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1 | // Copyright 2014 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 | ||
c34b1796 AL |
11 | use super::combine::{self, CombineFields}; |
12 | use super::higher_ranked::HigherRankedRelations; | |
13 | use super::{Subtype}; | |
14 | use super::type_variable::{EqTo}; | |
15 | ||
1a4d82fc JJ |
16 | use middle::ty::{self, Ty}; |
17 | use middle::ty::TyVar; | |
c34b1796 | 18 | use middle::ty_relate::{Relate, RelateResult, TypeRelation}; |
1a4d82fc | 19 | |
c34b1796 AL |
20 | pub struct Equate<'a, 'tcx: 'a> { |
21 | fields: CombineFields<'a, 'tcx> | |
1a4d82fc JJ |
22 | } |
23 | ||
c34b1796 AL |
24 | impl<'a, 'tcx> Equate<'a, 'tcx> { |
25 | pub fn new(fields: CombineFields<'a, 'tcx>) -> Equate<'a, 'tcx> { | |
26 | Equate { fields: fields } | |
1a4d82fc | 27 | } |
c34b1796 | 28 | } |
1a4d82fc | 29 | |
c34b1796 AL |
30 | impl<'a, 'tcx> TypeRelation<'a,'tcx> for Equate<'a, 'tcx> { |
31 | fn tag(&self) -> &'static str { "Equate" } | |
1a4d82fc | 32 | |
c34b1796 | 33 | fn tcx(&self) -> &'a ty::ctxt<'tcx> { self.fields.tcx() } |
1a4d82fc | 34 | |
c34b1796 | 35 | fn a_is_expected(&self) -> bool { self.fields.a_is_expected } |
1a4d82fc | 36 | |
c34b1796 AL |
37 | fn relate_with_variance<T:Relate<'a,'tcx>>(&mut self, |
38 | _: ty::Variance, | |
39 | a: &T, | |
40 | b: &T) | |
41 | -> RelateResult<'tcx, T> | |
1a4d82fc | 42 | { |
c34b1796 | 43 | self.relate(a, b) |
1a4d82fc JJ |
44 | } |
45 | ||
c34b1796 | 46 | fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> { |
62682a34 SL |
47 | debug!("{}.tys({:?}, {:?})", self.tag(), |
48 | a, b); | |
1a4d82fc JJ |
49 | if a == b { return Ok(a); } |
50 | ||
51 | let infcx = self.fields.infcx; | |
52 | let a = infcx.type_variables.borrow().replace_if_possible(a); | |
53 | let b = infcx.type_variables.borrow().replace_if_possible(b); | |
54 | match (&a.sty, &b.sty) { | |
62682a34 | 55 | (&ty::TyInfer(TyVar(a_id)), &ty::TyInfer(TyVar(b_id))) => { |
1a4d82fc JJ |
56 | infcx.type_variables.borrow_mut().relate_vars(a_id, EqTo, b_id); |
57 | Ok(a) | |
58 | } | |
59 | ||
62682a34 | 60 | (&ty::TyInfer(TyVar(a_id)), _) => { |
1a4d82fc JJ |
61 | try!(self.fields.instantiate(b, EqTo, a_id)); |
62 | Ok(a) | |
63 | } | |
64 | ||
62682a34 | 65 | (_, &ty::TyInfer(TyVar(b_id))) => { |
1a4d82fc JJ |
66 | try!(self.fields.instantiate(a, EqTo, b_id)); |
67 | Ok(a) | |
68 | } | |
69 | ||
70 | _ => { | |
c34b1796 | 71 | combine::super_combine_tys(self.fields.infcx, self, a, b) |
1a4d82fc JJ |
72 | } |
73 | } | |
74 | } | |
75 | ||
c34b1796 | 76 | fn regions(&mut self, a: ty::Region, b: ty::Region) -> RelateResult<'tcx, ty::Region> { |
62682a34 | 77 | debug!("{}.regions({:?}, {:?})", |
c34b1796 | 78 | self.tag(), |
62682a34 SL |
79 | a, |
80 | b); | |
c34b1796 AL |
81 | let origin = Subtype(self.fields.trace.clone()); |
82 | self.fields.infcx.region_vars.make_eqregion(origin, a, b); | |
83 | Ok(a) | |
84 | } | |
85 | ||
86 | fn binders<T>(&mut self, a: &ty::Binder<T>, b: &ty::Binder<T>) | |
87 | -> RelateResult<'tcx, ty::Binder<T>> | |
88 | where T: Relate<'a, 'tcx> | |
1a4d82fc | 89 | { |
c34b1796 AL |
90 | try!(self.fields.higher_ranked_sub(a, b)); |
91 | self.fields.higher_ranked_sub(b, a) | |
1a4d82fc JJ |
92 | } |
93 | } |