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//! Contains the secondary map implementation. use super::{is_older_version, Key, KeyData}; use std; #[cfg(feature = "unstable")] use std::collections::TryReserveError; use std::hint::unreachable_unchecked; use std::iter::{Enumerate, Extend, FromIterator, FusedIterator}; use std::marker::PhantomData; use std::ops::{Index, IndexMut}; // We could use unions to remove the memory overhead of Option here as well, but // until non-Copy elements inside unions stabilize it's better to give users at // least some place to store non-Copy elements. #[derive(Debug, Clone)] struct Slot<T> { version: u32, value: Option<T>, } impl<T> Slot<T> { // Is this slot occupied? #[inline(always)] pub fn occupied(&self) -> bool { self.version % 2 > 0 } } /// Secondary map, associate data with previously stored elements in a slot map. /// /// A `SecondaryMap` allows you to efficiently store additional information for /// each element in a slot map. You can have multiple secondary maps per slot /// map, but not multiple slot maps per secondary map. It is safe but /// unspecified behavior if you use keys from multiple different slot maps in /// the same `SecondaryMap`. /// /// A `SecondaryMap` does not leak memory even if you never remove elements. In /// return, when you remove a key from the primary slot map, after any insert /// the space associated with the removed element may be reclaimed. Don't expect /// the values associated with a removed key to stick around after an insertion /// has happened! /// /// Unlike a [`SlotMap`], a `SecondaryMap`s elements do not need to be /// [`Slottable`]. This means that if you can't or don't want to use nightly /// Rust, and your data is not [`Slottable`], you can store that data as /// secondary data. /// /// Finally a note on memory complexity, the `SecondaryMap` can use memory for /// each slot in the primary slot map, and has to iterate over every slot during /// iteration, regardless of whether you have inserted an associative value at /// that key or not. If you have some property that you only expect to set for a /// minority of keys, use a [`SparseSecondaryMap`], which is backed by a /// [`HashMap`]. /// /// [`SlotMap`]: ../struct.SlotMap.html /// [`Slottable`]: ../trait.Slottable.html /// [`SparseSecondaryMap`]: ../sparse_secondary/struct.SparseSecondaryMap.html /// [`HashMap`]: https://doc.rust-lang.org/std/collections/struct.HashMap.html /// /// Example usage: /// /// ``` /// # use slotmap::*; /// // Nightly Rust needed to store String which is not Copy. /// let mut players: SlotMap<_, &'static str> = SlotMap::new(); /// // But not for secondary maps. /// let mut nicks: SecondaryMap<_, String> = SecondaryMap::new(); /// let mut health = SecondaryMap::new(); /// let mut ammo = SecondaryMap::new(); /// /// let alice = players.insert("alice"); /// nicks.insert(alice, "the_dragon1".to_string()); /// let bob = players.insert("bob"); /// nicks.insert(bob, "bobby_".to_string()); /// /// for p in players.keys() { /// health.insert(p, 100); /// ammo.insert(p, 30); /// } /// /// // Alice attacks Bob with all her ammo! /// health[bob] -= ammo[alice] * 3; /// ammo[alice] = 0; /// ``` #[derive(Debug, Clone)] pub struct SecondaryMap<K: Key, V> { slots: Vec<Slot<V>>, num_elems: usize, _k: PhantomData<fn(K) -> K>, } impl<K: Key, V> SecondaryMap<K, V> { /// Constructs a new, empty `SecondaryMap`. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::new(); /// ``` pub fn new() -> Self { Self::with_capacity(0) } /// Creates an empty `SecondaryMap` with the given capacity of slots. /// /// The secondary map will not reallocate until it holds at least `capacity` /// slots. Even inserting a single key-value pair might require as many /// slots as the slot map the key comes from, so it's recommended to match /// the capacity of a secondary map to its corresponding slot map. