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Jan 20, 2024
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HashMap/HashSet: forward fold implementations of iterators #117756

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6318cbb
`HashMap`/`HashSet`: forward `fold` implementations of iterators
a1phyr Nov 9, 2023
7d369f9
Specialize `count` too
a1phyr Nov 27, 2023
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104 changes: 104 additions & 0 deletions library/std/src/collections/hash/map.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2232,6 +2232,18 @@ impl<'a, K, V> Iterator for Iter<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn count(self) -> usize {
self.base.len()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Iter<'_, K, V> {
Expand All @@ -2256,6 +2268,18 @@ impl<'a, K, V> Iterator for IterMut<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn count(self) -> usize {
self.base.len()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IterMut<'_, K, V> {
Expand Down Expand Up @@ -2290,6 +2314,18 @@ impl<K, V> Iterator for IntoIter<K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn count(self) -> usize {
self.base.len()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IntoIter<K, V> {
Expand Down Expand Up @@ -2320,6 +2356,18 @@ impl<'a, K, V> Iterator for Keys<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn count(self) -> usize {
self.inner.len()
}
#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.inner.fold(init, |acc, (k, _)| f(acc, k))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Keys<'_, K, V> {
Expand All @@ -2343,6 +2391,18 @@ impl<'a, K, V> Iterator for Values<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn count(self) -> usize {
self.inner.len()
}
#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.inner.fold(init, |acc, (_, v)| f(acc, v))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for Values<'_, K, V> {
Expand All @@ -2366,6 +2426,18 @@ impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn count(self) -> usize {
self.inner.len()
}
#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.inner.fold(init, |acc, (_, v)| f(acc, v))
}
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<K, V> ExactSizeIterator for ValuesMut<'_, K, V> {
Expand Down Expand Up @@ -2396,6 +2468,18 @@ impl<K, V> Iterator for IntoKeys<K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn count(self) -> usize {
self.inner.len()
}
#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.inner.fold(init, |acc, (k, _)| f(acc, k))
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V> ExactSizeIterator for IntoKeys<K, V> {
Expand Down Expand Up @@ -2426,6 +2510,18 @@ impl<K, V> Iterator for IntoValues<K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
#[inline]
fn count(self) -> usize {
self.inner.len()
}
#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.inner.fold(init, |acc, (_, v)| f(acc, v))
}
}
#[stable(feature = "map_into_keys_values", since = "1.54.0")]
impl<K, V> ExactSizeIterator for IntoValues<K, V> {
Expand Down Expand Up @@ -2456,6 +2552,14 @@ impl<'a, K, V> Iterator for Drain<'a, K, V> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "drain", since = "1.6.0")]
impl<K, V> ExactSizeIterator for Drain<'_, K, V> {
Expand Down
70 changes: 70 additions & 0 deletions library/std/src/collections/hash/set.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1500,6 +1500,18 @@ impl<'a, K> Iterator for Iter<'a, K> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn count(self) -> usize {
self.base.len()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K> ExactSizeIterator for Iter<'_, K> {
Expand Down Expand Up @@ -1530,6 +1542,18 @@ impl<K> Iterator for IntoIter<K> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn count(self) -> usize {
self.base.len()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K> ExactSizeIterator for IntoIter<K> {
Expand Down Expand Up @@ -1560,6 +1584,14 @@ impl<'a, K> Iterator for Drain<'a, K> {
fn size_hint(&self) -> (usize, Option<usize>) {
self.base.size_hint()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.base.fold(init, f)
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K> ExactSizeIterator for Drain<'_, K> {
Expand Down Expand Up @@ -1639,6 +1671,15 @@ where
let (_, upper) = self.iter.size_hint();
(0, upper)
}

#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.iter.fold(init, |acc, elt| if self.other.contains(elt) { f(acc, elt) } else { acc })
}
}

#[stable(feature = "std_debug", since = "1.16.0")]
Expand Down Expand Up @@ -1691,6 +1732,15 @@ where
let (_, upper) = self.iter.size_hint();
(0, upper)
}

#[inline]
fn fold<B, F>(self, init: B, mut f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.iter.fold(init, |acc, elt| if self.other.contains(elt) { acc } else { f(acc, elt) })
}
}

#[stable(feature = "fused", since = "1.26.0")]
Expand Down Expand Up @@ -1736,6 +1786,14 @@ where
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.iter.fold(init, f)
}
}

#[stable(feature = "fused", since = "1.26.0")]
Expand Down Expand Up @@ -1800,6 +1858,18 @@ where
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
#[inline]
fn count(self) -> usize {
self.iter.count()
}
#[inline]
fn fold<B, F>(self, init: B, f: F) -> B
where
Self: Sized,
F: FnMut(B, Self::Item) -> B,
{
self.iter.fold(init, f)
}
}

#[allow(dead_code)]
Expand Down