use alloc::alloc::{alloc, dealloc, handle_alloc_error};
use core::alloc::Layout;
use core::hint;
use core::iter::FusedIterator;
use core::marker::PhantomData;
use core::mem;
use core::mem::ManuallyDrop;
use core::ptr::NonNull;
use scopeguard::guard;
// Branch prediction hint. This is currently only available on nightly but it
// consistently improves performance by 10-15%.
#[cfg(feature = "nightly")]
use core::intrinsics::{likely, unlikely};
#[cfg(not(feature = "nightly"))]
#[inline]
fn likely(b: bool) -> bool {
b
}
#[cfg(not(feature = "nightly"))]
#[inline]
fn unlikely(b: bool) -> bool {
b
}
// Use the SSE2 implementation if possible: it allows us to scan 16 buckets at
// once instead of 8.
#[cfg(all(
target_feature = "sse2",
any(target_arch = "x86", target_arch = "x86_64")
))]
#[path = "sse2.rs"]
mod imp;
#[cfg(not(all(
target_feature = "sse2",
any(target_arch = "x86", target_arch = "x86_64")
)))]
#[path = "generic.rs"]
mod imp;
mod bitmask;
use raw::bitmask::BitMask;
use raw::imp::Group;
/// Control byte value for an empty bucket.
const EMPTY: u8 = 0b11111111;
/// Control byte value for a deleted bucket.
const DELETED: u8 = 0b10000000;
/// Checks whether a control byte represents a full bucket (top bit is clear).
#[inline]
fn is_full(ctrl: u8) -> bool {
ctrl & 0x80 == 0
}
/// Checks whether a control byte represents a special value (top bit is set).
#[inline]
fn is_special(ctrl: u8) -> bool {
ctrl & 0x80 != 0
}
/// Checks whether a special control value is EMPTY (just check 1 bit).
#[inline]
fn special_is_empty(ctrl: u8) -> bool {
debug_assert!(is_special(ctrl));
ctrl & 0x01 != 0
}
/// Primary hash function, used to select the initial bucket to probe from.
#[inline]
fn h1(hash: u64) -> usize {
hash as usize
}
/// Secondary hash function, saved in the low 7 bits of the control byte.
#[inline]
fn h2(hash: u64) -> u8 {
// Grab the top 7 bits of the hash. While the hash is normally a full 64-bit
// value, some hash functions (such as FxHash) produce a usize result
// instead, which means that the top 32 bits are 0 on 32-bit platforms.
let hash_len = usize::min(mem::size_of::<usize>(), mem::size_of::<u64>());
let top7 = hash >> (hash_len * 8 - 7);
(top7 & 0x7f) as u8
}
/// Probe sequence based on triangular numbers, which is guaranteed (since our
/// table size is a power of two) to visit every group of elements exactly once.
struct ProbeSeq {
mask: usize,
offset: usize,
index: usize,
}
impl Iterator for ProbeSeq {
type Item = usize;
#[inline]
fn next(&mut self) -> Option<usize> {
// We should have found an empty bucket by now and ended the probe.
debug_assert!(self.index <= self.mask, "Went past end of probe sequence");
let result = self.offset;
self.index += Group::WIDTH;
self.offset += self.index;
self.offset &= self.mask;
Some(result)
}
}
/// Returns the number of buckets needed to hold the given number of items,
/// taking the maximum load factor into account.
#[inline]
fn capacity_to_buckets(cap: usize) -> usize {
let adjusted_cap = if cap < 8 {
// Need at least 1 free bucket on small tables
cap + 1
} else {
// Otherwise require 1/8 buckets to be empty (87.5% load)
cap.checked_mul(8).expect("Hash table capacity overflow") / 7
};
// Any overflows will have been caught by the checked_mul.
adjusted_cap.next_power_of_two()
}
/// Returns the maximum effective capacity for the given bucket mask, taking
/// the maximum load factor into account.
#[inline]
fn bucket_mask_to_capacity(bucket_mask: usize) -> usize {
if bucket_mask < 8 {
bucket_mask
} else {
((bucket_mask + 1) / 8) * 7
}
}
// Returns a Layout which describes the allocation required for a hash table,
// and the offset of the buckets in the allocation.
