| //! This is the core implementation that doesn't depend on the hasher at all. |
| //! |
| //! The methods of `IndexMapCore` don't use any Hash properties of K. |
| //! |
| //! It's cleaner to separate them out, then the compiler checks that we are not |
| //! using Hash at all in these methods. |
| //! |
| //! However, we should probably not let this show in the public API or docs. |
| |
| mod entry; |
| mod raw; |
| |
| pub mod raw_entry_v1; |
| |
| use hashbrown::raw::RawTable; |
| |
| use crate::vec::{self, Vec}; |
| use crate::TryReserveError; |
| use core::mem; |
| use core::ops::RangeBounds; |
| |
| use crate::util::simplify_range; |
| use crate::{Bucket, Entries, Equivalent, HashValue}; |
| |
| pub use entry::{Entry, IndexedEntry, OccupiedEntry, VacantEntry}; |
| |
| /// Core of the map that does not depend on S |
| pub(crate) struct IndexMapCore<K, V> { |
| /// indices mapping from the entry hash to its index. |
| indices: RawTable<usize>, |
| /// entries is a dense vec of entries in their order. |
| entries: Vec<Bucket<K, V>>, |
| } |
| |
| #[inline(always)] |
| fn get_hash<K, V>(entries: &[Bucket<K, V>]) -> impl Fn(&usize) -> u64 + '_ { |
| move |&i| entries[i].hash.get() |
| } |
| |
| #[inline] |
| fn equivalent<'a, K, V, Q: ?Sized + Equivalent<K>>( |
| key: &'a Q, |
| entries: &'a [Bucket<K, V>], |
| ) -> impl Fn(&usize) -> bool + 'a { |
| move |&i| Q::equivalent(key, &entries[i].key) |
| } |
| |
| #[inline] |
| fn erase_index(table: &mut RawTable<usize>, hash: HashValue, index: usize) { |
| let erased = table.erase_entry(hash.get(), move |&i| i == index); |
| debug_assert!(erased); |
| } |
| |
| #[inline] |
| fn update_index(table: &mut RawTable<usize>, hash: HashValue, old: usize, new: usize) { |
| let index = table |
| .get_mut(hash.get(), move |&i| i == old) |
| .expect("index not found"); |
| *index = new; |
| } |
| |
| impl<K, V> Clone for IndexMapCore<K, V> |
| where |
| K: Clone, |
| V: Clone, |
| { |
| fn clone(&self) -> Self { |
| let mut new = Self::new(); |
| new.clone_from(self); |
| new |
| } |
| |
| fn clone_from(&mut self, other: &Self) { |
| let hasher = get_hash(&other.entries); |
| self.indices.clone_from_with_hasher(&other.indices, hasher); |
| if self.entries.capacity() < other.entries.len() { |
| // If we must resize, match the indices capacity. |
| let additional = other.entries.len() - self.entries.len(); |
| self.reserve_entries(additional); |
| } |
| self.entries.clone_from(&other.entries); |
| } |
| } |
| |
| #[cfg(feature = "test_debug")] |
| impl<K, V> core::fmt::Debug for IndexMapCore<K, V> |
| where |
| K: core::fmt::Debug, |
| V: core::fmt::Debug, |
| { |
| fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result { |
| f.debug_struct("IndexMapCore") |
| .field("indices", &raw::DebugIndices(&self.indices)) |
| .field("entries", &self.entries) |
| .finish() |
| } |
| } |
| |
| impl<K, V> Entries for IndexMapCore<K, V> { |
| type Entry = Bucket<K, V>; |
| |
| #[inline] |
| fn into_entries(self) -> Vec<Self::Entry> { |
| self.entries |
| } |
| |
| #[inline] |
| fn as_entries(&self) -> &[Self::Entry] { |
| &self.entries |
| } |
| |
| #[inline] |
| fn as_entries_mut(&mut self) -> &mut [Self::Entry] { |
| &mut self.entries |
| } |
| |
| fn with_entries<F>(&mut self, f: F) |
| where |
| F: FnOnce(&mut [Self::Entry]), |
| { |
| f(&mut self.entries); |
| self.rebuild_hash_table(); |
| } |
| } |
| |
| impl<K, V> IndexMapCore<K, V> { |
| /// The maximum capacity before the `entries` allocation would exceed `isize::MAX`. |
