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use std::ops::AddAssign; pub trait Rangeable: AddAssign + PartialOrd + Copy {} impl<T: AddAssign + PartialOrd + Copy> Rangeable for T {} pub struct GenRangeIterator<T: Rangeable> { curr: T, stop: T, step: T, } impl<T: Rangeable> GenRangeIterator<T> { pub fn new(start: T, stop: T, step: T) -> Self { GenRangeIterator { curr: start, stop, step, } } } impl<T: Rangeable> Iterator for GenRangeIterator<T> { type Item = T; fn next(&mut self) -> Option<Self::Item> { if self.curr >= self.stop { return None; } let res = self.curr; self.curr += self.step; Some(res) } } #[cfg(test)] mod tests { use super::*; #[test] fn gen_test1() { let mut m = 0.; let it = GenRangeIterator::new(5., 12., 2.5); for s in it { m += s; } assert_eq!(m, 5. + 7.5 + 10.); } #[test] fn filter() { let v: i32 = GenRangeIterator::new(3, 13, 3).filter(|x| x % 2 == 0).sum(); assert_eq!(v, 6 + 12); } }