Files
wasmtime/lib/entity/src/primary.rs

354 lines
8.1 KiB
Rust

//! Densely numbered entity references as mapping keys.
use std::marker::PhantomData;
use std::ops::{Deref, DerefMut, Index, IndexMut};
use std::slice;
use std::vec::Vec;
use {EntityRef, Iter, IterMut, Keys};
/// A primary mapping `K -> V` allocating dense entity references.
///
/// The `PrimaryMap` data structure uses the dense index space to implement a map with a vector.
///
/// A primary map contains the main definition of an entity, and it can be used to allocate new
/// entity references with the `push` method.
///
/// There should only be a single `PrimaryMap` instance for a given `EntityRef` type, otherwise
/// conflicting references will be created. Using unknown keys for indexing will cause a panic.
#[derive(Debug, Clone)]
pub struct PrimaryMap<K, V>
where
K: EntityRef,
{
elems: Vec<V>,
unused: PhantomData<K>,
}
impl<K, V> PrimaryMap<K, V>
where
K: EntityRef,
{
/// Create a new empty map.
pub fn new() -> Self {
Self {
elems: Vec::new(),
unused: PhantomData,
}
}
/// Check if `k` is a valid key in the map.
pub fn is_valid(&self, k: K) -> bool {
k.index() < self.elems.len()
}
/// Get the element at `k` if it exists.
pub fn get(&self, k: K) -> Option<&V> {
self.elems.get(k.index())
}
/// Is this map completely empty?
pub fn is_empty(&self) -> bool {
self.elems.is_empty()
}
/// Get the total number of entity references created.
pub fn len(&self) -> usize {
self.elems.len()
}
/// Iterate over all the keys in this map.
pub fn keys(&self) -> Keys<K> {
Keys::with_len(self.elems.len())
}
/// Iterate over all the values in this map.
pub fn values(&self) -> slice::Iter<V> {
self.elems.iter()
}
/// Iterate over all the values in this map, mutable edition.
pub fn values_mut(&mut self) -> slice::IterMut<V> {
self.elems.iter_mut()
}
/// Iterate over all the keys and values in this map.
pub fn iter(&self) -> Iter<K, V> {
Iter::new(self.elems.iter())
}
/// Iterate over all the keys and values in this map, mutable edition.
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut::new(self.elems.iter_mut())
}
/// Remove all entries from this map.
pub fn clear(&mut self) {
self.elems.clear()
}
/// Get the key that will be assigned to the next pushed value.
pub fn next_key(&self) -> K {
K::new(self.elems.len())
}
/// Append `v` to the mapping, assigning a new key which is returned.
pub fn push(&mut self, v: V) -> K {
let k = self.next_key();
self.elems.push(v);
k
}
}
/// Immutable indexing into an `PrimaryMap`.
/// The indexed value must be in the map.
impl<K, V> Index<K> for PrimaryMap<K, V>
where
K: EntityRef,
{
type Output = V;
fn index(&self, k: K) -> &V {
&self.elems[k.index()]
}
}
/// Mutable indexing into an `PrimaryMap`.
impl<K, V> IndexMut<K> for PrimaryMap<K, V>
where
K: EntityRef,
{
fn index_mut(&mut self, k: K) -> &mut V {
&mut self.elems[k.index()]
}
}
impl<'a, K, V> IntoIterator for &'a PrimaryMap<K, V>
where
K: EntityRef,
{
type Item = (K, &'a V);
type IntoIter = Iter<'a, K, V>;
fn into_iter(self) -> Self::IntoIter {
Iter::new(self.elems.iter())
}
}
impl<'a, K, V> IntoIterator for &'a mut PrimaryMap<K, V>
where
K: EntityRef,
{
type Item = (K, &'a mut V);
type IntoIter = IterMut<'a, K, V>;
fn into_iter(self) -> Self::IntoIter {
IterMut::new(self.elems.iter_mut())
}
}
impl<K, V> Deref for PrimaryMap<K, V>
where
K: EntityRef,
{
type Target = [V];
fn deref(&self) -> &Self::Target {
&self.elems
}
}
impl<K, V> DerefMut for PrimaryMap<K, V>
where
K: EntityRef,
{
fn deref_mut(&mut self) -> &mut [V] {
&mut self.elems
}
}
#[cfg(test)]
mod tests {
use super::*;
// `EntityRef` impl for testing.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct E(u32);
impl EntityRef for E {
fn new(i: usize) -> Self {
E(i as u32)
}
fn index(self) -> usize {
self.0 as usize
}
}
#[test]
fn basic() {
let r0 = E(0);
let r1 = E(1);
let m = PrimaryMap::<E, isize>::new();
let v: Vec<E> = m.keys().collect();
assert_eq!(v, []);
assert!(!m.is_valid(r0));
assert!(!m.is_valid(r1));
}
#[test]
fn push() {
let mut m = PrimaryMap::new();
let k0: E = m.push(12);
let k1 = m.push(33);
assert_eq!(m[k0], 12);
assert_eq!(m[k1], 33);
let v: Vec<E> = m.keys().collect();
assert_eq!(v, [k0, k1]);
}
#[test]
fn iter() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 0;
for (key, value) in &m {
assert_eq!(key.index(), i);
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
i += 1;
}
i = 0;
for (key_mut, value_mut) in m.iter_mut() {
assert_eq!(key_mut.index(), i);
match i {
0 => assert_eq!(*value_mut, 12),
1 => assert_eq!(*value_mut, 33),
_ => panic!(),
}
i += 1;
}
}
#[test]
fn iter_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for (key, value) in m.iter().rev() {
i -= 1;
assert_eq!(key.index(), i);
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
i = 2;
for (key, value) in m.iter_mut().rev() {
i -= 1;
assert_eq!(key.index(), i);
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
}
#[test]
fn keys() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 0;
for key in m.keys() {
assert_eq!(key.index(), i);
i += 1;
}
}
#[test]
fn keys_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for key in m.keys().rev() {
i -= 1;
assert_eq!(key.index(), i);
}
}
#[test]
fn values() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 0;
for value in m.values() {
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
i += 1;
}
i = 0;
for value_mut in m.values_mut() {
match i {
0 => assert_eq!(*value_mut, 12),
1 => assert_eq!(*value_mut, 33),
_ => panic!(),
}
i += 1;
}
}
#[test]
fn values_rev() {
let mut m: PrimaryMap<E, usize> = PrimaryMap::new();
m.push(12);
m.push(33);
let mut i = 2;
for value in m.values().rev() {
i -= 1;
match i {
0 => assert_eq!(*value, 12),
1 => assert_eq!(*value, 33),
_ => panic!(),
}
}
i = 2;
for value_mut in m.values_mut().rev() {
i -= 1;
match i {
0 => assert_eq!(*value_mut, 12),
1 => assert_eq!(*value_mut, 33),
_ => panic!(),
}
}
}
#[test]
fn deref() {
let mut m = PrimaryMap::<E, isize>::new();
let _: &[isize] = m.as_ref();
let _: &mut [isize] = m.as_mut();
let _: &[isize] = &m;
let _: &mut [isize] = &mut m;
}
}