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+//! [`IndexMap`] is a hash table where the iteration order of the key-value
+//! pairs is independent of the hash values of the keys.
+
+mod core;
+mod iter;
+mod mutable;
+mod slice;
+
+#[cfg(feature = "serde")]
+#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
+pub mod serde_seq;
+
+#[cfg(test)]
+mod tests;
+
+pub use self::core::raw_entry_v1::{self, RawEntryApiV1};
+pub use self::core::{Entry, IndexedEntry, OccupiedEntry, VacantEntry};
+pub use self::iter::{
+ Drain, IntoIter, IntoKeys, IntoValues, Iter, IterMut, IterMut2, Keys, Splice, Values, ValuesMut,
+};
+pub use self::mutable::MutableEntryKey;
+pub use self::mutable::MutableKeys;
+pub use self::slice::Slice;
+
+#[cfg(feature = "rayon")]
+pub use crate::rayon::map as rayon;
+
+use ::core::cmp::Ordering;
+use ::core::fmt;
+use ::core::hash::{BuildHasher, Hash, Hasher};
+use ::core::mem;
+use ::core::ops::{Index, IndexMut, RangeBounds};
+use alloc::boxed::Box;
+use alloc::vec::Vec;
+
+#[cfg(feature = "std")]
+use std::collections::hash_map::RandomState;
+
+use self::core::IndexMapCore;
+use crate::util::{third, try_simplify_range};
+use crate::{Bucket, Entries, Equivalent, GetDisjointMutError, HashValue, TryReserveError};
+
+/// A hash table where the iteration order of the key-value pairs is independent
+/// of the hash values of the keys.
+///
+/// The interface is closely compatible with the standard
+/// [`HashMap`][std::collections::HashMap],
+/// but also has additional features.
+///
+/// # Order
+///
+/// The key-value pairs have a consistent order that is determined by
+/// the sequence of insertion and removal calls on the map. The order does
+/// not depend on the keys or the hash function at all.
+///
+/// All iterators traverse the map in *the order*.
+///
+/// The insertion order is preserved, with **notable exceptions** like the
+/// [`.remove()`][Self::remove] or [`.swap_remove()`][Self::swap_remove] methods.
+/// Methods such as [`.sort_by()`][Self::sort_by] of
+/// course result in a new order, depending on the sorting order.
+///
+/// # Indices
+///
+/// The key-value pairs are indexed in a compact range without holes in the
+/// range `0..self.len()`. For example, the method `.get_full` looks up the
+/// index for a key, and the method `.get_index` looks up the key-value pair by
+/// index.
+///
+/// # Examples
+///
+/// ```
+/// use indexmap::IndexMap;
+///
+/// // count the frequency of each letter in a sentence.
+/// let mut letters = IndexMap::new();
+/// for ch in "a short treatise on fungi".chars() {
+/// *letters.entry(ch).or_insert(0) += 1;
+/// }
+///
+/// assert_eq!(letters[&'s'], 2);
+/// assert_eq!(letters[&'t'], 3);
+/// assert_eq!(letters[&'u'], 1);
+/// assert_eq!(letters.get(&'y'), None);
+/// ```
+#[cfg(feature = "std")]
+pub struct IndexMap<K, V, S = RandomState> {
+ pub(crate) core: IndexMapCore<K, V>,
+ hash_builder: S,
+}
+#[cfg(not(feature = "std"))]
+pub struct IndexMap<K, V, S> {
+ pub(crate) core: IndexMapCore<K, V>,
+ hash_builder: S,
+}
+
+impl<K, V, S> Clone for IndexMap<K, V, S>
+where
+ K: Clone,
+ V: Clone,
+ S: Clone,
+{
+ fn clone(&self) -> Self {
+ IndexMap {
+ core: self.core.clone(),
+ hash_builder: self.hash_builder.clone(),
+ }
+ }
+
+ fn clone_from(&mut self, other: &Self) {
+ self.core.clone_from(&other.core);
+ self.hash_builder.clone_from(&other.hash_builder);
+ }
+}
+
+impl<K, V, S> Entries for IndexMap<K, V, S> {
+ type Entry = Bucket<K, V>;
+
+ #[inline]
+ fn into_entries(self) -> Vec<Self::Entry> {
+ self.core.into_entries()
+ }
+
+ #[inline]
+ fn as_entries(&self) -> &[Self::Entry] {
+ self.core.as_entries()
+ }
+
+ #[inline]
+ fn as_entries_mut(&mut self) -> &mut [Self::Entry] {
+ self.core.as_entries_mut()
+ }
+
+ fn with_entries<F>(&mut self, f: F)
+ where
+ F: FnOnce(&mut [Self::Entry]),
+ {
+ self.core.with_entries(f);
+ }
+}
+
+impl<K, V, S> fmt::Debug for IndexMap<K, V, S>
+where
+ K: fmt::Debug,
+ V: fmt::Debug,
+{
+ #[cfg(not(feature = "test_debug"))]
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ f.debug_map().entries(self.iter()).finish()
+ }
+
+ #[cfg(feature = "test_debug")]
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ // Let the inner `IndexMapCore` print all of its details
+ f.debug_struct("IndexMap")
+ .field("core", &self.core)
+ .finish()
+ }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl<K, V> IndexMap<K, V> {
+ /// Create a new map. (Does not allocate.)
+ #[inline]
+ pub fn new() -> Self {
+ Self::with_capacity(0)
+ }
+
+ /// Create a new map with capacity for `n` key-value pairs. (Does not
+ /// allocate if `n` is zero.)
+ ///
+ /// Computes in **O(n)** time.
+ #[inline]
+ pub fn with_capacity(n: usize) -> Self {
+ Self::with_capacity_and_hasher(n, <_>::default())
+ }
+}
+
+impl<K, V, S> IndexMap<K, V, S> {
+ /// Create a new map with capacity for `n` key-value pairs. (Does not
+ /// allocate if `n` is zero.)
+ ///
+ /// Computes in **O(n)** time.
+ #[inline]
+ pub fn with_capacity_and_hasher(n: usize, hash_builder: S) -> Self {
+ if n == 0 {
+ Self::with_hasher(hash_builder)
+ } else {
+ IndexMap {
+ core: IndexMapCore::with_capacity(n),
+ hash_builder,
+ }
+ }
+ }
+
+ /// Create a new map with `hash_builder`.
+ ///
+ /// This function is `const`, so it
+ /// can be called in `static` contexts.
+ pub const fn with_hasher(hash_builder: S) -> Self {
+ IndexMap {
+ core: IndexMapCore::new(),
+ hash_builder,
+ }
+ }
+
+ /// Return the number of elements the map can hold without reallocating.
+ ///
+ /// This number is a lower bound; the map might be able to hold more,
+ /// but is guaranteed to be able to hold at least this many.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn capacity(&self) -> usize {
+ self.core.capacity()
+ }
+
+ /// Return a reference to the map's `BuildHasher`.
