//! Halfbrown is a hashmap implementation that provides
//! high performance for both small and large maps by
//! dymaically switching between different backend.
//!
//! The basic idea is that hash maps are expensive to
//! insert and lookup for small numbers of entries
//! but effective for larger numbers.
//!
//! So for smaller maps, we picked 32 entries as a rule
//! of thumb, we simply store data in a list of tuples.
//! Looking those up and iterating over them is still
//! faster then hasing strings on every lookup.
//!
//! Once we pass the 32 entires we transition the
//! backend to a `HashMap`.
//!
//! Note: Most of the documentation is taken from
//! rusts hashmap.rs and should be considered under
//! their copyright.
#![warn(unused_extern_crates)]
#![cfg_attr(
feature = "cargo-clippy",
deny(
clippy::all,
clippy::unwrap_used,
clippy::unnecessary_unwrap,
clippy::pedantic
),
// We might want to revisit inline_always
allow(clippy::module_name_repetitions, clippy::inline_always)
)]
#![deny(missing_docs)]
mod entry;
mod iter;
mod macros;
mod raw_entry;
#[cfg(feature = "serde")]
mod serde;
mod vecmap;
pub use crate::entry::*;
pub use crate::iter::*;
pub use crate::raw_entry::*;
use crate::vecmap::VecMap;
use core::borrow::Borrow;
use core::hash::{BuildHasher, Hash};
use hashbrown::{self, HashMap as HashBrown};
use std::default::Default;
use std::fmt::{self, Debug};
use std::ops::Index;
#[cfg(feature = "fxhash")]
pub use fxhash::FxBuildHasher as DefaultHashBuilder;
#[cfg(not(feature = "fxhash"))]
pub use hashbrown::hash_map::DefaultHashBuilder;
/// Maximum nymber of elements before the representaiton is swapped from
/// Vec to `HashMap`
pub const VEC_LIMIT_UPPER: usize = 32;
/// `HashMap` implementation that alternates between a vector
/// and a hashmap to improve performance for low key counts.
#[derive(Clone)]
pub struct HashMap<K, V, S = DefaultHashBuilder>(HashMapInt<K, V, S>);
impl<K, V, S: Default> Default for HashMap<K, V, S> {
#[inline]
fn default() -> Self {
Self(HashMapInt::default())
}
}
impl<K, V, S> Debug for HashMap<K, V, S>
where
K: Debug,
V: Debug,
{
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_map().entries(self.iter()).finish()
}
}
#[derive(Clone)]
enum HashMapInt<K, V, S = DefaultHashBuilder> {
Map(HashBrown<K, V, S>),
Vec(VecMap<K, V, S>),
None,
}
impl<K, V, S: Default> Default for HashMapInt<K, V, S> {
#[inline]
fn default() -> Self {
Self::Vec(VecMap::default())
}
}
impl<K, V> HashMap<K, V, DefaultHashBuilder> {
/// Creates an empty `HashMap`.
///
/// The hash map is initially created with a capacity of 0, so it will not allocate until it
/// is first inserted into.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::new();
/// ```
#[inline]
#[must_use]
pub fn new() -> Self {
Self(HashMapInt::Vec(VecMap::new()))
}
/// Creates an empty `HashMap` with the specified capacity.
///
/// The hash map will be able to hold at least `capacity` elements without
/// reallocating. If `capacity` is 0, the hash map will not allocate.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
/// ```
#[inline]
#[must_use]
pub fn with_capacity(capacity: usize) -> Self {
Self(if capacity > VEC_LIMIT_UPPER {
HashMapInt::Map(HashBrown::with_capacity_and_hasher(
capacity,
DefaultHashBuilder::default(),
))
} else {
HashMapInt::Vec(VecMap::with_capacity(capacity))
})
}
/// Same as with capacity with the difference that it, despite of the
/// requested size always returns a vector. This allows quicker generation
/// when used in combination with `insert_nocheck`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::vec_with_capacity(128);
/// assert!(map.is_vec());
/// ```
#[inline]
#[must_use]
pub fn vec_with_capacity(capacity: usize) -> Self {
Self(HashMapInt::Vec(VecMap::with_capacity(capacity)))
}
}
impl<K, V, S> HashMap<K, V, S> {
/// Creates an empty `HashMap` which will use the given hash builder to hash
/// keys.
///
/// The created map has the default initial capacity.
