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use self::Entry::*;
use self::VacantEntryState::*;
use intrinsics::unlikely;
use collections::CollectionAllocErr;
use cell::Cell;
use borrow::Borrow;
use cmp::max;
use fmt::{self, Debug};
#[allow(deprecated)]
use hash::{Hash, Hasher, BuildHasher, SipHasher13};
use iter::{FromIterator, FusedIterator};
use mem::{self, replace};
use ops::{Deref, DerefMut, Index};
use sys;
use super::table::{self, Bucket, EmptyBucket, Fallibility, FullBucket, FullBucketMut, RawTable,
SafeHash};
use super::table::BucketState::{Empty, Full};
use super::table::Fallibility::{Fallible, Infallible};
const MIN_NONZERO_RAW_CAPACITY: usize = 32; // must be a power of two
/// The default behavior of HashMap implements a maximum load factor of 90.9%.
#[derive(Clone)]
struct DefaultResizePolicy;
impl DefaultResizePolicy {
#[inline]
fn new() -> DefaultResizePolicy {
DefaultResizePolicy
}
/// A hash map's "capacity" is the number of elements it can hold without
/// being resized. Its "raw capacity" is the number of slots required to
/// provide that capacity, accounting for maximum loading. The raw capacity
/// is always zero or a power of two.
#[inline]
fn try_raw_capacity(&self, len: usize) -> Result<usize, CollectionAllocErr> {
if len == 0 {
Ok(0)
} else {
// 1. Account for loading: `raw_capacity >= len * 1.1`.
// 2. Ensure it is a power of two.
// 3. Ensure it is at least the minimum size.
let mut raw_cap = len.checked_mul(11)
.map(|l| l / 10)
.and_then(|l| l.checked_next_power_of_two())
.ok_or(CollectionAllocErr::CapacityOverflow)?;
raw_cap = max(MIN_NONZERO_RAW_CAPACITY, raw_cap);
Ok(raw_cap)
}
}
#[inline]
fn raw_capacity(&self, len: usize) -> usize {
self.try_raw_capacity(len).expect("raw_capacity overflow")
}
/// The capacity of the given raw capacity.
#[inline]
fn capacity(&self, raw_cap: usize) -> usize {
// This doesn't have to be checked for overflow since allocation size
// in bytes will overflow earlier than multiplication by 10.
//
// As per https://github.com/rust-lang/rust/pull/30991 this is updated
// to be: (raw_cap * den + den - 1) / num
(raw_cap * 10 + 10 - 1) / 11
}
}
// The main performance trick in this hashmap is called Robin Hood Hashing.
// It gains its excellent performance from one essential operation:
//
// If an insertion collides with an existing element, and that element's
// "probe distance" (how far away the element is from its ideal location)
// is higher than how far we've already probed, swap the elements.
//
// This massively lowers variance in probe distance, and allows us to get very
// high load factors with good performance. The 90% load factor I use is rather
// conservative.
//
// > Why a load factor of approximately 90%?
//
// In general, all the distances to initial buckets will converge on the mean.
// At a load factor of α, the odds of finding the target bucket after k
// probes is approximately 1-α^k. If we set this equal to 50% (since we converge
// on the mean) and set k=8 (64-byte cache line / 8-byte hash), α=0.92. I round
// this down to make the math easier on the CPU and avoid its FPU.
// Since on average we start the probing in the middle of a cache line, this
// strategy pulls in two cache lines of hashes on every lookup. I think that's
// pretty good, but if you want to trade off some space, it could go down to one
// cache line on average with an α of 0.84.
//
// > Wait, what? Where did you get 1-α^k from?
//
// On the first probe, your odds of a collision with an existing element is α.
// The odds of doing this twice in a row is approximately α^2. For three times,
// α^3, etc. Therefore, the odds of colliding k times is α^k. The odds of NOT
// colliding after k tries is 1-α^k.
//
// The paper from 1986 cited below mentions an implementation which keeps track
// of the distance-to-initial-bucket histogram. This approach is not suitable
// for modern architectures because it requires maintaining an internal data
// structure. This allows very good first guesses, but we are most concerned
// with guessing entire cache lines, not individual indexes. Furthermore, array
// accesses are no longer linear and in one direction, as we have now. There
// is also memory and cache pressure that this would entail that would be very
// difficult to properly see in a microbenchmark.
//
// ## Future Improvements (FIXME!)
//
// Allow the load factor to be changed dynamically and/or at initialization.
//
// Also, would it be possible for us to reuse storage when growing the
// underlying table? This is exactly the use case for 'realloc', and may
// be worth exploring.
//
// ## Future Optimizations (FIXME!)
//
// Another possible design choice that I made without any real reason is
// parameterizing the raw table over keys and values. Technically, all we need
// is the size and alignment of keys and values, and the code should be just as
// efficient (well, we might need one for power-of-two size and one for not...).
// This has the potential to reduce code bloat in rust executables, without
// really losing anything except 4 words (key size, key alignment, val size,
// val alignment) which can be passed in to every call of a `RawTable` function.
// This would definitely be an avenue worth exploring if people start complaining
// about the size of rust executables.
//
// Annotate exceedingly likely branches in `table::make_hash`
// and `search_hashed` to reduce instruction cache pressure
// and mispredictions once it becomes possible (blocked on issue #11092).
//
// Shrinking the table could simply reallocate in place after moving buckets
// to the first half.
//
// The growth algorithm (fragment of the Proof of Correctness)
// --------------------
//
// The growth algorithm is basically a fast path of the naive reinsertion-
// during-resize algorithm. Other paths should never be taken.
//
// Consider growing a robin hood hashtable of capacity n. Normally, we do this
// by allocating a new table of capacity `2n`, and then individually reinsert
// each element in the old table into the new one. This guarantees that the
// new table is a valid robin hood hashtable with all the desired statistical
// properties. Remark that the order we reinsert the elements in should not
// matter. For simplicity and efficiency, we will consider only linear
// reinsertions, which consist of reinserting all elements in the old table
// into the new one by increasing order of index. However we will not be
// starting our reinsertions from index 0 in general. If we start from index
// i, for the purpose of reinsertion we will consider all elements with real
// index j < i to have virtual index n + j.
//
// Our hash generation scheme consists of generating a 64-bit hash and
// truncating the most significant bits. When moving to the new table, we
// simply introduce a new bit to the front of the hash. Therefore, if an
// element has ideal index i in the old table, it can have one of two ideal
// locations in the new table. If the new bit is 0, then the new ideal index
// is i. If the new bit is 1, then the new ideal index is n + i. Intuitively,
// we are producing two independent tables of size n, and for each element we
// independently choose which table to insert it into with equal probability.
// However, rather than wrapping around themselves on overflowing their
// indexes, the first table overflows into the second, and the second into the
// first. Visually, our new table will look something like:
//
// [yy_xxx_xxxx_xxx|xx_yyy_yyyy_yyy]
//
// Where x's are elements inserted into the first table, y's are elements
// inserted into the second, and _'s are empty sections. We now define a few
// key concepts that we will use later. Note that this is a very abstract
// perspective of the table. A real resized table would be at least half
// empty.
//
// Theorem: A linear robin hood reinsertion from the first ideal element
// produces identical results to a linear naive reinsertion from the same
// element.
//
// FIXME(Gankro, pczarn): review the proof and put it all in a separate README.md
//
// Adaptive early resizing
// ----------------------
// To protect against degenerate performance scenarios (including DOS attacks),
// the implementation includes an adaptive behavior that can resize the map
// early (before its capacity is exceeded) when suspiciously long probe sequences
// are encountered.
//
// With this algorithm in place it would be possible to turn a CPU attack into
// a memory attack due to the aggressive resizing. To prevent that the
// adaptive behavior only triggers when the map is at least half full.
// This reduces the effectiveness of the algorithm but also makes it completely safe.
//
// The previous safety measure also prevents degenerate interactions with
// really bad quality hash algorithms that can make normal inputs look like a
// DOS attack.
//
const DISPLACEMENT_THRESHOLD: usize = 128;
//
// The threshold of 128 is chosen to minimize the chance of exceeding it.
// In particular, we want that chance to be less than 10^-8 with a load of 90%.
// For displacement, the smallest constant that fits our needs is 90,
// so we round that up to 128.
//
// At a load factor of α, the odds of finding the target bucket after exactly n
// unsuccessful probes[1] are
//
// Pr_α{displacement = n} =
// (1 - α) / α * ∑_{k≥1} e^(-kα) * (kα)^(k+n) / (k + n)! * (1 - kα / (k + n + 1))
//
// We use this formula to find the probability of triggering the adaptive behavior
//
// Pr_0.909{displacement > 128} = 1.601 * 10^-11
//
// 1. Alfredo Viola (2005). Distributional analysis of Robin Hood linear probing
// hashing with buckets.
/// A hash map implemented with linear probing and Robin Hood bucket stealing.
///
/// By default, `HashMap` uses a hashing algorithm selected to provide
/// resistance against HashDoS attacks. The algorithm is randomly seeded, and a
/// reasonable best-effort is made to generate this seed from a high quality,
/// secure source of randomness provided by the host without blocking the
/// program. Because of this, the randomness of the seed depends on the output
/// quality of the system's random number generator when the seed is created.
/// In particular, seeds generated when the system's entropy pool is abnormally
/// low such as during system boot may be of a lower quality.
///
/// The default hashing algorithm is currently SipHash 1-3, though this is
/// subject to change at any point in the future. While its performance is very
/// competitive for medium sized keys, other hashing algorithms will outperform
/// it for small keys such as integers as well as large keys such as long
/// strings, though those algorithms will typically *not* protect against
/// attacks such as HashDoS.
///
/// The hashing algorithm can be replaced on a per-`HashMap` basis using the
/// [`default`], [`with_hasher`], and [`with_capacity_and_hasher`] methods. Many
/// alternative algorithms are available on crates.io, such as the [`fnv`] crate.
///
/// It is required that the keys implement the [`Eq`] and [`Hash`] traits, although
/// this can frequently be achieved by using `#[derive(PartialEq, Eq, Hash)]`.
/// If you implement these yourself, it is important that the following
/// property holds:
///
/// ```text
/// k1 == k2 -> hash(k1) == hash(k2)
/// ```
///
/// In other words, if two keys are equal, their hashes must be equal.
///
/// It is a logic error for a key to be modified in such a way that the key's
/// hash, as determined by the [`Hash`] trait, or its equality, as determined by
/// the [`Eq`] trait, changes while it is in the map. This is normally only
/// possible through [`Cell`], [`RefCell`], global state, I/O, or unsafe code.
///
/// Relevant papers/articles:
///
/// 1. Pedro Celis. ["Robin Hood Hashing"](https://cs.uwaterloo.ca/research/tr/1986/CS-86-14.pdf)
/// 2. Emmanuel Goossaert. ["Robin Hood
/// hashing"](http://codecapsule.com/2013/11/11/robin-hood-hashing/)
/// 3. Emmanuel Goossaert. ["Robin Hood hashing: backward shift
/// deletion"](http://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/)
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// // Type inference lets us omit an explicit type signature (which
/// // would be `HashMap<String, String>` in this example).
/// let mut book_reviews = HashMap::new();
///
/// // Review some books.
/// book_reviews.insert(
/// "Adventures of Huckleberry Finn".to_string(),
/// "My favorite book.".to_string(),
/// );
/// book_reviews.insert(
/// "Grimms' Fairy Tales".to_string(),
/// "Masterpiece.".to_string(),
/// );
/// book_reviews.insert(
/// "Pride and Prejudice".to_string(),
/// "Very enjoyable.".to_string(),
/// );
/// book_reviews.insert(
/// "The Adventures of Sherlock Holmes".to_string(),
/// "Eye lyked it alot.".to_string(),
/// );
///
/// // Check for a specific one.
/// // When collections store owned values (String), they can still be
/// // queried using references (&str).
/// if !book_reviews.contains_key("Les Misérables") {
/// println!("We've got {} reviews, but Les Misérables ain't one.",
/// book_reviews.len());
/// }
///
/// // oops, this review has a lot of spelling mistakes, let's delete it.
/// book_reviews.remove("The Adventures of Sherlock Holmes");
///
/// // Look up the values associated with some keys.
/// let to_find = ["Pride and Prejudice", "Alice's Adventure in Wonderland"];
/// for &book in &to_find {
/// match book_reviews.get(book) {
/// Some(review) => println!("{}: {}", book, review),
/// None => println!("{} is unreviewed.", book)
/// }
/// }
///
/// // Look up the value for a key (will panic if the key is not found).
