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use rustc_data_structures::graph::{
self, DirectedGraph, WithNumNodes, WithStartNode, WithSuccessors,
};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_data_structures::sync::OnceCell;
use rustc_serialize::{Decodable, Decoder, Encodable, Encoder};
#[derive(Clone, Debug)]
pub(super) struct GraphIsCyclicCache {
cache: OnceCell<bool>,
}
impl GraphIsCyclicCache {
#[inline]
pub(super) fn new() -> Self {
GraphIsCyclicCache { cache: OnceCell::new() }
}
pub(super) fn is_cyclic<G>(&self, graph: &G) -> bool
where
G: ?Sized + DirectedGraph + WithStartNode + WithSuccessors + WithNumNodes,
{
*self.cache.get_or_init(|| graph::is_cyclic(graph))
}
#[inline]
pub(super) fn invalidate(&mut self) {
self.cache = OnceCell::new();
}
}
impl<S: Encoder> Encodable<S> for GraphIsCyclicCache {
#[inline]
fn encode(&self, s: &mut S) {
Encodable::encode(&(), s);
}
}
impl<D: Decoder> Decodable<D> for GraphIsCyclicCache {
#[inline]
fn decode(d: &mut D) -> Self {
let () = Decodable::decode(d);
Self::new()
}
}
impl<CTX> HashStable<CTX> for GraphIsCyclicCache {
#[inline]
fn hash_stable(&self, _: &mut CTX, _: &mut StableHasher) {
}
}
TrivialTypeTraversalAndLiftImpls! {
GraphIsCyclicCache,
}