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Extract out the filter_to_traits functionality

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This commit is contained in:
Niko Matsakis 2015-02-23 15:30:14 -05:00
parent ba1b5ee1d1
commit 4dfa81f6fa
1 changed files with 22 additions and 9 deletions
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31
src/librustc/middle/traits/util.rs
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@ -110,8 +110,8 @@ pub fn elaborate_predicates<'cx, 'tcx>(
}
impl<'cx, 'tcx> Elaborator<'cx, 'tcx> {
pub fn filter_to_traits(self) -> Supertraits<'cx, 'tcx> {
Supertraits { elaborator: self }
pub fn filter_to_traits(self) -> JustTraits<Elaborator<'cx, 'tcx>> {
JustTraits::new(self)
}
fn push(&mut self, predicate: &ty::Predicate<'tcx>) {
@ -185,11 +185,7 @@ impl<'cx, 'tcx> Iterator for Elaborator<'cx, 'tcx> {
// Supertrait iterator
///////////////////////////////////////////////////////////////////////////
/// A filter around the `Elaborator` that just yields up supertrait references,
/// not other kinds of predicates.
pub struct Supertraits<'cx, 'tcx:'cx> {
elaborator: Elaborator<'cx, 'tcx>,
}
pub type Supertraits<'cx, 'tcx> = JustTraits<Elaborator<'cx, 'tcx>>;
pub fn supertraits<'cx, 'tcx>(tcx: &'cx ty::ctxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>)
@ -205,12 +201,28 @@ pub fn transitive_bounds<'cx, 'tcx>(tcx: &'cx ty::ctxt<'tcx>,
elaborate_trait_refs(tcx, bounds).filter_to_traits()
}
impl<'cx, 'tcx> Iterator for Supertraits<'cx, 'tcx> {
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////
/// A filter around an iterator of predicates that makes it yield up
/// just trait references.
pub struct JustTraits<I> {
base_iterator: I
}
impl<I> JustTraits<I> {
fn new(base: I) -> JustTraits<I> {
JustTraits { base_iterator: base }
}
}
impl<'tcx,I:Iterator<Item=ty::Predicate<'tcx>>> Iterator for JustTraits<I> {
type Item = ty::PolyTraitRef<'tcx>;
fn next(&mut self) -> Option<ty::PolyTraitRef<'tcx>> {
loop {
match self.elaborator.next() {
match self.base_iterator.next() {
None => {
return None;
}
@ -224,6 +236,7 @@ impl<'cx, 'tcx> Iterator for Supertraits<'cx, 'tcx> {
}
}
///////////////////////////////////////////////////////////////////////////
// Other
///////////////////////////////////////////////////////////////////////////