/// println!("Review for Jane: {}", book_reviews["Pride and Prejudice"]);
///
/// // Iterate over everything.
/// for (book, review) in &book_reviews {
/// println!("{}: \"{}\"", book, review);
/// }
/// ```
///
/// `HashMap` also implements an [`Entry API`](#method.entry), which allows
/// for more complex methods of getting, setting, updating and removing keys and
/// their values:
///
/// ```
/// use std::collections::HashMap;
///
/// // type inference lets us omit an explicit type signature (which
/// // would be `HashMap<&str, u8>` in this example).
/// let mut player_stats = HashMap::new();
///
/// fn random_stat_buff() -> u8 {
/// // could actually return some random value here - let's just return
/// // some fixed value for now
/// 42
/// }
///
/// // insert a key only if it doesn't already exist
/// player_stats.entry("health").or_insert(100);
///
/// // insert a key using a function that provides a new value only if it
/// // doesn't already exist
/// player_stats.entry("defence").or_insert_with(random_stat_buff);
///
/// // update a key, guarding against the key possibly not being set
/// let stat = player_stats.entry("attack").or_insert(100);
/// *stat += random_stat_buff();
/// ```
///
/// The easiest way to use `HashMap` with a custom key type is to derive [`Eq`] and [`Hash`].
/// We must also derive [`PartialEq`].
///
/// [`Eq`]: ../../std/cmp/trait.Eq.html
/// [`Hash`]: ../../std/hash/trait.Hash.html
/// [`PartialEq`]: ../../std/cmp/trait.PartialEq.html
/// [`RefCell`]: ../../std/cell/struct.RefCell.html
/// [`Cell`]: ../../std/cell/struct.Cell.html
/// [`default`]: #method.default
/// [`with_hasher`]: #method.with_hasher
/// [`with_capacity_and_hasher`]: #method.with_capacity_and_hasher
/// [`fnv`]: https://crates.io/crates/fnv
///
/// ```
/// use std::collections::HashMap;
///
/// #[derive(Hash, Eq, PartialEq, Debug)]
/// struct Viking {
/// name: String,
/// country: String,
/// }
///
/// impl Viking {
/// /// Create a new Viking.
/// fn new(name: &str, country: &str) -> Viking {
/// Viking { name: name.to_string(), country: country.to_string() }
/// }
/// }
///
/// // Use a HashMap to store the vikings' health points.
/// let mut vikings = HashMap::new();
///
/// vikings.insert(Viking::new("Einar", "Norway"), 25);
/// vikings.insert(Viking::new("Olaf", "Denmark"), 24);
/// vikings.insert(Viking::new("Harald", "Iceland"), 12);
///
/// // Use derived implementation to print the status of the vikings.
/// for (viking, health) in &vikings {
/// println!("{:?} has {} hp", viking, health);
/// }
/// ```
///
/// A `HashMap` with fixed list of elements can be initialized from an array:
///
/// ```
/// use std::collections::HashMap;
///
/// fn main() {
/// let timber_resources: HashMap<&str, i32> =
/// [("Norway", 100),
/// ("Denmark", 50),
/// ("Iceland", 10)]
/// .iter().cloned().collect();
/// // use the values stored in map
/// }
/// ```
#[derive(Clone)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct HashMap<K, V, S = RandomState> {
// All hashes are keyed on these values, to prevent hash collision attacks.
hash_builder: S,
table: RawTable<K, V>,
resize_policy: DefaultResizePolicy,
}
/// Search for a pre-hashed key.
/// If you don't already know the hash, use search or search_mut instead
#[inline]
fn search_hashed<K, V, M, F>(table: M, hash: SafeHash, is_match: F) -> InternalEntry<K, V, M>
where M: Deref<Target = RawTable<K, V>>,
F: FnMut(&K) -> bool
{
// This is the only function where capacity can be zero. To avoid
// undefined behavior when Bucket::new gets the raw bucket in this
// case, immediately return the appropriate search result.
if table.capacity() == 0 {
return InternalEntry::TableIsEmpty;
}
search_hashed_nonempty(table, hash, is_match, true)
}
/// Search for a pre-hashed key when the hash map is known to be non-empty.
#[inline]
fn search_hashed_nonempty<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F,
compare_hashes: bool)
-> InternalEntry<K, V, M>
where M: Deref<Target = RawTable<K, V>>,
F: FnMut(&K) -> bool
{
// Do not check the capacity as an extra branch could slow the lookup.
let size = table.size();
let mut probe = Bucket::new(table, hash);
let mut displacement = 0;
loop {
let full = match probe.peek() {
Empty(bucket) => {
// Found a hole!
return InternalEntry::Vacant {
hash,
elem: NoElem(bucket, displacement),
};
}
Full(bucket) => bucket,
};
let probe_displacement = full.displacement();
if probe_displacement < displacement {
// Found a luckier bucket than me.
// We can finish the search early if we hit any bucket
// with a lower distance to initial bucket than we've probed.
return InternalEntry::Vacant {
hash,
elem: NeqElem(full, probe_displacement),
};
}
// If the hash doesn't match, it can't be this one..
if !compare_hashes || hash == full.hash() {
// If the key doesn't match, it can't be this one..
if is_match(full.read().0) {
return InternalEntry::Occupied { elem: full };
}
}
displacement += 1;
probe = full.next();
debug_assert!(displacement <= size);
}
}
/// Same as `search_hashed_nonempty` but for mutable access.
#[inline]
fn search_hashed_nonempty_mut<K, V, M, F>(table: M, hash: SafeHash, mut is_match: F,
compare_hashes: bool)
-> InternalEntry<K, V, M>
where M: DerefMut<Target = RawTable<K, V>>,
F: FnMut(&K) -> bool
{
// Do not check the capacity as an extra branch could slow the lookup.
let size = table.size();
let mut probe = Bucket::new(table, hash);
let mut displacement = 0;
loop {
let mut full = match probe.peek() {
Empty(bucket) => {
// Found a hole!
return InternalEntry::Vacant {
hash,
elem: NoElem(bucket, displacement),
};
}
Full(bucket) => bucket,
};
let probe_displacement = full.displacement();
if probe_displacement < displacement {
// Found a luckier bucket than me.
// We can finish the search early if we hit any bucket
// with a lower distance to initial bucket than we've probed.
return InternalEntry::Vacant {
hash,
elem: NeqElem(full, probe_displacement),
};
}
// If the hash doesn't match, it can't be this one..
if hash == full.hash() || !compare_hashes {
// If the key doesn't match, it can't be this one..
if is_match(full.read_mut().0) {
return InternalEntry::Occupied { elem: full };
}
}
displacement += 1;
probe = full.next();
debug_assert!(displacement <= size);
}
}
fn pop_internal<K, V>(starting_bucket: FullBucketMut<K, V>)
-> (K, V, &mut RawTable<K, V>)
{
let (empty, retkey, retval) = starting_bucket.take();
let mut gap = match empty.gap_peek() {
Ok(b) => b,
Err(b) => return (retkey, retval, b.into_table()),
};
while gap.full().displacement() != 0 {
gap = match gap.shift() {
Ok(b) => b,
Err(b) => {
return (retkey, retval, b.into_table());
},
};
}
// Now we've done all our shifting. Return the value we grabbed earlier.
(retkey, retval, gap.into_table())
}
/// Perform robin hood bucket stealing at the given `bucket`. You must
/// also pass that bucket's displacement so we don't have to recalculate it.
///
/// `hash`, `key`, and `val` are the elements to "robin hood" into the hashtable.
fn robin_hood<'a, K: 'a, V: 'a>(bucket: FullBucketMut<'a, K, V>,
mut displacement: usize,
mut hash: SafeHash,
mut key: K,
mut val: V)
-> FullBucketMut<'a, K, V> {
let size = bucket.table().size();
let raw_capacity = bucket.table().capacity();
// There can be at most `size - dib` buckets to displace, because
// in the worst case, there are `size` elements and we already are
// `displacement` buckets away from the initial one.
let idx_end = (bucket.index() + size - bucket.displacement()) % raw_capacity;
// Save the *starting point*.
let mut bucket = bucket.stash();
loop {
let (old_hash, old_key, old_val) = bucket.replace(hash, key, val);
hash = old_hash;
key = old_key;
val = old_val;
loop {
displacement += 1;
let probe = bucket.next();
debug_assert!(probe.index() != idx_end);
let full_bucket = match probe.peek() {
Empty(bucket) => {
// Found a hole!
let bucket = bucket.put(hash, key, val);
// Now that it's stolen, just read the value's pointer
// right out of the table! Go back to the *starting point*.
//
// This use of `into_table` is misleading. It turns the
// bucket, which is a FullBucket on top of a
// FullBucketMut, into just one FullBucketMut. The "table"
// refers to the inner FullBucketMut in this context.
return bucket.into_table();
}
Full(bucket) => bucket,
};
let probe_displacement = full_bucket.displacement();
bucket = full_bucket;
// Robin hood! Steal the spot.
if probe_displacement < displacement {
displacement = probe_displacement;
break;
}
}
}
}
impl<K, V, S> HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
fn make_hash<X: ?Sized>(&self, x: &X) -> SafeHash
where X: Hash
{
table::make_hash(&self.hash_builder, x)
}
/// Search for a key, yielding the index if it's found in the hashtable.
/// If you already have the hash for the key lying around, or if you need an
/// InternalEntry, use search_hashed or search_hashed_nonempty.
#[inline]
fn search<'a, Q: ?Sized>(&'a self, q: &Q)
-> Option<FullBucket<K, V, &'a RawTable<K, V>>>
where K: Borrow<Q>,
Q: Eq + Hash
{
if self.is_empty() {
return None;
}
let hash = self.make_hash(q);
search_hashed_nonempty(&self.table, hash, |k| q.eq(k.borrow()), true)
.into_occupied_bucket()
}
#[inline]
fn search_mut<'a, Q: ?Sized>(&'a mut self, q: &Q)
-> Option<FullBucket<K, V, &'a mut RawTable<K, V>>>
where K: Borrow<Q>,
Q: Eq + Hash
{
if self.is_empty() {
return None;
}
let hash = self.make_hash(q);
search_hashed_nonempty(&mut self.table, hash, |k| q.eq(k.borrow()), true)
.into_occupied_bucket()
}
// The caller should ensure that invariants by Robin Hood Hashing hold
// and that there's space in the underlying table.
fn insert_hashed_ordered(&mut self, hash: SafeHash, k: K, v: V) {
let mut buckets = Bucket::new(&mut self.table, hash);
let start_index = buckets.index();
loop {
// We don't need to compare hashes for value swap.
// Not even DIBs for Robin Hood.
buckets = match buckets.peek() {
Empty(empty) => {
empty.put(hash, k, v);
return;
}
Full(b) => b.into_bucket(),
};
buckets.next();
debug_assert!(buckets.index() != start_index);
}
}
}
impl<K: Hash + Eq, V> HashMap<K, V, RandomState> {
/// 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 std::collections::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::new();
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn new() -> HashMap<K, V, RandomState> {
Default::default()
}
/// 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 std::collections::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::with_capacity(10);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn with_capacity(capacity: usize) -> HashMap<K, V, RandomState> {
HashMap::with_capacity_and_hasher(capacity, Default::default())
}
}
impl<K, V, S> HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
/// 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 std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let mut map = HashMap::with_hasher(s);
/// map.insert(1, 2);
/// ```
#[inline]
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
pub fn with_hasher(hash_builder: S) -> HashMap<K, V, S> {
HashMap {
hash_builder,
resize_policy: DefaultResizePolicy::new(),
table: RawTable::new(0),
}
}
/// 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 std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let mut map = HashMap::with_capacity_and_hasher(10, s);
/// map.insert(1, 2);
/// ```
#[inline]
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> HashMap<K, V, S> {
let resize_policy = DefaultResizePolicy::new();
let raw_cap = resize_policy.raw_capacity(capacity);
HashMap {
hash_builder,
resize_policy,
table: RawTable::new(raw_cap),
}
}
/// Returns a reference to the map's [`BuildHasher`].
///
/// [`BuildHasher`]: ../../std/hash/trait.BuildHasher.html
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let hasher = RandomState::new();
/// let map: HashMap<i32, i32> = HashMap::with_hasher(hasher);
/// let hasher: &RandomState = map.hasher();
/// ```
#[stable(feature = "hashmap_public_hasher", since = "1.9.0")]
pub fn hasher(&self) -> &S {
&self.hash_builder
}
/// 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 std::collections::HashMap;
/// let map: HashMap<i32, i32> = HashMap::with_capacity(100);
/// assert!(map.capacity() >= 100);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn capacity(&self) -> usize {
self.resize_policy.capacity(self.raw_capacity())
}
/// Returns the hash map's raw capacity.
