66 lines
1.3 KiB
Rust
66 lines
1.3 KiB
Rust
//! A simple id-based arena, similar to https://github.com/fitzgen/id-arena.
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//! We use our own version for more compact id's and to allow inherent impls
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//! on Ids.
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use std::{
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fmt,
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hash::{Hash, Hasher},
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marker::PhantomData,
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};
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pub struct Id<T> {
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idx: u32,
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_ty: PhantomData<fn() -> T>,
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}
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impl<T> fmt::Debug for Id<T> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.debug_tuple("Id").field(&self.idx).finish()
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}
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}
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impl<T> Copy for Id<T> {}
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impl<T> Clone for Id<T> {
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fn clone(&self) -> Id<T> {
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*self
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}
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}
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impl<T> PartialEq for Id<T> {
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fn eq(&self, other: &Id<T>) -> bool {
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self.idx == other.idx
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}
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}
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impl<T> Eq for Id<T> {}
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impl<T> Hash for Id<T> {
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fn hash<H: Hasher>(&self, h: &mut H) {
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self.idx.hash(h);
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}
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}
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#[derive(Debug, PartialEq, Eq)]
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pub(crate) struct ArenaBehavior<T> {
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_ty: PhantomData<T>,
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}
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impl<T> id_arena::ArenaBehavior for ArenaBehavior<T> {
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type Id = Id<T>;
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fn new_arena_id() -> u32 {
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0
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}
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fn new_id(_arena_id: u32, index: usize) -> Id<T> {
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Id {
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idx: index as u32,
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_ty: PhantomData,
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}
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}
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fn index(id: Id<T>) -> usize {
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id.idx as usize
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}
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fn arena_id(_id: Id<T>) -> u32 {
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0
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}
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}
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pub(crate) type Arena<T> = id_arena::Arena<T, ArenaBehavior<T>>;
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