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Implement From between IndexedEntry and OccupiedEntry
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cuviper committed Aug 27, 2024
1 parent 9b93dd5 commit ba16981
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Showing 3 changed files with 60 additions and 6 deletions.
18 changes: 18 additions & 0 deletions src/map/core/entry.rs
Original file line number Diff line number Diff line change
Expand Up @@ -282,6 +282,17 @@ impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for OccupiedEntry<'_, K, V> {
}
}

impl<'a, K, V> From<IndexedEntry<'a, K, V>> for OccupiedEntry<'a, K, V> {
fn from(entry: IndexedEntry<'a, K, V>) -> Self {
Self {
raw: entry
.map
.index_raw_entry(entry.index)
.expect("index not found"),
}
}
}

/// A view into a vacant entry in an [`IndexMap`][crate::IndexMap].
/// It is part of the [`Entry`] enum.
pub struct VacantEntry<'a, K, V> {
Expand Down Expand Up @@ -491,3 +502,10 @@ impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for IndexedEntry<'_, K, V> {
.finish()
}
}

impl<'a, K, V> From<OccupiedEntry<'a, K, V>> for IndexedEntry<'a, K, V> {
fn from(entry: OccupiedEntry<'a, K, V>) -> Self {
let (map, index) = entry.raw.into_inner();
Self { map, index }
}
}
23 changes: 17 additions & 6 deletions src/map/core/raw.rs
Original file line number Diff line number Diff line change
Expand Up @@ -83,16 +83,19 @@ impl<K, V> IndexMapCore<K, V> {
let entries = &*self.entries;
let eq = move |&i: &usize| is_match(&entries[i].key);
match self.indices.find(hash.get(), eq) {
// SAFETY: The entry is created with a live raw bucket, at the same time
// we have a &mut reference to the map, so it can not be modified further.
Some(raw_bucket) => Ok(RawTableEntry {
map: self,
raw_bucket,
}),
// SAFETY: The bucket is valid because we *just* found it in this map.
Some(raw_bucket) => Ok(unsafe { RawTableEntry::new(self, raw_bucket) }),
None => Err(self),
}
}

pub(super) fn index_raw_entry(&mut self, index: usize) -> Option<RawTableEntry<'_, K, V>> {
let hash = self.entries.get(index)?.hash;
let raw_bucket = self.indices.find(hash.get(), move |&i| i == index)?;
// SAFETY: The bucket is valid because we *just* found it in this map.
Some(unsafe { RawTableEntry::new(self, raw_bucket) })
}

pub(super) fn indices_mut(&mut self) -> impl Iterator<Item = &mut usize> {
// SAFETY: we're not letting any of the buckets escape this function,
// only the item references that are appropriately bound to `&mut self`.
Expand All @@ -113,6 +116,13 @@ pub(super) struct RawTableEntry<'a, K, V> {
unsafe impl<K: Sync, V: Sync> Sync for RawTableEntry<'_, K, V> {}

impl<'a, K, V> RawTableEntry<'a, K, V> {
/// The caller must ensure that the `raw_bucket` is valid in the given `map`,
/// and then we hold the `&mut` reference for exclusive access.
#[inline]
unsafe fn new(map: &'a mut IndexMapCore<K, V>, raw_bucket: RawBucket) -> Self {
Self { map, raw_bucket }
}

/// Return the index of the key-value pair
#[inline]
pub(super) fn index(&self) -> usize {
Expand Down Expand Up @@ -146,6 +156,7 @@ impl<'a, K, V> RawTableEntry<'a, K, V> {
}

/// Take no action, just return the index and the original map reference.
#[inline]
pub(super) fn into_inner(self) -> (&'a mut IndexMapCore<K, V>, usize) {
let index = self.index();
(self.map, index)
Expand Down
25 changes: 25 additions & 0 deletions src/map/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -416,6 +416,31 @@ fn get_index_entry() {
assert_eq!(*map.get(&3).unwrap(), "4");
}

#[test]
fn from_entries() {
let mut map = IndexMap::from([(1, "1"), (2, "2"), (3, "3")]);

{
let e = match map.entry(1) {
Entry::Occupied(e) => IndexedEntry::from(e),
Entry::Vacant(_) => panic!(),
};
assert_eq!(e.index(), 0);
assert_eq!(*e.key(), 1);
assert_eq!(*e.get(), "1");
}

{
let e = match map.get_index_entry(1) {
Some(e) => OccupiedEntry::from(e),
None => panic!(),
};
assert_eq!(e.index(), 1);
assert_eq!(*e.key(), 2);
assert_eq!(*e.get(), "2");
}
}

#[test]
fn keys() {
let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
Expand Down

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