#[inline]
fn raw_capacity(&self) -> usize {
self.table.capacity()
}
/// 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 std::collections::HashMap;
/// let mut map: HashMap<&str, i32> = HashMap::new();
/// map.reserve(10);
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn reserve(&mut self, additional: usize) {
match self.reserve_internal(additional, Infallible) {
Err(CollectionAllocErr::CapacityOverflow) => panic!("capacity overflow"),
Err(CollectionAllocErr::AllocErr) => unreachable!(),
Ok(()) => { /* yay */ }
}
}
/// 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 std::collections::HashMap;
/// let mut map: HashMap<&str, isize> = HashMap::new();
/// map.try_reserve(10).expect("why is the test harness OOMing on 10 bytes?");
/// ```
#[unstable(feature = "try_reserve", reason = "new API", issue="48043")]
pub fn try_reserve(&mut self, additional: usize) -> Result<(), CollectionAllocErr> {
self.reserve_internal(additional, Fallible)
}
#[inline]
fn reserve_internal(&mut self, additional: usize, fallibility: Fallibility)
-> Result<(), CollectionAllocErr> {
let remaining = self.capacity() - self.len(); // this can't overflow
if remaining < additional {
let min_cap = self.len()
.checked_add(additional)
.ok_or(CollectionAllocErr::CapacityOverflow)?;
let raw_cap = self.resize_policy.try_raw_capacity(min_cap)?;
self.try_resize(raw_cap, fallibility)?;
} else if self.table.tag() && remaining <= self.len() {
// Probe sequence is too long and table is half full,
// resize early to reduce probing length.
let new_capacity = self.table.capacity() * 2;
self.try_resize(new_capacity, fallibility)?;
}
Ok(())
}
/// Resizes the internal vectors to a new capacity. It's your
/// responsibility to:
/// 1) Ensure `new_raw_cap` is enough for all the elements, accounting
/// for the load factor.
/// 2) Ensure `new_raw_cap` is a power of two or zero.
#[inline(never)]
#[cold]
fn try_resize(
&mut self,
new_raw_cap: usize,
fallibility: Fallibility,
) -> Result<(), CollectionAllocErr> {
assert!(self.table.size() <= new_raw_cap);
assert!(new_raw_cap.is_power_of_two() || new_raw_cap == 0);
let mut old_table = replace(
&mut self.table,
match fallibility {
Infallible => RawTable::new(new_raw_cap),
Fallible => RawTable::try_new(new_raw_cap)?,
}
);
let old_size = old_table.size();
if old_table.size() == 0 {
return Ok(());
}
let mut bucket = Bucket::head_bucket(&mut old_table);
// This is how the buckets might be laid out in memory:
// ($ marks an initialized bucket)
// ________________
// |$$$_$$$$$$_$$$$$|
//
// But we've skipped the entire initial cluster of buckets
// and will continue iteration in this order:
// ________________
// |$$$$$$_$$$$$
// ^ wrap around once end is reached
// ________________
// $$$_____________|
// ^ exit once table.size == 0
loop {
bucket = match bucket.peek() {
Full(bucket) => {
let h = bucket.hash();
let (b, k, v) = bucket.take();
self.insert_hashed_ordered(h, k, v);
if b.table().size() == 0 {
break;
}
b.into_bucket()
}
Empty(b) => b.into_bucket(),
};
bucket.next();
}
assert_eq!(self.table.size(), old_size);
Ok(())
}
/// 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 std::collections::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);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn shrink_to_fit(&mut self) {
let new_raw_cap = self.resize_policy.raw_capacity(self.len());
if self.raw_capacity() != new_raw_cap {
let old_table = replace(&mut self.table, RawTable::new(new_raw_cap));
let old_size = old_table.size();
// Shrink the table. Naive algorithm for resizing:
for (h, k, v) in old_table.into_iter() {
self.insert_hashed_nocheck(h, k, v);
}
debug_assert_eq!(self.table.size(), old_size);
}
}
/// Shrinks the capacity of the map with a lower limit. It will drop
/// down no lower than the supplied limit while maintaining the internal rules
/// and possibly leaving some space in accordance with the resize policy.
///
/// Panics if the current capacity is smaller than the supplied
/// minimum capacity.
///
/// # Examples
///
/// ```
/// #![feature(shrink_to)]
/// use std::collections::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(10);
/// assert!(map.capacity() >= 10);
/// map.shrink_to(0);
/// assert!(map.capacity() >= 2);
/// ```
#[unstable(feature = "shrink_to", reason = "new API", issue="56431")]
pub fn shrink_to(&mut self, min_capacity: usize) {
assert!(self.capacity() >= min_capacity, "Tried to shrink to a larger capacity");
let new_raw_cap = self.resize_policy.raw_capacity(max(self.len(), min_capacity));
if self.raw_capacity() != new_raw_cap {
let old_table = replace(&mut self.table, RawTable::new(new_raw_cap));
let old_size = old_table.size();
// Shrink the table. Naive algorithm for resizing:
for (h, k, v) in old_table.into_iter() {
self.insert_hashed_nocheck(h, k, v);
}
debug_assert_eq!(self.table.size(), old_size);
}
}
/// Insert a pre-hashed key-value pair, without first checking
/// that there's enough room in the buckets. Returns a reference to the
/// newly insert value.
///
/// If the key already exists, the hashtable will be returned untouched
/// and a reference to the existing element will be returned.
fn insert_hashed_nocheck(&mut self, hash: SafeHash, k: K, v: V) -> Option<V> {
let entry = search_hashed(&mut self.table, hash, |key| *key == k).into_entry(k);
match entry {
Some(Occupied(mut elem)) => Some(elem.insert(v)),
Some(Vacant(elem)) => {
elem.insert(v);
None
}
None => unreachable!(),
}
}
/// An iterator visiting all keys in arbitrary order.
/// The iterator element type is `&'a K`.
///
/// # Examples
///
/// ```
/// use std::collections::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);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
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 std::collections::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);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
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 std::collections::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);
/// }
/// ```
#[stable(feature = "map_values_mut", since = "1.10.0")]
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 std::collections::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);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter(&self) -> Iter<K, V> {
Iter { inner: self.table.iter() }
}
/// 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 std::collections::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);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut { inner: self.table.iter_mut() }
}
/// Gets the given key's corresponding entry in the map for in-place manipulation.
///
/// # Examples
///
/// ```
/// use std::collections::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);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn entry(&mut self, key: K) -> Entry<K, V> {
// Gotta resize now.
self.reserve(1);
let hash = self.make_hash(&key);
search_hashed(&mut self.table, hash, |q| q.eq(&key))
.into_entry(key).expect("unreachable")
}
/// Returns the number of elements in the map.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// assert_eq!(a.len(), 0);
/// a.insert(1, "a");
/// assert_eq!(a.len(), 1);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn len(&self) -> usize {
self.table.size()
}
/// Returns true if the map contains no elements.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// assert!(a.is_empty());
/// a.insert(1, "a");
/// assert!(!a.is_empty());
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Clears the map, returning all key-value pairs as an iterator. Keeps the
/// allocated memory for reuse.
///
/// # Examples
///
/// ```
/// use std::collections::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]
#[stable(feature = "drain", since = "1.6.0")]
pub fn drain(&mut self) -> Drain<K, V> {
Drain { inner: self.table.drain() }
}
/// Clears the map, removing all key-value pairs. Keeps the allocated memory
/// for reuse.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut a = HashMap::new();
/// a.insert(1, "a");
/// a.clear();
/// assert!(a.is_empty());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn clear(&mut self) {
self.drain();
}
/// 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 std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get(&1), Some(&"a"));
/// assert_eq!(map.get(&2), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn get<Q: ?Sized>(&self, k: &Q) -> Option<&V>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search(k).map(|bucket| bucket.into_refs().1)
}
/// Returns the key-value pair corresponding to the supplied key.
///
/// The supplied 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
///
/// ```
/// #![feature(map_get_key_value)]
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
/// assert_eq!(map.get_key_value(&2), None);
/// ```
#[unstable(feature = "map_get_key_value", issue = "49347")]
pub fn get_key_value<Q: ?Sized>(&self, k: &Q) -> Option<(&K, &V)>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search(k).map(|bucket| bucket.into_refs())
}
/// 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 std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.contains_key(&1), true);
/// assert_eq!(map.contains_key(&2), false);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> bool
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search(k).is_some()
}
/// 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 std::collections::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");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut<Q: ?Sized>(&mut self, k: &Q) -> Option<&mut V>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search_mut(k).map(|bucket| bucket.into_mut_refs().1)
}
/// 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 std::collections::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");
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, k: K, v: V) -> Option<V> {
let hash = self.make_hash(&k);
self.reserve(1);
self.insert_hashed_nocheck(hash, k, v)
}
/// 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 std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove(&1), Some("a"));
/// assert_eq!(map.remove(&1), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove<Q: ?Sized>(&mut self, k: &Q) -> Option<V>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search_mut(k).map(|bucket| pop_internal(bucket).1)
}
/// 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 std::collections::HashMap;
///
/// # fn main() {
/// let mut map = HashMap::new();
/// map.insert(1, "a");
/// assert_eq!(map.remove_entry(&1), Some((1, "a")));
/// assert_eq!(map.remove(&1), None);
/// # }
/// ```
#[stable(feature = "hash_map_remove_entry", since = "1.27.0")]
pub fn remove_entry<Q: ?Sized>(&mut self, k: &Q) -> Option<(K, V)>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.search_mut(k)
.map(|bucket| {
let (k, v, _) = pop_internal(bucket);
(k, v)
})
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all pairs `(k, v)` such that `f(&k,&mut v)` returns `false`.
///
/// # Examples
///
/// ```
/// use std::collections::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);
/// ```
#[stable(feature = "retain_hash_collection", since = "1.18.0")]
pub fn retain<F>(&mut self, mut f: F)
where F: FnMut(&K, &mut V) -> bool
{
if self.table.size() == 0 {
return;
}
let mut elems_left = self.table.size();
let mut bucket = Bucket::head_bucket(&mut self.table);
bucket.prev();
let start_index = bucket.index();
while elems_left != 0 {
bucket = match bucket.peek() {
Full(mut full) => {
elems_left -= 1;
let should_remove = {
let (k, v) = full.read_mut();
!f(k, v)
};
if should_remove {
let prev_raw = full.raw();
let (_, _, t) = pop_internal(full);
Bucket::new_from(prev_raw, t)
} else {
full.into_bucket()
}
},
Empty(b) => {
b.into_bucket()
}
};
bucket.prev(); // reverse iteration
debug_assert!(elems_left == 0 || bucket.index() != start_index);
}
}
}
impl<K, V, S> HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
/// 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(always)]
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn raw_entry_mut(&mut self) -> RawEntryBuilderMut<K, V, S> {
self.reserve(1);
RawEntryBuilderMut { map: self }
}
/// 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`.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn raw_entry(&self) -> RawEntryBuilder<K, V, S> {
RawEntryBuilder { map: self }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> PartialEq for HashMap<K, V, S>
where K: Eq + Hash,
V: PartialEq,
S: BuildHasher
{
fn eq(&self, other: &HashMap<K, V, S>) -> bool {
if self.len() != other.len() {
return false;
}
self.iter().all(|(key, value)| other.get(key).map_or(false, |v| *value == *v))
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Eq for HashMap<K, V, S>
where K: Eq + Hash,
V: Eq,
S: BuildHasher
{
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Debug for HashMap<K, V, S>
where K: Eq + Hash + Debug,
V: Debug,
S: BuildHasher
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_map().entries(self.iter()).finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Default for HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher + Default
{
/// Creates an empty `HashMap<K, V, S>`, with the `Default` value for the hasher.
fn default() -> HashMap<K, V, S> {
HashMap::with_hasher(Default::default())
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S>
where K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash,
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")
}
}
/// An iterator over the entries of a `HashMap`.
///
/// This `struct` is created by the [`iter`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`iter`]: struct.HashMap.html#method.iter
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Iter<'a, K: 'a, V: 'a> {
inner: table::Iter<'a, K, V>,
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Clone for Iter<'a, K, V> {
fn clone(&self) -> Iter<'a, K, V> {
Iter { inner: self.inner.clone() }
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K: Debug, V: Debug> fmt::Debug for Iter<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.clone())
.finish()
}
}
/// A mutable iterator over the entries of a `HashMap`.
