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BTreeMap::drain_filter: replace needless unsafety and test

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This commit is contained in:
Stein Somers 2020-07-22 22:37:54 +02:00
parent 7d31ffc1ac
commit facc46fd0a
2 changed files with 47 additions and 20 deletions
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9
src/liballoc/collections/btree/map.rs
View File

@ -1681,19 +1681,12 @@ pub(super) fn peek(&self) -> Option<(&K, &V)> {
edge.reborrow().next_kv().ok().map(|kv| kv.into_kv())
}
unsafe fn next_kv(
&mut self,
) -> Option<Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV>> {
let edge = self.cur_leaf_edge.as_ref()?;
unsafe { ptr::read(edge).next_kv().ok() }
}
/// Implementation of a typical `DrainFilter::next` method, given the predicate.
pub(super) fn next<F>(&mut self, pred: &mut F) -> Option<(K, V)>
where
F: FnMut(&K, &mut V) -> bool,
{
while let Some(mut kv) = unsafe { self.next_kv() } {
while let Ok(mut kv) = self.cur_leaf_edge.take()?.next_kv() {
let (k, v) = kv.kv_mut();
if pred(k, v) {
*self.length -= 1;

58
src/liballoc/tests/btree/map.rs
View File

@ -835,10 +835,8 @@ fn drop(&mut self) {
}
}
let mut map = BTreeMap::new();
map.insert(0, D);
map.insert(4, D);
map.insert(8, D);
// Keys are multiples of 4, so that each key is counted by a hexadecimal digit.
let mut map = (0..3).map(|i| (i * 4, D)).collect::<BTreeMap<_, _>>();
catch_unwind(move || {
drop(map.drain_filter(|i, _| {
@ -846,7 +844,7 @@ fn drop(&mut self) {
true
}))
})
.ok();
.unwrap_err();
assert_eq!(PREDS.load(Ordering::SeqCst), 0x011);
assert_eq!(DROPS.load(Ordering::SeqCst), 3);
@ -864,10 +862,8 @@ fn drop(&mut self) {
}
}
let mut map = BTreeMap::new();
map.insert(0, D);
map.insert(4, D);
map.insert(8, D);
// Keys are multiples of 4, so that each key is counted by a hexadecimal digit.
let mut map = (0..3).map(|i| (i * 4, D)).collect::<BTreeMap<_, _>>();
catch_unwind(AssertUnwindSafe(|| {
drop(map.drain_filter(|i, _| {
@ -878,7 +874,45 @@ fn drop(&mut self) {
}
}))
}))
.ok();
.unwrap_err();
assert_eq!(PREDS.load(Ordering::SeqCst), 0x011);
assert_eq!(DROPS.load(Ordering::SeqCst), 1);
assert_eq!(map.len(), 2);
assert_eq!(map.first_entry().unwrap().key(), &4);
assert_eq!(map.last_entry().unwrap().key(), &8);
}
// Same as above, but attempt to use the iterator again after the panic in the predicate
#[test]
fn pred_panic_reuse() {
static PREDS: AtomicUsize = AtomicUsize::new(0);
static DROPS: AtomicUsize = AtomicUsize::new(0);
struct D;
impl Drop for D {
fn drop(&mut self) {
DROPS.fetch_add(1, Ordering::SeqCst);
}
}
// Keys are multiples of 4, so that each key is counted by a hexadecimal digit.
let mut map = (0..3).map(|i| (i * 4, D)).collect::<BTreeMap<_, _>>();
{
let mut it = map.drain_filter(|i, _| {
PREDS.fetch_add(1usize << i, Ordering::SeqCst);
match i {
0 => true,
_ => panic!(),
}
});
catch_unwind(AssertUnwindSafe(|| while it.next().is_some() {})).unwrap_err();
// Iterator behaviour after a panic is explicitly unspecified,
// so this is just the current implementation:
let result = catch_unwind(AssertUnwindSafe(|| it.next()));
assert!(matches!(result, Ok(None)));
}
assert_eq!(PREDS.load(Ordering::SeqCst), 0x011);
assert_eq!(DROPS.load(Ordering::SeqCst), 1);
@ -1319,7 +1353,7 @@ fn drop(&mut self) {
map.insert("d", D);
map.insert("e", D);
catch_unwind(move || drop(map.into_iter())).ok();
catch_unwind(move || drop(map.into_iter())).unwrap_err();
assert_eq!(DROPS.load(Ordering::SeqCst), 5);
}
@ -1343,7 +1377,7 @@ fn drop(&mut self) {
DROPS.store(0, Ordering::SeqCst);
PANIC_POINT.store(panic_point, Ordering::SeqCst);
let map: BTreeMap<_, _> = (0..size).map(|i| (i, D)).collect();
catch_unwind(move || drop(map.into_iter())).ok();
catch_unwind(move || drop(map.into_iter())).unwrap_err();
assert_eq!(DROPS.load(Ordering::SeqCst), size);
}
}