////////////////////////////////////////////////////////////////////// |
87 | // UNRESOLVED TYPE FINDER | |
88 | ||
89 | /// The unresolved type **finder** walks your type and searches for | |
90 | /// type variables that don't yet have a value. They get pushed into a | |
91 | /// vector. It does not construct the fully resolved type (which might | |
92 | /// involve some hashing and so forth). | |
93 | pub struct UnresolvedTypeFinder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { | |
94 | infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, | |
95 | } | |
96 | ||
97 | impl<'a, 'gcx, 'tcx> UnresolvedTypeFinder<'a, 'gcx, 'tcx> { | |
98 | pub fn new(infcx: &'a InferCtxt<'a, 'gcx, 'tcx>) -> Self { | |
99 | UnresolvedTypeFinder { infcx } | |
100 | } | |
101 | } | |
102 | ||
103 | impl<'a, 'gcx, 'tcx> TypeVisitor<'tcx> for UnresolvedTypeFinder<'a, 'gcx, 'tcx> { | |
104 | fn visit_ty(&mut self, t: Ty<'tcx>) -> bool { | |
105 | let t = self.infcx.shallow_resolve(t); | |
106 | if t.has_infer_types() { | |
b7449926 | 107 | if let ty::Infer(_) = t.sty { |
3b2f2976 XL |
108 | // Since we called `shallow_resolve` above, this must |
109 | // be an (as yet...) unresolved inference variable. | |
110 | true | |
111 | } else { | |
112 | // Otherwise, visit its contents. | |
113 | t.super_visit_with(self) | |
114 | } | |
115 | } else { | |
116 | // Micro-optimize: no inference types at all Can't have unresolved type | |
117 | // variables, no need to visit the contents. | |
118 | false | |
119 | } | |
120 | } | |
121 | } | |
122 | ||
1a4d82fc JJ |
123 | /////////////////////////////////////////////////////////////////////////// |
124 | // FULL TYPE RESOLUTION | |
125 | ||
126 | /// Full type resolution replaces all type and region variables with | |
127 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
128 | /// then an `Err` result is returned. | |
a7813a04 XL |
129 | pub fn fully_resolve<'a, 'gcx, 'tcx, T>(infcx: &InferCtxt<'a, 'gcx, 'tcx>, |
130 | value: &T) -> FixupResult<T> | |
1a4d82fc JJ |
131 | where T : TypeFoldable<'tcx> |
132 | { | |
133 | let mut full_resolver = FullTypeResolver { infcx: infcx, err: None }; | |
134 | let result = value.fold_with(&mut full_resolver); | |
135 | match full_resolver.err { | |
136 | None => Ok(result), | |
137 | Some(e) => Err(e), | |
138 | } | |
139 | } | |
140 | ||
141 | // N.B. This type is not public because the protocol around checking the | |
142 | // `err` field is not enforcable otherwise. | |
a7813a04 XL |
143 | struct FullTypeResolver<'a, 'gcx: 'a+'tcx, 'tcx: 'a> { |
144 | infcx: &'a InferCtxt<'a, 'gcx, 'tcx>, | |
c1a9b12d | 145 | err: Option<FixupError>, |
1a4d82fc JJ |
146 | } |
147 | ||
a7813a04 XL |
148 | impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for FullTypeResolver<'a, 'gcx, 'tcx> { |
149 | fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { | |
1a4d82fc JJ |
150 | self.infcx.tcx |
151 | } | |
152 | ||
153 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
3b2f2976 | 154 | if !t.needs_infer() && !ty::keep_local(&t) { |
1a4d82fc | 155 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
0bf4aa26 XL |
156 | // ^ we need to have the `keep_local` check to un-default |
157 | // defaulted tuples. | |
1a4d82fc JJ |
158 | } else { |
159 | let t = self.infcx.shallow_resolve(t); | |
160 | match t.sty { | |
b7449926 | 161 | ty::Infer(ty::TyVar(vid)) => { |
c1a9b12d | 162 | self.err = Some(FixupError::UnresolvedTy(vid)); |
1a4d82fc JJ |
163 | self.tcx().types.err |
164 | } | |
b7449926 | 165 | ty::Infer(ty::IntVar(vid)) => { |
c1a9b12d | 166 | self.err = Some(FixupError::UnresolvedIntTy(vid)); |
1a4d82fc JJ |
167 | self.tcx().types.err |
168 | } | |
b7449926 | 169 | ty::Infer(ty::FloatVar(vid)) => { |
c1a9b12d | 170 | self.err = Some(FixupError::UnresolvedFloatTy(vid)); |
1a4d82fc JJ |
171 | self.tcx().types.err |
172 | } | |
b7449926 | 173 | ty::Infer(_) => { |
54a0048b | 174 | bug!("Unexpected type in full type resolver: {:?}", t); |
1a4d82fc JJ |
175 | } |
176 | _ => { | |
9cc50fc6 | 177 | t.super_fold_with(self) |
1a4d82fc JJ |
178 | } |
179 | } | |
180 | } | |
181 | } | |
182 | ||
7cac9316 | 183 | fn fold_region(&mut self, r: ty::Region<'tcx>) -> ty::Region<'tcx> { |
9e0c209e | 184 | match *r { |
abe05a73 XL |
185 | ty::ReVar(rid) => self.infcx.lexical_region_resolutions |
186 | .borrow() | |
187 | .as_ref() | |
188 | .expect("region resolution not performed") | |
189 | .resolve_var(rid), | |
9e0c209e | 190 | _ => r, |
1a4d82fc JJ |
191 | } |
192 | } | |
193 | } |