///
/// This `struct` is created by the [`iter_mut`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`iter_mut`]: struct.HashMap.html#method.iter_mut
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IterMut<'a, K: 'a, V: 'a> {
inner: table::IterMut<'a, K, V>,
}
/// An owning iterator over the entries of a `HashMap`.
///
/// This `struct` is created by the [`into_iter`] method on [`HashMap`][`HashMap`]
/// (provided by the `IntoIterator` trait). See its documentation for more.
///
/// [`into_iter`]: struct.HashMap.html#method.into_iter
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct IntoIter<K, V> {
pub(super) inner: table::IntoIter<K, V>,
}
/// An iterator over the keys of a `HashMap`.
///
/// This `struct` is created by the [`keys`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`keys`]: struct.HashMap.html#method.keys
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Keys<'a, K: 'a, V: 'a> {
inner: Iter<'a, K, V>,
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Clone for Keys<'a, K, V> {
fn clone(&self) -> Keys<'a, K, V> {
Keys { inner: self.inner.clone() }
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K: Debug, V> fmt::Debug for Keys<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.clone())
.finish()
}
}
/// An iterator over the values of a `HashMap`.
///
/// This `struct` is created by the [`values`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`values`]: struct.HashMap.html#method.values
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct Values<'a, K: 'a, V: 'a> {
inner: Iter<'a, K, V>,
}
// FIXME(#26925) Remove in favor of `#[derive(Clone)]`
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Clone for Values<'a, K, V> {
fn clone(&self) -> Values<'a, K, V> {
Values { inner: self.inner.clone() }
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K, V: Debug> fmt::Debug for Values<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.clone())
.finish()
}
}
/// A draining iterator over the entries of a `HashMap`.
///
/// This `struct` is created by the [`drain`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`drain`]: struct.HashMap.html#method.drain
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "drain", since = "1.6.0")]
pub struct Drain<'a, K: 'a, V: 'a> {
pub(super) inner: table::Drain<'a, K, V>,
}
/// A mutable iterator over the values of a `HashMap`.
///
/// This `struct` is created by the [`values_mut`] method on [`HashMap`]. See its
/// documentation for more.
///
/// [`values_mut`]: struct.HashMap.html#method.values_mut
/// [`HashMap`]: struct.HashMap.html
#[stable(feature = "map_values_mut", since = "1.10.0")]
pub struct ValuesMut<'a, K: 'a, V: 'a> {
inner: IterMut<'a, K, V>,
}
enum InternalEntry<K, V, M> {
Occupied { elem: FullBucket<K, V, M> },
Vacant {
hash: SafeHash,
elem: VacantEntryState<K, V, M>,
},
TableIsEmpty,
}
impl<K, V, M> InternalEntry<K, V, M> {
#[inline]
fn into_occupied_bucket(self) -> Option<FullBucket<K, V, M>> {
match self {
InternalEntry::Occupied { elem } => Some(elem),
_ => None,
}
}
}
impl<'a, K, V> InternalEntry<K, V, &'a mut RawTable<K, V>> {
#[inline]
fn into_entry(self, key: K) -> Option<Entry<'a, K, V>> {
match self {
InternalEntry::Occupied { elem } => {
Some(Occupied(OccupiedEntry {
key: Some(key),
elem,
}))
}
InternalEntry::Vacant { hash, elem } => {
Some(Vacant(VacantEntry {
hash,
key,
elem,
}))
}
InternalEntry::TableIsEmpty => None,
}
}
}
/// A builder for computing where in a HashMap a key-value pair would be stored.
///
/// See the [`HashMap::raw_entry_mut`] docs for usage examples.
///
/// [`HashMap::raw_entry_mut`]: struct.HashMap.html#method.raw_entry_mut
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub struct RawEntryBuilderMut<'a, K: 'a, V: 'a, S: 'a> {
map: &'a mut HashMap<K, V, S>,
}
/// A view into a single entry in a map, which may either be vacant or occupied.
///
/// This is a lower-level version of [`Entry`].
///
/// This `enum` is constructed from the [`raw_entry`] method on [`HashMap`].
///
/// [`HashMap`]: struct.HashMap.html
/// [`Entry`]: enum.Entry.html
/// [`raw_entry`]: struct.HashMap.html#method.raw_entry
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub enum RawEntryMut<'a, K: 'a, V: 'a, S: 'a> {
/// An occupied entry.
Occupied(RawOccupiedEntryMut<'a, K, V>),
/// A vacant entry.
Vacant(RawVacantEntryMut<'a, K, V, S>),
}
/// A view into an occupied entry in a `HashMap`.
/// It is part of the [`RawEntryMut`] enum.
///
/// [`RawEntryMut`]: enum.RawEntryMut.html
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub struct RawOccupiedEntryMut<'a, K: 'a, V: 'a> {
elem: FullBucket<K, V, &'a mut RawTable<K, V>>,
}
/// A view into a vacant entry in a `HashMap`.
/// It is part of the [`RawEntryMut`] enum.
///
/// [`RawEntryMut`]: enum.RawEntryMut.html
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub struct RawVacantEntryMut<'a, K: 'a, V: 'a, S: 'a> {
elem: VacantEntryState<K, V, &'a mut RawTable<K, V>>,
hash_builder: &'a S,
}
/// A builder for computing where in a HashMap a key-value pair would be stored.
///
/// See the [`HashMap::raw_entry`] docs for usage examples.
///
/// [`HashMap::raw_entry`]: struct.HashMap.html#method.raw_entry
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub struct RawEntryBuilder<'a, K: 'a, V: 'a, S: 'a> {
map: &'a HashMap<K, V, S>,
}
impl<'a, K, V, S> RawEntryBuilderMut<'a, K, V, S>
where S: BuildHasher,
K: Eq + Hash,
{
/// Create a `RawEntryMut` from the given key.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_key<Q: ?Sized>(self, k: &Q) -> RawEntryMut<'a, K, V, S>
where K: Borrow<Q>,
Q: Hash + Eq
{
let mut hasher = self.map.hash_builder.build_hasher();
k.hash(&mut hasher);
self.from_key_hashed_nocheck(hasher.finish(), k)
}
/// Create a `RawEntryMut` from the given key and its hash.
#[inline]
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> RawEntryMut<'a, K, V, S>
where K: Borrow<Q>,
Q: Eq
{
self.from_hash(hash, |q| q.borrow().eq(k))
}
#[inline]
fn search<F>(self, hash: u64, is_match: F, compare_hashes: bool) -> RawEntryMut<'a, K, V, S>
where for<'b> F: FnMut(&'b K) -> bool,
{
match search_hashed_nonempty_mut(&mut self.map.table,
SafeHash::new(hash),
is_match,
compare_hashes) {
InternalEntry::Occupied { elem } => {
RawEntryMut::Occupied(RawOccupiedEntryMut { elem })
}
InternalEntry::Vacant { elem, .. } => {
RawEntryMut::Vacant(RawVacantEntryMut {
elem,
hash_builder: &self.map.hash_builder,
})
}
InternalEntry::TableIsEmpty => {
unreachable!()
}
}
}
/// Create a `RawEntryMut` from the given hash.
#[inline]
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_hash<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S>
where for<'b> F: FnMut(&'b K) -> bool,
{
self.search(hash, is_match, true)
}
/// Search possible locations for an element with hash `hash` until `is_match` returns true for
/// one of them. There is no guarantee that all keys passed to `is_match` will have the provided
/// hash.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn search_bucket<F>(self, hash: u64, is_match: F) -> RawEntryMut<'a, K, V, S>
where for<'b> F: FnMut(&'b K) -> bool,
{
self.search(hash, is_match, false)
}
}
impl<'a, K, V, S> RawEntryBuilder<'a, K, V, S>
where S: BuildHasher,
{
/// Access an entry by key.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_key<Q: ?Sized>(self, k: &Q) -> Option<(&'a K, &'a V)>
where K: Borrow<Q>,
Q: Hash + Eq
{
let mut hasher = self.map.hash_builder.build_hasher();
k.hash(&mut hasher);
self.from_key_hashed_nocheck(hasher.finish(), k)
}
/// Access an entry by a key and its hash.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_key_hashed_nocheck<Q: ?Sized>(self, hash: u64, k: &Q) -> Option<(&'a K, &'a V)>
where K: Borrow<Q>,
Q: Hash + Eq
{
self.from_hash(hash, |q| q.borrow().eq(k))
}
fn search<F>(self, hash: u64, is_match: F, compare_hashes: bool) -> Option<(&'a K, &'a V)>
where F: FnMut(&K) -> bool
{
if unsafe { unlikely(self.map.table.size() == 0) } {
return None;
}
match search_hashed_nonempty(&self.map.table,
SafeHash::new(hash),
is_match,
compare_hashes) {
InternalEntry::Occupied { elem } => Some(elem.into_refs()),
InternalEntry::Vacant { .. } => None,
InternalEntry::TableIsEmpty => unreachable!(),
}
}
/// Access an entry by hash.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn from_hash<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)>
where F: FnMut(&K) -> bool
{
self.search(hash, is_match, true)
}
/// Search possible locations for an element with hash `hash` until `is_match` returns true for
/// one of them. There is no guarantee that all keys passed to `is_match` will have the provided
/// hash.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn search_bucket<F>(self, hash: u64, is_match: F) -> Option<(&'a K, &'a V)>
where F: FnMut(&K) -> bool
{
self.search(hash, is_match, false)
}
}
impl<'a, K, V, S> RawEntryMut<'a, K, V, S> {
/// Ensures a value is in the entry by inserting the default if empty, and returns
/// mutable references to the key and value in the entry.
///
/// # Examples
///
/// ```
/// #![feature(hash_raw_entry)]
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 3);
/// assert_eq!(map["poneyland"], 3);
///
/// *map.raw_entry_mut().from_key("poneyland").or_insert("poneyland", 10).1 *= 2;
/// assert_eq!(map["poneyland"], 6);
/// ```
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn or_insert(self, default_key: K, default_val: V) -> (&'a mut K, &'a mut V)
where K: Hash,
S: BuildHasher,
{
match self {
RawEntryMut::Occupied(entry) => entry.into_key_value(),
RawEntryMut::Vacant(entry) => entry.insert(default_key, default_val),
}
}
/// Ensures a value is in the entry by inserting the result of the default function if empty,
/// and returns mutable references to the key and value in the entry.
///
/// # Examples
///
/// ```
/// #![feature(hash_raw_entry)]
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, String> = HashMap::new();
///
/// map.raw_entry_mut().from_key("poneyland").or_insert_with(|| {
/// ("poneyland", "hoho".to_string())
/// });
///
/// assert_eq!(map["poneyland"], "hoho".to_string());
/// ```
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn or_insert_with<F>(self, default: F) -> (&'a mut K, &'a mut V)
where F: FnOnce() -> (K, V),
K: Hash,
S: BuildHasher,
{
match self {
RawEntryMut::Occupied(entry) => entry.into_key_value(),
RawEntryMut::Vacant(entry) => {
let (k, v) = default();
entry.insert(k, v)
}
}
}
/// Provides in-place mutable access to an occupied entry before any
/// potential inserts into the map.
