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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}; |
9cc50fc6 | 12 | use middle::ty::{self, Ty, TypeFoldable}; |
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13 | |
14 | /////////////////////////////////////////////////////////////////////////// | |
15 | // OPPORTUNISTIC TYPE RESOLVER | |
16 | ||
17 | /// The opportunistic type resolver can be used at any time. It simply replaces | |
18 | /// type variables that have been unified with the things they have | |
19 | /// been unified with (similar to `shallow_resolve`, but deep). This is | |
20 | /// useful for printing messages etc but also required at various | |
21 | /// points for correctness. | |
22 | pub struct OpportunisticTypeResolver<'a, 'tcx:'a> { | |
23 | infcx: &'a InferCtxt<'a, 'tcx>, | |
24 | } | |
25 | ||
26 | impl<'a, 'tcx> OpportunisticTypeResolver<'a, 'tcx> { | |
27 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> OpportunisticTypeResolver<'a, 'tcx> { | |
28 | OpportunisticTypeResolver { infcx: infcx } | |
29 | } | |
30 | } | |
31 | ||
e9174d1e | 32 | impl<'a, 'tcx> ty::fold::TypeFolder<'tcx> for OpportunisticTypeResolver<'a, 'tcx> { |
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33 | fn tcx(&self) -> &ty::ctxt<'tcx> { |
34 | self.infcx.tcx | |
35 | } | |
36 | ||
37 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
c1a9b12d | 38 | if !t.has_infer_types() { |
1a4d82fc JJ |
39 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
40 | } else { | |
41 | let t0 = self.infcx.shallow_resolve(t); | |
9cc50fc6 SL |
42 | t0.super_fold_with(self) |
43 | } | |
44 | } | |
45 | } | |
46 | ||
47 | /// The opportunistic type and region resolver is similar to the | |
48 | /// opportunistic type resolver, but also opportunistly resolves | |
49 | /// regions. It is useful for canonicalization. | |
50 | pub struct OpportunisticTypeAndRegionResolver<'a, 'tcx:'a> { | |
51 | infcx: &'a InferCtxt<'a, 'tcx>, | |
52 | } | |
53 | ||
54 | impl<'a, 'tcx> OpportunisticTypeAndRegionResolver<'a, 'tcx> { | |
55 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> Self { | |
56 | OpportunisticTypeAndRegionResolver { infcx: infcx } | |
57 | } | |
58 | } | |
59 | ||
60 | impl<'a, 'tcx> ty::fold::TypeFolder<'tcx> for OpportunisticTypeAndRegionResolver<'a, 'tcx> { | |
61 | fn tcx(&self) -> &ty::ctxt<'tcx> { | |
62 | self.infcx.tcx | |
63 | } | |
64 | ||
65 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
66 | if !t.needs_infer() { | |
67 | t // micro-optimize -- if there is nothing in this type that this fold affects... | |
68 | } else { | |
69 | let t0 = self.infcx.shallow_resolve(t); | |
70 | t0.super_fold_with(self) | |
71 | } | |
72 | } | |
73 | ||
74 | fn fold_region(&mut self, r: ty::Region) -> ty::Region { | |
75 | match r { | |
76 | ty::ReVar(rid) => self.infcx.region_vars.opportunistic_resolve_var(rid), | |
77 | _ => r, | |
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78 | } |
79 | } | |
80 | } | |
81 | ||
82 | /////////////////////////////////////////////////////////////////////////// | |
83 | // FULL TYPE RESOLUTION | |
84 | ||
85 | /// Full type resolution replaces all type and region variables with | |
86 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
87 | /// then an `Err` result is returned. | |
c1a9b12d | 88 | pub fn fully_resolve<'a, 'tcx, T>(infcx: &InferCtxt<'a,'tcx>, value: &T) -> FixupResult<T> |
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89 | where T : TypeFoldable<'tcx> |
90 | { | |
91 | let mut full_resolver = FullTypeResolver { infcx: infcx, err: None }; | |
92 | let result = value.fold_with(&mut full_resolver); | |
93 | match full_resolver.err { | |
94 | None => Ok(result), | |
95 | Some(e) => Err(e), | |
96 | } | |
97 | } | |
98 | ||
99 | // N.B. This type is not public because the protocol around checking the | |
100 | // `err` field is not enforcable otherwise. | |
101 | struct FullTypeResolver<'a, 'tcx:'a> { | |
102 | infcx: &'a InferCtxt<'a, 'tcx>, | |
c1a9b12d | 103 | err: Option<FixupError>, |
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104 | } |
105 | ||
e9174d1e | 106 | impl<'a, 'tcx> ty::fold::TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { |
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107 | fn tcx(&self) -> &ty::ctxt<'tcx> { |
108 | self.infcx.tcx | |
109 | } | |
110 | ||
111 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
c1a9b12d | 112 | if !t.needs_infer() { |
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113 | t // micro-optimize -- if there is nothing in this type that this fold affects... |
114 | } else { | |
115 | let t = self.infcx.shallow_resolve(t); | |
116 | match t.sty { | |
62682a34 | 117 | ty::TyInfer(ty::TyVar(vid)) => { |
c1a9b12d | 118 | self.err = Some(FixupError::UnresolvedTy(vid)); |
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119 | self.tcx().types.err |
120 | } | |
62682a34 | 121 | ty::TyInfer(ty::IntVar(vid)) => { |
c1a9b12d | 122 | self.err = Some(FixupError::UnresolvedIntTy(vid)); |
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123 | self.tcx().types.err |
124 | } | |
62682a34 | 125 | ty::TyInfer(ty::FloatVar(vid)) => { |
c1a9b12d | 126 | self.err = Some(FixupError::UnresolvedFloatTy(vid)); |
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127 | self.tcx().types.err |
128 | } | |
62682a34 | 129 | ty::TyInfer(_) => { |
1a4d82fc | 130 | self.infcx.tcx.sess.bug( |
62682a34 SL |
131 | &format!("Unexpected type in full type resolver: {:?}", |
132 | t)); | |
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133 | } |
134 | _ => { | |
9cc50fc6 | 135 | t.super_fold_with(self) |
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136 | } |
137 | } | |
138 | } | |
139 | } | |
140 | ||
141 | fn fold_region(&mut self, r: ty::Region) -> ty::Region { | |
142 | match r { | |
e9174d1e | 143 | ty::ReVar(rid) => self.infcx.region_vars.resolve_var(rid), |
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144 | _ => r, |
145 | } | |
146 | } | |
147 | } |