///
/// Warning: `hash_builder` is normally randomly generated, and
/// is designed to allow `HashMaps` to be resistant to attacks that
/// cause many collisions and very poor performance. Setting it
/// manually using this function can expose a `DoS` attack vector.
///
/// # Examples
///
/// ```
/// use hashbrown::HashMap;
/// use hashbrown::hash_map::DefaultHashBuilder;
///
/// let s = DefaultHashBuilder::default();
/// let mut map = HashMap::with_hasher(s);
/// map.insert(1, 2);
/// ```
#[inline]
pub fn with_hasher(hash_builder: S) -> Self {
Self(HashMapInt::Map(HashBrown::with_hasher(hash_builder)))
}
/// Creates an empty `HashMap` with the specified capacity, using `hash_builder`
/// to hash the keys.
///
/// The hash map will be able to hold at least `capacity` elements without
/// reallocating. If `capacity` is 0, the hash map will not allocate.
///
/// Warning: `hash_builder` is normally randomly generated, and
/// is designed to allow `HashMaps` to be resistant to attacks that
/// cause many collisions and very poor performance. Setting it
/// manually using this function can expose a `DoS` attack vector.
///
/// # Examples
///
/// ```
/// use hashbrown::HashMap;
/// use hashbrown::hash_map::DefaultHashBuilder;
///
/// let s = DefaultHashBuilder::default();
/// let mut map = HashMap::with_capacity_and_hasher(10, s);
/// map.insert(1, 2);
/// ```
#[inline]
pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self {
Self(HashMapInt::Map(HashBrown::with_capacity_and_hasher(
capacity,
hash_builder,
)))
}
/// Returns a reference to the map's [`BuildHasher`].
///
/// [`BuildHasher`]: https://doc.rust-lang.org/std/hash/trait.BuildHasher.html
///
/// # Examples
///
/// ```
/// use hashbrown::HashMap;
/// use hashbrown::hash_map::DefaultHashBuilder;
///
/// let hasher = DefaultHashBuilder::default();
/// let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
/// let hasher: &DefaultHashBuilder = map.hasher();
/// ```
pub fn hasher(&self) -> &S {
match &self.0 {
HashMapInt::Map(m) => m.hasher(),
HashMapInt::Vec(m) => m.hasher(),
HashMapInt::None => unreachable!(),
}
}
/// Returns the number of elements the map can hold without reallocating.
///
/// This number is a lower bound; the `HashMap<K, V>` might be able to hold
/// more, but is guaranteed to be able to hold at least this many.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
/// let map: HashMap<i32, i32> = HashMap::with_capacity(100);
/// assert!(map.capacity() >= 100);
/// ```
#[inline]
#[allow(clippy::missing_panics_doc)]
pub fn capacity(&self) -> usize {
match &self.0 {
HashMapInt::Map(m) => m.capacity(),
HashMapInt::Vec(m) => m.capacity(),
HashMapInt::None => unimplemented!(),
}
}
/// An iterator visiting all keys in arbitrary order.
/// The iterator element type is `&'a K`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for key in map.keys() {
/// println!("{}", key);
/// }
/// ```
pub fn keys(&self) -> Keys<'_, K, V> {
Keys { inner: self.iter() }
}
/// An iterator visiting all values in arbitrary order.
/// The iterator element type is `&'a V`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for val in map.values() {
/// println!("{}", val);
/// }
/// ```
pub fn values(&self) -> Values<'_, K, V> {
Values { inner: self.iter() }
}
/// An iterator visiting all values mutably in arbitrary order.
/// The iterator element type is `&'a mut V`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
///
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for val in map.values_mut() {
/// *val = *val + 10;
/// }
///
/// for val in map.values() {
/// println!("{}", val);
/// }
/// ```
pub fn values_mut(&mut self) -> ValuesMut<'_, K, V> {
ValuesMut {
inner: self.iter_mut(),
}
}
/// An iterator visiting all key-value pairs in arbitrary order.
/// The iterator element type is `(&'a K, &'a V)`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// for (key, val) in map.iter() {
/// println!("key: {} val: {}", key, val);
/// }
/// ```
pub fn iter(&self) -> Iter<'_, K, V> {
match &self.0 {
HashMapInt::Map(m) => IterInt::Map(m.iter()).into(),
HashMapInt::Vec(m) => IterInt::Vec(m.iter()).into(),
HashMapInt::None => unreachable!(),
}
}
/// An iterator visiting all key-value pairs in arbitrary order,
/// with mutable references to the values.
