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use super::{
Bucket, Entries, IndexMap, IntoIter, IntoKeys, IntoValues, Iter, IterMut, Keys, Values,
ValuesMut,
};
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, IndexMut, RangeBounds};
/// A dynamically-sized slice of key-value pairs in an [`IndexMap`].
///
/// This supports indexed operations much like a `[(K, V)]` slice,
/// but not any hashed operations on the map keys.
///
/// Unlike `IndexMap`, `Slice` does consider the order for [`PartialEq`]
/// and [`Eq`], and it also implements [`PartialOrd`], [`Ord`], and [`Hash`].
#[repr(transparent)]
pub struct Slice<K, V> {
pub(crate) entries: [Bucket<K, V>],
}
// SAFETY: `Slice<K, V>` is a transparent wrapper around `[Bucket<K, V>]`,
// and reference lifetimes are bound together in function signatures.
#[allow(unsafe_code)]
impl<K, V> Slice<K, V> {
pub(super) const fn from_slice(entries: &[Bucket<K, V>]) -> &Self {
unsafe { &*(entries as *const [Bucket<K, V>] as *const Self) }
}
pub(super) fn from_mut_slice(entries: &mut [Bucket<K, V>]) -> &mut Self {
unsafe { &mut *(entries as *mut [Bucket<K, V>] as *mut Self) }
}
pub(super) fn from_boxed(entries: Box<[Bucket<K, V>]>) -> Box<Self> {
unsafe { Box::from_raw(Box::into_raw(entries) as *mut Self) }
}
fn into_boxed(self: Box<Self>) -> Box<[Bucket<K, V>]> {
unsafe { Box::from_raw(Box::into_raw(self) as *mut [Bucket<K, V>]) }
}
}
impl<K, V> Slice<K, V> {
pub(crate) fn into_entries(self: Box<Self>) -> Vec<Bucket<K, V>> {
self.into_boxed().into_vec()
}
/// Returns an empty slice.
pub const fn new<'a>() -> &'a Self {
Self::from_slice(&[])
}
/// Returns an empty mutable slice.
pub fn new_mut<'a>() -> &'a mut Self {
Self::from_mut_slice(&mut [])
}
/// Return the number of key-value pairs in the map slice.
#[inline]
pub const fn len(&self) -> usize {
self.entries.len()
}
/// Returns true if the map slice contains no elements.
#[inline]
pub const fn is_empty(&self) -> bool {
self.entries.is_empty()
}
/// Get a key-value pair by index.
///
/// Valid indices are *0 <= index < self.len()*
pub fn get_index(&self, index: usize) -> Option<(&K, &V)> {
self.entries.get(index).map(Bucket::refs)
}
/// Get a key-value pair by index, with mutable access to the value.
///
/// Valid indices are *0 <= index < self.len()*
pub fn get_index_mut(&mut self, index: usize) -> Option<(&K, &mut V)> {
self.entries.get_mut(index).map(Bucket::ref_mut)
}
/// Returns a slice of key-value pairs 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(Slice::from_slice)
}
/// Returns a mutable slice of key-value pairs in the given range of indices.
///
/// Valid indices are *0 <= index < self.len()*
pub fn get_range_mut<R: RangeBounds<usize>>(&mut self, range: R) -> Option<&mut Self> {
let range = try_simplify_range(range, self.entries.len())?;
self.entries.get_mut(range).map(Slice::from_mut_slice)
}
/// Get the first key-value pair.
pub fn first(&self) -> Option<(&K, &V)> {
self.entries.first().map(Bucket::refs)
}
/// Get the first key-value pair, with mutable access to the value.
pub fn first_mut(&mut self) -> Option<(&K, &mut V)> {
self.entries.first_mut().map(Bucket::ref_mut)
}
/// Get the last key-value pair.
pub fn last(&self) -> Option<(&K, &V)> {
self.entries.last().map(Bucket::refs)
}
/// Get the last key-value pair, with mutable access to the value.
pub fn last_mut(&mut self) -> Option<(&K, &mut V)> {
self.entries.last_mut().map(Bucket::ref_mut)
}
/// 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))
}
/// Divides one mutable slice into two at an index.
///
/// ***Panics*** if `index > len`.
pub fn split_at_mut(&mut self, index: usize) -> (&mut Self, &mut Self) {
let (first, second) = self.entries.split_at_mut(index);
(Self::from_mut_slice(first), Self::from_mut_slice(second))
}
/// Returns the first key-value pair and the rest of the slice,
/// or `None` if it is empty.
pub fn split_first(&self) -> Option<((&K, &V), &Self)> {
if let [first, rest @ ..] = &self.entries {
Some((first.refs(), Self::from_slice(rest)))
} else {
None
}
}
/// Returns the first key-value pair and the rest of the slice,
/// with mutable access to the value, or `None` if it is empty.
pub fn split_first_mut(&mut self) -> Option<((&K, &mut V), &mut Self)> {
if let [first, rest @ ..] = &mut self.entries {
Some((first.ref_mut(), Self::from_mut_slice(rest)))
} else {
None
}
}
/// Returns the last key-value pair and the rest of the slice,
/// or `None` if it is empty.