| const MAX_ENTRIES_CAPACITY: usize = (isize::MAX as usize) / mem::size_of::<Bucket<K, V>>(); |
| |
| #[inline] |
| pub(crate) const fn new() -> Self { |
| IndexMapCore { |
| indices: RawTable::new(), |
| entries: Vec::new(), |
| } |
| } |
| |
| #[inline] |
| pub(crate) fn with_capacity(n: usize) -> Self { |
| IndexMapCore { |
| indices: RawTable::with_capacity(n), |
| entries: Vec::with_capacity(n), |
| } |
| } |
| |
| #[inline] |
| pub(crate) fn len(&self) -> usize { |
| self.indices.len() |
| } |
| |
| #[inline] |
| pub(crate) fn capacity(&self) -> usize { |
| Ord::min(self.indices.capacity(), self.entries.capacity()) |
| } |
| |
| pub(crate) fn clear(&mut self) { |
| self.indices.clear(); |
| self.entries.clear(); |
| } |
| |
| pub(crate) fn truncate(&mut self, len: usize) { |
| if len < self.len() { |
| self.erase_indices(len, self.entries.len()); |
| self.entries.truncate(len); |
| } |
| } |
| |
| pub(crate) fn drain<R>(&mut self, range: R) -> vec::Drain<'_, Bucket<K, V>> |
| where |
| R: RangeBounds<usize>, |
| { |
| let range = simplify_range(range, self.entries.len()); |
| self.erase_indices(range.start, range.end); |
| self.entries.drain(range) |
| } |
| |
| #[cfg(feature = "rayon")] |
| pub(crate) fn par_drain<R>(&mut self, range: R) -> rayon::vec::Drain<'_, Bucket<K, V>> |
| where |
| K: Send, |
| V: Send, |
| R: RangeBounds<usize>, |
| { |
| use rayon::iter::ParallelDrainRange; |
| let range = simplify_range(range, self.entries.len()); |
| self.erase_indices(range.start, range.end); |
| self.entries.par_drain(range) |
| } |
| |
| pub(crate) fn split_off(&mut self, at: usize) -> Self { |
| assert!(at <= self.entries.len()); |
| self.erase_indices(at, self.entries.len()); |
| let entries = self.entries.split_off(at); |
| |
| let mut indices = RawTable::with_capacity(entries.len()); |
| raw::insert_bulk_no_grow(&mut indices, &entries); |
| Self { indices, entries } |
| } |
| |
| pub(crate) fn split_splice<R>(&mut self, range: R) -> (Self, vec::IntoIter<Bucket<K, V>>) |
| where |
| R: RangeBounds<usize>, |
| { |
| let range = simplify_range(range, self.len()); |
| self.erase_indices(range.start, self.entries.len()); |
| let entries = self.entries.split_off(range.end); |
| let drained = self.entries.split_off(range.start); |
| |
| let mut indices = RawTable::with_capacity(entries.len()); |
| raw::insert_bulk_no_grow(&mut indices, &entries); |
| (Self { indices, entries }, drained.into_iter()) |
| } |
| |
| /// Append from another map without checking whether items already exist. |
| pub(crate) fn append_unchecked(&mut self, other: &mut Self) { |
| self.reserve(other.len()); |
| raw::insert_bulk_no_grow(&mut self.indices, &other.entries); |
| self.entries.append(&mut other.entries); |
| other.indices.clear(); |
| } |
| |
| /// Reserve capacity for `additional` more key-value pairs. |
| pub(crate) fn reserve(&mut self, additional: usize) { |
| self.indices.reserve(additional, get_hash(&self.entries)); |
| // Only grow entries if necessary, since we also round up capacity. |
| if additional > self.entries.capacity() - self.entries.len() { |
| self.reserve_entries(additional); |
| } |
| } |
| |
| /// Reserve entries capacity, rounded up to match the indices |
| fn reserve_entries(&mut self, additional: usize) { |
| // Use a soft-limit on the maximum capacity, but if the caller explicitly |
| // requested more, do it and let them have the resulting panic. |
| let new_capacity = Ord::min(self.indices.capacity(), Self::MAX_ENTRIES_CAPACITY); |