#[inline]
#[cfg(feature = "nightly")]
fn calculate_layout<T>(buckets: usize) -> Option<(Layout, usize)> {
debug_assert!(buckets.is_power_of_two());
// Array of buckets
let data = Layout::array::<T>(buckets).ok()?;
// Array of control bytes. This must be aligned to the group size.
//
// We add `Group::WIDTH` control bytes at the end of the array which
// replicate the bytes at the start of the array and thus avoids the need to
// perform bounds-checking while probing.
let ctrl = Layout::array::<u8>(buckets + Group::WIDTH)
.ok()?
.align_to(Group::WIDTH);
ctrl.extend(data).ok()
}
// Returns a Layout which describes the allocation required for a hash table,
// and the offset of the buckets in the allocation.
#[inline]
#[cfg(not(feature = "nightly"))]
fn calculate_layout<T>(buckets: usize) -> Option<(Layout, usize)> {
debug_assert!(buckets.is_power_of_two());
// Manual layout calculation since Layout methods are not yet stable.
let data_align = usize::max(mem::align_of::<T>(), Group::WIDTH);
let data_offset = (buckets + Group::WIDTH).checked_add(data_align - 1)? & !(data_align - 1);
let len = data_offset.checked_add(mem::size_of::<T>().checked_mul(buckets)?)?;
unsafe {
Some((
Layout::from_size_align_unchecked(len, data_align),
data_offset,
))
}
}
/// A reference to a hash table bucket containing a `T`.
pub struct Bucket<T> {
ptr: NonNull<T>,
}
impl<T> Clone for Bucket<T> {
#[inline]
fn clone(&self) -> Self {
Bucket { ptr: self.ptr }
}
}
impl<T> Bucket<T> {
#[inline]
unsafe fn from_ptr(ptr: *const T) -> Self {
Bucket {
ptr: NonNull::new_unchecked(ptr as *mut T),
}
}
#[inline]
pub unsafe fn drop(&self) {
self.ptr.as_ptr().drop_in_place();
}
#[inline]
pub unsafe fn read(&self) -> T {
self.ptr.as_ptr().read()
}
#[inline]
pub unsafe fn write(&self, val: T) {
self.ptr.as_ptr().write(val);
}
#[inline]
pub unsafe fn as_ref<'a>(&self) -> &'a T {
&*self.ptr.as_ptr()
}
#[inline]
pub unsafe fn as_mut<'a>(&self) -> &'a mut T {
&mut *self.ptr.as_ptr()
}
}
/// A raw hash table with an unsafe API.
pub struct RawTable<T> {
ctrl: NonNull<u8>,
bucket_mask: usize,
data: NonNull<T>,
items: usize,
growth_left: usize,
}
impl<T> RawTable<T> {
/// 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.
#[inline]
pub fn new() -> RawTable<T> {
RawTable {
data: NonNull::dangling(),
ctrl: NonNull::from(&Group::static_empty()[0]),
bucket_mask: 0,
items: 0,
growth_left: 0,
}
}
/// Allocates a new hash table with the given number of buckets.
///
/// The control bytes are left uninitialized.
#[inline]
unsafe fn new_uninitialized(buckets: usize) -> RawTable<T> {
let (layout, data_offset) =
calculate_layout::<T>(buckets).expect("Hash table capacity overflow");
let ctrl = NonNull::new(alloc(layout)).unwrap_or_else(|| handle_alloc_error(layout));
let data = NonNull::new_unchecked(ctrl.as_ptr().add(data_offset) as *mut T);
RawTable {
data,
ctrl,
bucket_mask: buckets - 1,
items: 0,
growth_left: bucket_mask_to_capacity(buckets - 1),
}
}
/// Allocates a new hash table with at least enough capacity for inserting
/// the given number of elements without reallocating.
pub fn with_capacity(capacity: usize) -> RawTable<T> {
if capacity == 0 {
RawTable::new()
} else {
unsafe {
let result = RawTable::new_uninitialized(capacity_to_buckets(capacity));
result
.ctrl(0)
.write_bytes(EMPTY, result.buckets() + Group::WIDTH);
// If we have fewer buckets than the group width then we need to
// fill in unused spaces in the trailing control bytes with
// DELETED entries. See the comments in set_ctrl.
if result.buckets() < Group::WIDTH {
result
.ctrl(result.buckets())
.write_bytes(DELETED, Group::WIDTH - result.buckets());
}
result
}
}
}
/// Deallocates the table without dropping any entries.
