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use std::{cell::Cell, fmt};

/// A unique identifier for an item, used to determine the
#[derive(Eq, PartialEq, Copy, Clone, Hash)]
pub struct ItemId {
    pub id: u32,
}

impl fmt::Display for ItemId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let id = self.id;
        write!(f, "item_{id}")
    }
}

impl fmt::Debug for ItemId {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        <Self as fmt::Display>::fmt(self, f)
    }
}

#[derive(Default)]
pub struct ItemIdAllocator {
    current: Cell<u32>,
}

impl ItemIdAllocator {
    pub fn next_id(&self) -> ItemId {
        let id = self.current.get();
        self.current.set(id + 1);
        ItemId { id }
    }
}