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use rustc_index::vec::{Idx, IndexVec};
pub fn iter<Ls>(
first: Option<Ls::LinkIndex>,
links: &Ls,
) -> impl Iterator<Item = Ls::LinkIndex> + '_
where
Ls: Links,
{
VecLinkedListIterator { links, current: first }
}
pub struct VecLinkedListIterator<Ls>
where
Ls: Links,
{
links: Ls,
current: Option<Ls::LinkIndex>,
}
impl<Ls> Iterator for VecLinkedListIterator<Ls>
where
Ls: Links,
{
type Item = Ls::LinkIndex;
fn next(&mut self) -> Option<Ls::LinkIndex> {
if let Some(c) = self.current {
self.current = <Ls as Links>::next(&self.links, c);
Some(c)
} else {
None
}
}
}
pub trait Links {
type LinkIndex: Copy;
fn next(links: &Self, index: Self::LinkIndex) -> Option<Self::LinkIndex>;
}
impl<Ls> Links for &Ls
where
Ls: Links,
{
type LinkIndex = Ls::LinkIndex;
fn next(links: &Self, index: Ls::LinkIndex) -> Option<Ls::LinkIndex> {
<Ls as Links>::next(links, index)
}
}
pub trait LinkElem {
type LinkIndex: Copy;
fn next(elem: &Self) -> Option<Self::LinkIndex>;
}
impl<L, E> Links for IndexVec<L, E>
where
E: LinkElem<LinkIndex = L>,
L: Idx,
{
type LinkIndex = L;
fn next(links: &Self, index: L) -> Option<L> {
<E as LinkElem>::next(&links[index])
}
}