#[inline]
unsafe fn free_buckets(&mut self) {
let (layout, _) =
calculate_layout::<T>(self.buckets()).unwrap_or_else(|| hint::unreachable_unchecked());
dealloc(self.ctrl.as_ptr(), layout);
}
/// Returns the index of a bucket from a `Bucket`.
#[inline]
#[cfg(feature = "nightly")]
unsafe fn bucket_index(&self, bucket: &Bucket<T>) -> usize {
bucket.ptr.as_ptr().offset_from(self.data.as_ptr()) as usize
}
/// Returns the index of a bucket from a `Bucket`.
#[inline]
#[cfg(not(feature = "nightly"))]
unsafe fn bucket_index(&self, bucket: &Bucket<T>) -> usize {
(bucket.ptr.as_ptr() as usize - self.data.as_ptr() as usize) / mem::size_of::<T>()
}
/// Returns a pointer to a control byte.
#[inline]
unsafe fn ctrl(&self, index: usize) -> *mut u8 {
debug_assert!(index < self.buckets() + Group::WIDTH);
self.ctrl.as_ptr().add(index)
}
/// Returns a pointer to an element in the table.
#[inline]
pub unsafe fn bucket(&self, index: usize) -> Bucket<T> {
debug_assert_ne!(self.bucket_mask, 0);
debug_assert!(index < self.buckets());
Bucket::from_ptr(self.data.as_ptr().add(index))
}
/// Erases an element from the table without dropping it.
#[inline]
pub unsafe fn erase_no_drop(&mut self, item: &Bucket<T>) {
let index = self.bucket_index(item);
let index_before = index.wrapping_sub(Group::WIDTH) & self.bucket_mask;
let empty_before = Group::load(self.ctrl(index_before)).match_empty();
let empty_after = Group::load(self.ctrl(index)).match_empty();
// If we are inside a continuous block of Group::WIDTH full or deleted
// cells then a probe window may have seen a full block when trying to
// insert. We therefore need to keep that block non-empty so that
// lookups will continue searching to the next probe window.
let ctrl = if empty_before.leading_zeros() + empty_after.trailing_zeros() >= Group::WIDTH {
DELETED
} else {
self.growth_left += 1;
EMPTY
};
self.set_ctrl(index, ctrl);
self.items -= 1;
}
/// Returns an iterator for a probe sequence on the table.
///
/// This iterator never terminates, but is guaranteed to visit each bucket
/// group exactly once.
#[inline]
fn probe_seq(&self, hash: u64) -> ProbeSeq {
ProbeSeq {
mask: self.bucket_mask,
offset: h1(hash) & self.bucket_mask,
index: 0,
}
}
/// Sets a control byte, and possibly also the replicated control byte at
/// the end of the array.
#[inline]
unsafe fn set_ctrl(&self, index: usize, ctrl: u8) {
// Replicate the first Group::WIDTH control bytes at the end of
// the array without using a branch:
// - If index >= Group::WIDTH then index == index2.
// - Otherwise index2 == self.bucket_mask + 1 + index.
//
// The very last replicated control byte is never actually read because
// we mask the initial index for unaligned loads, but we write it
// anyways because it makes the set_ctrl implementation simpler.
//
// If there are fewer buckets than Group::WIDTH then this code will
// replicate the buckets at the end of the trailing group. For example
// with 2 buckets and a group size of 4, the control bytes will look
// like this:
//
// Real | Replicated
// -------------------------------------------------
// | [A] | [B] | [DELETED] | [DELETED] | [A] | [B] |
// -------------------------------------------------
let index2 = ((index.wrapping_sub(Group::WIDTH)) & self.bucket_mask) + Group::WIDTH;
*self.ctrl(index) = ctrl;
*self.ctrl(index2) = ctrl;
}
/// Searches for an empty or deleted bucket which is suitable for inserting
/// a new element.
///
/// There must be at least 1 empty bucket in the table.