+ pub fn hasher(&self) -> &S {
+ &self.hash_builder
+ }
+
+ /// Return the number of key-value pairs in the map.
+ ///
+ /// Computes in **O(1)** time.
+ #[inline]
+ pub fn len(&self) -> usize {
+ self.core.len()
+ }
+
+ /// Returns true if the map contains no elements.
+ ///
+ /// Computes in **O(1)** time.
+ #[inline]
+ pub fn is_empty(&self) -> bool {
+ self.len() == 0
+ }
+
+ /// Return an iterator over the key-value pairs of the map, in their order
+ pub fn iter(&self) -> Iter<'_, K, V> {
+ Iter::new(self.as_entries())
+ }
+
+ /// Return an iterator over the key-value pairs of the map, in their order
+ pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
+ IterMut::new(self.as_entries_mut())
+ }
+
+ /// Return an iterator over the keys of the map, in their order
+ pub fn keys(&self) -> Keys<'_, K, V> {
+ Keys::new(self.as_entries())
+ }
+
+ /// Return an owning iterator over the keys of the map, in their order
+ pub fn into_keys(self) -> IntoKeys<K, V> {
+ IntoKeys::new(self.into_entries())
+ }
+
+ /// Return an iterator over the values of the map, in their order
+ pub fn values(&self) -> Values<'_, K, V> {
+ Values::new(self.as_entries())
+ }
+
+ /// Return an iterator over mutable references to the values of the map,
+ /// in their order
+ pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
+ ValuesMut::new(self.as_entries_mut())
+ }
+
+ /// Return an owning iterator over the values of the map, in their order
+ pub fn into_values(self) -> IntoValues<K, V> {
+ IntoValues::new(self.into_entries())
+ }
+
+ /// Remove all key-value pairs in the map, while preserving its capacity.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn clear(&mut self) {
+ self.core.clear();
+ }
+
+ /// Shortens the map, keeping the first `len` elements and dropping the rest.
+ ///
+ /// If `len` is greater than the map's current length, this has no effect.
+ pub fn truncate(&mut self, len: usize) {
+ self.core.truncate(len);
+ }
+
+ /// Clears the `IndexMap` in the given index range, returning those
+ /// key-value pairs as a drain iterator.
+ ///
+ /// The range may be any type that implements [`RangeBounds<usize>`],
+ /// including all of the `std::ops::Range*` types, or even a tuple pair of
+ /// `Bound` start and end values. To drain the map entirely, use `RangeFull`
+ /// like `map.drain(..)`.
+ ///
+ /// This shifts down all entries following the drained range to fill the
+ /// gap, and keeps the allocated memory for reuse.
+ ///
+ /// ***Panics*** if the starting point is greater than the end point or if
+ /// the end point is greater than the length of the map.
+ #[track_caller]
+ pub fn drain<R>(&mut self, range: R) -> Drain<'_, K, V>
+ where
+ R: RangeBounds<usize>,
+ {
+ Drain::new(self.core.drain(range))
+ }
+
+ /// Splits the collection into two at the given index.
+ ///
+ /// Returns a newly allocated map containing the elements in the range
+ /// `[at, len)`. After the call, the original map will be left containing
+ /// the elements `[0, at)` with its previous capacity unchanged.
+ ///
+ /// ***Panics*** if `at > len`.
+ #[track_caller]
+ pub fn split_off(&mut self, at: usize) -> Self
+ where
+ S: Clone,
+ {
+ Self {
+ core: self.core.split_off(at),
+ hash_builder: self.hash_builder.clone(),
+ }
+ }
+
+ /// Reserve capacity for `additional` more key-value pairs.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn reserve(&mut self, additional: usize) {
+ self.core.reserve(additional);
+ }
+
+ /// Reserve capacity for `additional` more key-value pairs, without over-allocating.
+ ///
+ /// Unlike `reserve`, this does not deliberately over-allocate the entry capacity to avoid
+ /// frequent re-allocations. However, the underlying data structures may still have internal
+ /// capacity requirements, and the allocator itself may give more space than requested, so this
+ /// cannot be relied upon to be precisely minimal.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn reserve_exact(&mut self, additional: usize) {
+ self.core.reserve_exact(additional);
+ }
+
+ /// Try to reserve capacity for `additional` more key-value pairs.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> {
+ self.core.try_reserve(additional)
+ }
+
+ /// Try to reserve capacity for `additional` more key-value pairs, without over-allocating.
+ ///
+ /// Unlike `try_reserve`, this does not deliberately over-allocate the entry capacity to avoid
+ /// frequent re-allocations. However, the underlying data structures may still have internal
+ /// capacity requirements, and the allocator itself may give more space than requested, so this
+ /// cannot be relied upon to be precisely minimal.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> {
+ self.core.try_reserve_exact(additional)
+ }
+
+ /// Shrink the capacity of the map as much as possible.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn shrink_to_fit(&mut self) {
+ self.core.shrink_to(0);
+ }
+
+ /// Shrink the capacity of the map with a lower limit.
+ ///
+ /// Computes in **O(n)** time.
+ pub fn shrink_to(&mut self, min_capacity: usize) {
+ self.core.shrink_to(min_capacity);
+ }
+}
+
+impl<K, V, S> IndexMap<K, V, S>
+where
+ K: Hash + Eq,
+ S: BuildHasher,
+{
+ /// Insert a key-value pair in the map.
+ ///
+ /// If an equivalent key already exists in the map: the key remains and
+ /// retains in its place in the order, its corresponding value is updated
+ /// with `value`, and the older value is returned inside `Some(_)`.
+ ///
+ /// If no equivalent key existed in the map: the new key-value pair is
+ /// inserted, last in order, and `None` is returned.
+ ///
+ /// Computes in **O(1)** time (amortized average).
+ ///
+ /// See also [`entry`][Self::entry] if you want to insert *or* modify,
+ /// or [`insert_full`][Self::insert_full] if you need to get the index of
+ /// the corresponding key-value pair.
+ pub fn insert(&mut self, key: K, value: V) -> Option<V> {
+ self.insert_full(key, value).1
+ }
+
+ /// Insert a key-value pair in the map, and get their index.
+ ///
+ /// If an equivalent key already exists in the map: the key remains and
+ /// retains in its place in the order, its corresponding value is updated
+ /// with `value`, and the older value is returned inside `(index, Some(_))`.
+ ///
+ /// If no equivalent key existed in the map: the new key-value pair is
+ /// inserted, last in order, and `(index, None)` is returned.
+ ///
+ /// Computes in **O(1)** time (amortized average).
+ ///
+ /// See also [`entry`][Self::entry] if you want to insert *or* modify.
+ pub fn insert_full(&mut self, key: K, value: V) -> (usize, Option<V>) {
+ let hash = self.hash(&key);
+ self.core.insert_full(hash, key, value)
+ }
+
+ /// Insert a key-value pair in the map at its ordered position among sorted keys.
