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Make HashMap, HashSet, and their iterators properly covariant #32635

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merged 3 commits into from
Apr 1, 2016
Merged

Make HashMap, HashSet, and their iterators properly covariant #32635

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285a40a
Make HashMap's RawBucket covariant
gereeter Mar 31, 2016
1639f2d
Fix the variances of HashMap and HashSet iterators
gereeter Mar 31, 2016
589108b
Test that HashMap, HashSet, and their iterators are properly covariant
gereeter Mar 31, 2016
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Make HashMap's RawBucket covariant
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@gereeter
gereeter committed Mar 31, 2016
commit 285a40a90691d1f3129bebcead8c6f83363d7c83
41 changes: 23 additions & 18 deletions src/libstd/collections/hash/table.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -75,8 +75,10 @@ unsafe impl<K: Sync, V: Sync> Sync for RawTable<K, V> {}

struct RawBucket<K, V> {
hash: *mut u64,
key: *mut K,
val: *mut V,

// We use *const to ensure covariance with respect to K and V
key: *const K,
val: *const V,
_marker: marker::PhantomData<(K,V)>,
}

Expand Down Expand Up @@ -354,8 +356,8 @@ impl<K, V, M> EmptyBucket<K, V, M> where M: Put<K, V> {
-> FullBucket<K, V, M> {
unsafe {
*self.raw.hash = hash.inspect();
ptr::write(self.raw.key, key);
ptr::write(self.raw.val, value);
ptr::write(self.raw.key as *mut K, key);
ptr::write(self.raw.val as *mut V, value);

self.table.borrow_table_mut().size += 1;
}
Expand Down Expand Up @@ -453,8 +455,8 @@ impl<K, V, M> FullBucket<K, V, M> where M: Put<K, V> {
pub fn replace(&mut self, h: SafeHash, k: K, v: V) -> (SafeHash, K, V) {
unsafe {
let old_hash = ptr::replace(self.raw.hash as *mut SafeHash, h);
let old_key = ptr::replace(self.raw.key, k);
let old_val = ptr::replace(self.raw.val, v);
let old_key = ptr::replace(self.raw.key as *mut K, k);
let old_val = ptr::replace(self.raw.val as *mut V, v);

(old_hash, old_key, old_val)
}
Expand All @@ -465,8 +467,8 @@ impl<K, V, M> FullBucket<K, V, M> where M: Deref<Target=RawTable<K, V>> + DerefM
/// Gets mutable references to the key and value at a given index.
pub fn read_mut(&mut self) -> (&mut K, &mut V) {
unsafe {
(&mut *self.raw.key,
&mut *self.raw.val)
(&mut *(self.raw.key as *mut K),
&mut *(self.raw.val as *mut V))
}
}
}
Expand All @@ -490,8 +492,8 @@ impl<'t, K, V, M> FullBucket<K, V, M> where M: Deref<Target=RawTable<K, V>> + De
/// for mutable references into the table.
pub fn into_mut_refs(self) -> (&'t mut K, &'t mut V) {
unsafe {
(&mut *self.raw.key,
&mut *self.raw.val)
(&mut *(self.raw.key as *mut K),
&mut *(self.raw.val as *mut V))
}
}
}
Expand All @@ -505,8 +507,8 @@ impl<K, V, M> GapThenFull<K, V, M> where M: Deref<Target=RawTable<K, V>> {
pub fn shift(mut self) -> Option<GapThenFull<K, V, M>> {
unsafe {
*self.gap.raw.hash = mem::replace(&mut *self.full.raw.hash, EMPTY_BUCKET);
ptr::copy_nonoverlapping(self.full.raw.key, self.gap.raw.key, 1);
ptr::copy_nonoverlapping(self.full.raw.val, self.gap.raw.val, 1);
ptr::copy_nonoverlapping(self.full.raw.key, self.gap.raw.key as *mut K, 1);
ptr::copy_nonoverlapping(self.full.raw.val, self.gap.raw.val as *mut V, 1);
}

let FullBucket { raw: prev_raw, idx: prev_idx, .. } = self.full;
Expand Down Expand Up @@ -649,7 +651,7 @@ impl<K, V> RawTable<K, V> {
let hashes_size = self.capacity * size_of::<u64>();
let keys_size = self.capacity * size_of::<K>();

let buffer = *self.hashes as *mut u8;
let buffer = *self.hashes as *const u8;
let (keys_offset, vals_offset, oflo) =
calculate_offsets(hashes_size,
keys_size, align_of::<K>(),
Expand All @@ -658,8 +660,8 @@ impl<K, V> RawTable<K, V> {
unsafe {
RawBucket {
hash: *self.hashes,
key: buffer.offset(keys_offset as isize) as *mut K,
val: buffer.offset(vals_offset as isize) as *mut V,
key: buffer.offset(keys_offset as isize) as *const K,
val: buffer.offset(vals_offset as isize) as *const V,
_marker: marker::PhantomData,
}
}
Expand Down Expand Up @@ -707,6 +709,7 @@ impl<K, V> RawTable<K, V> {
IterMut {
iter: self.raw_buckets(),
elems_left: self.size(),
_marker: marker::PhantomData,
}
}

Expand Down Expand Up @@ -858,6 +861,8 @@ impl<'a, K, V> Clone for Iter<'a, K, V> {
pub struct IterMut<'a, K: 'a, V: 'a> {
iter: RawBuckets<'a, K, V>,
elems_left: usize,
// To ensure invariance with respect to V
_marker: marker::PhantomData<&'a mut V>,
}

unsafe impl<'a, K: Sync, V: Sync> Sync for IterMut<'a, K, V> {}
Expand Down Expand Up @@ -912,7 +917,7 @@ impl<'a, K, V> Iterator for IterMut<'a, K, V> {
self.elems_left -= 1;
unsafe {
(&*bucket.key,
&mut *bucket.val)
&mut *(bucket.val as *mut V))
}
})
}
Expand Down Expand Up @@ -1003,8 +1008,8 @@ impl<K: Clone, V: Clone> Clone for RawTable<K, V> {
(full.hash(), k.clone(), v.clone())
};
*new_buckets.raw.hash = h.inspect();
ptr::write(new_buckets.raw.key, k);
ptr::write(new_buckets.raw.val, v);
ptr::write(new_buckets.raw.key as *mut K, k);
ptr::write(new_buckets.raw.val as *mut V, v);
}
Empty(..) => {
*new_buckets.raw.hash = EMPTY_BUCKET;
Expand Down