#[inline]
fn find_insert_slot(&self, hash: u64) -> usize {
for pos in self.probe_seq(hash) {
unsafe {
let group = Group::load(self.ctrl(pos));
if let Some(bit) = group.match_empty_or_deleted().lowest_set_bit() {
let result = (pos + bit) & self.bucket_mask;
// In tables smaller than the group width, trailing control
// bytes outside the range of the table are filled with
// DELETED entries. These will unfortunately trigger a
// match, but once masked will point to a full bucket that
// is already occupied. We detect this situation here and
// perform a second scan starting at the begining of the
// table. This second scan is guaranteed to find an empty
// slot (due to the load factor) before hitting the trailing
// control bytes (containing DELETED).
if unlikely(is_full(*self.ctrl(result))) {
debug_assert!(self.bucket_mask < Group::WIDTH);
debug_assert_ne!(pos, 0);
return Group::load_aligned(self.ctrl(0))
.match_empty_or_deleted()
.lowest_set_bit_nonzero();
} else {
return result;
}
}
}
}
// probe_seq never returns.
unreachable!();
}
/// Marks all table buckets as empty without dropping their contents.
#[inline]
fn clear_no_drop(&mut self) {
if self.bucket_mask != 0 {
unsafe {
self.ctrl(0)
.write_bytes(EMPTY, self.buckets() + Group::WIDTH);
}
}
self.items = 0;
self.growth_left = bucket_mask_to_capacity(self.bucket_mask);
}
/// Removes all elements from the table without freeing the backing memory.
#[inline]
pub fn clear(&mut self) {
// Ensure that the table is reset even if one of the drops panic
let self_ = guard(self, |self_| self_.clear_no_drop());
if mem::needs_drop::<T>() {
unsafe {
for item in self_.iter() {
item.drop();
}
}
}
}
/// Shrinks the table to fit `max(self.len(), min_size)` elements.
#[inline]
pub fn shrink_to(&mut self, min_size: usize, hasher: impl Fn(&T) -> u64) {
let min_size = usize::max(self.items, min_size);
if bucket_mask_to_capacity(self.bucket_mask) / 2 > min_size {
self.resize(min_size, hasher);
}
}
/// Ensures that at least `additional` items can be inserted into the table
/// without reallocation.
#[inline]
pub fn reserve(&mut self, additional: usize, hasher: impl Fn(&T) -> u64) {
if additional > self.growth_left {
self.reserve_rehash(additional, hasher);
}
}
/// Out-of-line slow path for `reserve`.
#[cold]
#[inline(never)]
fn reserve_rehash(&mut self, additional: usize, hasher: impl Fn(&T) -> u64) {
let new_items = self
.items
.checked_add(additional)
.expect("Hash table capacity overflow");
// Rehash in-place without re-allocating if we have plenty of spare
// capacity that is locked up due to DELETED entries.
if new_items < bucket_mask_to_capacity(self.bucket_mask) / 2 {
self.rehash_in_place(hasher);
} else {
self.resize(new_items, hasher);
}
}
/// Rehashes the contents of the table in place (i.e. without changing the
/// allocation).
///
/// If `hasher` panics then some the table's contents may be lost.
fn rehash_in_place(&mut self, hasher: impl Fn(&T) -> u64) {
unsafe {
// Bulk convert all full control bytes to DELETED, and all DELETED
// control bytes to EMPTY. This effectively frees up all buckets
// containing a DELETED entry.
for i in (0..self.buckets()).step_by(Group::WIDTH) {
let group = Group::load_aligned(self.ctrl(i));
let group = group.convert_special_to_empty_and_full_to_deleted();
group.store_aligned(self.ctrl(i));
}
// Fix up the trailing control bytes. See the comments in set_ctrl.
if self.buckets() < Group::WIDTH {
self.ctrl(0)
.copy_to(self.ctrl(Group::WIDTH), self.buckets());
self.ctrl(self.buckets())
.write_bytes(DELETED, Group::WIDTH - self.buckets());
} else {
self.ctrl(0)
.copy_to(self.ctrl(self.buckets()), Group::WIDTH);
}
// If the hash function panics then properly clean up any elements
// that we haven't rehashed yet. We unfortunately can't preserve the
// element since we lost their hash and have no way of recovering it
// without risking another panic.
let mut guard = guard(self, |self_| {
if mem::needs_drop::<T>() {
for i in 0..self_.buckets() {
if *self_.ctrl(i) == DELETED {
self_.set_ctrl(i, EMPTY);
self_.bucket(i).drop();
self_.items -= 1;
}
}
}
self_.growth_left = bucket_mask_to_capacity(self_.bucket_mask) - self_.items;
});
// At this point, DELETED elements are elements that we haven't
// rehashed yet. Find them and re-insert them at their ideal
// position.
