//! Arena adapted from the generational-arena crate.
//!
//! See https://github.com/fitzgen/generational-arena/blob/master/src/lib.rs.
//! This has been modified to have a fully deterministic deserialization (including for the order of
//! Index attribution after a deserialization of the arena.
use parry::partitioning::IndexedData;
use std::cmp;
use std::iter::{self, Extend, FromIterator, FusedIterator};
use std::mem;
use std::ops;
use std::slice;
use std::vec;
/// The `Arena` allows inserting and removing elements that are referred to by
/// `Index`.
///
/// [See the module-level documentation for example usage and motivation.](./index.html)
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
pub struct Arena<T> {
items: Vec<Entry<T>>,
generation: u64,
free_list_head: Option<usize>,
len: usize,
}
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
enum Entry<T> {
Free { next_free: Option<usize> },
Occupied { generation: u64, value: T },
}
/// An index (and generation) into an `Arena`.
///
/// To get an `Index`, insert an element into an `Arena`, and the `Index` for
/// that element will be returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx = arena.insert(123);
/// assert_eq!(arena[idx], 123);
/// ```
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
pub struct Index {
index: usize,
generation: u64,
}
impl IndexedData for Index {
fn default() -> Self {
Self::from_raw_parts(crate::INVALID_USIZE, crate::INVALID_U64)
}
fn index(&self) -> usize {
self.into_raw_parts().0
}
}
impl Index {
/// Create a new `Index` from its raw parts.
///
/// The parts must have been returned from an earlier call to
/// `into_raw_parts`.
///
/// Providing arbitrary values will lead to malformed indices and ultimately
/// panics.
pub fn from_raw_parts(a: usize, b: u64) -> Index {
Index {
index: a,
generation: b,
}
}
/// Convert this `Index` into its raw parts.
///
/// This niche method is useful for converting an `Index` into another
/// identifier type. Usually, you should prefer a newtype wrapper around
/// `Index` like `pub struct MyIdentifier(Index);`. However, for external
/// types whose definition you can't customize, but which you can construct
/// instances of, this method can be useful.
pub fn into_raw_parts(self) -> (usize, u64) {
(self.index, self.generation)
}
}
const DEFAULT_CAPACITY: usize = 4;
impl<T> Default for Arena<T> {
fn default() -> Arena<T> {
Arena::new()
}
}
impl<T> Arena<T> {
/// Constructs a new, empty `Arena`.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::<usize>::new();
/// # let _ = arena;
/// ```
pub fn new() -> Arena<T> {
Arena::with_capacity(DEFAULT_CAPACITY)
}
/// Constructs a new, empty `Arena<T>` with the specified capacity.
///
/// The `Arena<T>` will be able to hold `n` elements without further allocation.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::with_capacity(10);
///
/// // These insertions will not require further allocation.
/// for i in 0..10 {
/// assert!(arena.try_insert(i).is_ok());
/// }
///
/// // But now we are at capacity, and there is no more room.
/// assert!(arena.try_insert(99).is_err());
/// ```
pub fn with_capacity(n: usize) -> Arena<T> {
let n = cmp::max(n, 1);
let mut arena = Arena {
items: Vec::new(),
generation: 0,
free_list_head: None,
len: 0,
};
arena.reserve(n);
arena
}
/// Clear all the items inside the arena, but keep its allocation.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::with_capacity(1);
/// arena.insert(42);
/// arena.insert(43);
///
/// arena.clear();
///
/// assert_eq!(arena.capacity(), 2);
/// ```
pub fn clear(&mut self) {
self.items.clear();
let end = self.items.capacity();
self.items.extend((0..end).map(|i| {
if i == end - 1 {
Entry::Free { next_free: None }
} else {
Entry::Free {
next_free: Some(i + 1),
}
}
}));
self.free_list_head = Some(0);
self.len = 0;
}
/// Attempts to insert `value` into the arena using existing capacity.
///
/// This method will never allocate new capacity in the arena.
///
/// If insertion succeeds, then the `value`'s index is returned. If
/// insertion fails, then `Err(value)` is returned to give ownership of
/// `value` back to the caller.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
///
/// match arena.try_insert(42) {
/// Ok(idx) => {
/// // Insertion succeeded.
