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use ty::{self, Ty, TyCtxt};
use ty::error::TypeError;
use ty::relate::{self, Relate, TypeRelation, RelateResult};
pub struct Match<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
tcx: TyCtxt<'a, 'gcx, 'tcx>
}
impl<'a, 'gcx, 'tcx> Match<'a, 'gcx, 'tcx> {
pub fn new(tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Match<'a, 'gcx, 'tcx> {
Match { tcx: tcx }
}
}
impl<'a, 'gcx, 'tcx> TypeRelation<'a, 'gcx, 'tcx> for Match<'a, 'gcx, 'tcx> {
fn tag(&self) -> &'static str { "Match" }
fn tcx(&self) -> TyCtxt<'a, 'gcx, 'tcx> { self.tcx }
fn a_is_expected(&self) -> bool { true }
fn relate_with_variance<T: Relate<'tcx>>(&mut self,
_: ty::Variance,
a: &T,
b: &T)
-> RelateResult<'tcx, T>
{
self.relate(a, b)
}
fn regions(&mut self, a: &'tcx ty::Region, b: &'tcx ty::Region)
-> RelateResult<'tcx, &'tcx ty::Region> {
debug!("{}.regions({:?}, {:?})",
self.tag(),
a,
b);
Ok(a)
}
fn tys(&mut self, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
debug!("{}.tys({:?}, {:?})", self.tag(),
a, b);
if a == b { return Ok(a); }
match (&a.sty, &b.sty) {
(_, &ty::TyInfer(ty::FreshTy(_))) |
(_, &ty::TyInfer(ty::FreshIntTy(_))) |
(_, &ty::TyInfer(ty::FreshFloatTy(_))) => {
Ok(a)
}
(&ty::TyInfer(_), _) |
(_, &ty::TyInfer(_)) => {
Err(TypeError::Sorts(relate::expected_found(self, &a, &b)))
}
(&ty::TyError, _) | (_, &ty::TyError) => {
Ok(self.tcx().types.err)
}
_ => {
relate::super_relate_tys(self, a, b)
}
}
}
fn binders<T>(&mut self, a: &ty::Binder<T>, b: &ty::Binder<T>)
-> RelateResult<'tcx, ty::Binder<T>>
where T: Relate<'tcx>
{
Ok(ty::Binder(self.relate(a.skip_binder(), b.skip_binder())?))
}
}