'outer: for i in 0..guard.buckets() {
if *guard.ctrl(i) != DELETED {
continue;
}
'inner: loop {
// Hash the current item
let item = guard.bucket(i);
let hash = hasher(item.as_ref());
// Search for a suitable place to put it
let new_i = guard.find_insert_slot(hash);
// Probing works by scanning through all of the control
// bytes in groups, which may not be aligned to the group
// size. If both the new and old position fall within the
// same unaligned group, then there is no benefit in moving
// it and we can just continue to the next item.
let probe_index = |pos| {
((pos - guard.probe_seq(hash).offset) & guard.bucket_mask) / Group::WIDTH
};
if likely(probe_index(i) == probe_index(new_i)) {
guard.set_ctrl(i, h2(hash));
continue 'outer;
}
// We are moving the current item to a new position. Write
// our H2 to the control byte of the new position.
let prev_ctrl = *guard.ctrl(new_i);
guard.set_ctrl(new_i, h2(hash));
if prev_ctrl == EMPTY {
// If the target slot is empty, simply move the current
// element into the new slot and clear the old control
// byte.
guard.set_ctrl(i, EMPTY);
guard.bucket(new_i).write(item.read());
continue 'outer;
} else {
// If the target slot is occupied, swap the two elements
// and then continue processing the element that we just
// swapped into the old slot.
debug_assert_eq!(prev_ctrl, DELETED);
mem::swap(guard.bucket(new_i).as_mut(), item.as_mut());
continue 'inner;
}
}
}
guard.growth_left = bucket_mask_to_capacity(guard.bucket_mask) - guard.items;
mem::forget(guard);
}
}
/// Allocates a new table of a different size and moves the contents of the
/// current table into it.
fn resize(&mut self, capacity: usize, hasher: impl Fn(&T) -> u64) {
unsafe {
debug_assert!(self.items <= capacity);
// Allocate and initialize the new table.
let mut new_table = RawTable::with_capacity(capacity);
new_table.growth_left -= self.items;
new_table.items = self.items;
// The hash function may panic, in which case we simply free the new
// table without dropping any elements that may have been copied into
// it.
let mut new_table = guard(ManuallyDrop::new(new_table), |new_table| {
if new_table.bucket_mask != 0 {
new_table.free_buckets();
}
});
// Copy all elements to the new table.
for item in self.iter() {
// This may panic.
let hash = hasher(item.as_ref());
// We can use a simpler version of insert() here since there are no
// DELETED entries.
let index = new_table.find_insert_slot(hash);
new_table.set_ctrl(index, h2(hash));
new_table.bucket(index).write(item.read());
}
// We successfully copied all elements without panicking. Now replace
// self with the new table. The old table will have its memory freed but
// the items will not be dropped (since they have been moved into the
// new table).
mem::swap(self, &mut new_table);
}
}
/// Inserts a new element into the table.
///
/// This does not check if the given element already exists in the table.
#[inline]
pub fn insert(&mut self, hash: u64, value: T, hasher: impl Fn(&T) -> u64) -> Bucket<T> {
self.reserve(1, hasher);
unsafe {
let index = self.find_insert_slot(hash);
let bucket = self.bucket(index);
// If we are replacing a DELETED entry then we don't need to update
// the load counter.
let old_ctrl = *self.ctrl(index);
self.growth_left -= special_is_empty(old_ctrl) as usize;
self.set_ctrl(index, h2(hash));
bucket.write(value);
self.items += 1;
bucket
}
}
/// Searches for an element in the table.