///
/// # Examples
///
/// ```
/// #![feature(hash_raw_entry)]
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// map.raw_entry_mut()
/// .from_key("poneyland")
/// .and_modify(|_k, v| { *v += 1 })
/// .or_insert("poneyland", 42);
/// assert_eq!(map["poneyland"], 42);
///
/// map.raw_entry_mut()
/// .from_key("poneyland")
/// .and_modify(|_k, v| { *v += 1 })
/// .or_insert("poneyland", 0);
/// assert_eq!(map["poneyland"], 43);
/// ```
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn and_modify<F>(self, f: F) -> Self
where F: FnOnce(&mut K, &mut V)
{
match self {
RawEntryMut::Occupied(mut entry) => {
{
let (k, v) = entry.get_key_value_mut();
f(k, v);
}
RawEntryMut::Occupied(entry)
},
RawEntryMut::Vacant(entry) => RawEntryMut::Vacant(entry),
}
}
}
impl<'a, K, V> RawOccupiedEntryMut<'a, K, V> {
/// Gets a reference to the key in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn key(&self) -> &K {
self.elem.read().0
}
/// Gets a mutable reference to the key in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn key_mut(&mut self) -> &mut K {
self.elem.read_mut().0
}
/// Converts the entry into a mutable reference to the key in the entry
/// with a lifetime bound to the map itself.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn into_key(self) -> &'a mut K {
self.elem.into_mut_refs().0
}
/// Gets a reference to the value in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn get(&self) -> &V {
self.elem.read().1
}
/// Converts the OccupiedEntry into a mutable reference to the value in the entry
/// with a lifetime bound to the map itself.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn into_mut(self) -> &'a mut V {
self.elem.into_mut_refs().1
}
/// Gets a mutable reference to the value in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn get_mut(&mut self) -> &mut V {
self.elem.read_mut().1
}
/// Gets a reference to the key and value in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn get_key_value(&mut self) -> (&K, &V) {
self.elem.read()
}
/// Gets a mutable reference to the key and value in the entry.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn get_key_value_mut(&mut self) -> (&mut K, &mut V) {
self.elem.read_mut()
}
/// Converts the OccupiedEntry into a mutable reference to the key and value in the entry
/// with a lifetime bound to the map itself.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn into_key_value(self) -> (&'a mut K, &'a mut V) {
self.elem.into_mut_refs()
}
/// Sets the value of the entry, and returns the entry's old value.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn insert(&mut self, value: V) -> V {
mem::replace(self.get_mut(), value)
}
/// Sets the value of the entry, and returns the entry's old value.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn insert_key(&mut self, key: K) -> K {
mem::replace(self.key_mut(), key)
}
/// Takes the value out of the entry, and returns it.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn remove(self) -> V {
pop_internal(self.elem).1
}
/// Take the ownership of the key and value from the map.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn remove_entry(self) -> (K, V) {
let (k, v, _) = pop_internal(self.elem);
(k, v)
}
}
impl<'a, K, V, S> RawVacantEntryMut<'a, K, V, S> {
/// Sets the value of the entry with the VacantEntry's key,
/// and returns a mutable reference to it.
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn insert(self, key: K, value: V) -> (&'a mut K, &'a mut V)
where K: Hash,
S: BuildHasher,
{
let mut hasher = self.hash_builder.build_hasher();
key.hash(&mut hasher);
self.insert_hashed_nocheck(hasher.finish(), key, value)
}
/// Sets the value of the entry with the VacantEntry's key,
/// and returns a mutable reference to it.
#[inline]
#[unstable(feature = "hash_raw_entry", issue = "56167")]
pub fn insert_hashed_nocheck(self, hash: u64, key: K, value: V) -> (&'a mut K, &'a mut V) {
let hash = SafeHash::new(hash);
let b = match self.elem {
NeqElem(mut bucket, disp) => {
if disp >= DISPLACEMENT_THRESHOLD {
bucket.table_mut().set_tag(true);
}
robin_hood(bucket, disp, hash, key, value)
},
NoElem(mut bucket, disp) => {
if disp >= DISPLACEMENT_THRESHOLD {
bucket.table_mut().set_tag(true);
}
bucket.put(hash, key, value)
},
};
b.into_mut_refs()
}
}
#[unstable(feature = "hash_raw_entry", issue = "56167")]
impl<'a, K, V, S> Debug for RawEntryBuilderMut<'a, K, V, S> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RawEntryBuilder")
.finish()
}
}
#[unstable(feature = "hash_raw_entry", issue = "56167")]
impl<'a, K: Debug, V: Debug, S> Debug for RawEntryMut<'a, K, V, S> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
RawEntryMut::Vacant(ref v) => {
f.debug_tuple("RawEntry")
.field(v)
.finish()
}
RawEntryMut::Occupied(ref o) => {
f.debug_tuple("RawEntry")
.field(o)
.finish()
}
}
}
}
#[unstable(feature = "hash_raw_entry", issue = "56167")]
impl<'a, K: Debug, V: Debug> Debug for RawOccupiedEntryMut<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RawOccupiedEntryMut")
.field("key", self.key())
.field("value", self.get())
.finish()
}
}
#[unstable(feature = "hash_raw_entry", issue = "56167")]
impl<'a, K, V, S> Debug for RawVacantEntryMut<'a, K, V, S> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RawVacantEntryMut")
.finish()
}
}
#[unstable(feature = "hash_raw_entry", issue = "56167")]
impl<'a, K, V, S> Debug for RawEntryBuilder<'a, K, V, S> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("RawEntryBuilder")
.finish()
}
}
/// A view into a single entry in a map, which may either be vacant or occupied.
///
/// This `enum` is constructed from the [`entry`] method on [`HashMap`].
///
/// [`HashMap`]: struct.HashMap.html
/// [`entry`]: struct.HashMap.html#method.entry
#[stable(feature = "rust1", since = "1.0.0")]
pub enum Entry<'a, K: 'a, V: 'a> {
/// An occupied entry.
#[stable(feature = "rust1", since = "1.0.0")]
Occupied(#[stable(feature = "rust1", since = "1.0.0")]
OccupiedEntry<'a, K, V>),
/// A vacant entry.
#[stable(feature = "rust1", since = "1.0.0")]
Vacant(#[stable(feature = "rust1", since = "1.0.0")]
VacantEntry<'a, K, V>),
}
#[stable(feature= "debug_hash_map", since = "1.12.0")]
impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for Entry<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Vacant(ref v) => {
f.debug_tuple("Entry")
.field(v)
.finish()
}
Occupied(ref o) => {
f.debug_tuple("Entry")
.field(o)
.finish()
}
}
}
}
/// A view into an occupied entry in a `HashMap`.
/// It is part of the [`Entry`] enum.
///
/// [`Entry`]: enum.Entry.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct OccupiedEntry<'a, K: 'a, V: 'a> {
key: Option<K>,
elem: FullBucket<K, V, &'a mut RawTable<K, V>>,
}
#[stable(feature= "debug_hash_map", since = "1.12.0")]
impl<'a, K: 'a + Debug, V: 'a + Debug> Debug for OccupiedEntry<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("OccupiedEntry")
.field("key", self.key())
.field("value", self.get())
.finish()
}
}
/// A view into a vacant entry in a `HashMap`.
/// It is part of the [`Entry`] enum.
///
/// [`Entry`]: enum.Entry.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct VacantEntry<'a, K: 'a, V: 'a> {
hash: SafeHash,
key: K,
elem: VacantEntryState<K, V, &'a mut RawTable<K, V>>,
}
#[stable(feature= "debug_hash_map", since = "1.12.0")]
impl<'a, K: 'a + Debug, V: 'a> Debug for VacantEntry<'a, K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_tuple("VacantEntry")
.field(self.key())
.finish()
}
}
/// Possible states of a VacantEntry.
enum VacantEntryState<K, V, M> {
/// The index is occupied, but the key to insert has precedence,
/// and will kick the current one out on insertion.
NeqElem(FullBucket<K, V, M>, usize),
/// The index is genuinely vacant.
NoElem(EmptyBucket<K, V, M>, usize),
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
type Item = (&'a K, &'a V);
type IntoIter = Iter<'a, K, V>;
fn into_iter(self) -> Iter<'a, K, V> {
self.iter()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
type Item = (&'a K, &'a mut V);
type IntoIter = IterMut<'a, K, V>;
fn into_iter(self) -> IterMut<'a, K, V> {
self.iter_mut()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> IntoIterator for HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
type Item = (K, V);
type IntoIter = IntoIter<K, V>;
/// Creates a consuming iterator, that is, one that moves each key-value
/// pair out of the map in arbitrary order. The map cannot be used after
/// calling this.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map = HashMap::new();
/// map.insert("a", 1);
/// map.insert("b", 2);
/// map.insert("c", 3);
///
/// // Not possible with .iter()
/// let vec: Vec<(&str, i32)> = map.into_iter().collect();
/// ```
fn into_iter(self) -> IntoIter<K, V> {
IntoIter { inner: self.table.into_iter() }
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for Iter<'a, K, V> {
type Item = (&'a K, &'a V);
#[inline]
fn next(&mut self) -> Option<(&'a K, &'a V)> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Iter<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for Iter<'a, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> Iterator for IterMut<'a, K, V> {
type Item = (&'a K, &'a mut V);
#[inline]
fn next(&mut self) -> Option<(&'a K, &'a mut V)> {
self.inner.next()
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for IterMut<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for IterMut<'a, K, V> {}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K, V> fmt::Debug for IterMut<'a, K, V>
where K: fmt::Debug,
V: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.inner.iter())
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> Iterator for IntoIter<K, V> {
type Item = (K, V);
#[inline]
fn next(&mut self) -> Option<(K, V)> {
self.inner.next().map(|(_, k, v)| (k, v))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V> ExactSizeIterator for IntoIter<K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<K, V> FusedIterator for IntoIter<K, V> {}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<K: Debug, V: Debug> fmt::Debug for IntoIter<K, V> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.inner.iter())
.finish()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
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()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Keys<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for Keys<'a, K, V> {}
#[stable(feature = "rust1", since = "1.0.0")]
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()
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a, K, V> ExactSizeIterator for Values<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for Values<'a, K, V> {}
#[stable(feature = "map_values_mut", since = "1.10.0")]
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()
}
}
#[stable(feature = "map_values_mut", since = "1.10.0")]
impl<'a, K, V> ExactSizeIterator for ValuesMut<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for ValuesMut<'a, K, V> {}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K, V> fmt::Debug for ValuesMut<'a, K, V>
where K: fmt::Debug,
V: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.inner.inner.iter())
.finish()
}
}
#[stable(feature = "drain", since = "1.6.0")]
impl<'a, K, V> Iterator for Drain<'a, K, V> {
type Item = (K, V);
#[inline]
fn next(&mut self) -> Option<(K, V)> {
self.inner.next().map(|(_, k, v)| (k, v))
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.inner.size_hint()
}
}
#[stable(feature = "drain", since = "1.6.0")]
impl<'a, K, V> ExactSizeIterator for Drain<'a, K, V> {
#[inline]
fn len(&self) -> usize {
self.inner.len()
}
}
#[stable(feature = "fused", since = "1.26.0")]
impl<'a, K, V> FusedIterator for Drain<'a, K, V> {}
#[stable(feature = "std_debug", since = "1.16.0")]
impl<'a, K, V> fmt::Debug for Drain<'a, K, V>
where K: fmt::Debug,
V: fmt::Debug,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_list()
.entries(self.inner.iter())
.finish()
}
}
impl<'a, K, V> Entry<'a, K, V> {
#[stable(feature = "rust1", since = "1.0.0")]
/// Ensures a value is in the entry by inserting the default if empty, and returns
/// a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// map.entry("poneyland").or_insert(3);
/// assert_eq!(map["poneyland"], 3);
///
/// *map.entry("poneyland").or_insert(10) *= 2;
/// assert_eq!(map["poneyland"], 6);
/// ```
pub fn or_insert(self, default: V) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default),
}
}
#[stable(feature = "rust1", since = "1.0.0")]
/// Ensures a value is in the entry by inserting the result of the default function if empty,
/// and returns a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, String> = HashMap::new();
/// let s = "hoho".to_string();
///
/// map.entry("poneyland").or_insert_with(|| s);
///
/// assert_eq!(map["poneyland"], "hoho".to_string());
/// ```
pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(default()),
}
}
/// Returns a reference to this entry's key.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
match *self {
Occupied(ref entry) => entry.key(),
Vacant(ref entry) => entry.key(),
}
}
/// Provides in-place mutable access to an occupied entry before any
/// potential inserts into the map.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// map.entry("poneyland")
/// .and_modify(|e| { *e += 1 })
/// .or_insert(42);
/// assert_eq!(map["poneyland"], 42);
///
/// map.entry("poneyland")
/// .and_modify(|e| { *e += 1 })
/// .or_insert(42);
/// assert_eq!(map["poneyland"], 43);
/// ```
#[stable(feature = "entry_and_modify", since = "1.26.0")]
pub fn and_modify<F>(self, f: F) -> Self
where F: FnOnce(&mut V)
{
match self {
Occupied(mut entry) => {
f(entry.get_mut());
Occupied(entry)
},
Vacant(entry) => Vacant(entry),
}
}
}
impl<'a, K, V: Default> Entry<'a, K, V> {
#[stable(feature = "entry_or_default", since = "1.28.0")]
/// Ensures a value is in the entry by inserting the default value if empty,
/// and returns a mutable reference to the value in the entry.
///
/// # Examples
///
/// ```
/// # fn main() {
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, Option<u32>> = HashMap::new();
/// map.entry("poneyland").or_default();
///
/// assert_eq!(map["poneyland"], None);
/// # }
/// ```
pub fn or_default(self) -> &'a mut V {
match self {
Occupied(entry) => entry.into_mut(),
Vacant(entry) => entry.insert(Default::default()),
}
}
}
impl<'a, K, V> OccupiedEntry<'a, K, V> {
/// Gets a reference to the key in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
self.elem.read().0
}
/// Take the ownership of the key and value from the map.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// // We delete the entry from the map.
