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//! Yet another index-based arena.
use std::{
fmt,
marker::PhantomData,
ops::{Index, IndexMut},
};
pub mod map;
#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct RawId(u32);
impl From<RawId> for u32 {
fn from(raw: RawId) -> u32 {
raw.0
}
}
impl From<u32> for RawId {
fn from(id: u32) -> RawId {
RawId(id)
}
}
impl fmt::Debug for RawId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.0.fmt(f)
}
}
impl fmt::Display for RawId {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
self.0.fmt(f)
}
}
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Arena<ID: ArenaId, T> {
data: Vec<T>,
_ty: PhantomData<ID>,
}
#[macro_export]
macro_rules! impl_arena_id {
($name:ident) => {
impl $crate::ArenaId for $name {
fn from_raw(raw: $crate::RawId) -> Self {
$name(raw)
}
fn into_raw(self) -> $crate::RawId {
self.0
}
}
};
}
pub trait ArenaId {
fn from_raw(raw: RawId) -> Self;
fn into_raw(self) -> RawId;
}
impl<ID: ArenaId, T> Arena<ID, T> {
pub fn alloc(&mut self, value: T) -> ID {
let id = RawId(self.data.len() as u32);
self.data.push(value);
ID::from_raw(id)
}
pub fn iter<'a>(&'a self) -> impl Iterator<Item = (ID, &'a T)> {
self.data
.iter()
.enumerate()
.map(|(idx, value)| (ID::from_raw(RawId(idx as u32)), value))
}
}
impl<ID: ArenaId, T> Default for Arena<ID, T> {
fn default() -> Arena<ID, T> {
Arena {
data: Vec::new(),
_ty: PhantomData,
}
}
}
impl<ID: ArenaId, T> Index<ID> for Arena<ID, T> {
type Output = T;
fn index(&self, idx: ID) -> &T {
let idx = idx.into_raw().0 as usize;
&self.data[idx]
}
}
impl<ID: ArenaId, T> IndexMut<ID> for Arena<ID, T> {
fn index_mut(&mut self, idx: ID) -> &mut T {
let idx = idx.into_raw().0 as usize;
&mut self.data[idx]
}
}
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