src/librustc/middle/infer/unify_key.rs

   1 // Copyright 2012-2014 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
  11 use syntax::ast;
  12 use middle::ty::{self, IntVarValue, Ty};
  13 use rustc_data_structures::unify::{Combine, UnifyKey};
  14
  15 pub trait ToType<'tcx> {
  16     fn to_type(&self, tcx: &ty::ctxt<'tcx>) -> Ty<'tcx>;
  17 }
  18
  19 impl UnifyKey for ty::IntVid {
  20     type Value = Option<IntVarValue>;
  21     fn index(&self) -> u32 { self.index }
  22     fn from_index(i: u32) -> ty::IntVid { ty::IntVid { index: i } }
  23     fn tag(_: Option<ty::IntVid>) -> &'static str { "IntVid" }
  24 }
  25
  26 #[derive(PartialEq, Copy, Clone, Debug)]
  27 pub struct RegionVidKey {
  28     /// The minimum region vid in the unification set. This is needed
  29     /// to have a canonical name for a type to prevent infinite
  30     /// recursion.
  31     pub min_vid: ty::RegionVid
  32 }
  33
  34 impl Combine for RegionVidKey {
  35     fn combine(&self, other: &RegionVidKey) -> RegionVidKey {
  36         let min_vid = if self.min_vid.index < other.min_vid.index {
  37             self.min_vid
  38         } else {
  39             other.min_vid
  40         };
  41
  42         RegionVidKey { min_vid: min_vid }
  43     }
  44 }
  45
  46 impl UnifyKey for ty::RegionVid {
  47     type Value = RegionVidKey;
  48     fn index(&self) -> u32 { self.index }
  49     fn from_index(i: u32) -> ty::RegionVid { ty::RegionVid { index: i } }
  50     fn tag(_: Option<ty::RegionVid>) -> &'static str { "RegionVid" }
  51 }
  52
  53 impl<'tcx> ToType<'tcx> for IntVarValue {
  54     fn to_type(&self, tcx: &ty::ctxt<'tcx>) -> Ty<'tcx> {
  55         match *self {
  56             ty::IntType(i) => tcx.mk_mach_int(i),
  57             ty::UintType(i) => tcx.mk_mach_uint(i),
  58         }
  59     }
  60 }
  61
  62 // Floating point type keys
  63
  64 impl UnifyKey for ty::FloatVid {
  65     type Value = Option<ast::FloatTy>;
  66     fn index(&self) -> u32 { self.index }
  67     fn from_index(i: u32) -> ty::FloatVid { ty::FloatVid { index: i } }
  68     fn tag(_: Option<ty::FloatVid>) -> &'static str { "FloatVid" }
  69 }
  70
  71 impl<'tcx> ToType<'tcx> for ast::FloatTy {
  72     fn to_type(&self, tcx: &ty::ctxt<'tcx>) -> Ty<'tcx> {
  73         tcx.mk_mach_float(*self)
  74     }
  75 }