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use iter::{Iter, IterMut};
use keys::Keys;
use std::marker::PhantomData;
use std::ops::{Index, IndexMut};
use std::slice;
use std::vec::Vec;
use EntityRef;
#[derive(Debug, Clone)]
pub struct SecondaryMap<K, V>
where
K: EntityRef,
V: Clone,
{
elems: Vec<V>,
default: V,
unused: PhantomData<K>,
}
impl<K, V> SecondaryMap<K, V>
where
K: EntityRef,
V: Clone,
{
pub fn new() -> Self
where
V: Default,
{
Self {
elems: Vec::new(),
default: Default::default(),
unused: PhantomData,
}
}
pub fn with_default(default: V) -> Self {
Self {
elems: Vec::new(),
default,
unused: PhantomData,
}
}
pub fn get(&self, k: K) -> Option<&V> {
self.elems.get(k.index())
}
pub fn is_empty(&self) -> bool {
self.elems.is_empty()
}
pub fn clear(&mut self) {
self.elems.clear()
}
pub fn iter(&self) -> Iter<K, V> {
Iter::new(self.elems.iter())
}
pub fn iter_mut(&mut self) -> IterMut<K, V> {
IterMut::new(self.elems.iter_mut())
}
pub fn keys(&self) -> Keys<K> {
Keys::with_len(self.elems.len())
}
pub fn values(&self) -> slice::Iter<V> {
self.elems.iter()
}
pub fn values_mut(&mut self) -> slice::IterMut<V> {
self.elems.iter_mut()
}
pub fn resize(&mut self, n: usize) {
self.elems.resize(n, self.default.clone());
}
}
impl<K, V> Index<K> for SecondaryMap<K, V>
where
K: EntityRef,
V: Clone,
{
type Output = V;
fn index(&self, k: K) -> &V {
self.get(k).unwrap_or(&self.default)
}
}
impl<K, V> IndexMut<K> for SecondaryMap<K, V>
where
K: EntityRef,
V: Clone,
{
fn index_mut(&mut self, k: K) -> &mut V {
let i = k.index();
if i >= self.elems.len() {
self.resize(i + 1);
}
&mut self.elems[i]
}
}
#[cfg(test)]
mod tests {
use super::*;
#[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 r2 = E(2);
let mut m = SecondaryMap::new();
let v: Vec<E> = m.keys().collect();
assert_eq!(v, []);
m[r2] = 3;
m[r1] = 5;
assert_eq!(m[r1], 5);
assert_eq!(m[r2], 3);
let v: Vec<E> = m.keys().collect();
assert_eq!(v, [r0, r1, r2]);
let shared = &m;
assert_eq!(shared[r0], 0);
assert_eq!(shared[r1], 5);
assert_eq!(shared[r2], 3);
}
}