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm: SlotMap<_, i32> = SlotMap::with_capacity(10); /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::with_capacity(sm.capacity()); /// ``` pub fn with_capacity(capacity: usize) -> Self { let mut slots = Vec::with_capacity(capacity + 1); // Sentinel. slots.push(Slot { version: 0, value: None, }); Self { slots, num_elems: 0, _k: PhantomData, } } /// Returns the number of elements in the secondary map. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let k = sm.insert(4); /// let mut squared = SecondaryMap::new(); /// assert_eq!(squared.len(), 0); /// squared.insert(k, 16); /// assert_eq!(squared.len(), 1); /// ``` pub fn len(&self) -> usize { self.num_elems as usize } /// Returns if the secondary map is empty. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::new(); /// assert!(sec.is_empty()); /// ``` pub fn is_empty(&self) -> bool { self.num_elems == 0 } /// Returns the number of elements the `SecondaryMap` can hold without /// reallocating. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::with_capacity(10); /// assert!(sec.capacity() >= 10); /// ``` pub fn capacity(&self) -> usize { self.slots.capacity() - 1 // Sentinel. } /// Sets the capacity of the `SecondaryMap` to `new_capacity`, if it is /// bigger than the current capacity. /// /// It is recommended to set the capacity of a `SecondaryMap` to the /// capacity of its corresponding slot map before inserting many new /// elements to prevent frequent reallocations. The collection may reserve /// more space than requested. /// /// # Panics /// /// Panics if the new allocation size overflows `usize`. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::with_capacity(10); /// assert!(sec.capacity() >= 10); /// sec.set_capacity(1000); /// assert!(sec.capacity() >= 1000); /// ``` pub fn set_capacity(&mut self, new_capacity: usize) { let new_capacity = new_capacity + 1; // Sentinel. if new_capacity > self.slots.capacity() { let needed = new_capacity - self.slots.len(); self.slots.reserve(needed); } } /// Tries to set the capacity of the `SecondaryMap` to `new_capacity`, if it /// is bigger than the current capacity. /// /// It is recommended to set the capacity of a `SecondaryMap` to the /// capacity of its corresponding slot map before inserting many new /// elements to prevent frequent reallocations. The collection may reserve /// more space than requested. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sec: SecondaryMap<DefaultKey, i32> = SecondaryMap::with_capacity(10); /// assert!(sec.capacity() >= 10); /// sec.try_set_capacity(1000).unwrap(); /// assert!(sec.capacity() >= 1000); /// ``` #[cfg(feature = "unstable")] pub fn try_set_capacity(&mut self, new_capacity: usize) -> Result<(), TryReserveError> { let new_capacity = new_capacity + 1; // Sentinel. if new_capacity > self.slots.capacity() { let needed = new_capacity - self.slots.len(); self.slots.try_reserve(needed) } else { Ok(()) } } /// Returns `true` if the secondary map contains `key`. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let k = sm.insert(4); /// let mut squared = SecondaryMap::new(); /// assert!(!squared.contains_key(k)); /// squared.insert(k, 16); /// assert!(squared.contains_key(k)); /// ``` pub fn contains_key(&self, key: K) -> bool { let key = key.into(); self.slots .get(key.idx as usize) .map_or(false, |slot| slot.version == key.version.get()) } /// Inserts a value into the secondary map at the given `key`. Can silently /// fail if `key` was removed from the originating slot map. /// /// Returns `None` if this key was not present in the map, the old value /// otherwise. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let k = sm.insert(4); /// let mut squared = SecondaryMap::new(); /// assert_eq!(squared.insert(k, 0), None); /// assert_eq!