/// assert_eq!(arena[idx], 42);
/// }
/// Err(x) => {
/// // Insertion failed.
/// assert_eq!(x, 42);
/// }
/// };
/// ```
#[inline]
pub fn try_insert(&mut self, value: T) -> Result<Index, T> {
match self.try_alloc_next_index() {
None => Err(value),
Some(index) => {
self.items[index.index] = Entry::Occupied {
generation: self.generation,
value,
};
Ok(index)
}
}
}
/// Attempts to insert the value returned by `create` into the arena using existing capacity.
/// `create` is called with the new value's associated index, allowing values that know their own index.
///
/// This method will never allocate new capacity in the arena.
///
/// If insertion succeeds, then the new index is returned. If
/// insertion fails, then `Err(create)` is returned to give ownership of
/// `create` back to the caller.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::{Arena, Index};
///
/// let mut arena = Arena::new();
///
/// match arena.try_insert_with(|idx| (42, idx)) {
/// Ok(idx) => {
/// // Insertion succeeded.
/// assert_eq!(arena[idx].0, 42);
/// assert_eq!(arena[idx].1, idx);
/// }
/// Err(x) => {
/// // Insertion failed.
/// }
/// };
/// ```
#[inline]
pub fn try_insert_with<F: FnOnce(Index) -> T>(&mut self, create: F) -> Result<Index, F> {
match self.try_alloc_next_index() {
None => Err(create),
Some(index) => {
self.items[index.index] = Entry::Occupied {
generation: self.generation,
value: create(index),
};
Ok(index)
}
}
}
#[inline]
fn try_alloc_next_index(&mut self) -> Option<Index> {
match self.free_list_head {
None => None,
Some(i) => match self.items[i] {
Entry::Occupied { .. } => panic!("corrupt free list"),
Entry::Free { next_free } => {
self.free_list_head = next_free;
self.len += 1;
Some(Index {
index: i,
generation: self.generation,
})
}
},
}
}
/// Insert `value` into the arena, allocating more capacity if necessary.
///
/// The `value`'s associated index in the arena is returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
///
/// let idx = arena.insert(42);
/// assert_eq!(arena[idx], 42);
/// ```
#[inline]
pub fn insert(&mut self, value: T) -> Index {
match self.try_insert(value) {
Ok(i) => i,
Err(value) => self.insert_slow_path(value),
}
}
/// Insert the value returned by `create` into the arena, allocating more capacity if necessary.
/// `create` is called with the new value's associated index, allowing values that know their own index.
///
/// The new value's associated index in the arena is returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::{Arena, Index};
///
/// let mut arena = Arena::new();
///
/// let idx = arena.insert_with(|idx| (42, idx));
/// assert_eq!(arena[idx].0, 42);
/// assert_eq!(arena[idx].1, idx);
/// ```
#[inline]
pub fn insert_with(&mut self, create: impl FnOnce(Index) -> T) -> Index {
match self.try_insert_with(create) {
Ok(i) => i,
Err(create) => self.insert_with_slow_path(create),
}
}
#[inline(never)]
fn insert_slow_path(&mut self, value: T) -> Index {
let len = self.items.len();
self.reserve(len);
self.try_insert(value)
.map_err(|_| ())
.expect("inserting will always succeed after reserving additional space")
}
#[inline(never)]
fn insert_with_slow_path(&mut self, create: impl FnOnce(Index) -> T) -> Index {
let len = self.items.len();
self.reserve(len);
self.try_insert_with(create)
.map_err(|_| ())
.expect("inserting will always succeed after reserving additional space")
}
/// Remove the element at index `i` from the arena.
///
/// If the element at index `i` is still in the arena, then it is
/// returned. If it is not in the arena, then `None` is returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx = arena.insert(42);
///
/// assert_eq!(arena.remove(idx), Some(42));
/// assert_eq!(arena.remove(idx), None);
/// ```
pub fn remove(&mut self, i: Index) -> Option<T> {
if i.index >= self.items.len() {
return None;
}
match self.items[i.index] {
Entry::Occupied { generation, .. } if i.generation == generation => {
let entry = mem::replace(
&mut self.items[i.index],
Entry::Free {
next_free: self.free_list_head,
},
);
self.generation += 1;
self.free_list_head = Some(i.index);
self.len -= 1;
match entry {
Entry::Occupied {
generation: _,
value,
} => Some(value),
_ => unreachable!(),
}
}
_ => None,
}
}
/// Retains only the elements specified by the predicate.
