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use std::fmt;

/// A generated id
#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
pub struct UniqueId(u32);

impl UniqueId {
    /// Generate a new, globally unique id
    pub fn new() -> UniqueId {
        use std::sync::atomic::{AtomicUsize, Ordering};

        lazy_static! {
            static ref NEXT_ID: AtomicUsize = AtomicUsize::new(0);
        }

        // FIXME: check for integer overflow
        UniqueId(NEXT_ID.fetch_add(1, Ordering::SeqCst) as u32)
    }
}

impl fmt::Display for UniqueId {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        fmt::Display::fmt(&self.0, f)
    }
}