(squared.insert(k, 4), Some(0)); /// // You don't have to use insert if the key is already in the secondary map. /// squared[k] *= squared[k]; /// assert_eq!(squared[k], 16); /// ``` pub fn insert(&mut self, key: K, value: V) -> Option<V> { let key = key.into(); self.slots .extend((self.slots.len()..=key.idx as usize).map(|_| Slot { version: 0, value: None, })); let slot = &mut self.slots[key.idx as usize]; if slot.version == key.version.get() { return std::mem::replace(&mut slot.value, Some(value)); } if slot.occupied() { // Don't replace existing newer values. if is_older_version(key.version.get(), slot.version) { return None; } } else { self.num_elems += 1; } *slot = Slot { version: key.version.get(), value: Some(value), }; None } /// Removes a key from the secondary map, returning the value at the key if /// the key was not previously removed. If `key` was removed from the /// originating slot map, its corresponding entry in the secondary map may /// or may not already be removed. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let mut squared = SecondaryMap::new(); /// let k = sm.insert(4); /// squared.insert(k, 16); /// squared.remove(k); /// assert!(!squared.contains_key(k)); /// /// // It's not necessary to remove keys deleted from the primary slot map, they /// // get deleted automatically when their slots are reused on a subsequent insert. /// squared.insert(k, 16); /// sm.remove(k); // Remove k from the slot map, making an empty slot. /// let new_k = sm.insert(2); // Since sm only has one empty slot, this reuses it. /// assert!(!squared.contains_key(new_k)); // Space reuse does not mean equal keys. /// assert!(squared.contains_key(k)); // Slot has not been reused in squared yet. /// squared.insert(new_k, 4); /// assert!(!squared.contains_key(k)); // Old key is no longer available. /// ``` pub fn remove(&mut self, key: K) -> Option<V> { let key = key.into(); if let Some(slot) = self.slots.get_mut(key.idx as usize) { if slot.version == key.version.get() { // We actually decrement version here, to ensure that if the // user re-inserts a value at this key the version does not get // denied as outdated. slot.version -= 1; self.num_elems -= 1; return Some(std::mem::replace(&mut slot.value, None).unwrap()); } } None } /// Retains only the elements specified by the predicate. /// /// In other words, remove all key-value pairs `(k, v)` such that /// `f(k, &mut v)` returns false. This method invalidates any removed keys. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// /// let k1 = sm.insert(0); sec.insert(k1, 10); /// let k2 = sm.insert(1); sec.insert(k2, 11); /// let k3 = sm.insert(2); sec.insert(k3, 12); /// /// sec.retain(|key, val| key == k1 || *val == 11); /// /// assert!(sec.contains_key(k1)); /// assert!(sec.contains_key(k2)); /// assert!(!sec.contains_key(k3)); /// /// assert_eq!(2, sec.len()); /// ``` pub fn retain<F>(&mut self, mut f: F) where F: FnMut(K, &mut V) -> bool, { let len = self.slots.len(); for i in 0..len { // This is safe because removing elements does not shrink slots. let slot = unsafe { self.slots.get_unchecked_mut(i) }; let should_remove = { if let Some(value) = &mut slot.value { let key = KeyData::new(i as u32, slot.version).into(); !f(key, value) } else { false } }; if should_remove { self.num_elems -= 1; slot.version -= 1; slot.value = None; } } } /// Clears the secondary map. Keeps the allocated memory for reuse. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// for i in 0..10 { /// sec.insert(sm.insert(i), i); /// } /// assert_eq!(sec.len(), 10); /// sec.clear(); /// assert_eq!(sec.len(), 0); /// ``` pub fn clear(&mut self) { self.drain(); } /// Clears the slot map, returning all key-value pairs in arbitrary order as /// an iterator. Keeps the allocated memory for reuse. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// # use std::iter::FromIterator; /// let mut sm = SlotMap::new(); /// let k = sm.insert(0); /// let mut sec = SecondaryMap::new(); /// sec.insert(k, 1); /// let v: Vec<_> = sec.drain().collect(); /// assert_eq!