+ ///
+ /// This is equivalent to finding the position with
+ /// [`binary_search_keys`][Self::binary_search_keys], then either updating
+ /// it or calling [`insert_before`][Self::insert_before] for a new key.
+ ///
+ /// If the sorted key is found in the map, its corresponding value is
+ /// updated with `value`, and the older value is returned inside
+ /// `(index, Some(_))`. Otherwise, the new key-value pair is inserted at
+ /// the sorted position, and `(index, None)` is returned.
+ ///
+ /// If the existing keys are **not** already sorted, then the insertion
+ /// index is unspecified (like [`slice::binary_search`]), but the key-value
+ /// pair is moved to or inserted at that position regardless.
+ ///
+ /// Computes in **O(n)** time (average). Instead of repeating calls to
+ /// `insert_sorted`, it may be faster to call batched [`insert`][Self::insert]
+ /// or [`extend`][Self::extend] and only call [`sort_keys`][Self::sort_keys]
+ /// or [`sort_unstable_keys`][Self::sort_unstable_keys] once.
+ pub fn insert_sorted(&mut self, key: K, value: V) -> (usize, Option<V>)
+ where
+ K: Ord,
+ {
+ match self.binary_search_keys(&key) {
+ Ok(i) => (i, Some(mem::replace(&mut self[i], value))),
+ Err(i) => self.insert_before(i, key, value),
+ }
+ }
+
+ /// Insert a key-value pair in the map before the entry at the given index, or at the end.
+ ///
+ /// If an equivalent key already exists in the map: the key remains and
+ /// is moved to the new position in the map, its corresponding value is updated
+ /// with `value`, and the older value is returned inside `Some(_)`. The returned index
+ /// will either be the given index or one less, depending on how the entry moved.
+ /// (See [`shift_insert`](Self::shift_insert) for different behavior here.)
+ ///
+ /// If no equivalent key existed in the map: the new key-value pair is
+ /// inserted exactly at the given index, and `None` is returned.
+ ///
+ /// ***Panics*** if `index` is out of bounds.
+ /// Valid indices are `0..=map.len()` (inclusive).
+ ///
+ /// Computes in **O(n)** time (average).
+ ///
+ /// See also [`entry`][Self::entry] if you want to insert *or* modify,
+ /// perhaps only using the index for new entries with [`VacantEntry::shift_insert`].
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use indexmap::IndexMap;
+ /// let mut map: IndexMap<char, ()> = ('a'..='z').map(|c| (c, ())).collect();
+ ///
+ /// // The new key '*' goes exactly at the given index.
+ /// assert_eq!(map.get_index_of(&'*'), None);
+ /// assert_eq!(map.insert_before(10, '*', ()), (10, None));
+ /// assert_eq!(map.get_index_of(&'*'), Some(10));
+ ///
+ /// // Moving the key 'a' up will shift others down, so this moves *before* 10 to index 9.
+ /// assert_eq!(map.insert_before(10, 'a', ()), (9, Some(())));
+ /// assert_eq!(map.get_index_of(&'a'), Some(9));
+ /// assert_eq!(map.get_index_of(&'*'), Some(10));
+ ///
+ /// // Moving the key 'z' down will shift others up, so this moves to exactly 10.
+ /// assert_eq!(map.insert_before(10, 'z', ()), (10, Some(())));
+ /// assert_eq!(map.get_index_of(&'z'), Some(10));
+ /// assert_eq!(map.get_index_of(&'*'), Some(11));
+ ///
+ /// // Moving or inserting before the endpoint is also valid.
+ /// assert_eq!(map.len(), 27);
+ /// assert_eq!(map.insert_before(map.len(), '*', ()), (26, Some(())));
+ /// assert_eq!(map.get_index_of(&'*'), Some(26));
+ /// assert_eq!(map.insert_before(map.len(), '+', ()), (27, None));
+ /// assert_eq!(map.get_index_of(&'+'), Some(27));
+ /// assert_eq!(map.len(), 28);
+ /// ```
+ #[track_caller]
+ pub fn insert_before(&mut self, mut index: usize, key: K, value: V) -> (usize, Option<V>) {
+ let len = self.len();
+
+ assert!(
+ index <= len,
+ "index out of bounds: the len is {len} but the index is {index}. Expected index <= len"
+ );
+
+ match self.entry(key) {
+ Entry::Occupied(mut entry) => {
+ if index > entry.index() {
+ // Some entries will shift down when this one moves up,
+ // so "insert before index" becomes "move to index - 1",
+ // keeping the entry at the original index unmoved.
+ index -= 1;
+ }
+ let old = mem::replace(entry.get_mut(), value);
+ entry.move_index(index);
+ (index, Some(old))
+ }
+ Entry::Vacant(entry) => {
+ entry.shift_insert(index, value);
+ (index, None)
+ }
+ }
+ }
+
+ /// Insert a key-value pair in the map at the given index.
+ ///
+ /// If an equivalent key already exists in the map: the key remains and
+ /// is moved to the given index in the map, its corresponding value is updated
+ /// with `value`, and the older value is returned inside `Some(_)`.
+ /// Note that existing entries **cannot** be moved to `index == map.len()`!
+ /// (See [`insert_before`](Self::insert_before) for different behavior here.)
+ ///
+ /// If no equivalent key existed in the map: the new key-value pair is
+ /// inserted at the given index, and `None` is returned.
+ ///
+ /// ***Panics*** if `index` is out of bounds.
+ /// Valid indices are `0..map.len()` (exclusive) when moving an existing entry, or
+ /// `0..=map.len()` (inclusive) when inserting a new key.
+ ///
+ /// Computes in **O(n)** time (average).
+ ///
+ /// See also [`entry`][Self::entry] if you want to insert *or* modify,
+ /// perhaps only using the index for new entries with [`VacantEntry::shift_insert`].
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use indexmap::IndexMap;
+ /// let mut map: IndexMap<char, ()> = ('a'..='z').map(|c| (c, ())).collect();
+ ///
+ /// // The new key '*' goes exactly at the given index.
+ /// assert_eq!(map.get_index_of(&'*'), None);
+ /// assert_eq!(map.shift_insert(10, '*', ()), None);
+ /// assert_eq!(map.get_index_of(&'*'), Some(10));
+ ///
+ /// // Moving the key 'a' up to 10 will shift others down, including the '*' that was at 10.
+ /// assert_eq!(map.shift_insert(10, 'a', ()), Some(()));
+ /// assert_eq!(map.get_index_of(&'a'), Some(10));
+ /// assert_eq!(map.get_index_of(&'*'), Some(9));
+ ///
+ /// // Moving the key 'z' down to 9 will shift others up, including the '*' that was at 9.
+ /// assert_eq!(map.shift_insert(9, 'z', ()), Some(()));
+ /// assert_eq!(map.get_index_of(&'z'), Some(9));
+ /// assert_eq!(map.get_index_of(&'*'), Some(10));
+ ///
+ /// // Existing keys can move to len-1 at most, but new keys can insert at the endpoint.