///
/// In other words, remove all indices such that `predicate(index, &value)` returns `false`.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut crew = Arena::new();
/// crew.extend(&["Jim Hawkins", "John Silver", "Alexander Smollett", "Israel Hands"]);
/// let pirates = ["John Silver", "Israel Hands"]; // too dangerous to keep them around
/// crew.retain(|_index, member| !pirates.contains(member));
/// let mut crew_members = crew.iter().map(|(_, member)| **member);
/// assert_eq!(crew_members.next(), Some("Jim Hawkins"));
/// assert_eq!(crew_members.next(), Some("Alexander Smollett"));
/// assert!(crew_members.next().is_none());
/// ```
pub fn retain(&mut self, mut predicate: impl FnMut(Index, &mut T) -> bool) {
for i in 0..self.capacity() {
let remove = match &mut self.items[i] {
Entry::Occupied { generation, value } => {
let index = Index {
index: i,
generation: *generation,
};
if predicate(index, value) {
None
} else {
Some(index)
}
}
_ => None,
};
if let Some(index) = remove {
self.remove(index);
}
}
}
/// Is the element at index `i` in the arena?
///
/// Returns `true` if the element at `i` is in the arena, `false` otherwise.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx = arena.insert(42);
///
/// assert!(arena.contains(idx));
/// arena.remove(idx);
/// assert!(!arena.contains(idx));
/// ```
pub fn contains(&self, i: Index) -> bool {
self.get(i).is_some()
}
/// Get a shared reference to the element at index `i` if it is in the
/// arena.
///
/// If the element at index `i` is not in the arena, then `None` is returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx = arena.insert(42);
///
/// assert_eq!(arena.get(idx), Some(&42));
/// arena.remove(idx);
/// assert!(arena.get(idx).is_none());
/// ```
pub fn get(&self, i: Index) -> Option<&T> {
match self.items.get(i.index) {
Some(Entry::Occupied { generation, value }) if *generation == i.generation => {
Some(value)
}
_ => None,
}
}
/// Get an exclusive reference to the element at index `i` if it is in the
/// arena.
///
/// If the element at index `i` is not in the arena, then `None` is returned.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx = arena.insert(42);
///
/// *arena.get_mut(idx).unwrap() += 1;
/// assert_eq!(arena.remove(idx), Some(43));
/// assert!(arena.get_mut(idx).is_none());
/// ```
pub fn get_mut(&mut self, i: Index) -> Option<&mut T> {
match self.items.get_mut(i.index) {
Some(Entry::Occupied { generation, value }) if *generation == i.generation => {
Some(value)
}
_ => None,
}
}
/// Get a pair of exclusive references to the elements at index `i1` and `i2` if it is in the
/// arena.
///
/// If the element at index `i1` or `i2` is not in the arena, then `None` is returned for this
/// element.
///
/// # Panics
///
/// Panics if `i1` and `i2` are pointing to the same item of the arena.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx1 = arena.insert(0);
/// let idx2 = arena.insert(1);
///
/// {
/// let (item1, item2) = arena.get2_mut(idx1, idx2);
///
/// *item1.unwrap() = 3;
/// *item2.unwrap() = 4;
/// }
///
/// assert_eq!(arena[idx1], 3);
/// assert_eq!(arena[idx2], 4);
/// ```
pub fn get2_mut(&mut self, i1: Index, i2: Index) -> (Option<&mut T>, Option<&mut T>) {
let len = self.items.len();
if i1.index == i2.index {
assert!(i1.generation != i2.generation);
if i1.generation > i2.generation {
return (self.get_mut(i1), None);
}
return (None, self.get_mut(i2));
}
if i1.index >= len {
return (None, self.get_mut(i2));
} else if i2.index >= len {
return (self.get_mut(i1), None);
}
let (raw_item1, raw_item2) = {
let (xs, ys) = self.items.split_at_mut(cmp::max(i1.index, i2.index));
if i1.index < i2.index {
(&mut xs[i1.index], &mut ys[0])
} else {
(&mut ys[0], &mut xs[i2.index])
}
};
let item1 = match raw_item1 {
Entry::Occupied { generation, value } if *generation == i1.generation => Some(value),
_ => None,
};
let item2 = match raw_item2 {
Entry::Occupied { generation, value } if *generation == i2.generation => Some(value),
_ => None,
};
(item1, item2)
}
/// Get the length of this arena.