| let try_add = new_capacity - self.entries.len(); |
| if try_add > additional && self.entries.try_reserve_exact(try_add).is_ok() { |
| return; |
| } |
| self.entries.reserve_exact(additional); |
| } |
| |
| /// Reserve capacity for `additional` more key-value pairs, without over-allocating. |
| pub(crate) fn reserve_exact(&mut self, additional: usize) { |
| self.indices.reserve(additional, get_hash(&self.entries)); |
| self.entries.reserve_exact(additional); |
| } |
| |
| /// Try to reserve capacity for `additional` more key-value pairs. |
| pub(crate) fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError> { |
| self.indices |
| .try_reserve(additional, get_hash(&self.entries)) |
| .map_err(TryReserveError::from_hashbrown)?; |
| // Only grow entries if necessary, since we also round up capacity. |
| if additional > self.entries.capacity() - self.entries.len() { |
| self.try_reserve_entries(additional) |
| } else { |
| Ok(()) |
| } |
| } |
| |
| /// Try to reserve entries capacity, rounded up to match the indices |
| fn try_reserve_entries(&mut self, additional: usize) -> Result<(), TryReserveError> { |
| // Use a soft-limit on the maximum capacity, but if the caller explicitly |
| // requested more, do it and let them have the resulting error. |
| let new_capacity = Ord::min(self.indices.capacity(), Self::MAX_ENTRIES_CAPACITY); |
| let try_add = new_capacity - self.entries.len(); |
| if try_add > additional && self.entries.try_reserve_exact(try_add).is_ok() { |
| return Ok(()); |
| } |
| self.entries |
| .try_reserve_exact(additional) |
| .map_err(TryReserveError::from_alloc) |
| } |
| |
| /// Try to reserve capacity for `additional` more key-value pairs, without over-allocating. |
| pub(crate) fn try_reserve_exact(&mut self, additional: usize) -> Result<(), TryReserveError> { |
| self.indices |
| .try_reserve(additional, get_hash(&self.entries)) |
| .map_err(TryReserveError::from_hashbrown)?; |
| self.entries |
| .try_reserve_exact(additional) |
| .map_err(TryReserveError::from_alloc) |
| } |
| |
| /// Shrink the capacity of the map with a lower bound |
| pub(crate) fn shrink_to(&mut self, min_capacity: usize) { |
| self.indices |
| .shrink_to(min_capacity, get_hash(&self.entries)); |
| self.entries.shrink_to(min_capacity); |
| } |
| |
| /// Remove the last key-value pair |
| pub(crate) fn pop(&mut self) -> Option<(K, V)> { |
| if let Some(entry) = self.entries.pop() { |
| let last = self.entries.len(); |
| erase_index(&mut self.indices, entry.hash, last); |
| Some((entry.key, entry.value)) |
| } else { |
| None |
| } |
| } |
| |
| /// Append a key-value pair to `entries`, *without* checking whether it already exists. |
| fn push_entry(&mut self, hash: HashValue, key: K, value: V) { |
| if self.entries.len() == self.entries.capacity() { |
| // Reserve our own capacity synced to the indices, |
| // rather than letting `Vec::push` just double it. |
| self.reserve_entries(1); |
| } |
| self.entries.push(Bucket { hash, key, value }); |
| } |
| |
| /// Insert a key-value pair in `entries` at a particular index, |
| /// *without* checking whether it already exists. |
| fn insert_entry(&mut self, index: usize, hash: HashValue, key: K, value: V) { |
| if self.entries.len() == self.entries.capacity() { |
| // Reserve our own capacity synced to the indices, |
| // rather than letting `Vec::insert` just double it. |
| self.reserve_entries(1); |
| } |
| self.entries.insert(index, Bucket { hash, key, value }); |