+ /// assert_eq!(map.len(), 27);
+ /// assert_eq!(map.shift_insert(map.len() - 1, '*', ()), Some(()));
+ /// assert_eq!(map.get_index_of(&'*'), Some(26));
+ /// assert_eq!(map.shift_insert(map.len(), '+', ()), None);
+ /// assert_eq!(map.get_index_of(&'+'), Some(27));
+ /// assert_eq!(map.len(), 28);
+ /// ```
+ ///
+ /// ```should_panic
+ /// use indexmap::IndexMap;
+ /// let mut map: IndexMap<char, ()> = ('a'..='z').map(|c| (c, ())).collect();
+ ///
+ /// // This is an invalid index for moving an existing key!
+ /// map.shift_insert(map.len(), 'a', ());
+ /// ```
+ #[track_caller]
+ pub fn shift_insert(&mut self, index: usize, key: K, value: V) -> Option<V> {
+ let len = self.len();
+ match self.entry(key) {
+ Entry::Occupied(mut entry) => {
+ assert!(
+ index < len,
+ "index out of bounds: the len is {len} but the index is {index}"
+ );
+
+ let old = mem::replace(entry.get_mut(), value);
+ entry.move_index(index);
+ Some(old)
+ }
+ Entry::Vacant(entry) => {
+ assert!(
+ index <= len,
+ "index out of bounds: the len is {len} but the index is {index}. Expected index <= len"
+ );
+
+ entry.shift_insert(index, value);
+ None
+ }
+ }
+ }
+
+ /// Get the given key’s corresponding entry in the map for insertion and/or
+ /// in-place manipulation.
+ ///
+ /// Computes in **O(1)** time (amortized average).
+ pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
+ let hash = self.hash(&key);
+ self.core.entry(hash, key)
+ }
+
+ /// Creates a splicing iterator that replaces the specified range in the map
+ /// with the given `replace_with` key-value iterator and yields the removed
+ /// items. `replace_with` does not need to be the same length as `range`.
+ ///
+ /// The `range` is removed even if the iterator is not consumed until the
+ /// end. It is unspecified how many elements are removed from the map if the
+ /// `Splice` value is leaked.
+ ///
+ /// The input iterator `replace_with` is only consumed when the `Splice`
+ /// value is dropped. If a key from the iterator matches an existing entry
+ /// in the map (outside of `range`), then the value will be updated in that
+ /// position. Otherwise, the new key-value pair will be inserted in the
+ /// replaced `range`.
+ ///
+ /// ***Panics*** if the starting point is greater than the end point or if
+ /// the end point is greater than the length of the map.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use indexmap::IndexMap;
+ ///
+ /// let mut map = IndexMap::from([(0, '_'), (1, 'a'), (2, 'b'), (3, 'c'), (4, 'd')]);
+ /// let new = [(5, 'E'), (4, 'D'), (3, 'C'), (2, 'B'), (1, 'A')];
+ /// let removed: Vec<_> = map.splice(2..4, new).collect();
+ ///
+ /// // 1 and 4 got new values, while 5, 3, and 2 were newly inserted.
+ /// assert!(map.into_iter().eq([(0, '_'), (1, 'A'), (5, 'E'), (3, 'C'), (2, 'B'), (4, 'D')]));
+ /// assert_eq!(removed, &[(2, 'b'), (3, 'c')]);
+ /// ```
+ #[track_caller]
+ pub fn splice<R, I>(&mut self, range: R, replace_with: I) -> Splice<'_, I::IntoIter, K, V, S>
+ where
+ R: RangeBounds<usize>,
+ I: IntoIterator<Item = (K, V)>,
+ {
+ Splice::new(self, range, replace_with.into_iter())
+ }
+
+ /// Moves all key-value pairs from `other` into `self`, leaving `other` empty.
+ ///
+ /// This is equivalent to calling [`insert`][Self::insert] for each
+ /// key-value pair from `other` in order, which means that for keys that
+ /// already exist in `self`, their value is updated in the current position.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use indexmap::IndexMap;
+ ///
+ /// // Note: Key (3) is present in both maps.
+ /// let mut a = IndexMap::from([(3, "c"), (2, "b"), (1, "a")]);
+ /// let mut b = IndexMap::from([(3, "d"), (4, "e"), (5, "f")]);
+ /// let old_capacity = b.capacity();
+ ///
+ /// a.append(&mut b);
+ ///
+ /// assert_eq!(a.len(), 5);
+ /// assert_eq!(b.len(), 0);
+ /// assert_eq!(b.capacity(), old_capacity);
+ ///
+ /// assert!(a.keys().eq(&[3, 2, 1, 4, 5]));
+ /// assert_eq!(a[&3], "d"); // "c" was overwritten.
+ /// ```
+ pub fn append<S2>(&mut self, other: &mut IndexMap<K, V, S2>) {
+ self.extend(other.drain(..));
+ }
+}
+
+impl<K, V, S> IndexMap<K, V, S>
+where
+ S: BuildHasher,
+{
+ pub(crate) fn hash<Q: ?Sized + Hash>(&self, key: &Q) -> HashValue {
+ let mut h = self.hash_builder.build_hasher();
+ key.hash(&mut h);
+ HashValue(h.finish() as usize)
+ }
+
+ /// Return `true` if an equivalent to `key` exists in the map.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn contains_key<Q>(&self, key: &Q) -> bool
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ self.get_index_of(key).is_some()
+ }
+
+ /// Return a reference to the value stored for `key`, if it is present,
+ /// else `None`.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn get<Q>(&self, key: &Q) -> Option<&V>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ if let Some(i) = self.get_index_of(key) {
+ let entry = &self.as_entries()[i];
+ Some(&entry.value)
+ } else {
+ None
+ }
+ }
+
+ /// Return references to the key-value pair stored for `key`,
+ /// if it is present, else `None`.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn get_key_value<Q>(&self, key: &Q) -> Option<(&K, &V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ if let Some(i) = self.get_index_of(key) {
+ let entry = &self.as_entries()[i];
+ Some((&entry.key, &entry.value))
+ } else {
+ None
+ }
+ }
+
+ /// Return item index, key and value
+ pub fn get_full<Q>(&self, key: &Q) -> Option<(usize, &K, &V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ if let Some(i) = self.get_index_of(key) {
+ let entry = &self.as_entries()[i];
+ Some((i, &entry.key, &entry.value))
+ } else {
+ None
+ }
+ }
+
+ /// Return item index, if it exists in the map
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn get_index_of<Q>(&self, key: &Q) -> Option<usize>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ match self.as_entries() {
+ [] => None,
+ [x] => key.equivalent(&x.key).then_some(0),
+ _ => {
+ let hash = self.hash(key);
+ self.core.get_index_of(hash, key)
+ }
+ }
+ }
+
+ pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut V>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ if let Some(i) = self.get_index_of(key) {
+ let entry = &mut self.as_entries_mut()[i];
+ Some(&mut entry.value)
+ } else {
+ None
+ }
+ }
+
+ pub fn get_full_mut<Q>(&mut self, key: &Q) -> Option<(usize, &K, &mut V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ if let Some(i) = self.get_index_of(key) {
+ let entry = &mut self.as_entries_mut()[i];
+ Some((i, &entry.key, &mut entry.value))
+ } else {
+ None
+ }
+ }
+
+ /// Return the values for `N` keys. If any key is duplicated, this function will panic.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut map = indexmap::IndexMap::from([(1, 'a'), (3, 'b'), (2, 'c')]);
+ /// assert_eq!(map.get_disjoint_mut([&2, &1]), [Some(&mut 'c'), Some(&mut 'a')]);
+ /// ```
+ pub fn get_disjoint_mut<Q, const N: usize>(&mut self, keys: [&Q; N]) -> [Option<&mut V>; N]
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ let indices = keys.map(|key| self.get_index_of(key));
+ match self.as_mut_slice().get_disjoint_opt_mut(indices) {
+ Err(GetDisjointMutError::IndexOutOfBounds) => {
+ unreachable!(
+ "Internal error: indices should never be OOB as we got them from get_index_of"
+ );
+ }
+ Err(GetDisjointMutError::OverlappingIndices) => {
+ panic!("duplicate keys found");
+ }
+ Ok(key_values) => key_values.map(|kv_opt| kv_opt.map(|kv| kv.1)),
+ }
+ }
+
+ /// Remove the key-value pair equivalent to `key` and return
+ /// its value.