#[inline]
pub fn find(&self, hash: u64, eq: impl Fn(&T) -> bool) -> Option<Bucket<T>> {
unsafe {
for pos in self.probe_seq(hash) {
let group = Group::load(self.ctrl(pos));
for bit in group.match_byte(h2(hash)) {
let index = (pos + bit) & self.bucket_mask;
let bucket = self.bucket(index);
if likely(eq(bucket.as_ref())) {
return Some(bucket);
}
}
if likely(group.match_empty().any_bit_set()) {
return None;
}
}
}
// probe_seq never returns.
unreachable!();
}
/// 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.
#[inline]
pub fn capacity(&self) -> usize {
self.items + self.growth_left
}
/// Returns the number of elements in the table.
#[inline]
pub fn len(&self) -> usize {
self.items
}
/// Returns the number of buckets in the table.
#[inline]
fn buckets(&self) -> usize {
self.bucket_mask + 1
}
/// 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.
#[inline]
pub unsafe fn iter(&self) -> RawIter<T> {
let current_group = Group::load_aligned(self.ctrl.as_ptr())
.match_empty_or_deleted()
.invert();
RawIter {
data: self.data.as_ptr(),
ctrl: self.ctrl.as_ptr(),
current_group,
end: self.ctrl(self.bucket_mask),
items: self.items,
}
}
/// Returns an iterator which removes all elements from the table without
/// freeing the memory. It is up to the caller to ensure that the `RawTable`
/// outlives the `RawDrain`. Because we cannot make the `next` method unsafe
/// on the `RawDrain`, we have to make the `drain` method unsafe.
#[inline]
pub unsafe fn drain(&mut self) -> RawDrain<T> {
RawDrain {
iter: self.iter(),
table: NonNull::from(self),
_marker: PhantomData,
}
}
}
unsafe impl<T> Send for RawTable<T> where T: Send {}
unsafe impl<T> Sync for RawTable<T> where T: Sync {}
impl<T: Clone> Clone for RawTable<T> {
fn clone(&self) -> Self {
if self.bucket_mask == 0 {
Self::new()
} else {
unsafe {
let mut new_table = ManuallyDrop::new(Self::new_uninitialized(self.buckets()));
// Copy the control bytes unchanged. We do this in a single pass
self.ctrl(0)
.copy_to_nonoverlapping(new_table.ctrl(0), self.buckets() + Group::WIDTH);
{
// The cloning of elements may panic, in which case we need
// to make sure we drop only the elements that have been
// cloned so far.
let mut guard = guard((0, &mut new_table), |(index, new_table)| {
if mem::needs_drop::<T>() {
for i in 0..=*index {
if is_full(*new_table.ctrl(i)) {
new_table.bucket(i).drop();
}
}
}
new_table.free_buckets();
});
for from in self.iter() {
let index = self.bucket_index(&from);
let to = guard.1.bucket(index);
to.write(from.as_ref().clone());
// Update the index in case we need to unwind.
guard.0 = index;
}
// Successfully cloned all items, no need to clean up.
mem::forget(guard);
}
// Return the newly created table.
new_table.items = self.items;
new_table.growth_left = self.growth_left;
ManuallyDrop::into_inner(new_table)
}
}
}
}
impl<T> Drop for RawTable<T> {
#[inline]
fn drop(&mut self) {
if self.bucket_mask != 0 {
unsafe {
if mem::needs_drop::<T>() {
for item in self.iter() {
item.drop();
}
}
self.free_buckets();
}
}
}
}
impl<T> IntoIterator for RawTable<T> {
type Item = T;
type IntoIter = RawIntoIter<T>;
#[inline]
fn into_iter(self) -> RawIntoIter<T> {
unsafe {
let alloc = if self.bucket_mask != 0 {
let (layout, _) = calculate_layout::<T>(self.buckets())
.unwrap_or_else(|| hint::unreachable_unchecked());
Some((self.ctrl.cast(), layout))
} else {
None
};
let iter = self.iter();
mem::forget(self);
RawIntoIter { iter, alloc }
}
}
}
/// Iterator which returns a raw pointer to every full bucket in the table.