/// o.remove_entry();
/// }
///
/// assert_eq!(map.contains_key("poneyland"), false);
/// ```
#[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
pub fn remove_entry(self) -> (K, V) {
let (k, v, _) = pop_internal(self.elem);
(k, v)
}
/// Gets a reference to the value in the entry.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// assert_eq!(o.get(), &12);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get(&self) -> &V {
self.elem.read().1
}
/// Gets a mutable reference to the value in the entry.
///
/// If you need a reference to the `OccupiedEntry` which may outlive the
/// destruction of the `Entry` value, see [`into_mut`].
///
/// [`into_mut`]: #method.into_mut
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// assert_eq!(map["poneyland"], 12);
/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
/// *o.get_mut() += 10;
/// assert_eq!(*o.get(), 22);
///
/// // We can use the same Entry multiple times.
/// *o.get_mut() += 2;
/// }
///
/// assert_eq!(map["poneyland"], 24);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn get_mut(&mut self) -> &mut V {
self.elem.read_mut().1
}
/// Converts the OccupiedEntry into a mutable reference to the value in the entry
/// with a lifetime bound to the map itself.
///
/// If you need multiple references to the `OccupiedEntry`, see [`get_mut`].
///
/// [`get_mut`]: #method.get_mut
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// assert_eq!(map["poneyland"], 12);
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// *o.into_mut() += 10;
/// }
///
/// assert_eq!(map["poneyland"], 22);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_mut(self) -> &'a mut V {
self.elem.into_mut_refs().1
}
/// Sets the value of the entry, and returns the entry's old value.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(mut o) = map.entry("poneyland") {
/// assert_eq!(o.insert(15), 12);
/// }
///
/// assert_eq!(map["poneyland"], 15);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(&mut self, mut value: V) -> V {
let old_value = self.get_mut();
mem::swap(&mut value, old_value);
value
}
/// Takes the value out of the entry, and returns it.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// map.entry("poneyland").or_insert(12);
///
/// if let Entry::Occupied(o) = map.entry("poneyland") {
/// assert_eq!(o.remove(), 12);
/// }
///
/// assert_eq!(map.contains_key("poneyland"), false);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn remove(self) -> V {
pop_internal(self.elem).1
}
/// Returns a key that was used for search.
///
/// The key was retained for further use.
fn take_key(&mut self) -> Option<K> {
self.key.take()
}
/// Replaces the entry, returning the old key and value. The new key in the hash map will be
/// the key used to create this entry.
///
/// # Examples
///
/// ```
/// #![feature(map_entry_replace)]
/// use std::collections::hash_map::{Entry, HashMap};
/// use std::rc::Rc;
///
/// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
/// map.insert(Rc::new("Stringthing".to_string()), 15);
///
/// let my_key = Rc::new("Stringthing".to_string());
///
/// if let Entry::Occupied(entry) = map.entry(my_key) {
/// // Also replace the key with a handle to our other key.
/// let (old_key, old_value): (Rc<String>, u32) = entry.replace_entry(16);
/// }
///
/// ```
#[unstable(feature = "map_entry_replace", issue = "44286")]
pub fn replace_entry(mut self, value: V) -> (K, V) {
let (old_key, old_value) = self.elem.read_mut();
let old_key = mem::replace(old_key, self.key.unwrap());
let old_value = mem::replace(old_value, value);
(old_key, old_value)
}
/// Replaces the key in the hash map with the key used to create this entry.
///
/// # Examples
///
/// ```
/// #![feature(map_entry_replace)]
/// use std::collections::hash_map::{Entry, HashMap};
/// use std::rc::Rc;
///
/// let mut map: HashMap<Rc<String>, u32> = HashMap::new();
/// let mut known_strings: Vec<Rc<String>> = Vec::new();
///
/// // Initialise known strings, run program, etc.
///
/// reclaim_memory(&mut map, &known_strings);
///
/// fn reclaim_memory(map: &mut HashMap<Rc<String>, u32>, known_strings: &[Rc<String>] ) {
/// for s in known_strings {
/// if let Entry::Occupied(entry) = map.entry(s.clone()) {
/// // Replaces the entry's key with our version of it in `known_strings`.
/// entry.replace_key();
/// }
/// }
/// }
/// ```
#[unstable(feature = "map_entry_replace", issue = "44286")]
pub fn replace_key(mut self) -> K {
let (old_key, _) = self.elem.read_mut();
mem::replace(old_key, self.key.unwrap())
}
}
impl<'a, K: 'a, V: 'a> VacantEntry<'a, K, V> {
/// Gets a reference to the key that would be used when inserting a value
/// through the `VacantEntry`.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
/// assert_eq!(map.entry("poneyland").key(), &"poneyland");
/// ```
#[stable(feature = "map_entry_keys", since = "1.10.0")]
pub fn key(&self) -> &K {
&self.key
}
/// Take ownership of the key.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// if let Entry::Vacant(v) = map.entry("poneyland") {
/// v.into_key();
/// }
/// ```
#[stable(feature = "map_entry_recover_keys2", since = "1.12.0")]
pub fn into_key(self) -> K {
self.key
}
/// Sets the value of the entry with the VacantEntry's key,
/// and returns a mutable reference to it.
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::Entry;
///
/// let mut map: HashMap<&str, u32> = HashMap::new();
///
/// if let Entry::Vacant(o) = map.entry("poneyland") {
/// o.insert(37);
/// }
/// assert_eq!(map["poneyland"], 37);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn insert(self, value: V) -> &'a mut V {
let b = match self.elem {
NeqElem(mut bucket, disp) => {
if disp >= DISPLACEMENT_THRESHOLD {
bucket.table_mut().set_tag(true);
}
robin_hood(bucket, disp, self.hash, self.key, value)
},
NoElem(mut bucket, disp) => {
if disp >= DISPLACEMENT_THRESHOLD {
bucket.table_mut().set_tag(true);
}
bucket.put(self.hash, self.key, value)
},
};
b.into_mut_refs().1
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> FromIterator<(K, V)> for HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher + Default
{
fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> HashMap<K, V, S> {
let mut map = HashMap::with_hasher(Default::default());
map.extend(iter);
map
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<K, V, S> Extend<(K, V)> for HashMap<K, V, S>
where K: Eq + Hash,
S: BuildHasher
{
fn extend<T: IntoIterator<Item = (K, V)>>(&mut self, iter: T) {
// 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 = iter.into_iter();
let reserve = if self.is_empty() {
iter.size_hint().0
} else {
(iter.size_hint().0 + 1) / 2
};
self.reserve(reserve);
for (k, v) in iter {
self.insert(k, v);
}
}
}
#[stable(feature = "hash_extend_copy", since = "1.4.0")]
impl<'a, K, V, S> Extend<(&'a K, &'a V)> for HashMap<K, V, S>
where K: Eq + Hash + Copy,
V: Copy,
S: BuildHasher
{
fn extend<T: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: T) {
self.extend(iter.into_iter().map(|(&key, &value)| (key, value)));
}
}
/// `RandomState` is the default state for [`HashMap`] types.
///
/// A particular instance `RandomState` will create the same instances of
/// [`Hasher`], but the hashers created by two different `RandomState`
/// instances are unlikely to produce the same result for the same values.
///
/// [`HashMap`]: struct.HashMap.html
/// [`Hasher`]: ../../hash/trait.Hasher.html
///
/// # Examples
///
/// ```
/// use std::collections::HashMap;
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// let mut map = HashMap::with_hasher(s);
/// map.insert(1, 2);
/// ```
#[derive(Clone)]
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
pub struct RandomState {
k0: u64,
k1: u64,
}
impl RandomState {
/// Constructs a new `RandomState` that is initialized with random keys.
///
/// # Examples
///
/// ```
/// use std::collections::hash_map::RandomState;
///
/// let s = RandomState::new();
/// ```
#[inline]
#[allow(deprecated)]
// rand
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
pub fn new() -> RandomState {
// Historically this function did not cache keys from the OS and instead
// simply always called `rand::thread_rng().gen()` twice. In #31356 it
// was discovered, however, that because we re-seed the thread-local RNG
// from the OS periodically that this can cause excessive slowdown when
// many hash maps are created on a thread. To solve this performance
// trap we cache the first set of randomly generated keys per-thread.
//
// Later in #36481 it was discovered that exposing a deterministic
// iteration order allows a form of DOS attack. To counter that we
// increment one of the seeds on every RandomState creation, giving
// every corresponding HashMap a different iteration order.
thread_local!(static KEYS: Cell<(u64, u64)> = {
Cell::new(sys::hashmap_random_keys())
});
KEYS.with(|keys| {
let (k0, k1) = keys.get();
keys.set((k0.wrapping_add(1), k1));
RandomState { k0: k0, k1: k1 }
})
}
}
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
impl BuildHasher for RandomState {
type Hasher = DefaultHasher;
#[inline]
#[allow(deprecated)]
fn build_hasher(&self) -> DefaultHasher {
DefaultHasher(SipHasher13::new_with_keys(self.k0, self.k1))
}
}
/// The default [`Hasher`] used by [`RandomState`].
///
/// The internal algorithm is not specified, and so it and its hashes should
/// not be relied upon over releases.
///
/// [`RandomState`]: struct.RandomState.html
/// [`Hasher`]: ../../hash/trait.Hasher.html
#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
#[allow(deprecated)]
#[derive(Clone, Debug)]
pub struct DefaultHasher(SipHasher13);
impl DefaultHasher {
/// Creates a new `DefaultHasher`.
///
/// This hasher is not guaranteed to be the same as all other
/// `DefaultHasher` instances, but is the same as all other `DefaultHasher`
/// instances created through `new` or `default`.
#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
#[allow(deprecated)]
pub fn new() -> DefaultHasher {
DefaultHasher(SipHasher13::new_with_keys(0, 0))
}
}
#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
impl Default for DefaultHasher {
/// Creates a new `DefaultHasher` using [`new`][DefaultHasher::new].
/// See its documentation for more.
fn default() -> DefaultHasher {
DefaultHasher::new()
}
}
#[stable(feature = "hashmap_default_hasher", since = "1.13.0")]
impl Hasher for DefaultHasher {
#[inline]
fn write(&mut self, msg: &[u8]) {
self.0.write(msg)
}
#[inline]
fn finish(&self) -> u64 {
self.0.finish()
}
}
#[stable(feature = "hashmap_build_hasher", since = "1.7.0")]
impl Default for RandomState {
/// Constructs a new `RandomState`.
