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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 | ||
11 | use super::{InferCtxt, fixup_err, fres, unresolved_ty, unresolved_int_ty, unresolved_float_ty}; | |
12 | use middle::ty::{self, Ty}; | |
13 | use middle::ty_fold::{self, TypeFoldable}; | |
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. | |
23 | pub struct OpportunisticTypeResolver<'a, 'tcx:'a> { | |
24 | infcx: &'a InferCtxt<'a, 'tcx>, | |
25 | } | |
26 | ||
27 | impl<'a, 'tcx> OpportunisticTypeResolver<'a, 'tcx> { | |
28 | pub fn new(infcx: &'a InferCtxt<'a, 'tcx>) -> OpportunisticTypeResolver<'a, 'tcx> { | |
29 | OpportunisticTypeResolver { infcx: infcx } | |
30 | } | |
31 | } | |
32 | ||
33 | impl<'a, 'tcx> ty_fold::TypeFolder<'tcx> for OpportunisticTypeResolver<'a, 'tcx> { | |
34 | fn tcx(&self) -> &ty::ctxt<'tcx> { | |
35 | self.infcx.tcx | |
36 | } | |
37 | ||
38 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
39 | if !ty::type_has_ty_infer(t) { | |
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); | |
43 | ty_fold::super_fold_ty(self, t0) | |
44 | } | |
45 | } | |
46 | } | |
47 | ||
48 | /////////////////////////////////////////////////////////////////////////// | |
49 | // FULL TYPE RESOLUTION | |
50 | ||
51 | /// Full type resolution replaces all type and region variables with | |
52 | /// their concrete results. If any variable cannot be replaced (never unified, etc) | |
53 | /// then an `Err` result is returned. | |
54 | pub fn fully_resolve<'a, 'tcx, T>(infcx: &InferCtxt<'a,'tcx>, value: &T) -> fres<T> | |
55 | where T : TypeFoldable<'tcx> | |
56 | { | |
57 | let mut full_resolver = FullTypeResolver { infcx: infcx, err: None }; | |
58 | let result = value.fold_with(&mut full_resolver); | |
59 | match full_resolver.err { | |
60 | None => Ok(result), | |
61 | Some(e) => Err(e), | |
62 | } | |
63 | } | |
64 | ||
65 | // N.B. This type is not public because the protocol around checking the | |
66 | // `err` field is not enforcable otherwise. | |
67 | struct FullTypeResolver<'a, 'tcx:'a> { | |
68 | infcx: &'a InferCtxt<'a, 'tcx>, | |
69 | err: Option<fixup_err>, | |
70 | } | |
71 | ||
72 | impl<'a, 'tcx> ty_fold::TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> { | |
73 | fn tcx(&self) -> &ty::ctxt<'tcx> { | |
74 | self.infcx.tcx | |
75 | } | |
76 | ||
77 | fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> { | |
78 | if !ty::type_needs_infer(t) { | |
79 | t // micro-optimize -- if there is nothing in this type that this fold affects... | |
80 | } else { | |
81 | let t = self.infcx.shallow_resolve(t); | |
82 | match t.sty { | |
62682a34 | 83 | ty::TyInfer(ty::TyVar(vid)) => { |
1a4d82fc JJ |
84 | self.err = Some(unresolved_ty(vid)); |
85 | self.tcx().types.err | |
86 | } | |
62682a34 | 87 | ty::TyInfer(ty::IntVar(vid)) => { |
1a4d82fc JJ |
88 | self.err = Some(unresolved_int_ty(vid)); |
89 | self.tcx().types.err | |
90 | } | |
62682a34 | 91 | ty::TyInfer(ty::FloatVar(vid)) => { |
1a4d82fc JJ |
92 | self.err = Some(unresolved_float_ty(vid)); |
93 | self.tcx().types.err | |
94 | } | |
62682a34 | 95 | ty::TyInfer(_) => { |
1a4d82fc | 96 | self.infcx.tcx.sess.bug( |
62682a34 SL |
97 | &format!("Unexpected type in full type resolver: {:?}", |
98 | t)); | |
1a4d82fc JJ |
99 | } |
100 | _ => { | |
101 | ty_fold::super_fold_ty(self, t) | |
102 | } | |
103 | } | |
104 | } | |
105 | } | |
106 | ||
107 | fn fold_region(&mut self, r: ty::Region) -> ty::Region { | |
108 | match r { | |
109 | ty::ReInfer(ty::ReVar(rid)) => self.infcx.region_vars.resolve_var(rid), | |
110 | _ => r, | |
111 | } | |
112 | } | |
113 | } |