(sec.len(), 0); /// assert_eq!(v, vec![(k, 1)]); /// ``` pub fn drain(&mut self) -> Drain<K, V> { Drain { cur: 1, num_left: self.len(), sm: self, } } /// Returns a reference to the value corresponding to the key. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let key = sm.insert("foo"); /// let mut sec = SecondaryMap::new(); /// sec.insert(key, "bar"); /// assert_eq!(sec.get(key), Some(&"bar")); /// sec.remove(key); /// assert_eq!(sec.get(key), None); /// ``` pub fn get(&self, key: K) -> Option<&V> { let key = key.into(); self.slots .get(key.idx as usize) .filter(|slot| slot.version == key.version.get()) .map(|slot| slot.value.as_ref().unwrap()) } /// Returns a reference to the value corresponding to the key without /// version or bounds checking. /// /// # Safety /// /// This should only be used if `contains_key(key)` is true. Otherwise it is /// potentially unsafe. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let key = sm.insert("foo"); /// let mut sec = SecondaryMap::new(); /// sec.insert(key, "bar"); /// assert_eq!(unsafe { sec.get_unchecked(key) }, &"bar"); /// sec.remove(key); /// // sec.get_unchecked(key) is now dangerous! /// ``` pub unsafe fn get_unchecked(&self, key: K) -> &V { let key = key.into(); if let Some(value) = self.slots.get_unchecked(key.idx as usize).value.as_ref() { value } else { unreachable_unchecked() } } /// Returns a mutable reference to the value corresponding to the key. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let key = sm.insert("test"); /// let mut sec = SecondaryMap::new(); /// sec.insert(key, 3.5); /// if let Some(x) = sec.get_mut(key) { /// *x += 3.0; /// } /// assert_eq!(sec[key], 6.5); /// ``` pub fn get_mut(&mut self, key: K) -> Option<&mut V> { let key = key.into(); self.slots .get_mut(key.idx as usize) .filter(|slot| slot.version == key.version.get()) .map(|slot| slot.value.as_mut().unwrap()) } /// Returns a mutable reference to the value corresponding to the key /// without version or bounds checking. /// /// # Safety /// /// This should only be used if `contains_key(key)` is true. Otherwise it is /// potentially unsafe. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let key = sm.insert("foo"); /// let mut sec = SecondaryMap::new(); /// sec.insert(key, "bar"); /// unsafe { *sec.get_unchecked_mut(key) = "baz" }; /// assert_eq!(sec[key], "baz"); /// sec.remove(key); /// // sec.get_unchecked_mut(key) is now dangerous! /// ``` pub unsafe fn get_unchecked_mut(&mut self, key: K) -> &mut V { let key = key.into(); if let Some(value) = self .slots .get_unchecked_mut(key.idx as usize) .value .as_mut() { value } else { unreachable_unchecked() } } /// An iterator visiting all key-value pairs in arbitrary order. The /// iterator element type is `(K, &'a V)`. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// let k0 = sm.insert(0); sec.insert(k0, 10); /// let k1 = sm.insert(1); sec.insert(k1, 11); /// let k2 = sm.insert(2); sec.insert(k2, 12); /// /// for (k, v) in sm.iter() { /// println!("key: {:?}, val: {}", k, v); /// } /// ``` pub fn iter(&self) -> Iter<K, V> { Iter { num_left: self.num_elems, slots: self.slots.iter().enumerate(), _k: PhantomData, } } /// An iterator visiting all key-value pairs in arbitrary order, with /// mutable references to the values. The iterator element type is /// `(K, &'a mut V)`. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// let k0 = sm.insert(1); sec.insert(k0, 10); /// let k1 = sm.insert(2); sec.insert(k1, 20); /// let k2 = sm.insert(3); sec.insert(k2, 30); /// /// for (k, v) in sec.iter_mut() { /// if k != k1 { /// *v *= -1; /// } /// } /// /// assert_eq!(sec[k0], -10); /// assert_eq!(sec[k1], 20); /// assert_eq!