Struct hashbrown::raw::RawTable

pub struct RawTable<T, A: Allocator = Global> { /* private fields */ }

A raw hash table with an unsafe API.

Implementations

impl<T> RawTable<T, Global>

pub const fn new() -> Self

Creates a new empty hash table without allocating any memory.

In effect this returns a table with exactly 1 bucket. However we can leave the data pointer dangling since that bucket is never written to due to our load factor forcing us to always have at least 1 free bucket.

pub fn try_with_capacity(capacity: usize) -> Result<Self, TryReserveError>

Attempts to allocate a new hash table with at least enough capacity for inserting the given number of elements without reallocating.

pub fn with_capacity(capacity: usize) -> Self

Allocates a new hash table with at least enough capacity for inserting the given number of elements without reallocating.

impl<T, A: Allocator> RawTable<T, A>

pub const fn new_in(alloc: A) -> Self

Creates a new empty hash table without allocating any memory, using the given allocator.

In effect this returns a table with exactly 1 bucket. However we can leave the data pointer dangling since that bucket is never written to due to our load factor forcing us to always have at least 1 free bucket.

pub fn try_with_capacity_in( capacity: usize, alloc: A ) -> Result<Self, TryReserveError>

Attempts to allocate a new hash table using the given allocator, with at least enough capacity for inserting the given number of elements without reallocating.

pub fn with_capacity_in(capacity: usize, alloc: A) -> Self

Allocates a new hash table using the given allocator, with at least enough capacity for inserting the given number of elements without reallocating.

pub fn allocator(&self) -> &A

Returns a reference to the underlying allocator.

pub fn data_end(&self) -> NonNull<T>

Returns pointer to one past last data element in the table as viewed from the start point of the allocation.

The caller must ensure that the RawTable outlives the returned NonNull<T>, otherwise using it may result in undefined behavior.

pub unsafe fn data_start(&self) -> NonNull<T>

Returns pointer to start of data table.

pub fn allocation_info(&self) -> (NonNull<u8>, Layout)

Return the information about memory allocated by the table.

RawTable allocates single memory block to store both data and metadata. This function returns allocation size and alignment and the beginning of the area. These are the arguments which will be passed to dealloc when the table is dropped.

This function might be useful for memory profiling.

pub unsafe fn bucket_index(&self, bucket: &Bucket<T>) -> usize

Returns the index of a bucket from a Bucket.

pub unsafe fn bucket(&self, index: usize) -> Bucket<T>

Returns a pointer to an element in the table.

The caller must ensure that the RawTable outlives the returned Bucket<T>, otherwise using it may result in undefined behavior.

Safety

If mem::size_of::<T>() != 0, then the caller of this function must observe the following safety rules:

• The table must already be allocated;

• The index must not be greater than the number returned by the RawTable::buckets function, i.e. (index + 1) <= self.buckets().

It is safe to call this function with index of zero (index == 0) on a table that has not been allocated, but using the returned Bucket results in undefined behavior.

If mem::size_of::<T>() == 0, then the only requirement is that the index must not be greater than the number returned by the RawTable::buckets function, i.e. (index + 1) <= self.buckets().

pub unsafe fn erase(&mut self, item: Bucket<T>)

Erases an element from the table, dropping it in place.

pub fn erase_entry(&mut self, hash: u64, eq: impl FnMut(&T) -> bool) -> bool

Finds and erases an element from the table, dropping it in place. Returns true if an element was found.

pub unsafe fn remove(&mut self, item: Bucket<T>) -> (T, InsertSlot)

Removes an element from the table, returning it.

This also returns an InsertSlot pointing to the newly free bucket.

pub fn remove_entry( &mut self, hash: u64, eq: impl FnMut(&T) -> bool ) -> Option<T>

Finds and removes an element from the table, returning it.

pub fn clear_no_drop(&mut self)

Marks all table buckets as empty without dropping their contents.

pub fn clear(&mut self)

Removes all elements from the table without freeing the backing memory.

pub fn shrink_to(&mut self, min_size: usize, hasher: impl Fn(&T) -> u64)

Shrinks the table to fit max(self.len(), min_size) elements.

pub fn reserve(&mut self, additional: usize, hasher: impl Fn(&T) -> u64)

Ensures that at least additional items can be inserted into the table without reallocation.

pub fn try_reserve( &mut self, additional: usize, hasher: impl Fn(&T) -> u64 ) -> Result<(), TryReserveError>

Tries to ensure that at least additional items can be inserted into the table without reallocation.

pub fn insert( &mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64 ) -> Bucket<T>

Inserts a new element into the table, and returns its raw bucket.

This does not check if the given element already exists in the table.

pub fn try_insert_no_grow( &mut self, hash: u64, value: T ) -> Result<Bucket<T>, T>

Attempts to insert a new element without growing the table and return its raw bucket.

Returns an Err containing the given element if inserting it would require growing the table.

This does not check if the given element already exists in the table.

pub fn insert_entry( &mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64 ) -> &mut T

Inserts a new element into the table, and returns a mutable reference to it.

This does not check if the given element already exists in the table.

pub unsafe fn insert_no_grow(&mut self, hash: u64, value: T) -> Bucket<T>

Inserts a new element into the table, without growing the table.

There must be enough space in the table to insert the new element.

