Revision control
Copy as Markdown
Other Tools
//! [`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, Keys, Splice, Values, ValuesMut,
};
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, 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.
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`.
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 [`shift_insert`][Self::shift_insert] 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) => (i, self.shift_insert(i, key, value)),
}
}
/// 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 new position in the map, 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 at the given index, and `None` is returned.
///
/// ***Panics*** if `index` is out of bounds.
///
/// 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`].
pub fn shift_insert(&mut self, index: usize, key: K, value: V) -> Option<V> {
match self.entry(key) {
Entry::Occupied(mut entry) => {
let old = mem::replace(entry.get_mut(), value);
entry.move_index(index);
Some(old)
}
Entry::Vacant(entry) => {
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')]);
/// ```
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())
}
}
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
}
}
/// 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).
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))
}
/// 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.
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 last key-value pair
///
/// Computes in **O(1)** time.
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)
}
/// 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).
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).
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("IndexMap: key not found")
}
}
/// 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("IndexMap: key not found")
}
}
/// 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)
.expect("IndexMap: index out of bounds")
.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 {
self.get_index_mut(index)
.expect("IndexMap: index out of bounds")
.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,
{
}