(sec[k2], -30); /// ``` pub fn iter_mut(&mut self) -> IterMut<K, V> { IterMut { num_left: self.num_elems, slots: self.slots.iter_mut().enumerate(), _k: PhantomData, } } /// An iterator visiting all keys in arbitrary order. The iterator element /// type is `K`. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// # use std::collections::HashSet; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// let k0 = sm.insert(1); sec.insert(k0, 10); /// let k1 = sm.insert(2); sec.insert(k1, 20); /// let k2 = sm.insert(3); sec.insert(k2, 30); /// let keys: HashSet<_> = sec.keys().collect(); /// let check: HashSet<_> = vec![k0, k1, k2].into_iter().collect(); /// assert_eq!(keys, check); /// ``` 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`. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// # use std::collections::HashSet; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// let k0 = sm.insert(1); sec.insert(k0, 10); /// let k1 = sm.insert(2); sec.insert(k1, 20); /// let k2 = sm.insert(3); sec.insert(k2, 30); /// let values: HashSet<_> = sec.values().collect(); /// let check: HashSet<_> = vec![&10, &20, &30].into_iter().collect(); /// assert_eq!(values, check); /// ``` 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`. /// /// This function must iterate over all slots, empty or not. In the face of /// many deleted elements it can be inefficient. /// /// # Examples /// /// ``` /// # use slotmap::*; /// # use std::collections::HashSet; /// let mut sm = SlotMap::new(); /// let mut sec = SecondaryMap::new(); /// sec.insert(sm.insert(1), 10); /// sec.insert(sm.insert(2), 20); /// sec.insert(sm.insert(3), 30); /// sec.values_mut().for_each(|n| { *n *= 3 }); /// let values: HashSet<_> = sec.into_iter().map(|(_k, v)| v).collect(); /// let check: HashSet<_> = vec![30, 60, 90].into_iter().collect(); /// assert_eq!(values, check); /// ``` pub fn values_mut(&mut self) -> ValuesMut<K, V> { ValuesMut { inner: self.iter_mut(), } } } impl<K: Key, V> Default for SecondaryMap<K, V> { fn default() -> Self { Self::new() } } impl<K: Key, V> Index<K> for SecondaryMap<K, V> { type Output = V; fn index(&self, key: K) -> &V { match self.get(key) { Some(r) => r, None => panic!("invalid SecondaryMap key used"), } } } impl<K: Key, V> IndexMut<K> for SecondaryMap<K, V> { fn index_mut(&mut self, key: K) -> &mut V { match self.get_mut(key) { Some(r) => r, None => panic!("invalid SecondaryMap key used"), } } } impl<K: Key, V: PartialEq> PartialEq for SecondaryMap<K, V> { fn eq(&self, other: &Self) -> bool { if self.len() != other.len() { return false; } self.iter().all(|(key, value)| { other .get(key) .map_or(false, |other_value| *value == *other_value) }) } } impl<K: Key, V: Eq> Eq for SecondaryMap<K, V> {} impl<K: Key, V> FromIterator<(K, V)> for SecondaryMap<K, V> { fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I) -> Self { let mut sec = Self::new(); sec.extend(iter); sec } } impl<K: Key, V> Extend<(K, V)> for SecondaryMap<K, V> { fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I) { let iter = iter.into_iter(); for (k, v) in iter { self.insert(k, v); } } } impl<'a, K: Key, V: 'a + Copy> Extend<(K, &'a V)> for SecondaryMap<K, V> { fn extend<I: IntoIterator<Item = (K, &'a V)>>(&mut self, iter: I) { let iter = iter.into_iter(); for (k, v) in iter { self.insert(k, *v); } } } // Iterators. /// A draining iterator for `SecondaryMap`. #[derive(Debug)] pub struct Drain<'a, K: Key + 'a, V: 'a> { num_left: usize, sm: &'a mut SecondaryMap<K, V>, cur: usize, } /// An iterator that moves key-value pairs out of a `SecondaryMap`. #[derive(Debug)] pub struct IntoIter<K: Key, V> { num_left: usize, slots: Enumerate<std::vec::IntoIter<Slot<V>>>, _k: PhantomData<fn(K) -> K>, } /// An iterator over the key-value pairs in a `SecondaryMap`. #[derive(Debug)] pub struct Iter<'a, K: Key + 'a, V: 'a> { num_left: usize, slots: Enumerate<std::slice::Iter<'a, Slot<V>>>, _k: PhantomData<fn(K) -> K>, } /// A mutable iterator over the key-value pairs in a `SecondaryMap`. #[derive(Debug)] pub