use std::mem;

pub trait Seq {
    fn next(&self) -> Self;
}

macro_rules! impl_seq {
    ($($ty:ty)*) => { $(
        impl Seq for $ty {
            fn next(&self) -> Self { (*self).wrapping_add(1) }
        }
    )* }
}

impl_seq!(u8 u16 u32 u64 usize);

#[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord, Default)]
pub struct SeqGenerator<T: Seq>(T);

impl<T: Seq> SeqGenerator<T> {
    pub fn new(value: T) -> Self {
        SeqGenerator(value)
    }

    pub fn get(&mut self) -> T {
        let value = self.0.next();
        mem::replace(&mut self.0, value)
    }
}