#[inline]
fn default() -> RandomState {
RandomState::new()
}
}
#[stable(feature = "std_debug", since = "1.16.0")]
impl fmt::Debug for RandomState {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.pad("RandomState { .. }")
}
}
impl<K, S, Q: ?Sized> super::Recover<Q> for HashMap<K, (), S>
where K: Eq + Hash + Borrow<Q>,
S: BuildHasher,
Q: Eq + Hash
{
type Key = K;
#[inline]
fn get(&self, key: &Q) -> Option<&K> {
self.search(key).map(|bucket| bucket.into_refs().0)
}
fn take(&mut self, key: &Q) -> Option<K> {
self.search_mut(key).map(|bucket| pop_internal(bucket).0)
}
#[inline]
fn replace(&mut self, key: K) -> Option<K> {
self.reserve(1);
match self.entry(key) {
Occupied(mut occupied) => {
let key = occupied.take_key().unwrap();
Some(mem::replace(occupied.elem.read_mut().0, key))
}
Vacant(vacant) => {
vacant.insert(());
None
}
}
}
}
#[allow(dead_code)]
fn assert_covariance() {
fn map_key<'new>(v: HashMap<&'static str, u8>) -> HashMap<&'new str, u8> {
v
}
fn map_val<'new>(v: HashMap<u8, &'static str>) -> HashMap<u8, &'new str> {
v
}
fn iter_key<'a, 'new>(v: Iter<'a, &'static str, u8>) -> Iter<'a, &'new str, u8> {
v
}
fn iter_val<'a, 'new>(v: Iter<'a, u8, &'static str>) -> Iter<'a, u8, &'new str> {
v
}
fn into_iter_key<'new>(v: IntoIter<&'static str, u8>) -> IntoIter<&'new str, u8> {
v
}
fn into_iter_val<'new>(v: IntoIter<u8, &'static str>) -> IntoIter<u8, &'new str> {
v
}
fn keys_key<'a, 'new>(v: Keys<'a, &'static str, u8>) -> Keys<'a, &'new str, u8> {
v
}
fn keys_val<'a, 'new>(v: Keys<'a, u8, &'static str>) -> Keys<'a, u8, &'new str> {
v
}
fn values_key<'a, 'new>(v: Values<'a, &'static str, u8>) -> Values<'a, &'new str, u8> {
v
}
fn values_val<'a, 'new>(v: Values<'a, u8, &'static str>) -> Values<'a, u8, &'new str> {
v
}
fn drain<'new>(d: Drain<'static, &'static str, &'static str>)
-> Drain<'new, &'new str, &'new str> {
d
}
}
#[cfg(test)]
mod test_map {
use super::HashMap;
use super::Entry::{Occupied, Vacant};
use super::RandomState;
use cell::RefCell;
use rand::{thread_rng, Rng};
use realstd::collections::CollectionAllocErr::*;
use realstd::mem::size_of;
use realstd::usize;
#[test]
fn test_zero_capacities() {
type HM = HashMap<i32, i32>;
let m = HM::new();
assert_eq!(m.capacity(), 0);
let m = HM::default();
assert_eq!(m.capacity(), 0);
let m = HM::with_hasher(RandomState::new());
assert_eq!(m.capacity(), 0);
let m = HM::with_capacity(0);
assert_eq!(m.capacity(), 0);
let m = HM::with_capacity_and_hasher(0, RandomState::new());
assert_eq!(m.capacity(), 0);
let mut m = HM::new();
m.insert(1, 1);
m.insert(2, 2);
m.remove(&1);
m.remove(&2);
m.shrink_to_fit();
assert_eq!(m.capacity(), 0);
let mut m = HM::new();
m.reserve(0);
assert_eq!(m.capacity(), 0);
}
#[test]
fn test_create_capacity_zero() {
let mut m = HashMap::with_capacity(0);
assert!(m.insert(1, 1).is_none());
assert!(m.contains_key(&1));
assert!(!m.contains_key(&0));
}
#[test]
fn test_insert() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.insert(1, 2).is_none());
assert_eq!(m.len(), 1);
assert!(m.insert(2, 4).is_none());
assert_eq!(m.len(), 2);
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&2).unwrap(), 4);
}
#[test]
fn test_clone() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.insert(1, 2).is_none());
assert_eq!(m.len(), 1);
assert!(m.insert(2, 4).is_none());
assert_eq!(m.len(), 2);
let m2 = m.clone();
assert_eq!(*m2.get(&1).unwrap(), 2);
assert_eq!(*m2.get(&2).unwrap(), 4);
assert_eq!(m2.len(), 2);
}
thread_local! { static DROP_VECTOR: RefCell<Vec<i32>> = RefCell::new(Vec::new()) }
#[derive(Hash, PartialEq, Eq)]
struct Droppable {
k: usize,
}
impl Droppable {
fn new(k: usize) -> Droppable {
DROP_VECTOR.with(|slot| {
slot.borrow_mut()[k] += 1;
});
Droppable { k }
}
}
impl Drop for Droppable {
fn drop(&mut self) {
DROP_VECTOR.with(|slot| {
slot.borrow_mut()[self.k] -= 1;
});
}
}
impl Clone for Droppable {
fn clone(&self) -> Droppable {
Droppable::new(self.k)
}
}
#[test]
fn test_drops() {
DROP_VECTOR.with(|slot| {
*slot.borrow_mut() = vec![0; 200];
});
{
let mut m = HashMap::new();
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
for i in 0..100 {
let d1 = Droppable::new(i);
let d2 = Droppable::new(i + 100);
m.insert(d1, d2);
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
for i in 0..50 {
let k = Droppable::new(i);
let v = m.remove(&k);
assert!(v.is_some());
DROP_VECTOR.with(|v| {
assert_eq!(v.borrow()[i], 1);
assert_eq!(v.borrow()[i+100], 1);
});
}
DROP_VECTOR.with(|v| {
for i in 0..50 {
assert_eq!(v.borrow()[i], 0);
assert_eq!(v.borrow()[i+100], 0);
}
for i in 50..100 {
assert_eq!(v.borrow()[i], 1);
assert_eq!(v.borrow()[i+100], 1);
}
});
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
}
#[test]
fn test_into_iter_drops() {
DROP_VECTOR.with(|v| {
*v.borrow_mut() = vec![0; 200];
});
let hm = {
let mut hm = HashMap::new();
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
for i in 0..100 {
let d1 = Droppable::new(i);
let d2 = Droppable::new(i + 100);
hm.insert(d1, d2);
}
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
hm
};
// By the way, ensure that cloning doesn't screw up the dropping.
drop(hm.clone());
{
let mut half = hm.into_iter().take(50);
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 1);
}
});
for _ in half.by_ref() {}
DROP_VECTOR.with(|v| {
let nk = (0..100)
.filter(|&i| v.borrow()[i] == 1)
.count();
let nv = (0..100)
.filter(|&i| v.borrow()[i + 100] == 1)
.count();
assert_eq!(nk, 50);
assert_eq!(nv, 50);
});
};
DROP_VECTOR.with(|v| {
for i in 0..200 {
assert_eq!(v.borrow()[i], 0);
}
});
}
#[test]
fn test_empty_remove() {
let mut m: HashMap<i32, bool> = HashMap::new();
assert_eq!(m.remove(&0), None);
}
#[test]
fn test_empty_entry() {
let mut m: HashMap<i32, bool> = HashMap::new();
match m.entry(0) {
Occupied(_) => panic!(),
Vacant(_) => {}
}
assert!(*m.entry(0).or_insert(true));
assert_eq!(m.len(), 1);
}
#[test]
fn test_empty_iter() {
let mut m: HashMap<i32, bool> = HashMap::new();
assert_eq!(m.drain().next(), None);
assert_eq!(m.keys().next(), None);
assert_eq!(m.values().next(), None);
assert_eq!(m.values_mut().next(), None);
assert_eq!(m.iter().next(), None);
assert_eq!(m.iter_mut().next(), None);
assert_eq!(m.len(), 0);
assert!(m.is_empty());
assert_eq!(m.into_iter().next(), None);
}
#[test]
fn test_lots_of_insertions() {
let mut m = HashMap::new();
// Try this a few times to make sure we never screw up the hashmap's
// internal state.
for _ in 0..10 {
assert!(m.is_empty());
for i in 1..1001 {
assert!(m.insert(i, i).is_none());
for j in 1..=i {
let r = m.get(&j);
assert_eq!(r, Some(&j));
}
for j in i + 1..1001 {
let r = m.get(&j);
assert_eq!(r, None);
}
}
for i in 1001..2001 {
assert!(!m.contains_key(&i));
}
// remove forwards
for i in 1..1001 {
assert!(m.remove(&i).is_some());
for j in 1..=i {
assert!(!m.contains_key(&j));
}
for j in i + 1..1001 {
assert!(m.contains_key(&j));
}
}
for i in 1..1001 {
assert!(!m.contains_key(&i));
}
for i in 1..1001 {
assert!(m.insert(i, i).is_none());
}
// remove backwards
for i in (1..1001).rev() {
assert!(m.remove(&i).is_some());
for j in i..1001 {
assert!(!m.contains_key(&j));
}
for j in 1..i {
assert!(m.contains_key(&j));
}
}
}
}
#[test]
fn test_find_mut() {
let mut m = HashMap::new();
assert!(m.insert(1, 12).is_none());
assert!(m.insert(2, 8).is_none());
assert!(m.insert(5, 14).is_none());
let new = 100;
match m.get_mut(&5) {
None => panic!(),
Some(x) => *x = new,
}
assert_eq!(m.get(&5), Some(&new));
}
#[test]
fn test_insert_overwrite() {
let mut m = HashMap::new();
assert!(m.insert(1, 2).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert!(!m.insert(1, 3).is_none());
assert_eq!(*m.get(&1).unwrap(), 3);
}
#[test]
fn test_insert_conflicts() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert!(m.insert(5, 3).is_none());
assert!(m.insert(9, 4).is_none());
assert_eq!(*m.get(&9).unwrap(), 4);
assert_eq!(*m.get(&5).unwrap(), 3);
assert_eq!(*m.get(&1).unwrap(), 2);
}
#[test]
fn test_conflict_remove() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert!(m.insert(5, 3).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&5).unwrap(), 3);
assert!(m.insert(9, 4).is_none());
assert_eq!(*m.get(&1).unwrap(), 2);
assert_eq!(*m.get(&5).unwrap(), 3);
assert_eq!(*m.get(&9).unwrap(), 4);
assert!(m.remove(&1).is_some());
assert_eq!(*m.get(&9).unwrap(), 4);
assert_eq!(*m.get(&5).unwrap(), 3);
}
#[test]
fn test_is_empty() {
let mut m = HashMap::with_capacity(4);
assert!(m.insert(1, 2).is_none());
assert!(!m.is_empty());
assert!(m.remove(&1).is_some());
assert!(m.is_empty());
}
#[test]
fn test_remove() {
let mut m = HashMap::new();
m.insert(1, 2);
assert_eq!(m.remove(&1), Some(2));
assert_eq!(m.remove(&1), None);
}
#[test]
fn test_remove_entry() {
let mut m = HashMap::new();
m.insert(1, 2);
assert_eq!(m.remove_entry(&1), Some((1, 2)));
assert_eq!(m.remove(&1), None);
}
#[test]
fn test_iterate() {
let mut m = HashMap::with_capacity(4);
for i in 0..32 {
assert!(m.insert(i, i*2).is_none());
}
assert_eq!(m.len(), 32);
let mut observed: u32 = 0;
for (k, v) in &m {
assert_eq!(*v, *k * 2);
observed |= 1 << *k;
}
assert_eq!(observed, 0xFFFF_FFFF);
}
#[test]
fn test_keys() {
let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
let map: HashMap<_, _> = vec.into_iter().collect();
let keys: Vec<_> = map.keys().cloned().collect();
assert_eq!(keys.len(), 3);
assert!(keys.contains(&1));
assert!(keys.contains(&2));
assert!(keys.contains(&3));
}
#[test]
fn test_values() {
let vec = vec![(1, 'a'), (2, 'b'), (3, 'c')];
let map: HashMap<_, _> = vec.into_iter().collect();
let values: Vec<_> = map.values().cloned().collect();
assert_eq!(values.len(), 3);
assert!(values.contains(&'a'));
assert!(values.contains(&'b'));
assert!(values.contains(&'c'));
}
#[test]
fn test_values_mut() {
let vec = vec![(1, 1), (2, 2), (3, 3)];
let mut map: HashMap<_, _> = vec.into_iter().collect();
for value in map.values_mut() {
*value = (*value) * 2
}
let values: Vec<_> = map.values().cloned().collect();
assert_eq!(values.len(), 3);
assert!(values.contains(&2));
assert!(values.contains(&4));
assert!(values.contains(&6));
}
#[test]
fn test_find() {
let mut m = HashMap::new();
assert!(m.get(&1).is_none());
m.insert(1, 2);
match m.get(&1) {
None => panic!(),
Some(v) => assert_eq!(*v, 2),
}
}
#[test]
fn test_eq() {
let mut m1 = HashMap::new();
m1.insert(1, 2);
m1.insert(2, 3);
m1.insert(3, 4);
let mut m2 = HashMap::new();
m2.insert(1, 2);
m2.insert(2, 3);
assert!(m1 != m2);
m2.insert(3, 4);
assert_eq!(m1, m2);
}
#[test]
fn test_show() {
let mut map = HashMap::new();
let empty: HashMap<i32, i32> = HashMap::new();
map.insert(1, 2);
map.insert(3, 4);
let map_str = format!("{:?}", map);
assert!(map_str == "{1: 2, 3: 4}" ||
map_str == "{3: 4, 1: 2}");
assert_eq!(format!("{:?}", empty), "{}");
}
#[test]
fn test_expand() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert!(m.is_empty());
let mut i = 0;
let old_raw_cap = m.raw_capacity();
while old_raw_cap == m.raw_capacity() {
m.insert(i, i);
i += 1;
}
assert_eq!(m.len(), i);
assert!(!m.is_empty());
}
#[test]
fn test_behavior_resize_policy() {
let mut m = HashMap::new();
assert_eq!(m.len(), 0);
assert_eq!(m.raw_capacity(), 0);
assert!(m.is_empty());
m.insert(0, 0);
m.remove(&0);
assert!(m.is_empty());
let initial_raw_cap = m.raw_capacity();
m.reserve(initial_raw_cap);
let raw_cap = m.raw_capacity();
assert_eq!(raw_cap, initial_raw_cap * 2);
let mut i = 0;
for _ in 0..raw_cap * 3 / 4 {
m.insert(i, i);
i += 1;
}
// three quarters full
assert_eq!(m.len(), i);
assert_eq!(m.raw_capacity(), raw_cap);
for _ in 0..raw_cap / 4 {
m.insert(i, i);
i += 1;
}
// half full
let new_raw_cap = m.raw_capacity();
assert_eq!(new_raw_cap, raw_cap * 2);
for _ in 0..raw_cap / 2 - 1 {
i -= 1;
m.remove(&i);
assert_eq!(m.raw_capacity(), new_raw_cap);
}
// A little more than one quarter full.