struct IterMut<'a, K: Key + 'a, V: 'a> { num_left: usize, slots: Enumerate<std::slice::IterMut<'a, Slot<V>>>, _k: PhantomData<fn(K) -> K>, } /// An iterator over the keys in a `SecondaryMap`. #[derive(Debug)] pub struct Keys<'a, K: Key + 'a, V: 'a> { inner: Iter<'a, K, V>, } /// An iterator over the values in a `SecondaryMap`. #[derive(Debug)] pub struct Values<'a, K: Key + 'a, V: 'a> { inner: Iter<'a, K, V>, } /// A mutable iterator over the values in a `SecondaryMap`. #[derive(Debug)] pub struct ValuesMut<'a, K: Key + 'a, V: 'a> { inner: IterMut<'a, K, V>, } impl<'a, K: Key, V> Iterator for Drain<'a, K, V> { type Item = (K, V); fn next(&mut self) -> Option<(K, V)> { let len = self.sm.slots.len(); while self.cur < len { let idx = self.cur; self.cur += 1; if let Some(value) = std::mem::replace(&mut self.sm.slots[idx].value, None) { let key = KeyData::new(idx as u32, self.sm.slots[idx].version); self.sm.slots[idx].version -= 1; self.sm.num_elems -= 1; self.num_left -= 1; return Some((key.into(), value)); } } None } fn size_hint(&self) -> (usize, Option<usize>) { (self.num_left, Some(self.num_left)) } } impl<'a, K: Key, V> Drop for Drain<'a, K, V> { fn drop(&mut self) { self.for_each(|_drop| {}); } } impl<K: Key, V> Iterator for IntoIter<K, V> { type Item = (K, V); fn next(&mut self) -> Option<(K, V)> { while let Some((idx, mut slot)) = self.slots.next() { if let Some(value) = std::mem::replace(&mut slot.value, None) { let key = KeyData::new(idx as u32, slot.version); self.num_left -= 1; return Some((key.into(), value)); } } None } fn size_hint(&self) -> (usize, Option<usize>) { (self.num_left, Some(self.num_left)) } } impl<'a, K: Key, V> Iterator for Iter<'a, K, V> { type Item = (K, &'a V); fn next(&mut self) -> Option<(K, &'a V)> { while let Some((idx, slot)) = self.slots.next() { if let Some(value) = &slot.value { let key = KeyData::new(idx as u32, slot.version); self.num_left -= 1; return Some((key.into(), value)); } } None } fn size_hint(&self) -> (usize, Option<usize>) { (self.num_left, Some(self.num_left)) } } impl<'a, K: Key, V> Iterator for IterMut<'a, K, V> { type Item = (K, &'a mut V); fn next(&mut self) -> Option<(K, &'a mut V)> { while let Some((idx, slot)) = self.slots.next() { if let Some(value) = &mut slot.value { let key = KeyData::new(idx as u32, slot.version); self.num_left -= 1; return Some((key.into(), value)); } } None } fn size_hint(&self) -> (usize, Option<usize>) { (self.num_left, Some(self.num_left)) } } impl<'a, K: Key, V> Iterator for Keys<'a, K, V> { type Item = K; fn next(&mut self) -> Option<K> { self.inner.next().map(|(key, _)| key) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } } impl<'a, K: Key, V> Iterator for Values<'a, K, V> { type Item = &'a V; fn next(&mut self) -> Option<&'a V> { self.inner.next().map(|(_, value)| value) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } } impl<'a, K: Key, V> Iterator for ValuesMut<'a, K, V> { type Item = &'a mut V; fn next(&mut self) -> Option<&'a mut V> { self.inner.next().map(|(_, value)| value) } fn size_hint(&self) -> (usize, Option<usize>) { self.inner.size_hint() } } impl<'a, K: Key, V> IntoIterator for &'a SecondaryMap<K, V> { type Item = (K, &'a V); type IntoIter = Iter<'a, K, V>; fn into_iter(self) -> Self::IntoIter { self.iter() } } impl<'a, K: Key, V> IntoIterator for &'a mut SecondaryMap<K, V> { type Item = (K, &'a mut V); type IntoIter = IterMut<'a, K, V>; fn into_iter(self) -> Self::IntoIter { self.iter_mut() } } impl<K: Key, V> IntoIterator for SecondaryMap<K, V> { type Item = (K, V); type IntoIter = IntoIter<K, V>; fn into_iter(self) -> Self::IntoIter { let len = self.len(); let mut it = self.slots.into_iter().enumerate(); it.next(); // Skip sentinel. IntoIter { num_left: len, slots: it, _k: PhantomData, } } } impl<'a, K: Key, V> FusedIterator for Iter<'a, K, V> {} impl<'a, K: Key, V> FusedIterator for