///
/// The length is the number of elements the arena holds.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// assert_eq!(arena.len(), 0);
///
/// let idx = arena.insert(42);
/// assert_eq!(arena.len(), 1);
///
/// let _ = arena.insert(0);
/// assert_eq!(arena.len(), 2);
///
/// assert_eq!(arena.remove(idx), Some(42));
/// assert_eq!(arena.len(), 1);
/// ```
pub fn len(&self) -> usize {
self.len
}
/// Returns true if the arena contains no elements
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// assert!(arena.is_empty());
///
/// let idx = arena.insert(42);
/// assert!(!arena.is_empty());
///
/// assert_eq!(arena.remove(idx), Some(42));
/// assert!(arena.is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.len == 0
}
/// Get the capacity of this arena.
///
/// The capacity is the maximum number of elements the arena can hold
/// without further allocation, including however many it currently
/// contains.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::with_capacity(10);
/// assert_eq!(arena.capacity(), 10);
///
/// // `try_insert` does not allocate new capacity.
/// for i in 0..10 {
/// assert!(arena.try_insert(1).is_ok());
/// assert_eq!(arena.capacity(), 10);
/// }
///
/// // But `insert` will if the arena is already at capacity.
/// arena.insert(0);
/// assert!(arena.capacity() > 10);
/// ```
pub fn capacity(&self) -> usize {
self.items.len()
}
/// Allocate space for `additional_capacity` more elements in the arena.
///
/// # Panics
///
/// Panics if this causes the capacity to overflow.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::with_capacity(10);
/// arena.reserve(5);
/// assert_eq!(arena.capacity(), 15);
/// # let _: Arena<usize> = arena;
/// ```
pub fn reserve(&mut self, additional_capacity: usize) {
let start = self.items.len();
let end = self.items.len() + additional_capacity;
let old_head = self.free_list_head;
self.items.reserve_exact(additional_capacity);
self.items.extend((start..end).map(|i| {
if i == end - 1 {
Entry::Free {
next_free: old_head,
}
} else {
Entry::Free {
next_free: Some(i + 1),
}
}
}));
self.free_list_head = Some(start);
}
/// Iterate over shared references to the elements in this arena.
///
/// Yields pairs of `(Index, &T)` items.
///
/// Order of iteration is not defined.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// for i in 0..10 {
/// arena.insert(i * i);
/// }
///
/// for (idx, value) in arena.iter() {
/// println!("{} is at index {:?}", value, idx);
/// }
/// ```
pub fn iter(&self) -> Iter<T> {
Iter {
len: self.len,
inner: self.items.iter().enumerate(),
}
}
/// Iterate over exclusive references to the elements in this arena.
///
/// Yields pairs of `(Index, &mut T)` items.
///
/// Order of iteration is not defined.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// for i in 0..10 {
/// arena.insert(i * i);
/// }
///
/// for (_idx, value) in arena.iter_mut() {
/// *value += 5;
/// }
/// ```
pub fn iter_mut(&mut self) -> IterMut<T> {
IterMut {
len: self.len,
inner: self.items.iter_mut().enumerate(),
}
}
/// Iterate over elements of the arena and remove them.
///
/// Yields pairs of `(Index, T)` items.
///
/// Order of iteration is not defined.