| } |
| |
| /// Return the index in `entries` where an equivalent key can be found |
| pub(crate) fn get_index_of<Q>(&self, hash: HashValue, key: &Q) -> Option<usize> |
| where |
| Q: ?Sized + Equivalent<K>, |
| { |
| let eq = equivalent(key, &self.entries); |
| self.indices.get(hash.get(), eq).copied() |
| } |
| |
| pub(crate) fn insert_full(&mut self, hash: HashValue, key: K, value: V) -> (usize, Option<V>) |
| where |
| K: Eq, |
| { |
| match self.find_or_insert(hash, &key) { |
| Ok(i) => (i, Some(mem::replace(&mut self.entries[i].value, value))), |
| Err(i) => { |
| debug_assert_eq!(i, self.entries.len()); |
| self.push_entry(hash, key, value); |
| (i, None) |
| } |
| } |
| } |
| |
| /// Same as `insert_full`, except it also replaces the key |
| pub(crate) fn replace_full( |
| &mut self, |
| hash: HashValue, |
| key: K, |
| value: V, |
| ) -> (usize, Option<(K, V)>) |
| where |
| K: Eq, |
| { |
| match self.find_or_insert(hash, &key) { |
| Ok(i) => { |
| let entry = &mut self.entries[i]; |
| let kv = ( |
| mem::replace(&mut entry.key, key), |
| mem::replace(&mut entry.value, value), |
| ); |
| (i, Some(kv)) |
| } |
| Err(i) => { |
| debug_assert_eq!(i, self.entries.len()); |
| self.push_entry(hash, key, value); |
| (i, None) |
| } |
| } |
| } |
| |
| fn insert_unique(&mut self, hash: HashValue, key: K, value: V) -> usize { |
| let i = self.indices.len(); |
| self.indices.insert(hash.get(), i, get_hash(&self.entries)); |
| debug_assert_eq!(i, self.entries.len()); |
| self.push_entry(hash, key, value); |
| i |
| } |
| |
| fn shift_insert_unique(&mut self, index: usize, hash: HashValue, key: K, value: V) { |
| let end = self.indices.len(); |
| assert!(index <= end); |
| // Increment others first so we don't have duplicate indices. |
| self.increment_indices(index, end); |
| let entries = &*self.entries; |
| self.indices.insert(hash.get(), index, move |&i| { |
| // Adjust for the incremented indices to find hashes. |
| debug_assert_ne!(i, index); |
| let i = if i < index { i } else { i - 1 }; |
| entries[i].hash.get() |
| }); |
| self.insert_entry(index, hash, key, value); |
| } |
| |
| /// Remove an entry by shifting all entries that follow it |
| pub(crate) fn shift_remove_full<Q>(&mut self, hash: HashValue, key: &Q) -> Option<(usize, K, V)> |
| where |
| Q: ?Sized + Equivalent<K>, |
| { |
| let eq = equivalent(key, &self.entries); |
| match self.indices.remove_entry(hash.get(), eq) { |
| Some(index) => { |
| let (key, value) = self.shift_remove_finish(index); |
| Some((index, key, value)) |
| } |
| None => None, |
| } |
| } |
| |
| /// Remove an entry by shifting all entries that follow it |
| pub(crate) fn shift_remove_index(&mut self, index: usize) -> Option<(K, V)> { |
| match self.entries.get(index) { |
| Some(entry) => { |
| erase_index(&mut self.indices, entry.hash, index); |
| Some(self.shift_remove_finish(index)) |
| } |
| None => None, |
| } |
| } |
| |
| /// Remove an entry by shifting all entries that follow it |
| /// |
| /// The index should already be removed from `self.indices`. |
| fn shift_remove_finish(&mut self, index: usize) -> (K, V) { |
| // Correct indices that point to the entries that followed the removed entry. |
| self.decrement_indices(index + 1, self.entries.len()); |
| |
| // Use Vec::remove to actually remove the entry. |
| let entry = self.entries.remove(index); |
| (entry.key, entry.value) |
| } |
| |
| /// Decrement all indices in the range `start..end`. |
| /// |
