Merge pull request #197 from cuviper/par_drain

impl ParallelDrainRange

Author: cuviper

Cargo.toml

@@ -34,7 +34,7 @@ bench = false
 autocfg = "1"
 [dependencies]
 serde = { version = "1.0", optional = true, default-features = false }
-rayon = { version = "1.2", optional = true }
+rayon = { version = "1.4.1", optional = true }
 
 # Internal feature, only used when building as part of rustc,
 # not part of the stable interface of this crate.

src/map.rs

@@ -69,12 +69,12 @@ pub use self::core::{Entry, OccupiedEntry, VacantEntry};
 /// ```
 #[cfg(has_std)]
 pub struct IndexMap<K, V, S = RandomState> {
-    core: IndexMapCore<K, V>,
+    pub(crate) core: IndexMapCore<K, V>,
     hash_builder: S,
 }
 #[cfg(not(has_std))]
 pub struct IndexMap<K, V, S> {
-    core: IndexMapCore<K, V>,
+    pub(crate) core: IndexMapCore<K, V>,
     hash_builder: S,
 }
 

src/map/core.rs

@@ -166,6 +166,19 @@ impl<K, V> IndexMapCore<K, V> {
         self.entries.drain(range)
     }
 
+    #[cfg(feature = "rayon")]
+    pub(crate) fn par_drain<R>(&mut self, range: R) -> rayon::vec::Drain<'_, Bucket<K, V>>
+    where
+        K: Send,
+        V: Send,
+        R: RangeBounds<usize>,
+    {
+        use rayon::iter::ParallelDrainRange;
+        let range = simplify_range(range, self.entries.len());
+        self.erase_indices(range.start, range.end);
+        self.entries.par_drain(range)
+    }
+
     pub(crate) fn split_off(&mut self, at: usize) -> Self {
         assert!(at <= self.entries.len());
         self.erase_indices(at, self.entries.len());

src/rayon/map.rs

@@ -13,6 +13,7 @@ use crate::vec::Vec;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{BuildHasher, Hash};
+use core::ops::RangeBounds;
 
 use crate::Bucket;
 use crate::Entries;
@@ -156,6 +157,43 @@ impl<K: Sync + Send, V: Send> IndexedParallelIterator for ParIterMut<'_, K, V> {
     indexed_parallel_iterator_methods!(Bucket::ref_mut);
 }
 
+/// Requires crate feature `"rayon"`.
+impl<'a, K, V, S> ParallelDrainRange<usize> for &'a mut IndexMap<K, V, S>
+where
+    K: Send,
+    V: Send,
+{
+    type Item = (K, V);
+    type Iter = ParDrain<'a, K, V>;
+
+    fn par_drain<R: RangeBounds<usize>>(self, range: R) -> Self::Iter {
+        ParDrain {
+            entries: self.core.par_drain(range),
+        }
+    }
+}
+
+/// A parallel draining iterator over the entries of a `IndexMap`.
+///
+/// This `struct` is created by the [`par_drain`] method on [`IndexMap`]
+/// (provided by rayon's `ParallelDrainRange` trait). See its documentation for more.
+///
+/// [`par_drain`]: ../struct.IndexMap.html#method.par_drain
+/// [`IndexMap`]: ../struct.IndexMap.html
+pub struct ParDrain<'a, K: Send, V: Send> {
+    entries: rayon::vec::Drain<'a, Bucket<K, V>>,
+}
+
+impl<K: Send, V: Send> ParallelIterator for ParDrain<'_, K, V> {
+    type Item = (K, V);
+
+    parallel_iterator_methods!(Bucket::key_value);
+}
+
+impl<K: Send, V: Send> IndexedParallelIterator for ParDrain<'_, K, V> {
+    indexed_parallel_iterator_methods!(Bucket::key_value);
+}
+
 /// Parallel iterator methods and other parallel methods.
 ///
 /// The following methods **require crate feature `"rayon"`**.

src/rayon/set.rs

@@ -13,6 +13,7 @@ use crate::vec::Vec;
 use core::cmp::Ordering;
 use core::fmt;
 use core::hash::{BuildHasher, Hash};
+use core::ops::RangeBounds;
 
 use crate::Entries;
 use crate::IndexSet;
@@ -111,6 +112,42 @@ impl<T: Sync> IndexedParallelIterator for ParIter<'_, T> {
     indexed_parallel_iterator_methods!(Bucket::key_ref);
 }
 
+/// Requires crate feature `"rayon"`.
+impl<'a, T, S> ParallelDrainRange<usize> for &'a mut IndexSet<T, S>
+where
+    T: Send,
+{
+    type Item = T;
+    type Iter = ParDrain<'a, T>;
+
+    fn par_drain<R: RangeBounds<usize>>(self, range: R) -> Self::Iter {
+        ParDrain {
+            entries: self.map.core.par_drain(range),
+        }
+    }
+}
+
+/// A parallel draining iterator over the items of a `IndexSet`.
+///
+/// This `struct` is created by the [`par_drain`] method on [`IndexSet`]
+/// (provided by rayon's `ParallelDrainRange` trait). See its documentation for more.
+///
+/// [`par_drain`]: ../struct.IndexSet.html#method.par_drain
+/// [`IndexSet`]: ../struct.IndexSet.html
+pub struct ParDrain<'a, T: Send> {
+    entries: rayon::vec::Drain<'a, Bucket<T>>,
+}
+
+impl<T: Send> ParallelIterator for ParDrain<'_, T> {
+    type Item = T;
+
+    parallel_iterator_methods!(Bucket::key);
+}
+
+impl<T: Send> IndexedParallelIterator for ParDrain<'_, T> {
+    indexed_parallel_iterator_methods!(Bucket::key);
+}
+
 /// Parallel iterator methods and other parallel methods.
 ///
 /// The following methods **require crate feature `"rayon"`**.

src/set.rs

@@ -61,11 +61,11 @@ type Bucket<T> = super::Bucket<T, ()>;
 /// ```
 #[cfg(has_std)]
 pub struct IndexSet<T, S = RandomState> {
-    map: IndexMap<T, (), S>,
+    pub(crate) map: IndexMap<T, (), S>,
 }
 #[cfg(not(has_std))]
 pub struct IndexSet<T, S> {
-    map: IndexMap<T, (), S>,
+    pub(crate) map: IndexMap<T, (), S>,
 }
 
 impl<T, S> Clone for IndexSet<T, S>