m.shrink_to_fit();
assert_eq!(m.raw_capacity(), raw_cap);
// again, a little more than half full
for _ in 0..raw_cap / 2 - 1 {
i -= 1;
m.remove(&i);
}
m.shrink_to_fit();
assert_eq!(m.len(), i);
assert!(!m.is_empty());
assert_eq!(m.raw_capacity(), initial_raw_cap);
}
#[test]
fn test_reserve_shrink_to_fit() {
let mut m = HashMap::new();
m.insert(0, 0);
m.remove(&0);
assert!(m.capacity() >= m.len());
for i in 0..128 {
m.insert(i, i);
}
m.reserve(256);
let usable_cap = m.capacity();
for i in 128..(128 + 256) {
m.insert(i, i);
assert_eq!(m.capacity(), usable_cap);
}
for i in 100..(128 + 256) {
assert_eq!(m.remove(&i), Some(i));
}
m.shrink_to_fit();
assert_eq!(m.len(), 100);
assert!(!m.is_empty());
assert!(m.capacity() >= m.len());
for i in 0..100 {
assert_eq!(m.remove(&i), Some(i));
}
m.shrink_to_fit();
m.insert(0, 0);
assert_eq!(m.len(), 1);
assert!(m.capacity() >= m.len());
assert_eq!(m.remove(&0), Some(0));
}
#[test]
fn test_from_iter() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
for &(k, v) in &xs {
assert_eq!(map.get(&k), Some(&v));
}
}
#[test]
fn test_size_hint() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.size_hint(), (3, Some(3)));
}
#[test]
fn test_iter_len() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.len(), 3);
}
#[test]
fn test_mut_size_hint() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter_mut();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.size_hint(), (3, Some(3)));
}
#[test]
fn test_iter_mut_len() {
let xs = [(1, 1), (2, 2), (3, 3), (4, 4), (5, 5), (6, 6)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
let mut iter = map.iter_mut();
for _ in iter.by_ref().take(3) {}
assert_eq!(iter.len(), 3);
}
#[test]
fn test_index() {
let mut map = HashMap::new();
map.insert(1, 2);
map.insert(2, 1);
map.insert(3, 4);
assert_eq!(map[&2], 1);
}
#[test]
#[should_panic]
fn test_index_nonexistent() {
let mut map = HashMap::new();
map.insert(1, 2);
map.insert(2, 1);
map.insert(3, 4);
map[&4];
}
#[test]
fn test_entry() {
let xs = [(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
// Existing key (insert)
match map.entry(1) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
assert_eq!(view.get(), &10);
assert_eq!(view.insert(100), 10);
}
}
assert_eq!(map.get(&1).unwrap(), &100);
assert_eq!(map.len(), 6);
// Existing key (update)
match map.entry(2) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
let v = view.get_mut();
let new_v = (*v) * 10;
*v = new_v;
}
}
assert_eq!(map.get(&2).unwrap(), &200);
assert_eq!(map.len(), 6);
// Existing key (take)
match map.entry(3) {
Vacant(_) => unreachable!(),
Occupied(view) => {
assert_eq!(view.remove(), 30);
}
}
assert_eq!(map.get(&3), None);
assert_eq!(map.len(), 5);
// Inexistent key (insert)
match map.entry(10) {
Occupied(_) => unreachable!(),
Vacant(view) => {
assert_eq!(*view.insert(1000), 1000);
}
}
assert_eq!(map.get(&10).unwrap(), &1000);
assert_eq!(map.len(), 6);
}
#[test]
fn test_entry_take_doesnt_corrupt() {
#![allow(deprecated)] //rand
// Test for #19292
fn check(m: &HashMap<i32, ()>) {
for k in m.keys() {
assert!(m.contains_key(k),
"{} is in keys() but not in the map?", k);
}
}
let mut m = HashMap::new();
let mut rng = thread_rng();
// Populate the map with some items.
for _ in 0..50 {
let x = rng.gen_range(-10, 10);
m.insert(x, ());
}
for _ in 0..1000 {
let x = rng.gen_range(-10, 10);
match m.entry(x) {
Vacant(_) => {}
Occupied(e) => {
e.remove();
}
}
check(&m);
}
}
#[test]
fn test_extend_ref() {
let mut a = HashMap::new();
a.insert(1, "one");
let mut b = HashMap::new();
b.insert(2, "two");
b.insert(3, "three");
a.extend(&b);
assert_eq!(a.len(), 3);
assert_eq!(a[&1], "one");
assert_eq!(a[&2], "two");
assert_eq!(a[&3], "three");
}
#[test]
fn test_capacity_not_less_than_len() {
let mut a = HashMap::new();
let mut item = 0;
for _ in 0..116 {
a.insert(item, 0);
item += 1;
}
assert!(a.capacity() > a.len());
let free = a.capacity() - a.len();
for _ in 0..free {
a.insert(item, 0);
item += 1;
}
assert_eq!(a.len(), a.capacity());
// Insert at capacity should cause allocation.
a.insert(item, 0);
assert!(a.capacity() > a.len());
}
#[test]
fn test_occupied_entry_key() {
let mut a = HashMap::new();
let key = "hello there";
let value = "value goes here";
assert!(a.is_empty());
a.insert(key.clone(), value.clone());
assert_eq!(a.len(), 1);
assert_eq!(a[key], value);
match a.entry(key.clone()) {
Vacant(_) => panic!(),
Occupied(e) => assert_eq!(key, *e.key()),
}
assert_eq!(a.len(), 1);
assert_eq!(a[key], value);
}
#[test]
fn test_vacant_entry_key() {
let mut a = HashMap::new();
let key = "hello there";
let value = "value goes here";
assert!(a.is_empty());
match a.entry(key.clone()) {
Occupied(_) => panic!(),
Vacant(e) => {
assert_eq!(key, *e.key());
e.insert(value.clone());
}
}
assert_eq!(a.len(), 1);
assert_eq!(a[key], value);
}
#[test]
fn test_retain() {
let mut map: HashMap<i32, i32> = (0..100).map(|x|(x, x*10)).collect();
map.retain(|&k, _| k % 2 == 0);
assert_eq!(map.len(), 50);
assert_eq!(map[&2], 20);
assert_eq!(map[&4], 40);
assert_eq!(map[&6], 60);
}
#[test]
fn test_adaptive() {
const TEST_LEN: usize = 5000;
// by cloning we get maps with the same hasher seed
let mut first = HashMap::new();
let mut second = first.clone();
first.extend((0..TEST_LEN).map(|i| (i, i)));
second.extend((TEST_LEN..TEST_LEN * 2).map(|i| (i, i)));
for (&k, &v) in &second {
let prev_cap = first.capacity();
let expect_grow = first.len() == prev_cap;
first.insert(k, v);
if !expect_grow && first.capacity() != prev_cap {
return;
}
}
panic!("Adaptive early resize failed");
}
#[test]
fn test_try_reserve() {
let mut empty_bytes: HashMap<u8,u8> = HashMap::new();
const MAX_USIZE: usize = usize::MAX;
// HashMap and RawTables use complicated size calculations
// hashes_size is sizeof(HashUint) * capacity;
// pairs_size is sizeof((K. V)) * capacity;
// alignment_hashes_size is 8
// alignment_pairs size is 4
let size_of_multiplier = (size_of::<usize>() + size_of::<(u8, u8)>()).next_power_of_two();
// The following formula is used to calculate the new capacity
let max_no_ovf = ((MAX_USIZE / 11) * 10) / size_of_multiplier - 1;
if let Err(CapacityOverflow) = empty_bytes.try_reserve(MAX_USIZE) {
} else { panic!("usize::MAX should trigger an overflow!"); }
if size_of::<usize>() < 8 {
if let Err(CapacityOverflow) = empty_bytes.try_reserve(max_no_ovf) {
} else { panic!("isize::MAX + 1 should trigger a CapacityOverflow!") }
} else {
if let Err(AllocErr) = empty_bytes.try_reserve(max_no_ovf) {
} else { panic!("isize::MAX + 1 should trigger an OOM!") }
}
}
#[test]
fn test_raw_entry() {
use super::RawEntryMut::{Occupied, Vacant};
let xs = [(1i32, 10i32), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)];
let mut map: HashMap<_, _> = xs.iter().cloned().collect();
let compute_hash = |map: &HashMap<i32, i32>, k: i32| -> u64 {
use core::hash::{BuildHasher, Hash, Hasher};
let mut hasher = map.hasher().build_hasher();
k.hash(&mut hasher);
hasher.finish()
};
// Existing key (insert)
match map.raw_entry_mut().from_key(&1) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
assert_eq!(view.get(), &10);
assert_eq!(view.insert(100), 10);
}
}
let hash1 = compute_hash(&map, 1);
assert_eq!(map.raw_entry().from_key(&1).unwrap(), (&1, &100));
assert_eq!(map.raw_entry().from_hash(hash1, |k| *k == 1).unwrap(), (&1, &100));
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash1, &1).unwrap(), (&1, &100));
assert_eq!(map.raw_entry().search_bucket(hash1, |k| *k == 1).unwrap(), (&1, &100));
assert_eq!(map.len(), 6);
// Existing key (update)
match map.raw_entry_mut().from_key(&2) {
Vacant(_) => unreachable!(),
Occupied(mut view) => {
let v = view.get_mut();
let new_v = (*v) * 10;
*v = new_v;
}
}
let hash2 = compute_hash(&map, 2);
assert_eq!(map.raw_entry().from_key(&2).unwrap(), (&2, &200));
assert_eq!(map.raw_entry().from_hash(hash2, |k| *k == 2).unwrap(), (&2, &200));
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash2, &2).unwrap(), (&2, &200));
assert_eq!(map.raw_entry().search_bucket(hash2, |k| *k == 2).unwrap(), (&2, &200));
assert_eq!(map.len(), 6);
// Existing key (take)
let hash3 = compute_hash(&map, 3);
match map.raw_entry_mut().from_key_hashed_nocheck(hash3, &3) {
Vacant(_) => unreachable!(),
Occupied(view) => {
assert_eq!(view.remove_entry(), (3, 30));
}
}
assert_eq!(map.raw_entry().from_key(&3), None);
assert_eq!(map.raw_entry().from_hash(hash3, |k| *k == 3), None);
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash3, &3), None);
assert_eq!(map.raw_entry().search_bucket(hash3, |k| *k == 3), None);
assert_eq!(map.len(), 5);
// Nonexistent key (insert)
match map.raw_entry_mut().from_key(&10) {
Occupied(_) => unreachable!(),
Vacant(view) => {
assert_eq!(view.insert(10, 1000), (&mut 10, &mut 1000));
}
}
assert_eq!(map.raw_entry().from_key(&10).unwrap(), (&10, &1000));
assert_eq!(map.len(), 6);
// Ensure all lookup methods produce equivalent results.
for k in 0..12 {
let hash = compute_hash(&map, k);
let v = map.get(&k).cloned();
let kv = v.as_ref().map(|v| (&k, v));
assert_eq!(map.raw_entry().from_key(&k), kv);
assert_eq!(map.raw_entry().from_hash(hash, |q| *q == k), kv);
assert_eq!(map.raw_entry().from_key_hashed_nocheck(hash, &k), kv);
assert_eq!(map.raw_entry().search_bucket(hash, |q| *q == k), kv);
match map.raw_entry_mut().from_key(&k) {
Occupied(mut o) => assert_eq!(Some(o.get_key_value()), kv),
Vacant(_) => assert_eq!(v, None),
}
match map.raw_entry_mut().from_key_hashed_nocheck(hash, &k) {
Occupied(mut o) => assert_eq!(Some(o.get_key_value()), kv),
Vacant(_) => assert_eq!(v, None),
}
match map.raw_entry_mut().from_hash(hash, |q| *q == k) {
Occupied(mut o) => assert_eq!(Some(o.get_key_value()), kv),
Vacant(_) => assert_eq!(v, None),
}
match map.raw_entry_mut().search_bucket(hash, |q| *q == k) {
Occupied(mut o) => assert_eq!(Some(o.get_key_value()), kv),
Vacant(_) => assert_eq!(v, None),
}
}
}
}