/// The iterator element type is `(&'a K, &'a mut V)`.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// // Update all values
/// for (_, val) in map.iter_mut() {
/// *val *= 2;
/// }
///
/// for (key, val) in &map {
/// println!("key: {} val: {}", key, val);
/// }
/// ```
pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
match &mut self.0 {
HashMapInt::Map(m) => IterMutInt::Map(m.iter_mut()).into(),
HashMapInt::Vec(m) => IterMutInt::Vec(m.iter_mut()).into(),
HashMapInt::None => unreachable!(),
}
}
/// Returns the number of elements in the map.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut a = HashMap::new();
/// assert_eq!(a.len(), 0);
/// a.insert(1, "a");
/// assert_eq!(a.len(), 1);
/// ```
#[inline]
pub fn len(&self) -> usize {
match &self.0 {
HashMapInt::Map(m) => m.len(),
HashMapInt::Vec(m) => m.len(),
HashMapInt::None => unreachable!(),
}
}
/// Returns `true` if the map contains no elements.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut a = HashMap::new();
/// assert!(a.is_empty());
/// a.insert(1, "a");
/// assert!(!a.is_empty());
/// ```
#[inline]
pub fn is_empty(&self) -> bool {
match &self.0 {
HashMapInt::Map(m) => m.is_empty(),
HashMapInt::Vec(m) => m.is_empty(),
HashMapInt::None => unreachable!(),
}
}
/// Clears the map, returning all key-value pairs as an iterator. Keeps the
/// allocated memory for reuse.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut a = HashMap::new();
/// a.insert(1, "a");
/// a.insert(2, "b");
///
/// for (k, v) in a.drain().take(1) {
/// assert!(k == 1 || k == 2);
/// assert!(v == "a" || v == "b");
/// }
///
/// assert!(a.is_empty());
/// ```
#[inline]
pub fn drain(&mut self) -> Drain<K, V> {
match &mut self.0 {
HashMapInt::Map(m) => Drain(DrainInt::Map(m.drain())),
HashMapInt::Vec(m) => Drain(DrainInt::Vec(m.drain())),
HashMapInt::None => unreachable!(),
}
}
/// Clears the map, removing all key-value pairs. Keeps the allocated memory
/// for reuse.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut a = HashMap::new();
/// a.insert(1, "a");
/// a.clear();
/// assert!(a.is_empty());
/// ```
#[inline]
pub fn clear(&mut self) {
match &mut self.0 {
HashMapInt::Map(m) => m.clear(),
HashMapInt::Vec(m) => m.clear(),
HashMapInt::None => unreachable!(),
}
}
}
impl<K, V, S> HashMap<K, V, S>
where
K: Eq + Hash,
S: BuildHasher,
{
/// Reserves capacity for at least `additional` more elements to be inserted
/// in the `HashMap`. The collection may reserve more space to avoid
/// frequent reallocations.
///
/// # Panics
///
/// Panics if the new allocation size overflows [`usize`].
///
/// [`usize`]: ../../std/primitive.usize.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::new();
/// map.reserve(10);
/// ```
#[inline]
pub fn reserve(&mut self, additional: usize) {
match &mut self.0 {
HashMapInt::Map(m) => m.reserve(additional),
HashMapInt::Vec(m) => m.reserve(additional),
HashMapInt::None => unreachable!(),
}
}
/*
/// Tries to reserve capacity for at least `additional` more elements to be inserted
/// in the given `HashMap<K,V>`. The collection may reserve more space to avoid
/// frequent reallocations.
///
/// # Errors
///
/// If the capacity overflows, or the allocator reports a failure, then an error
/// is returned.