pub fn split_last(&self) -> Option<((&K, &V), &Self)> {
if let [rest @ .., last] = &self.entries {
Some((last.refs(), Self::from_slice(rest)))
} else {
None
}
}
/// Returns the last key-value pair and the rest of the slice,
/// with mutable access to the value, or `None` if it is empty.
pub fn split_last_mut(&mut self) -> Option<((&K, &mut V), &mut Self)> {
if let [rest @ .., last] = &mut self.entries {
Some((last.ref_mut(), Self::from_mut_slice(rest)))
} else {
None
}
}
/// Return an iterator over the key-value pairs of the map slice.
pub fn iter(&self) -> Iter<'_, K, V> {
Iter::new(&self.entries)
}
/// Return an iterator over the key-value pairs of the map slice.
pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
IterMut::new(&mut self.entries)
}
/// Return an iterator over the keys of the map slice.
pub fn keys(&self) -> Keys<'_, K, V> {
Keys::new(&self.entries)
}
/// Return an owning iterator over the keys of the map slice.
pub fn into_keys(self: Box<Self>) -> IntoKeys<K, V> {
IntoKeys::new(self.into_entries())
}
/// Return an iterator over the values of the map slice.
pub fn values(&self) -> Values<'_, K, V> {
Values::new(&self.entries)
}
/// Return an iterator over mutable references to the the values of the map slice.
pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
ValuesMut::new(&mut self.entries)
}
/// Return an owning iterator over the values of the map slice.
pub fn into_values(self: Box<Self>) -> IntoValues<K, V> {
IntoValues::new(self.into_entries())
}
/// Search over a sorted map for a key.
///
/// Returns the position where that key 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 key up in
/// the map this is a slice from using [`IndexMap::get_index_of`], but this can also position
/// missing keys.
pub fn binary_search_keys(&self, x: &K) -> Result<usize, usize>
where
K: Ord,
{
self.binary_search_by(|p, _| p.cmp(x))
}
/// Search over a sorted map 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 K, &'a V) -> Ordering,
{
self.entries.binary_search_by(move |a| f(&a.key, &a.value))
}
/// Search over a sorted map 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 K, &'a V) -> B,
B: Ord,
{
self.binary_search_by(|k, v| f(k, v).cmp(b))
}
/// Returns the index of the partition point of a sorted map 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(&K, &V) -> bool,
{
self.entries
.partition_point(move |a| pred(&a.key, &a.value))
}
}
impl<'a, K, V> IntoIterator for &'a Slice<K, V> {
type IntoIter = Iter<'a, K, V>;
type Item = (&'a K, &'a V);
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
impl<'a, K, V> IntoIterator for &'a mut Slice<K, V> {
type IntoIter = IterMut<'a, K, V>;
type Item = (&'a K, &'a mut V);
fn into_iter(self) -> Self::IntoIter {
self.iter_mut()
}
}
impl<K, V> IntoIterator for Box<Slice<K, V>> {
type IntoIter = IntoIter<K, V>;
type Item = (K, V);
fn into_iter(self) -> Self::IntoIter {
IntoIter::new(self.into_entries())
}
}
impl<K, V> Default for &'_ Slice<K, V> {
fn default() -> Self {
Slice::from_slice(&[])
}
}
impl<K, V> Default for &'_ mut Slice<K, V> {
fn default() -> Self {
Slice::from_mut_slice(&mut [])
}
}
impl<K, V> Default for Box<Slice<K, V>> {
fn default() -> Self {
Slice::from_boxed(Box::default())
}
}
impl<K: Clone, V: Clone> Clone for Box<Slice<K, V>> {
fn clone(&self) -> Self {
Slice::from_boxed(self.entries.to_vec().into_boxed_slice())
}
}
impl<K: Copy, V: Copy> From<&Slice<K, V>> for Box<Slice<K, V>> {
fn from(slice: &Slice<K, V>) -> Self {
Slice::from_boxed(Box::from(&slice.entries))
}
}
impl<K: fmt::Debug, V: fmt::Debug> fmt::Debug for Slice<K, V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_list().entries(self).finish()
}
}
impl<K: PartialEq, V: PartialEq> PartialEq for Slice<K, V> {
fn eq(&self, other: &Self) -> bool {
self.len() == other.len() && self.iter().eq(other)
}
}
impl<K: Eq, V: Eq> Eq for Slice<K, V> {}
impl<K: PartialOrd, V: PartialOrd> PartialOrd for Slice<K, V> {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
self.iter().partial_cmp(other)
}
}
impl<K: Ord, V: Ord> Ord for Slice<K, V> {
fn cmp(&self, other: &Self) -> Ordering {
self.iter().cmp(other)
}
}
impl<K: Hash, V: Hash> Hash for Slice<K, V> {
fn hash<H: Hasher>(&self, state: &mut H) {
self.len().hash(state);
for (key, value) in self {
key.hash(state);
value.hash(state);
}
}
}
impl<K, V> Index<usize> for Slice<K, V> {
type Output = V;
fn index(&self, index: usize) -> &V {
&self.entries[index].value
}
}
impl<K, V> IndexMut<usize> for Slice<K, V> {
fn index_mut(&mut self, index: usize) -> &mut V {
&mut self.entries[index].value
}
}
// We can't have `impl<I: RangeBounds<usize>> Index<I>` because that conflicts
// both upstream with `Index<usize>` and downstream with `Index<&Q>`.