+ ///
+ /// **NOTE:** This is equivalent to [`.swap_remove(key)`][Self::swap_remove], replacing this
+ /// entry's position with the last element, and it is deprecated in favor of calling that
+ /// explicitly. If you need to preserve the relative order of the keys in the map, use
+ /// [`.shift_remove(key)`][Self::shift_remove] instead.
+ #[deprecated(note = "`remove` disrupts the map order -- \
+ use `swap_remove` or `shift_remove` for explicit behavior.")]
+ pub fn remove<Q>(&mut self, key: &Q) -> Option<V>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ self.swap_remove(key)
+ }
+
+ /// Remove and return the key-value pair equivalent to `key`.
+ ///
+ /// **NOTE:** This is equivalent to [`.swap_remove_entry(key)`][Self::swap_remove_entry],
+ /// replacing this entry's position with the last element, and it is deprecated in favor of
+ /// calling that explicitly. If you need to preserve the relative order of the keys in the map,
+ /// use [`.shift_remove_entry(key)`][Self::shift_remove_entry] instead.
+ #[deprecated(note = "`remove_entry` disrupts the map order -- \
+ use `swap_remove_entry` or `shift_remove_entry` for explicit behavior.")]
+ pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ self.swap_remove_entry(key)
+ }
+
+ /// Remove the key-value pair equivalent to `key` and return
+ /// its value.
+ ///
+ /// Like [`Vec::swap_remove`], the pair is removed by swapping it with the
+ /// last element of the map and popping it off. **This perturbs
+ /// the position of what used to be the last element!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn swap_remove<Q>(&mut self, key: &Q) -> Option<V>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ self.swap_remove_full(key).map(third)
+ }
+
+ /// Remove and return the key-value pair equivalent to `key`.
+ ///
+ /// Like [`Vec::swap_remove`], the pair is removed by swapping it with the
+ /// last element of the map and popping it off. **This perturbs
+ /// the position of what used to be the last element!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn swap_remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ match self.swap_remove_full(key) {
+ Some((_, key, value)) => Some((key, value)),
+ None => None,
+ }
+ }
+
+ /// Remove the key-value pair equivalent to `key` and return it and
+ /// the index it had.
+ ///
+ /// Like [`Vec::swap_remove`], the pair is removed by swapping it with the
+ /// last element of the map and popping it off. **This perturbs
+ /// the position of what used to be the last element!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn swap_remove_full<Q>(&mut self, key: &Q) -> Option<(usize, K, V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ match self.as_entries() {
+ [x] if key.equivalent(&x.key) => {
+ let (k, v) = self.core.pop()?;
+ Some((0, k, v))
+ }
+ [_] | [] => None,
+ _ => {
+ let hash = self.hash(key);
+ self.core.swap_remove_full(hash, key)
+ }
+ }
+ }
+
+ /// Remove the key-value pair equivalent to `key` and return
+ /// its value.
+ ///
+ /// Like [`Vec::remove`], the pair is removed by shifting all of the
+ /// elements that follow it, preserving their relative order.
+ /// **This perturbs the index of all of those elements!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(n)** time (average).
+ pub fn shift_remove<Q>(&mut self, key: &Q) -> Option<V>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ self.shift_remove_full(key).map(third)
+ }
+
+ /// Remove and return the key-value pair equivalent to `key`.
+ ///
+ /// Like [`Vec::remove`], the pair is removed by shifting all of the
+ /// elements that follow it, preserving their relative order.
+ /// **This perturbs the index of all of those elements!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(n)** time (average).
+ pub fn shift_remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ match self.shift_remove_full(key) {
+ Some((_, key, value)) => Some((key, value)),
+ None => None,
+ }
+ }
+
+ /// Remove the key-value pair equivalent to `key` and return it and
+ /// the index it had.
+ ///
+ /// Like [`Vec::remove`], the pair is removed by shifting all of the
+ /// elements that follow it, preserving their relative order.
+ /// **This perturbs the index of all of those elements!**
+ ///
+ /// Return `None` if `key` is not in map.
+ ///
+ /// Computes in **O(n)** time (average).
+ pub fn shift_remove_full<Q>(&mut self, key: &Q) -> Option<(usize, K, V)>
+ where
+ Q: ?Sized + Hash + Equivalent<K>,
+ {
+ match self.as_entries() {
+ [x] if key.equivalent(&x.key) => {
+ let (k, v) = self.core.pop()?;
+ Some((0, k, v))
+ }
+ [_] | [] => None,
+ _ => {
+ let hash = self.hash(key);
+ self.core.shift_remove_full(hash, key)
+ }
+ }
+ }
+}
+
+impl<K, V, S> IndexMap<K, V, S> {
+ /// Remove the last key-value pair
+ ///
+ /// This preserves the order of the remaining elements.
+ ///
+ /// Computes in **O(1)** time (average).
+ #[doc(alias = "pop_last")] // like `BTreeMap`
+ pub fn pop(&mut self) -> Option<(K, V)> {
+ self.core.pop()
+ }
+
+ /// Scan through each key-value pair in the map and keep those where the
+ /// closure `keep` returns `true`.
+ ///
+ /// The elements are visited in order, and remaining elements keep their
+ /// order.
+ ///
+ /// Computes in **O(n)** time (average).
+ pub fn retain<F>(&mut self, mut keep: F)
+ where
+ F: FnMut(&K, &mut V) -> bool,
+ {
+ self.core.retain_in_order(move |k, v| keep(k, v));
+ }
+
+ /// Sort the map’s key-value pairs by the default ordering of the keys.