///
/// # Examples
///
/// ```
/// #![feature(try_reserve)]
/// use halfbrown::HashMap;
/// let mut map: HashMap<&str, isize> = HashMap::new();
/// map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
/// ```
#[inline]
pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
match &mut self.0 {
HashMapInt::Map(m) => m.try_reserve(additional),
HashMapInt::Vec(m) => m.try_reserve(additional),
HashMapInt::None => unreachable!(),
}
}
*/
/// Shrinks the capacity of the map as much as possible. It will drop
/// down as much as possible while maintaining the internal rules
/// and possibly leaving some space in accordance with the resize policy.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map: HashMap<i32, i32> = HashMap::with_capacity(100);
/// map.insert(1, 2);
/// map.insert(3, 4);
/// assert!(map.capacity() >= 100);
/// map.shrink_to_fit();
/// assert!(map.capacity() >= 2);
/// ```
pub fn shrink_to_fit(&mut self) {
match &mut self.0 {
HashMapInt::Map(m) => m.shrink_to_fit(),
HashMapInt::Vec(m) => m.shrink_to_fit(),
HashMapInt::None => unreachable!(),
}
}
/// Gets the given key's corresponding entry in the map for in-place manipulation.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut letters = HashMap::new();
///
/// for ch in "a short treatise on fungi".chars() {
/// let counter = letters.entry(ch).or_insert(0);
/// *counter += 1;
/// }
///
/// assert_eq!(letters[&'s'], 2);
/// assert_eq!(letters[&'t'], 3);
/// assert_eq!(letters[&'u'], 1);
/// assert_eq!(letters.get(&'y'), None);
/// ```
pub fn entry(&mut self, key: K) -> Entry<K, V, S> {
match &mut self.0 {
HashMapInt::Map(m) => m.entry(key).into(),
HashMapInt::Vec(m) => m.entry(key).into(),
HashMapInt::None => unreachable!(),
}
}
/// Returns a reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get(&1), Some(&"a"));
/// assert_eq!(map.get(&2), None);
/// ```
#[inline]
pub fn get<Q>(&self, k: &Q) -> Option<&V>
where
K: Borrow<Q>,
Q: ?Sized + Hash + Eq,
{
match &self.0 {
HashMapInt::Map(m) => m.get(k),
HashMapInt::Vec(m) => m.get(k),
HashMapInt::None => unreachable!(),
}
}
/// Returns `true` if the map contains a value for the specified key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.contains_key(&1), true);
/// assert_eq!(map.contains_key(&2), false);
/// ```
pub fn contains_key<Q>(&self, k: &Q) -> bool
where
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
match &self.0 {
HashMapInt::Map(m) => m.contains_key(k),
HashMapInt::Vec(m) => m.contains_key(k),
HashMapInt::None => unreachable!(),
}
}
/// Returns a mutable reference to the value corresponding to the key.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// if let Some(x) = map.get_mut(&1) {
/// *x = "b";
/// }
/// assert_eq!(map[&1], "b");
/// ```
#[inline]
pub fn get_mut<Q>(&mut self, k: &Q) -> Option<&mut V>
where
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
match &mut self.0 {
HashMapInt::Map(m) => m.get_mut(k),
HashMapInt::Vec(m) => m.get_mut(k),
HashMapInt::None => unreachable!(),
}
}
/// Inserts a key-value pair into the map.
///
/// If the map did not have this key present, [`None`] is returned.
///
/// If the map did have this key present, the value is updated, and the old
/// value is returned. The key is not updated, though; this matters for
/// types that can be `==` without being identical. See the [module-level
/// documentation] for more.
///
/// [`None`]: ../../std/option/enum.Option.html#variant.None
/// [module-level documentation]: index.html#insert-and-complex-keys
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// assert_eq!(map.insert(37, "a"), None);
/// assert_eq!(map.is_empty(), false);
///
/// map.insert(37, "b");
/// assert_eq!(map.insert(37, "c"), Some("b"));
/// assert_eq!(map[&37], "c");
/// ```
#[inline]
pub fn insert(&mut self, k: K, v: V) -> Option<V>
where
S: Default,
{
match &mut self.0 {
HashMapInt::Map(m) => m.insert(k, v),
HashMapInt::Vec(m) => {
if m.len() >= VEC_LIMIT_UPPER {
let r;
self.0 = match std::mem::replace(&mut self.0, HashMapInt::None) {
HashMapInt::Vec(mut m) => {
let mut m1: HashBrown<K, V, S> = m.drain().collect();
r = m1.insert(k, v);
HashMapInt::Map(m1)
}
_ => unreachable!(),
};
r
} else {
m.insert(k, v)
}
}
HashMapInt::None => unreachable!(),
}
}
/// Removes a key from the map, returning the value at the key if the key
/// was previously in the map.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove(&1), Some("a"));
/// assert_eq!(map.remove(&1), None);
/// ```
#[inline]
pub fn remove<Q>(&mut self, k: &Q) -> Option<V>
where
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
match &mut self.0 {
HashMapInt::Map(m) => m.remove(k),
HashMapInt::Vec(m) => m.remove(k),
HashMapInt::None => unreachable!(),
}
}
/// Removes a key from the map, returning the stored key and value if the
/// key was previously in the map.
