1 files changed, 340 insertions, 0 deletions
diff --git a/third_party/rust/indexmap/src/set/slice.rs b/third_party/rust/indexmap/src/set/slice.rs
new file mode 100644
index 0000000000..9fc208c706
--- /dev/null
+++ b/third_party/rust/indexmap/src/set/slice.rs
@@ -0,0 +1,340 @@
+use super::{Bucket, Entries, IndexSet, IntoIter, Iter};
+use crate::util::try_simplify_range;
+
+use alloc::boxed::Box;
+use alloc::vec::Vec;
+use core::cmp::Ordering;
+use core::fmt;
+use core::hash::{Hash, Hasher};
+use core::ops::{self, Bound, Index, RangeBounds};
+
+/// A dynamically-sized slice of values in an [`IndexSet`].
+///
+/// This supports indexed operations much like a `[T]` slice,
+/// but not any hashed operations on the values.
+///
+/// Unlike `IndexSet`, `Slice` does consider the order for [`PartialEq`]
+/// and [`Eq`], and it also implements [`PartialOrd`], [`Ord`], and [`Hash`].
+#[repr(transparent)]
+pub struct Slice<T> {
+    pub(crate) entries: [Bucket<T>],
+}
+
+// SAFETY: `Slice<T>` is a transparent wrapper around `[Bucket<T>]`,
+// and reference lifetimes are bound together in function signatures.
+#[allow(unsafe_code)]
+impl<T> Slice<T> {
+    pub(super) const fn from_slice(entries: &[Bucket<T>]) -> &Self {
+        unsafe { &*(entries as *const [Bucket<T>] as *const Self) }
+    }
+
+    pub(super) fn from_boxed(entries: Box<[Bucket<T>]>) -> Box<Self> {
+        unsafe { Box::from_raw(Box::into_raw(entries) as *mut Self) }
+    }
+
+    fn into_boxed(self: Box<Self>) -> Box<[Bucket<T>]> {
+        unsafe { Box::from_raw(Box::into_raw(self) as *mut [Bucket<T>]) }
+    }
+}
+
+impl<T> Slice<T> {
+    pub(crate) fn into_entries(self: Box<Self>) -> Vec<Bucket<T>> {
+        self.into_boxed().into_vec()
+    }
+
+    /// Returns an empty slice.
+    pub const fn new<'a>() -> &'a Self {
+        Self::from_slice(&[])
+    }
+
+    /// Return the number of elements in the set slice.
+    pub const fn len(&self) -> usize {
+        self.entries.len()
+    }
+
+    /// Returns true if the set slice contains no elements.
+    pub const fn is_empty(&self) -> bool {
+        self.entries.is_empty()
+    }
+
+    /// Get a value by index.
+    ///
+    /// Valid indices are *0 <= index < self.len()*
+    pub fn get_index(&self, index: usize) -> Option<&T> {
+        self.entries.get(index).map(Bucket::key_ref)
+    }
+
+    /// Returns a slice of values in the given range of indices.
+    ///
+    /// Valid indices are *0 <= index < self.len()*
+    pub fn get_range<R: RangeBounds<usize>>(&self, range: R) -> Option<&Self> {
+        let range = try_simplify_range(range, self.entries.len())?;
+        self.entries.get(range).map(Self::from_slice)
+    }
+
+    /// Get the first value.
+    pub fn first(&self) -> Option<&T> {
+        self.entries.first().map(Bucket::key_ref)
+    }
+
+    /// Get the last value.
+    pub fn last(&self) -> Option<&T> {
+        self.entries.last().map(Bucket::key_ref)
+    }
+
+    /// Divides one slice into two at an index.
+    ///
+    /// ***Panics*** if `index > len`.
+    pub fn split_at(&self, index: usize) -> (&Self, &Self) {
+        let (first, second) = self.entries.split_at(index);
+        (Self::from_slice(first), Self::from_slice(second))
+    }
+
+    /// Returns the first value and the rest of the slice,
+    /// or `None` if it is empty.
+    pub fn split_first(&self) -> Option<(&T, &Self)> {
+        if let [first, rest @ ..] = &self.entries {
+            Some((&first.key, Self::from_slice(rest)))
+        } else {
+            None
+        }
+    }
+
+    /// Returns the last value and the rest of the slice,
+    /// or `None` if it is empty.
+    pub fn split_last(&self) -> Option<(&T, &Self)> {
+        if let [rest @ .., last] = &self.entries {
+            Some((&last.key, Self::from_slice(rest)))
+        } else {
+            None
+        }
+    }
+
+    /// Return an iterator over the values of the set slice.
+    pub fn iter(&self) -> Iter<'_, T> {
+        Iter::new(&self.entries)
+    }
+
+    /// Search over a sorted set for a value.
+    ///
+    /// Returns the position where that value is present, or the position where it can be inserted
+    /// to maintain the sort. See [`slice::binary_search`] for more details.
+    ///
+    /// Computes in **O(log(n))** time, which is notably less scalable than looking the value up in
+    /// the set this is a slice from using [`IndexSet::get_index_of`], but this can also position
+    /// missing values.
+    pub fn binary_search(&self, x: &T) -> Result<usize, usize>
+    where
+        T: Ord,
+    {
+        self.binary_search_by(|p| p.cmp(x))
+    }
+
+    /// Search over a sorted set with a comparator function.
+    ///
+    /// Returns the position where that value is present, or the position where it can be inserted
+    /// to maintain the sort. See [`slice::binary_search_by`] for more details.
+    ///
+    /// Computes in **O(log(n))** time.