+ ///
+ /// This is a stable sort -- but equivalent keys should not normally coexist in
+ /// a map at all, so [`sort_unstable_keys`][Self::sort_unstable_keys] is preferred
+ /// because it is generally faster and doesn't allocate auxiliary memory.
+ ///
+ /// See [`sort_by`](Self::sort_by) for details.
+ pub fn sort_keys(&mut self)
+ where
+ K: Ord,
+ {
+ self.with_entries(move |entries| {
+ entries.sort_by(move |a, b| K::cmp(&a.key, &b.key));
+ });
+ }
+
+ /// Sort the map’s key-value pairs in place using the comparison
+ /// function `cmp`.
+ ///
+ /// The comparison function receives two key and value pairs to compare (you
+ /// can sort by keys or values or their combination as needed).
+ ///
+ /// Computes in **O(n log n + c)** time and **O(n)** space where *n* is
+ /// the length of the map and *c* the capacity. The sort is stable.
+ pub fn sort_by<F>(&mut self, mut cmp: F)
+ where
+ F: FnMut(&K, &V, &K, &V) -> Ordering,
+ {
+ self.with_entries(move |entries| {
+ entries.sort_by(move |a, b| cmp(&a.key, &a.value, &b.key, &b.value));
+ });
+ }
+
+ /// Sort the key-value pairs of the map and return a by-value iterator of
+ /// the key-value pairs with the result.
+ ///
+ /// The sort is stable.
+ pub fn sorted_by<F>(self, mut cmp: F) -> IntoIter<K, V>
+ where
+ F: FnMut(&K, &V, &K, &V) -> Ordering,
+ {
+ let mut entries = self.into_entries();
+ entries.sort_by(move |a, b| cmp(&a.key, &a.value, &b.key, &b.value));
+ IntoIter::new(entries)
+ }
+
+ /// Sort the map's key-value pairs by the default ordering of the keys, but
+ /// may not preserve the order of equal elements.
+ ///
+ /// See [`sort_unstable_by`](Self::sort_unstable_by) for details.
+ pub fn sort_unstable_keys(&mut self)
+ where
+ K: Ord,
+ {
+ self.with_entries(move |entries| {
+ entries.sort_unstable_by(move |a, b| K::cmp(&a.key, &b.key));
+ });
+ }
+
+ /// Sort the map's key-value pairs in place using the comparison function `cmp`, but
+ /// may not preserve the order of equal elements.
+ ///
+ /// The comparison function receives two key and value pairs to compare (you
+ /// can sort by keys or values or their combination as needed).
+ ///
+ /// Computes in **O(n log n + c)** time where *n* is
+ /// the length of the map and *c* is the capacity. The sort is unstable.
+ pub fn sort_unstable_by<F>(&mut self, mut cmp: F)
+ where
+ F: FnMut(&K, &V, &K, &V) -> Ordering,
+ {
+ self.with_entries(move |entries| {
+ entries.sort_unstable_by(move |a, b| cmp(&a.key, &a.value, &b.key, &b.value));
+ });
+ }
+
+ /// Sort the key-value pairs of the map and return a by-value iterator of
+ /// the key-value pairs with the result.
+ ///
+ /// The sort is unstable.
+ #[inline]
+ pub fn sorted_unstable_by<F>(self, mut cmp: F) -> IntoIter<K, V>
+ where
+ F: FnMut(&K, &V, &K, &V) -> Ordering,
+ {
+ let mut entries = self.into_entries();
+ entries.sort_unstable_by(move |a, b| cmp(&a.key, &a.value, &b.key, &b.value));
+ IntoIter::new(entries)
+ }
+
+ /// Sort the map’s key-value pairs in place using a sort-key extraction function.
+ ///
+ /// During sorting, the function is called at most once per entry, by using temporary storage
+ /// to remember the results of its evaluation. The order of calls to the function is
+ /// unspecified and may change between versions of `indexmap` or the standard library.
+ ///
+ /// Computes in **O(m n + n log n + c)** time () and **O(n)** space, where the function is
+ /// **O(m)**, *n* is the length of the map, and *c* the capacity. The sort is stable.
+ pub fn sort_by_cached_key<T, F>(&mut self, mut sort_key: F)
+ where
+ T: Ord,
+ F: FnMut(&K, &V) -> T,
+ {
+ self.with_entries(move |entries| {
+ entries.sort_by_cached_key(move |a| sort_key(&a.key, &a.value));
+ });
+ }
+
+ /// 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
+ /// using [`get_index_of`][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.as_slice().binary_search_keys(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, f: F) -> Result<usize, usize>
+ where
+ F: FnMut(&'a K, &'a V) -> Ordering,
+ {
+ self.as_slice().binary_search_by(f)
+ }
+
+ /// 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, f: F) -> Result<usize, usize>
+ where
+ F: FnMut(&'a K, &'a V) -> B,
+ B: Ord,
+ {
+ self.as_slice().binary_search_by_key(b, f)
+ }
+
+ /// 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, pred: P) -> usize
+ where
+ P: FnMut(&K, &V) -> bool,
+ {
+ self.as_slice().partition_point(pred)
+ }
+
+ /// Reverses the order of the map’s key-value pairs in place.
+ ///
+ /// Computes in **O(n)** time and **O(1)** space.
+ pub fn reverse(&mut self) {
+ self.core.reverse()
+ }
+
+ /// Returns a slice of all the key-value pairs in the map.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn as_slice(&self) -> &Slice<K, V> {
+ Slice::from_slice(self.as_entries())
+ }
+
+ /// Returns a mutable slice of all the key-value pairs in the map.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn as_mut_slice(&mut self) -> &mut Slice<K, V> {
+ Slice::from_mut_slice(self.as_entries_mut())
+ }
+
+ /// Converts into a boxed slice of all the key-value pairs in the map.
+ ///
+ /// Note that this will drop the inner hash table and any excess capacity.
+ pub fn into_boxed_slice(self) -> Box<Slice<K, V>> {
+ Slice::from_boxed(self.into_entries().into_boxed_slice())
+ }
+
+ /// Get a key-value pair by index
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn get_index(&self, index: usize) -> Option<(&K, &V)> {
+ self.as_entries().get(index).map(Bucket::refs)
+ }
+
+ /// Get a key-value pair by index
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn get_index_mut(&mut self, index: usize) -> Option<(&K, &mut V)> {
+ self.as_entries_mut().get_mut(index).map(Bucket::ref_mut)
+ }
+
+ /// Get an entry in the map by index for in-place manipulation.