///
/// The key may be any borrowed form of the map's key type, but
/// [`Hash`] and [`Eq`] on the borrowed form *must* match those for
/// the key type.
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove_entry(&1), Some((1, "a")));
/// assert_eq!(map.remove(&1), None);
/// ```
#[inline]
pub fn remove_entry<Q>(&mut self, k: &Q) -> Option<(K, V)>
where
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
match &mut self.0 {
HashMapInt::Map(m) => m.remove_entry(k),
HashMapInt::Vec(m) => m.remove_entry(k),
HashMapInt::None => unreachable!(),
}
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all pairs `(k, v)` such that `f(&k, &mut v)` returns `false`.
/// The elements are visited in unsorted (and unspecified) order.
///
/// # Examples
///
/// ```
/// use halfbrown::HashMap;
///
/// let mut map: HashMap<i32, i32> = (0..8).map(|x| (x, x*10)).collect();
/// map.retain(|&k, _| k % 2 == 0);
/// assert_eq!(map.len(), 4);
/// ```
#[inline]
pub fn retain<F>(&mut self, f: F)
where
F: FnMut(&K, &mut V) -> bool,
{
match &mut self.0 {
HashMapInt::Map(m) => m.retain(f),
HashMapInt::Vec(m) => m.retain(f),
HashMapInt::None => unreachable!(),
}
}
/// Inserts element, this ignores check in the vector
/// map if keys are present - it's a fast way to build
/// a new map when uniqueness is known ahead of time.
#[inline]
pub fn insert_nocheck(&mut self, k: K, v: V) {
match &mut self.0 {
HashMapInt::Map(m) => {
m.insert_unique_unchecked(k, v);
}
HashMapInt::Vec(m) => m.insert_nocheck(k, v),
HashMapInt::None => unreachable!(),
}
}
/// Checks if the current backend is a map, if so returns
/// true.
pub fn is_map(&self) -> bool {
match &self.0 {
HashMapInt::Map(_m) => true,
HashMapInt::Vec(_m) => false,
HashMapInt::None => unreachable!(),
}
}
/// Checks if the current backend is a vector, if so returns
/// true.
pub fn is_vec(&self) -> bool {
match &self.0 {
HashMapInt::Map(_m) => false,
HashMapInt::Vec(_m) => true,
HashMapInt::None => unreachable!(),
}
}
}
impl<K, Q, V, S> Index<&Q> for HashMap<K, V, S>
where
K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash + ?Sized,
S: BuildHasher,
{
type Output = V;
/// Returns a reference to the value corresponding to the supplied key.
///
/// # Panics
///
/// Panics if the key is not present in the `HashMap`.
#[inline]
fn index(&self, key: &Q) -> &V {
self.get(key).expect("no entry found for key")
}
}
impl<K, V, S> HashMap<K, V, S>
where
S: BuildHasher,
K: Eq + Hash,
{
/// Creates a raw entry builder for the `HashMap`.
///
/// Raw entries provide the lowest level of control for searching and
/// manipulating a map. They must be manually initialized with a hash and
/// then manually searched. After this, insertions into a vacant entry
/// still require an owned key to be provided.
///
/// Raw entries are useful for such exotic situations as:
///
/// * Hash memoization
/// * Deferring the creation of an owned key until it is known to be required
/// * Using a search key that doesn't work with the Borrow trait
/// * Using custom comparison logic without newtype wrappers
///
/// Because raw entries provide much more low-level control, it's much easier
/// to put the `HashMap` into an inconsistent state which, while memory-safe,
/// will cause the map to produce seemingly random results. Higher-level and
/// more foolproof APIs like `entry` should be preferred when possible.
///
/// In particular, the hash used to initialized the raw entry must still be
/// consistent with the hash of the key that is ultimately stored in the entry.
/// This is because implementations of `HashMap` may need to recompute hashes
/// when resizing, at which point only the keys are available.
///
/// Raw entries give mutable access to the keys. This must not be used
/// to modify how the key would compare or hash, as the map will not re-evaluate
/// where the key should go, meaning the keys may become "lost" if their
/// location does not reflect their state. For instance, if you change a key
/// so that the map now contains keys which compare equal, search may start
/// acting erratically, with two keys randomly masking each other. Implementations
/// are free to assume this doesn't happen (within the limits of memory-safety).