// Instead, we repeat the implementations for all the core range types.
macro_rules! impl_index {
($($range:ty),*) => {$(
impl<K, V, S> Index<$range> for IndexMap<K, V, S> {
type Output = Slice<K, V>;
fn index(&self, range: $range) -> &Self::Output {
Slice::from_slice(&self.as_entries()[range])
}
}
impl<K, V, S> IndexMut<$range> for IndexMap<K, V, S> {
fn index_mut(&mut self, range: $range) -> &mut Self::Output {
Slice::from_mut_slice(&mut self.as_entries_mut()[range])
}
}
impl<K, V> Index<$range> for Slice<K, V> {
type Output = Slice<K, V>;
fn index(&self, range: $range) -> &Self {
Self::from_slice(&self.entries[range])
}
}
impl<K, V> IndexMut<$range> for Slice<K, V> {
fn index_mut(&mut self, range: $range) -> &mut Self {
Self::from_mut_slice(&mut 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, i32)],
map_slice: &Slice<i32, i32>,
sub_slice: &Slice<i32, i32>,
) {
assert_eq!(map_slice as *const _, sub_slice as *const _);
itertools::assert_equal(
vec_slice.iter().copied(),
map_slice.iter().map(|(&k, &v)| (k, v)),
);
itertools::assert_equal(vec_slice.iter().map(|(k, _)| k), map_slice.keys());
itertools::assert_equal(vec_slice.iter().map(|(_, v)| v), map_slice.values());
}
let vec: Vec<(i32, i32)> = (0..10).map(|i| (i, i * i)).collect();
let map: IndexMap<i32, i32> = vec.iter().cloned().collect();
let slice = map.as_slice();
// RangeFull
check(&vec[..], &map[..], &slice[..]);
for i in 0usize..10 {
// Index
assert_eq!(vec[i].1, map[i]);
assert_eq!(vec[i].1, slice[i]);
assert_eq!(map[&(i as i32)], map[i]);
assert_eq!(map[&(i as i32)], slice[i]);
// RangeFrom
check(&vec[i..], &map[i..], &slice[i..]);
// RangeTo
check(&vec[..i], &map[..i], &slice[..i]);
// RangeToInclusive
check(&vec[..=i], &map[..=i], &slice[..=i]);
// (Bound<usize>, Bound<usize>)
let bounds = (Bound::Excluded(i), Bound::Unbounded);
check(&vec[i + 1..], &map[bounds], &slice[bounds]);
for j in i..=10 {
// Range
check(&vec[i..j], &map[i..j], &slice[i..j]);
}
for j in i..10 {
// RangeInclusive
check(&vec[i..=j], &map[i..=j], &slice[i..=j]);
}
}
}
#[test]
fn slice_index_mut() {
fn check_mut(
vec_slice: &[(i32, i32)],
map_slice: &mut Slice<i32, i32>,
sub_slice: &mut Slice<i32, i32>,
) {
assert_eq!(map_slice, sub_slice);
itertools::assert_equal(
vec_slice.iter().copied(),
map_slice.iter_mut().map(|(&k, &mut v)| (k, v)),
);
itertools::assert_equal(
vec_slice.iter().map(|&(_, v)| v),
map_slice.values_mut().map(|&mut v| v),
);
}
let vec: Vec<(i32, i32)> = (0..10).map(|i| (i, i * i)).collect();
let mut map: IndexMap<i32, i32> = vec.iter().cloned().collect();
let mut map2 = map.clone();
let slice = map2.as_mut_slice();
// RangeFull
check_mut(&vec[..], &mut map[..], &mut slice[..]);
for i in 0usize..10 {
// IndexMut
assert_eq!(&mut map[i], &mut slice[i]);
// RangeFrom
check_mut(&vec[i..], &mut map[i..], &mut slice[i..]);
// RangeTo
check_mut(&vec[..i], &mut map[..i], &mut slice[..i]);
// RangeToInclusive
check_mut(&vec[..=i], &mut map[..=i], &mut slice[..=i]);
// (Bound<usize>, Bound<usize>)
let bounds = (Bound::Excluded(i), Bound::Unbounded);
check_mut(&vec[i + 1..], &mut map[bounds], &mut slice[bounds]);
for j in i..=10 {
// Range
check_mut(&vec[i..j], &mut map[i..j], &mut slice[i..j]);
}
for j in i..10 {
// RangeInclusive
check_mut(&vec[i..=j], &mut map[i..=j], &mut slice[i..=j]);
}
}
}
}