| /// The index `start - 1` should not exist in `self.indices`. |
| /// All entries should still be in their original positions. |
| fn decrement_indices(&mut self, start: usize, end: usize) { |
| // Use a heuristic between a full sweep vs. a `find()` for every shifted item. |
| let shifted_entries = &self.entries[start..end]; |
| if shifted_entries.len() > self.indices.buckets() / 2 { |
| // Shift all indices in range. |
| for i in self.indices_mut() { |
| if start <= *i && *i < end { |
| *i -= 1; |
| } |
| } |
| } else { |
| // Find each entry in range to shift its index. |
| for (i, entry) in (start..end).zip(shifted_entries) { |
| update_index(&mut self.indices, entry.hash, i, i - 1); |
| } |
| } |
| } |
| |
| /// Increment all indices in the range `start..end`. |
| /// |
| /// The index `end` should not exist in `self.indices`. |
| /// All entries should still be in their original positions. |
| fn increment_indices(&mut self, start: usize, end: usize) { |
| // Use a heuristic between a full sweep vs. a `find()` for every shifted item. |
| let shifted_entries = &self.entries[start..end]; |
| if shifted_entries.len() > self.indices.buckets() / 2 { |
| // Shift all indices in range. |
| for i in self.indices_mut() { |
| if start <= *i && *i < end { |
| *i += 1; |
| } |
| } |
| } else { |
| // Find each entry in range to shift its index, updated in reverse so |
| // we never have duplicated indices that might have a hash collision. |
| for (i, entry) in (start..end).zip(shifted_entries).rev() { |
| update_index(&mut self.indices, entry.hash, i, i + 1); |
| } |
| } |
| } |
| |
| pub(super) fn move_index(&mut self, from: usize, to: usize) { |
| let from_hash = self.entries[from].hash; |
| if from != to { |
| // Use a sentinel index so other indices don't collide. |
| update_index(&mut self.indices, from_hash, from, usize::MAX); |
| |
| // Update all other indices and rotate the entry positions. |
| if from < to { |
| self.decrement_indices(from + 1, to + 1); |
| self.entries[from..=to].rotate_left(1); |
| } else if to < from { |
| self.increment_indices(to, from); |
| self.entries[to..=from].rotate_right(1); |
| } |
| |
| // Change the sentinel index to its final position. |
| update_index(&mut self.indices, from_hash, usize::MAX, to); |
| } |
| } |
| |
| pub(crate) fn swap_indices(&mut self, a: usize, b: usize) { |
| // If they're equal and in-bounds, there's nothing to do. |
| if a == b && a < self.entries.len() { |
| return; |
| } |
| |
| // We'll get a "nice" bounds-check from indexing `self.entries`, |
| // and then we expect to find it in the table as well. |
| let [ref_a, ref_b] = self |
| .indices |
| .get_many_mut( |
| [self.entries[a].hash.get(), self.entries[b].hash.get()], |
| move |i, &x| if i == 0 { x == a } else { x == b }, |
| ) |
| .expect("indices not found"); |
| |
| mem::swap(ref_a, ref_b); |
| self.entries.swap(a, b); |
| } |
| |
| /// Remove an entry by swapping it with the last |
| pub(crate) fn swap_remove_full<Q>(&mut self, hash: HashValue, key: &Q) -> Option<(usize, K, V)> |
| where |
| Q: ?Sized + Equivalent<K>, |
| { |
| let eq = equivalent(key, &self.entries); |
| match self.indices.remove_entry(hash.get(), eq) { |
| Some(index) => { |
| let (key, value) = self.swap_remove_finish(index); |
| Some((index, key, value)) |
| } |
| None => None, |
| } |
| } |
| |
| /// Remove an entry by swapping it with the last |
| pub(crate) fn swap_remove_index(&mut self, index: usize) -> Option<(K, V)> { |
| match self.entries.get(index) { |