pub struct RawIter<T> {
// Using *const here for covariance
data: *const T,
ctrl: *const u8,
current_group: BitMask,
end: *const u8,
items: usize,
}
unsafe impl<T> Send for RawIter<T> where T: Send {}
unsafe impl<T> Sync for RawIter<T> where T: Sync {}
impl<T> Clone for RawIter<T> {
#[inline]
fn clone(&self) -> Self {
RawIter {
data: self.data,
ctrl: self.ctrl,
current_group: self.current_group,
end: self.end,
items: self.items,
}
}
}
impl<T> Iterator for RawIter<T> {
type Item = Bucket<T>;
#[inline]
fn next(&mut self) -> Option<Bucket<T>> {
unsafe {
loop {
if let Some(index) = self.current_group.lowest_set_bit() {
self.current_group = self.current_group.remove_lowest_bit();
self.items -= 1;
return Some(Bucket::from_ptr(self.data.add(index)));
}
self.ctrl = self.ctrl.add(Group::WIDTH);
if self.ctrl >= self.end {
// We don't check against items == 0 here to allow the
// compiler to optimize away the item count entirely if the
// iterator length is never queried.
debug_assert_eq!(self.items, 0);
return None;
}
self.data = self.data.add(Group::WIDTH);
self.current_group = Group::load_aligned(self.ctrl)
.match_empty_or_deleted()
.invert();
}
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
(self.items, Some(self.items))
}
}
impl<T> ExactSizeIterator for RawIter<T> {}
impl<T> FusedIterator for RawIter<T> {}
/// Iterator which consumes a table and returns elements.
pub struct RawIntoIter<T> {
iter: RawIter<T>,
alloc: Option<(NonNull<u8>, Layout)>,
}
impl<'a, T> RawIntoIter<T> {
#[inline]
pub fn iter(&self) -> RawIter<T> {
self.iter.clone()
}
}
unsafe impl<T> Send for RawIntoIter<T> where T: Send {}
unsafe impl<T> Sync for RawIntoIter<T> where T: Sync {}
impl<T> Drop for RawIntoIter<T> {
#[inline]
fn drop(&mut self) {
unsafe {
// Drop all remaining elements
if mem::needs_drop::<T>() {
while let Some(item) = self.iter.next() {
item.drop();
}
}
// Free the table
if let Some((ptr, layout)) = self.alloc {
dealloc(ptr.as_ptr(), layout);
}
}
}
}
impl<T> Iterator for RawIntoIter<T> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
unsafe { Some(self.iter.next()?.read()) }
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<T> ExactSizeIterator for RawIntoIter<T> {}
impl<T> FusedIterator for RawIntoIter<T> {}
/// Iterator which consumes elements without freeing the table storage.
pub struct RawDrain<'a, T: 'a> {
iter: RawIter<T>,
// We don't use a &'a RawTable<T> because we want RawDrain to be covariant
// over 'a.
table: NonNull<RawTable<T>>,
_marker: PhantomData<&'a RawTable<T>>,
}
impl<'a, T> RawDrain<'a, T> {
#[inline]
pub fn iter(&self) -> RawIter<T> {
self.iter.clone()
}
}
unsafe impl<'a, T> Send for RawDrain<'a, T> where T: Send {}
unsafe impl<'a, T> Sync for RawDrain<'a, T> where T: Sync {}
impl<'a, T> Drop for RawDrain<'a, T> {
#[inline]
fn drop(&mut self) {
unsafe {
// Ensure that the table is reset even if one of the drops panic
let _guard = guard(self.table, |table| table.as_mut().clear_no_drop());
// Drop all remaining elements
if mem::needs_drop::<T>() {
while let Some(item) = self.iter.next() {
item.drop();
}
}
}
}
}
impl<'a, T> Iterator for RawDrain<'a, T> {
type Item = T;
#[inline]
fn next(&mut self) -> Option<T> {
unsafe {
let item = self.iter.next()?;
// Mark the item as DELETED in the table and decrement the item
// counter. We don't need to use the full delete algorithm like
// erase_no_drop since we will just clear the control bytes when
// the RawDrain is dropped.
let index = self.table.as_ref().bucket_index(&item);
*self.table.as_mut().ctrl(index) = DELETED;
self.table.as_mut().items -= 1;
Some(item.read())
}
}
#[inline]
fn size_hint(&self) -> (usize, Option<usize>) {
self.iter.size_hint()
}
}
impl<'a, T> ExactSizeIterator for RawDrain<'a, T> {}
impl<'a, T> FusedIterator for RawDrain<'a, T> {}