#[inline]
pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<'_, K, V, S> {
match &mut self.0 {
HashMapInt::Vec(m) => RawEntryBuilderMut::from(m.raw_entry_mut()),
HashMapInt::Map(m) => RawEntryBuilderMut::from(m.raw_entry_mut()),
HashMapInt::None => unreachable!(),
}
}
/// Creates a raw immutable entry builder for the `HashMap`.
///
/// Raw entries provide the lowest level of control for searching and
/// manipulating a map. They must be manually initialized with a hash and
/// then manually searched.
///
/// This is useful for
/// * Hash memoization
/// * Using a search key that doesn't work with the Borrow trait
/// * Using custom comparison logic without newtype wrappers
///
/// Unless you are in such a situation, higher-level and more foolproof APIs like
/// `get` should be preferred.
///
/// Immutable raw entries have very limited use; you might instead want `raw_entry_mut`.
#[inline]
pub fn raw_entry(&self) -> RawEntryBuilder<'_, K, V, S> {
match &self.0 {
HashMapInt::Vec(m) => RawEntryBuilder::from(m.raw_entry()),
HashMapInt::Map(m) => RawEntryBuilder::from(m.raw_entry()),
HashMapInt::None => unreachable!(),
}
}
}
impl<K, V, S, S1> PartialEq<HashMap<K, V, S1>> for HashMap<K, V, S>
where
K: Eq + Hash,
V: PartialEq,
S1: BuildHasher,
{
fn eq(&self, other: &HashMap<K, V, S1>) -> 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 HashMap<K, V, S>
where
K: Eq + Hash,
V: Eq,
S: BuildHasher,
{
}
//#[derive(Clone)]
/// Iterator over the keys
pub struct Keys<'a, K, V> {
inner: Iter<'a, K, V>,
}
impl<'a, K, V> Iterator for Keys<'a, K, V> {
type Item = &'a K;
#[inline]
fn next(&mut self) -> Option<&'a K> {
self.inner.next().map(|(k, _)| k)
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
//#[derive(Clone)]
/// Iterator over the values
pub struct Values<'a, K, V> {
inner: Iter<'a, K, V>,
}
impl<'a, K, V> Iterator for Values<'a, K, V> {
type Item = &'a V;
#[inline]
fn next(&mut self) -> Option<&'a V> {
self.inner.next().map(|(_, v)| v)
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
//#[derive(Clone)]
/// Mutable iterator over the values
pub struct ValuesMut<'a, K, V> {
inner: IterMut<'a, K, V>,
}
impl<'a, K, V> Iterator for ValuesMut<'a, K, V> {
type Item = &'a mut V;
#[inline]
fn next(&mut self) -> Option<&'a mut V> {
self.inner.next().map(|(_, v)| v)
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
/// Drains the map
pub struct Drain<'a, K, V>(DrainInt<'a, K, V>);
enum DrainInt<'a, K, V> {
Map(hashbrown::hash_map::Drain<'a, K, V>),
Vec(std::vec::Drain<'a, (K, V)>),
}
impl<'a, K, V> Iterator for Drain<'a, K, V> {
type Item = (K, V);
#[inline]
fn next(&mut self) -> Option<Self::Item> {
match &mut self.0 {
DrainInt::Map(m) => m.next(),
DrainInt::Vec(m) => m.next(),
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
match &self.0 {
DrainInt::Map(m) => m.size_hint(),
DrainInt::Vec(m) => m.size_hint(),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn scale_up() {
let mut v = HashMap::new();
assert!(v.is_vec());
for i in 1..33 {
// 32 entries
v.insert(i, i);
assert!(v.is_vec());
}
v.insert(33, 33);
assert!(v.is_map());
}
#[test]
fn str_key() {
let mut v: HashMap<String, u32> = HashMap::new();
v.insert("hello".to_owned(), 42);
assert_eq!(v["hello"], 42);
}
#[test]
fn add_remove() {
let mut v = HashMap::new();
v.insert(1, 1);
v.insert(2, 2);
v.insert(3, 3);
assert_eq!(v.get(&1), Some(&1));
assert_eq!(v.get(&2), Some(&2));
assert_eq!(v.get(&3), Some(&3));
v.remove(&2);
assert_eq!(v.get(&1), Some(&1));
assert_eq!(v.get(&2), None);
assert_eq!(v.get(&3), Some(&3));
}
}