| Some(entry) => { |
| erase_index(&mut self.indices, entry.hash, index); |
| Some(self.swap_remove_finish(index)) |
| } |
| None => None, |
| } |
| } |
| |
| /// Finish removing an entry by swapping it with the last |
| /// |
| /// The index should already be removed from `self.indices`. |
| fn swap_remove_finish(&mut self, index: usize) -> (K, V) { |
| // use swap_remove, but then we need to update the index that points |
| // to the other entry that has to move |
| let entry = self.entries.swap_remove(index); |
| |
| // correct index that points to the entry that had to swap places |
| if let Some(entry) = self.entries.get(index) { |
| // was not last element |
| // examine new element in `index` and find it in indices |
| let last = self.entries.len(); |
| update_index(&mut self.indices, entry.hash, last, index); |
| } |
| |
| (entry.key, entry.value) |
| } |
| |
| /// Erase `start..end` from `indices`, and shift `end..` indices down to `start..` |
| /// |
| /// All of these items should still be at their original location in `entries`. |
| /// This is used by `drain`, which will let `Vec::drain` do the work on `entries`. |
| fn erase_indices(&mut self, start: usize, end: usize) { |
| let (init, shifted_entries) = self.entries.split_at(end); |
| let (start_entries, erased_entries) = init.split_at(start); |
| |
| let erased = erased_entries.len(); |
| let shifted = shifted_entries.len(); |
| let half_capacity = self.indices.buckets() / 2; |
| |
| // Use a heuristic between different strategies |
| if erased == 0 { |
| // Degenerate case, nothing to do |
| } else if start + shifted < half_capacity && start < erased { |
| // Reinsert everything, as there are few kept indices |
| self.indices.clear(); |
| |
| // Reinsert stable indices, then shifted indices |
| raw::insert_bulk_no_grow(&mut self.indices, start_entries); |
| raw::insert_bulk_no_grow(&mut self.indices, shifted_entries); |
| } else if erased + shifted < half_capacity { |
| // Find each affected index, as there are few to adjust |
| |
| // Find erased indices |
| for (i, entry) in (start..).zip(erased_entries) { |
| erase_index(&mut self.indices, entry.hash, i); |
| } |
| |
| // Find shifted indices |
| for ((new, old), entry) in (start..).zip(end..).zip(shifted_entries) { |
| update_index(&mut self.indices, entry.hash, old, new); |
| } |
| } else { |
| // Sweep the whole table for adjustments |
| self.erase_indices_sweep(start, end); |
| } |
| |
| debug_assert_eq!(self.indices.len(), start + shifted); |
| } |
| |
| pub(crate) fn retain_in_order<F>(&mut self, mut keep: F) |
| where |
| F: FnMut(&mut K, &mut V) -> bool, |
| { |
| self.entries |
| .retain_mut(|entry| keep(&mut entry.key, &mut entry.value)); |
| if self.entries.len() < self.indices.len() { |
| self.rebuild_hash_table(); |
| } |
| } |
| |
| fn rebuild_hash_table(&mut self) { |
| self.indices.clear(); |
| raw::insert_bulk_no_grow(&mut self.indices, &self.entries); |
| } |
| |
| pub(crate) fn reverse(&mut self) { |
| self.entries.reverse(); |
| |
| // No need to save hash indices, can easily calculate what they should |
| // be, given that this is an in-place reversal. |
| let len = self.entries.len(); |
| for i in self.indices_mut() { |
| *i = len - *i - 1; |
| } |
| } |
| } |
| |
| #[test] |
| fn assert_send_sync() { |
| fn assert_send_sync<T: Send + Sync>() {} |
| assert_send_sync::<IndexMapCore<i32, i32>>(); |
| assert_send_sync::<Entry<'_, i32, i32>>(); |
| assert_send_sync::<IndexedEntry<'_, i32, i32>>(); |
| } |