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn get_index_entry(&mut self, index: usize) -> Option<IndexedEntry<'_, K, V>> {
+ if index >= self.len() {
+ return None;
+ }
+ Some(IndexedEntry::new(&mut self.core, index))
+ }
+
+ /// Get an array of `N` key-value pairs by `N` indices
+ ///
+ /// Valid indices are *0 <= index < self.len()* and each index needs to be unique.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut map = indexmap::IndexMap::from([(1, 'a'), (3, 'b'), (2, 'c')]);
+ /// assert_eq!(map.get_disjoint_indices_mut([2, 0]), Ok([(&2, &mut 'c'), (&1, &mut 'a')]));
+ /// ```
+ pub fn get_disjoint_indices_mut<const N: usize>(
+ &mut self,
+ indices: [usize; N],
+ ) -> Result<[(&K, &mut V); N], GetDisjointMutError> {
+ self.as_mut_slice().get_disjoint_mut(indices)
+ }
+
+ /// Returns a slice of key-value pairs in the given range of indices.
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn get_range<R: RangeBounds<usize>>(&self, range: R) -> Option<&Slice<K, V>> {
+ let entries = self.as_entries();
+ let range = try_simplify_range(range, entries.len())?;
+ 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()`.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn get_range_mut<R: RangeBounds<usize>>(&mut self, range: R) -> Option<&mut Slice<K, V>> {
+ let entries = self.as_entries_mut();
+ let range = try_simplify_range(range, entries.len())?;
+ entries.get_mut(range).map(Slice::from_mut_slice)
+ }
+
+ /// Get the first key-value pair
+ ///
+ /// Computes in **O(1)** time.
+ #[doc(alias = "first_key_value")] // like `BTreeMap`
+ pub fn first(&self) -> Option<(&K, &V)> {
+ self.as_entries().first().map(Bucket::refs)
+ }
+
+ /// Get the first key-value pair, with mutable access to the value
+ ///
+ /// Computes in **O(1)** time.
+ pub fn first_mut(&mut self) -> Option<(&K, &mut V)> {
+ self.as_entries_mut().first_mut().map(Bucket::ref_mut)
+ }
+
+ /// Get the first entry in the map for in-place manipulation.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn first_entry(&mut self) -> Option<IndexedEntry<'_, K, V>> {
+ self.get_index_entry(0)
+ }
+
+ /// Get the last key-value pair
+ ///
+ /// Computes in **O(1)** time.
+ #[doc(alias = "last_key_value")] // like `BTreeMap`
+ pub fn last(&self) -> Option<(&K, &V)> {
+ self.as_entries().last().map(Bucket::refs)
+ }
+
+ /// Get the last key-value pair, with mutable access to the value
+ ///
+ /// Computes in **O(1)** time.
+ pub fn last_mut(&mut self) -> Option<(&K, &mut V)> {
+ self.as_entries_mut().last_mut().map(Bucket::ref_mut)
+ }
+
+ /// Get the last entry in the map for in-place manipulation.
+ ///
+ /// Computes in **O(1)** time.
+ pub fn last_entry(&mut self) -> Option<IndexedEntry<'_, K, V>> {
+ self.get_index_entry(self.len().checked_sub(1)?)
+ }
+
+ /// Remove the key-value pair by index
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Like [`Vec::swap_remove`], the pair is removed by swapping it with the
+ /// last element of the map and popping it off. **This perturbs
+ /// the position of what used to be the last element!**
+ ///
+ /// Computes in **O(1)** time (average).
+ pub fn swap_remove_index(&mut self, index: usize) -> Option<(K, V)> {
+ self.core.swap_remove_index(index)
+ }
+
+ /// Remove the key-value pair by index
+ ///
+ /// Valid indices are `0 <= index < self.len()`.
+ ///
+ /// Like [`Vec::remove`], the pair is removed by shifting all of the
+ /// elements that follow it, preserving their relative order.
+ /// **This perturbs the index of all of those elements!**
+ ///
+ /// Computes in **O(n)** time (average).
+ pub fn shift_remove_index(&mut self, index: usize) -> Option<(K, V)> {
+ self.core.shift_remove_index(index)
+ }
+
+ /// Moves the position of a key-value pair from one index to another
+ /// by shifting all other pairs in-between.
+ ///
+ /// * If `from < to`, the other pairs will shift down while the targeted pair moves up.
+ /// * If `from > to`, the other pairs will shift up while the targeted pair moves down.
+ ///
+ /// ***Panics*** if `from` or `to` are out of bounds.
+ ///
+ /// Computes in **O(n)** time (average).
+ #[track_caller]
+ pub fn move_index(&mut self, from: usize, to: usize) {
+ self.core.move_index(from, to)
+ }
+
+ /// Swaps the position of two key-value pairs in the map.
+ ///
+ /// ***Panics*** if `a` or `b` are out of bounds.
+ ///
+ /// Computes in **O(1)** time (average).
+ #[track_caller]
+ pub fn swap_indices(&mut self, a: usize, b: usize) {
+ self.core.swap_indices(a, b)
+ }
+}
+
+/// Access [`IndexMap`] values corresponding to a key.
+///
+/// # Examples
+///
+/// ```
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// for word in "Lorem ipsum dolor sit amet".split_whitespace() {
+/// map.insert(word.to_lowercase(), word.to_uppercase());
+/// }
+/// assert_eq!(map["lorem"], "LOREM");
+/// assert_eq!(map["ipsum"], "IPSUM");
+/// ```
+///
+/// ```should_panic
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// map.insert("foo", 1);
+/// println!("{:?}", map["bar"]); // panics!
+/// ```
+impl<K, V, Q: ?Sized, S> Index<&Q> for IndexMap<K, V, S>
+where
+ Q: Hash + Equivalent<K>,
+ S: BuildHasher,
+{
+ type Output = V;
+
+ /// Returns a reference to the value corresponding to the supplied `key`.
+ ///
+ /// ***Panics*** if `key` is not present in the map.
+ fn index(&self, key: &Q) -> &V {
+ self.get(key).expect("no entry found for key")
+ }
+}
+
+/// Access [`IndexMap`] values corresponding to a key.
+///
+/// Mutable indexing allows changing / updating values of key-value
+/// pairs that are already present.
+///
+/// You can **not** insert new pairs with index syntax, use `.insert()`.
+///
+/// # Examples
+///
+/// ```
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// for word in "Lorem ipsum dolor sit amet".split_whitespace() {
+/// map.insert(word.to_lowercase(), word.to_string());
+/// }
+/// let lorem = &mut map["lorem"];
+/// assert_eq!(lorem, "Lorem");
+/// lorem.retain(char::is_lowercase);
+/// assert_eq!(map["lorem"], "orem");
+/// ```
+///
+/// ```should_panic
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// map.insert("foo", 1);
+/// map["bar"] = 1; // panics!
+/// ```
+impl<K, V, Q: ?Sized, S> IndexMut<&Q> for IndexMap<K, V, S>
+where
+ Q: Hash + Equivalent<K>,
+ S: BuildHasher,
+{
+ /// Returns a mutable reference to the value corresponding to the supplied `key`.
+ ///
+ /// ***Panics*** if `key` is not present in the map.
