bjoernager/rust
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Simplify impl of Elaborator now that we don't need stack traces anymore.

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This commit is contained in:
Niko Matsakis 2015-02-23 15:00:49 -05:00
parent 3b3bb0e682
commit ba1b5ee1d1
1 changed files with 12 additions and 44 deletions
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56
src/librustc/middle/traits/util.rs
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@ -76,15 +76,10 @@ impl<'a,'tcx> PredicateSet<'a,'tcx> {
/// 'static`.
pub struct Elaborator<'cx, 'tcx:'cx> {
tcx: &'cx ty::ctxt<'tcx>,
stack: Vec<StackEntry<'tcx>>,
stack: Vec<ty::Predicate<'tcx>>,
visited: PredicateSet<'cx,'tcx>,
}
struct StackEntry<'tcx> {
position: uint,
predicates: Vec<ty::Predicate<'tcx>>,
}
pub fn elaborate_trait_ref<'cx, 'tcx>(
tcx: &'cx ty::ctxt<'tcx>,
trait_ref: ty::PolyTraitRef<'tcx>)
@ -111,8 +106,7 @@ pub fn elaborate_predicates<'cx, 'tcx>(
{
let mut visited = PredicateSet::new(tcx);
predicates.retain(|pred| visited.insert(pred));
let entry = StackEntry { position: 0, predicates: predicates };
Elaborator { tcx: tcx, stack: vec![entry], visited: visited }
Elaborator { tcx: tcx, stack: predicates, visited: visited }
}
impl<'cx, 'tcx> Elaborator<'cx, 'tcx> {
@ -134,8 +128,7 @@ impl<'cx, 'tcx> Elaborator<'cx, 'tcx> {
// Sized { }`.
predicates.retain(|r| self.visited.insert(r));
self.stack.push(StackEntry { position: 0,
predicates: predicates });
self.stack.extend(predicates.into_iter());
}
ty::Predicate::Equate(..) => {
// Currently, we do not "elaborate" predicates like
@ -175,41 +168,16 @@ impl<'cx, 'tcx> Iterator for Elaborator<'cx, 'tcx> {
type Item = ty::Predicate<'tcx>;
fn next(&mut self) -> Option<ty::Predicate<'tcx>> {
loop {
// Extract next item from top-most stack frame, if any.
let next_predicate = match self.stack.last_mut() {
None => {
// No more stack frames. Done.
return None;
}
Some(entry) => {
let p = entry.position;
if p < entry.predicates.len() {
// Still more predicates left in the top stack frame.
entry.position += 1;
let next_predicate =
entry.predicates[p].clone();
Some(next_predicate)
} else {
None
}
}
};
match next_predicate {
Some(next_predicate) => {
self.push(&next_predicate);
return Some(next_predicate);
}
None => {
// Top stack frame is exhausted, pop it.
self.stack.pop();
}
// Extract next item from top-most stack frame, if any.
let next_predicate = match self.stack.pop() {
Some(predicate) => predicate,
None => {
// No more stack frames. Done.
return None;
}
}
};
self.push(&next_predicate);
return Some(next_predicate);
}
}