+    #[inline]
+    pub fn binary_search_by<'a, F>(&'a self, mut f: F) -> Result<usize, usize>
+    where
+        F: FnMut(&'a T) -> Ordering,
+    {
+        self.entries.binary_search_by(move |a| f(&a.key))
+    }
+
+    /// Search over a sorted set with an extraction function.
+    ///
+    /// Returns the position where that value is present, or the position where it can be inserted
+    /// to maintain the sort. See [`slice::binary_search_by_key`] for more details.
+    ///
+    /// Computes in **O(log(n))** time.
+    #[inline]
+    pub fn binary_search_by_key<'a, B, F>(&'a self, b: &B, mut f: F) -> Result<usize, usize>
+    where
+        F: FnMut(&'a T) -> B,
+        B: Ord,
+    {
+        self.binary_search_by(|k| f(k).cmp(b))
+    }
+
+    /// Returns the index of the partition point of a sorted set according to the given predicate
+    /// (the index of the first element of the second partition).
+    ///
+    /// See [`slice::partition_point`] for more details.
+    ///
+    /// Computes in **O(log(n))** time.
+    #[must_use]
+    pub fn partition_point<P>(&self, mut pred: P) -> usize
+    where
+        P: FnMut(&T) -> bool,
+    {
+        self.entries.partition_point(move |a| pred(&a.key))
+    }
+}
+
+impl<'a, T> IntoIterator for &'a Slice<T> {
+    type IntoIter = Iter<'a, T>;
+    type Item = &'a T;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<T> IntoIterator for Box<Slice<T>> {
+    type IntoIter = IntoIter<T>;
+    type Item = T;
+
+    fn into_iter(self) -> Self::IntoIter {
+        IntoIter::new(self.into_entries())
+    }
+}
+
+impl<T> Default for &'_ Slice<T> {
+    fn default() -> Self {
+        Slice::from_slice(&[])
+    }
+}
+
+impl<T> Default for Box<Slice<T>> {
+    fn default() -> Self {
+        Slice::from_boxed(Box::default())
+    }
+}
+
+impl<T: Clone> Clone for Box<Slice<T>> {
+    fn clone(&self) -> Self {
+        Slice::from_boxed(self.entries.to_vec().into_boxed_slice())
+    }
+}
+
+impl<T: Copy> From<&Slice<T>> for Box<Slice<T>> {
+    fn from(slice: &Slice<T>) -> Self {
+        Slice::from_boxed(Box::from(&slice.entries))
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for Slice<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self).finish()
+    }
+}
+
+impl<T: PartialEq> PartialEq for Slice<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.len() == other.len() && self.iter().eq(other)
+    }
+}
+
+impl<T: Eq> Eq for Slice<T> {}
+
+impl<T: PartialOrd> PartialOrd for Slice<T> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        self.iter().partial_cmp(other)
+    }
+}
+
+impl<T: Ord> Ord for Slice<T> {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.iter().cmp(other)
+    }
+}
+
+impl<T: Hash> Hash for Slice<T> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.len().hash(state);
+        for value in self {
+            value.hash(state);
+        }
+    }
+}
+
+impl<T> Index<usize> for Slice<T> {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.entries[index].key
+    }
+}
+
+// We can't have `impl<I: RangeBounds<usize>> Index<I>` because that conflicts with `Index<usize>`.
+// Instead, we repeat the implementations for all the core range types.
+macro_rules! impl_index {
+    ($($range:ty),*) => {$(
+        impl<T, S> Index<$range> for IndexSet<T, S> {
+            type Output = Slice<T>;
+
+            fn index(&self, range: $range) -> &Self::Output {
+                Slice::from_slice(&self.as_entries()[range])
+            }
+        }
+
+        impl<T> Index<$range> for Slice<T> {
+            type Output = Self;
+
+            fn index(&self, range: $range) -> &Self::Output {
+                Slice::from_slice(&self.entries[range])
+            }
+        }
+    )*}
+}
+impl_index!(
+    ops::Range<usize>,
+    ops::RangeFrom<usize>,
+    ops::RangeFull,
+    ops::RangeInclusive<usize>,
+    ops::RangeTo<usize>,
+    ops::RangeToInclusive<usize>,
+    (Bound<usize>, Bound<usize>)
+);
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn slice_index() {
+        fn check(vec_slice: &[i32], set_slice: &Slice<i32>, sub_slice: &Slice<i32>) {
+            assert_eq!(set_slice as *const _, sub_slice as *const _);
+            itertools::assert_equal(vec_slice, set_slice);
+        }
+
+        let vec: Vec<i32> = (0..10).map(|i| i * i).collect();
+        let set: IndexSet<i32> = vec.iter().cloned().collect();
+        let slice = set.as_slice();
+
+        // RangeFull
+        check(&vec[..], &set[..], &slice[..]);
+
+        for i in 0usize..10 {
+            // Index
+            assert_eq!(vec[i], set[i]);
+            assert_eq!(vec[i], slice[i]);
+
+            // RangeFrom
+            check(&vec[i..], &set[i..], &slice[i..]);
+
+            // RangeTo
+            check(&vec[..i], &set[..i], &slice[..i]);
+
+            // RangeToInclusive
+            check(&vec[..=i], &set[..=i], &slice[..=i]);
+
+            // (Bound<usize>, Bound<usize>)
+            let bounds = (Bound::Excluded(i), Bound::Unbounded);
+            check(&vec[i + 1..], &set[bounds], &slice[bounds]);
+
+            for j in i..=10 {
+                // Range
+                check(&vec[i..j], &set[i..j], &slice[i..j]);
+            }
+
+            for j in i..10 {
+                // RangeInclusive
+                check(&vec[i..=j], &set[i..=j], &slice[i..=j]);
+            }
+        }
+    }
+}