+ fn index_mut(&mut self, key: &Q) -> &mut V {
+ self.get_mut(key).expect("no entry found for key")
+ }
+}
+
+/// Access [`IndexMap`] values at indexed positions.
+///
+/// See [`Index<usize> for Keys`][keys] to access a map's keys instead.
+///
+/// [keys]: Keys#impl-Index<usize>-for-Keys<'a,+K,+V>
+///
+/// # Examples
+///
+/// ```
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// for word in "Lorem ipsum dolor sit amet".split_whitespace() {
+/// map.insert(word.to_lowercase(), word.to_uppercase());
+/// }
+/// assert_eq!(map[0], "LOREM");
+/// assert_eq!(map[1], "IPSUM");
+/// map.reverse();
+/// assert_eq!(map[0], "AMET");
+/// assert_eq!(map[1], "SIT");
+/// map.sort_keys();
+/// assert_eq!(map[0], "AMET");
+/// assert_eq!(map[1], "DOLOR");
+/// ```
+///
+/// ```should_panic
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// map.insert("foo", 1);
+/// println!("{:?}", map[10]); // panics!
+/// ```
+impl<K, V, S> Index<usize> for IndexMap<K, V, S> {
+ type Output = V;
+
+ /// Returns a reference to the value at the supplied `index`.
+ ///
+ /// ***Panics*** if `index` is out of bounds.
+ fn index(&self, index: usize) -> &V {
+ self.get_index(index)
+ .unwrap_or_else(|| {
+ panic!(
+ "index out of bounds: the len is {len} but the index is {index}",
+ len = self.len()
+ );
+ })
+ .1
+ }
+}
+
+/// Access [`IndexMap`] values at indexed positions.
+///
+/// Mutable indexing allows changing / updating indexed values
+/// that are already present.
+///
+/// You can **not** insert new values with index syntax -- use [`.insert()`][IndexMap::insert].
+///
+/// # Examples
+///
+/// ```
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// for word in "Lorem ipsum dolor sit amet".split_whitespace() {
+/// map.insert(word.to_lowercase(), word.to_string());
+/// }
+/// let lorem = &mut map[0];
+/// assert_eq!(lorem, "Lorem");
+/// lorem.retain(char::is_lowercase);
+/// assert_eq!(map["lorem"], "orem");
+/// ```
+///
+/// ```should_panic
+/// use indexmap::IndexMap;
+///
+/// let mut map = IndexMap::new();
+/// map.insert("foo", 1);
+/// map[10] = 1; // panics!
+/// ```
+impl<K, V, S> IndexMut<usize> for IndexMap<K, V, S> {
+ /// Returns a mutable reference to the value at the supplied `index`.
+ ///
+ /// ***Panics*** if `index` is out of bounds.
+ fn index_mut(&mut self, index: usize) -> &mut V {
+ let len: usize = self.len();
+
+ self.get_index_mut(index)
+ .unwrap_or_else(|| {
+ panic!("index out of bounds: the len is {len} but the index is {index}");
+ })
+ .1
+ }
+}
+
+impl<K, V, S> FromIterator<(K, V)> for IndexMap<K, V, S>
+where
+ K: Hash + Eq,
+ S: BuildHasher + Default,
+{
+ /// Create an `IndexMap` from the sequence of key-value pairs in the
+ /// iterable.
+ ///
+ /// `from_iter` uses the same logic as `extend`. See
+ /// [`extend`][IndexMap::extend] for more details.
+ fn from_iter<I: IntoIterator<Item = (K, V)>>(iterable: I) -> Self {
+ let iter = iterable.into_iter();
+ let (low, _) = iter.size_hint();
+ let mut map = Self::with_capacity_and_hasher(low, <_>::default());
+ map.extend(iter);
+ map
+ }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
+impl<K, V, const N: usize> From<[(K, V); N]> for IndexMap<K, V, RandomState>
+where
+ K: Hash + Eq,
+{
+ /// # Examples
+ ///
+ /// ```
+ /// use indexmap::IndexMap;
+ ///
+ /// let map1 = IndexMap::from([(1, 2), (3, 4)]);
+ /// let map2: IndexMap<_, _> = [(1, 2), (3, 4)].into();
+ /// assert_eq!(map1, map2);
+ /// ```
+ fn from(arr: [(K, V); N]) -> Self {
+ Self::from_iter(arr)
+ }
+}
+
+impl<K, V, S> Extend<(K, V)> for IndexMap<K, V, S>
+where
+ K: Hash + Eq,
+ S: BuildHasher,
+{
+ /// Extend the map with all key-value pairs in the iterable.
+ ///
+ /// This is equivalent to calling [`insert`][IndexMap::insert] for each of
+ /// them in order, which means that for keys that already existed
+ /// in the map, their value is updated but it keeps the existing order.
+ ///
+ /// New keys are inserted in the order they appear in the sequence. If
+ /// equivalents of a key occur more than once, the last corresponding value
+ /// prevails.
+ fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iterable: I) {
+ // (Note: this is a copy of `std`/`hashbrown`'s reservation logic.)
+ // Keys may be already present or show multiple times in the iterator.
+ // Reserve the entire hint lower bound if the map is empty.
+ // Otherwise reserve half the hint (rounded up), so the map
+ // will only resize twice in the worst case.
+ let iter = iterable.into_iter();
+ let reserve = if self.is_empty() {
+ iter.size_hint().0
+ } else {
+ (iter.size_hint().0 + 1) / 2
+ };
+ self.reserve(reserve);
+ iter.for_each(move |(k, v)| {
+ self.insert(k, v);
+ });
+ }
+}
+
+impl<'a, K, V, S> Extend<(&'a K, &'a V)> for IndexMap<K, V, S>
+where
+ K: Hash + Eq + Copy,
+ V: Copy,
+ S: BuildHasher,
+{
+ /// Extend the map with all key-value pairs in the iterable.
+ ///
+ /// See the first extend method for more details.
+ fn extend<I: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iterable: I) {
+ self.extend(iterable.into_iter().map(|(&key, &value)| (key, value)));
+ }
+}
+
+impl<K, V, S> Default for IndexMap<K, V, S>
+where
+ S: Default,
+{
+ /// Return an empty [`IndexMap`]
+ fn default() -> Self {
+ Self::with_capacity_and_hasher(0, S::default())
+ }
+}
+
+impl<K, V1, S1, V2, S2> PartialEq<IndexMap<K, V2, S2>> for IndexMap<K, V1, S1>
+where
+ K: Hash + Eq,
+ V1: PartialEq<V2>,
+ S1: BuildHasher,
+ S2: BuildHasher,
+{
+ fn eq(&self, other: &IndexMap<K, V2, S2>) -> bool {
+ if self.len() != other.len() {
+ return false;
+ }
+
+ self.iter()
+ .all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
+ }
+}
+
+impl<K, V, S> Eq for IndexMap<K, V, S>
+where
+ K: Eq + Hash,
+ V: Eq,
+ S: BuildHasher,
+{
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-02-02 23:55:37 +0000