This does not check if the given element already exists in the table.

pub unsafe fn replace_bucket_with<F>(&mut self, bucket: Bucket<T>, f: F) -> bool

where F: FnOnce(T) -> Option<T>,

Temporary removes a bucket, applying the given function to the removed element and optionally put back the returned value in the same bucket.

Returns true if the bucket still contains an element

This does not check if the given bucket is actually occupied.

pub fn find_or_find_insert_slot( &mut self, hash: u64, eq: impl FnMut(&T) -> bool, hasher: impl Fn(&T) -> u64 ) -> Result<Bucket<T>, InsertSlot>

Searches for an element in the table. If the element is not found, returns Err with the position of a slot where an element with the same hash could be inserted.

This function may resize the table if additional space is required for inserting an element.

pub unsafe fn insert_in_slot( &mut self, hash: u64, slot: InsertSlot, value: T ) -> Bucket<T>

Inserts a new element into the table in the given slot, and returns its raw bucket.

Safety

slot must point to a slot previously returned by find_or_find_insert_slot, and no mutation of the table must have occurred since that call.

pub fn find(&self, hash: u64, eq: impl FnMut(&T) -> bool) -> Option<Bucket<T>>

Searches for an element in the table.

pub fn get(&self, hash: u64, eq: impl FnMut(&T) -> bool) -> Option<&T>

Gets a reference to an element in the table.

pub fn get_mut( &mut self, hash: u64, eq: impl FnMut(&T) -> bool ) -> Option<&mut T>

Gets a mutable reference to an element in the table.

pub fn get_many_mut<const N: usize>( &mut self, hashes: [u64; N], eq: impl FnMut(usize, &T) -> bool ) -> Option<[&mut T; N]>

Attempts to get mutable references to N entries in the table at once.

Returns an array of length N with the results of each query.

At most one mutable reference will be returned to any entry. None will be returned if any of the hashes are duplicates. None will be returned if the hash is not found.

The eq argument should be a closure such that eq(i, k) returns true if k is equal to the ith key to be looked up.

pub unsafe fn get_many_unchecked_mut<const N: usize>( &mut self, hashes: [u64; N], eq: impl FnMut(usize, &T) -> bool ) -> Option<[&mut T; N]>

pub fn capacity(&self) -> usize

Returns the number of elements the map can hold without reallocating.

This number is a lower bound; the table might be able to hold more, but is guaranteed to be able to hold at least this many.

pub fn len(&self) -> usize

Returns the number of elements in the table.

pub fn is_empty(&self) -> bool

Returns true if the table contains no elements.

pub fn buckets(&self) -> usize

Returns the number of buckets in the table.

pub unsafe fn is_bucket_full(&self, index: usize) -> bool

Checks whether the bucket at index is full.

Safety

The caller must ensure index is less than the number of buckets.

pub unsafe fn iter(&self) -> RawIter<T>

Returns an iterator over every element in the table. It is up to the caller to ensure that the RawTable outlives the RawIter. Because we cannot make the next method unsafe on the RawIter struct, we have to make the iter method unsafe.

pub unsafe fn iter_hash(&self, hash: u64) -> RawIterHash<T>

Returns an iterator over occupied buckets that could match a given hash.

RawTable only stores 7 bits of the hash value, so this iterator may return items that have a hash value different than the one provided. You should always validate the returned values before using them.

It is up to the caller to ensure that the RawTable outlives the RawIterHash. Because we cannot make the next method unsafe on the RawIterHash struct, we have to make the iter_hash method unsafe.

pub fn drain(&mut self) -> RawDrain<'_, T, A>

Returns an iterator which removes all elements from the table without freeing the memory.

pub unsafe fn drain_iter_from(&mut self, iter: RawIter<T>) -> RawDrain<'_, T, A>

Returns an iterator which removes all elements from the table without freeing the memory.

Iteration starts at the provided iterator’s current location.

It is up to the caller to ensure that the iterator is valid for this RawTable and covers all items that remain in the table.

pub unsafe fn into_iter_from(self, iter: RawIter<T>) -> RawIntoIter<T, A>

Returns an iterator which consumes all elements from the table.

Iteration starts at the provided iterator’s current location.

It is up to the caller to ensure that the iterator is valid for this RawTable and covers all items that remain in the table.

impl<T: Clone, A: Allocator + Clone> RawTable<T, A>

pub fn clone_from_with_hasher( &mut self, source: &Self, hasher: impl Fn(&T) -> u64 )

Variant of clone_from to use when a hasher is available.

Trait Implementations

impl<T: Clone, A: Allocator + Clone> Clone for RawTable<T, A>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T, A: Allocator + Default> Default for RawTable<T, A>

fn default() -> Self

Returns the “default value” for a type.

impl<T, A: Allocator> Drop for RawTable<T, A>

fn drop(&mut self)

Executes the destructor for this type.

impl<T, A: Allocator> IntoIterator for RawTable<T, A>

type Item = T

The type of the elements being iterated over.

type IntoIter = RawIntoIter<T, A>

Which kind of iterator are we turning this into?

fn into_iter(self) -> RawIntoIter<T, A>

Creates an iterator from a value.

impl<T, A> Send for RawTable<T, A>

where T: Send, A: Send + Allocator,

impl<T, A> Sync for RawTable<T, A>

where T: Sync, A: Sync + Allocator,