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use crate::token::{Id, Span};
use std::cell::Cell;
thread_local!(static NEXT: Cell<u32> = Cell::new(0));
pub fn reset() {
NEXT.with(|c| c.set(0));
}
pub fn gen(span: Span) -> Id<'static> {
NEXT.with(|next| {
let gen = next.get() + 1;
next.set(gen);
Id::gensym(span, gen)
})
}
pub fn fill<'a>(span: Span, slot: &mut Option<Id<'a>>) -> Id<'a> {
*slot.get_or_insert_with(|| gen(span))
}