///
/// Note: All elements are removed even if the iterator is only partially consumed or not consumed at all.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx_1 = arena.insert("hello");
/// let idx_2 = arena.insert("world");
///
/// assert!(arena.get(idx_1).is_some());
/// assert!(arena.get(idx_2).is_some());
/// for (idx, value) in arena.drain() {
/// assert!((idx == idx_1 && value == "hello") || (idx == idx_2 && value == "world"));
/// }
/// assert!(arena.get(idx_1).is_none());
/// assert!(arena.get(idx_2).is_none());
/// ```
pub fn drain(&mut self) -> Drain<T> {
Drain {
inner: self.items.drain(..).enumerate(),
}
}
/// Given an i of `usize` without a generation, get a shared reference
/// to the element and the matching `Index` of the entry behind `i`.
///
/// This method is useful when you know there might be an element at the
/// position i, but don't know its generation or precise Index.
///
/// Use cases include using indexing such as Hierarchical BitMap Indexing or
/// other kinds of bit-efficient indexing.
///
/// You should use the `get` method instead most of the time.
pub fn get_unknown_gen(&self, i: usize) -> Option<(&T, Index)> {
match self.items.get(i) {
Some(Entry::Occupied { generation, value }) => Some((
value,
Index {
generation: *generation,
index: i,
},
)),
_ => None,
}
}
/// Given an i of `usize` without a generation, get an exclusive reference
/// to the element and the matching `Index` of the entry behind `i`.
///
/// This method is useful when you know there might be an element at the
/// position i, but don't know its generation or precise Index.
///
/// Use cases include using indexing such as Hierarchical BitMap Indexing or
/// other kinds of bit-efficient indexing.
///
/// You should use the `get_mut` method instead most of the time.
pub fn get_unknown_gen_mut(&mut self, i: usize) -> Option<(&mut T, Index)> {
match self.items.get_mut(i) {
Some(Entry::Occupied { generation, value }) => Some((
value,
Index {
generation: *generation,
index: i,
},
)),
_ => None,
}
}
}
impl<T> IntoIterator for Arena<T> {
type Item = T;
type IntoIter = IntoIter<T>;
fn into_iter(self) -> Self::IntoIter {
IntoIter {
len: self.len,
inner: self.items.into_iter(),
}
}
}
/// An iterator over the elements in an arena.
///
/// Yields `T` items.
///
/// Order of iteration is not defined.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// for i in 0..10 {
/// arena.insert(i * i);
/// }
///
/// for value in arena {
/// assert!(value < 100);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct IntoIter<T> {
len: usize,
inner: vec::IntoIter<Entry<T>>,
}
impl<T> Iterator for IntoIter<T> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next() {
Some(Entry::Free { .. }) => continue,
Some(Entry::Occupied { value, .. }) => {
self.len -= 1;
return Some(value);
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.len, Some(self.len))
}
}
impl<T> DoubleEndedIterator for IntoIter<T> {
fn next_back(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next_back() {
Some(Entry::Free { .. }) => continue,
Some(Entry::Occupied { value, .. }) => {
self.len -= 1;
return Some(value);
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
}
impl<T> ExactSizeIterator for IntoIter<T> {
fn len(&self) -> usize {
self.len
}
}
impl<T> FusedIterator for IntoIter<T> {}
impl<'a, T> IntoIterator for &'a Arena<T> {
type Item = (Index, &'a T);
type IntoIter = Iter<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.iter()
}
}
/// An iterator over shared references to the elements in an arena.
///
/// Yields pairs of `(Index, &T)` items.
///
/// Order of iteration is not defined.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// for i in 0..10 {
/// arena.insert(i * i);
/// }
///
/// for (idx, value) in &arena {
/// println!("{} is at index {:?}", value, idx);
/// }
/// ```
#[derive(Clone, Debug)]
pub struct Iter<'a, T: 'a> {
len: usize,
inner: iter::Enumerate<slice::Iter<'a, Entry<T>>>,
}
impl<'a, T> Iterator for Iter<'a, T> {
type Item = (Index, &'a T);
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next() {
Some((_, &Entry::Free { .. })) => continue,
Some((
index,
&Entry::Occupied {
generation,
ref value,
},
)) => {
self.len -= 1;
let idx = Index { index, generation };
return Some((idx, value));
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.len, Some(self.len))
}
}
impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
fn next_back(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next_back() {
Some((_, &Entry::Free { .. })) => continue,
Some((
index,
&Entry::Occupied {
generation,
ref value,
},
)) => {
self.len -= 1;
let idx = Index { index, generation };
return Some((idx, value));
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
}
impl<'a, T> ExactSizeIterator for Iter<'a, T> {
fn len(&self) -> usize {
self.len
}
}
impl<'a, T> FusedIterator for Iter<'a, T> {}
impl<'a, T> IntoIterator for &'a mut Arena<T> {
type Item = (Index, &'a mut T);
type IntoIter = IterMut<'a, T>;
fn into_iter(self) -> Self::IntoIter {
self.iter_mut()
}
}
/// An iterator over exclusive references to elements in this arena.