IterMut<'a, K, V> {} impl<'a, K: Key, V> FusedIterator for Keys<'a, K, V> {} impl<'a, K: Key, V> FusedIterator for Values<'a, K, V> {} impl<'a, K: Key, V> FusedIterator for ValuesMut<'a, K, V> {} impl<'a, K: Key, V> FusedIterator for Drain<'a, K, V> {} impl<K: Key, V> FusedIterator for IntoIter<K, V> {} impl<'a, K: Key, V> ExactSizeIterator for Iter<'a, K, V> {} impl<'a, K: Key, V> ExactSizeIterator for IterMut<'a, K, V> {} impl<'a, K: Key, V> ExactSizeIterator for Keys<'a, K, V> {} impl<'a, K: Key, V> ExactSizeIterator for Values<'a, K, V> {} impl<'a, K: Key, V> ExactSizeIterator for ValuesMut<'a, K, V> {} impl<'a, K: Key, V> ExactSizeIterator for Drain<'a, K, V> {} impl<K: Key, V> ExactSizeIterator for IntoIter<K, V> {} // Serialization with serde. #[cfg(feature = "serde")] mod serialize { use super::*; use serde::{de, Deserialize, Deserializer, Serialize, Serializer}; #[derive(Serialize, Deserialize)] struct SerdeSlot<T> { value: Option<T>, version: u32, } impl<T: Serialize> Serialize for Slot<T> { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer, { let serde_slot = SerdeSlot { version: self.version, value: self.value.as_ref(), }; serde_slot.serialize(serializer) } } impl<'de, T> Deserialize<'de> for Slot<T> where T: Deserialize<'de>, { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { let serde_slot: SerdeSlot<T> = Deserialize::deserialize(deserializer)?; let occupied = serde_slot.version % 2 > 0; if occupied ^ serde_slot.value.is_some() { return Err(de::Error::custom(&"inconsistent occupation in Slot")); } Ok(Self { value: serde_slot.value, version: serde_slot.version, }) } } impl<K: Key, V: Serialize> Serialize for SecondaryMap<K, V> { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer, { self.slots.serialize(serializer) } } impl<'de, K: Key, V: Deserialize<'de>> Deserialize<'de> for SecondaryMap<K, V> { fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { let mut slots: Vec<Slot<V>> = Deserialize::deserialize(deserializer)?; if slots.len() >= u32::max_value() as usize { return Err(de::Error::custom(&"too many slots")); } // Ensure the first slot exists and is empty for the sentinel. if slots.get(0).map_or(true, |slot| slot.version % 2 > 0) { return Err(de::Error::custom(&"first slot not empty")); } slots[0] = Slot { value: None, version: 0, }; let num_elems = slots.iter().map(|s| s.value.is_some() as usize).sum(); Ok(Self { num_elems, slots, _k: PhantomData, }) } } } #[cfg(test)] mod tests { use crate::*; use std::collections::HashMap; #[cfg(feature = "serde")] use serde_json; quickcheck! { fn qc_secmap_equiv_hashmap(operations: Vec<(u8, u32)>) -> bool { let mut hm = HashMap::new(); let mut hm_keys = Vec::new(); let mut unique_key = 0u32; let mut sm = SlotMap::new(); let mut sec = SecondaryMap::new(); let mut sm_keys = Vec::new(); #[cfg(not(feature = "serde"))] let num_ops = 4; #[cfg(feature = "serde")] let num_ops = 5; for (op, val) in operations { match op % num_ops { // Insert. 0 => { hm.insert(unique_key, val); hm_keys.push(unique_key); unique_key += 1; let k = sm.insert(val); sec.insert(k, val); sm_keys.push(k); } // Delete. 1 => { if hm_keys.len() == 0 { continue; } let idx = val as usize % hm_keys.len(); sm.remove(sm_keys[idx]); if hm.remove(&hm_keys[idx]) != sec.remove(sm_keys[idx]) { return false; } } // Access. 2 => { if hm_keys.len() == 0 { continue; } let idx = val as usize % hm_keys.len(); let (hm_key, sm_key) = (&hm_keys[idx], sm_keys[idx]); if hm.contains_key(hm_key) != sec.contains_key(sm_key) || hm.get(hm_key) != sec.get(sm_key) { return false; } } // Clone. 3 => { sec = sec.clone(); } // Serde round-trip. #[cfg(feature = "serde")] 4 => { let ser = serde_json::to_string(&sec).unwrap(); sec = serde_json::from_str(&ser).unwrap(); } _ => unreachable!(), } } let mut secv: Vec<_> = sec.values().collect(); let mut hmv: Vec<_> = hm.values().collect(); secv.sort(); hmv.sort(); secv == hmv } } }