///
/// Yields pairs of `(Index, &mut T)` items.
///
/// Order of iteration is not defined.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// for i in 0..10 {
/// arena.insert(i * i);
/// }
///
/// for (_idx, value) in &mut arena {
/// *value += 5;
/// }
/// ```
#[derive(Debug)]
pub struct IterMut<'a, T: 'a> {
len: usize,
inner: iter::Enumerate<slice::IterMut<'a, Entry<T>>>,
}
impl<'a, T> Iterator for IterMut<'a, T> {
type Item = (Index, &'a mut T);
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next() {
Some((_, &mut Entry::Free { .. })) => continue,
Some((
index,
&mut Entry::Occupied {
generation,
ref mut value,
},
)) => {
self.len -= 1;
let idx = Index { index, generation };
return Some((idx, value));
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
(self.len, Some(self.len))
}
}
impl<'a, T> DoubleEndedIterator for IterMut<'a, T> {
fn next_back(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next_back() {
Some((_, &mut Entry::Free { .. })) => continue,
Some((
index,
&mut Entry::Occupied {
generation,
ref mut value,
},
)) => {
self.len -= 1;
let idx = Index { index, generation };
return Some((idx, value));
}
None => {
debug_assert_eq!(self.len, 0);
return None;
}
}
}
}
}
impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
fn len(&self) -> usize {
self.len
}
}
impl<'a, T> FusedIterator for IterMut<'a, T> {}
/// An iterator that removes elements from the arena.
///
/// Yields pairs of `(Index, T)` items.
///
/// Order of iteration is not defined.
///
/// Note: All elements are removed even if the iterator is only partially consumed or not consumed at all.
///
/// # Examples
///
/// ```ignore
/// use rapier::data::arena::Arena;
///
/// let mut arena = Arena::new();
/// let idx_1 = arena.insert("hello");
/// let idx_2 = arena.insert("world");
///
/// assert!(arena.get(idx_1).is_some());
/// assert!(arena.get(idx_2).is_some());
/// for (idx, value) in arena.drain() {
/// assert!((idx == idx_1 && value == "hello") || (idx == idx_2 && value == "world"));
/// }
/// assert!(arena.get(idx_1).is_none());
/// assert!(arena.get(idx_2).is_none());
/// ```
#[derive(Debug)]
pub struct Drain<'a, T: 'a> {
inner: iter::Enumerate<vec::Drain<'a, Entry<T>>>,
}
impl<'a, T> Iterator for Drain<'a, T> {
type Item = (Index, T);
fn next(&mut self) -> Option<Self::Item> {
loop {
match self.inner.next() {
Some((_, Entry::Free { .. })) => continue,
Some((index, Entry::Occupied { generation, value })) => {
let idx = Index { index, generation };
return Some((idx, value));
}
None => return None,
}
}
}
}
impl<T> Extend<T> for Arena<T> {
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I) {
for t in iter {
self.insert(t);
}
}
}
impl<T> FromIterator<T> for Arena<T> {
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> Self {
let iter = iter.into_iter();
let (lower, upper) = iter.size_hint();
let cap = upper.unwrap_or(lower);
let cap = cmp::max(cap, 1);
let mut arena = Arena::with_capacity(cap);
arena.extend(iter);
arena
}
}
impl<T> ops::Index<Index> for Arena<T> {
type Output = T;
fn index(&self, index: Index) -> &Self::Output {
self.get(index).expect("No element at index")
}
}
impl<T> ops::IndexMut<Index> for Arena<T> {
fn index_mut(&mut self, index: Index) -> &mut Self::Output {
self.get_mut(index).expect("No element at index")
}
}