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5fbdfc3e10
This adds an `iter!` macro that can be used to create movable generators. This also adds a yield_expr feature so the `yield` keyword can be used within iter! macro bodies. This was needed because several unstable features each need `yield` expressions, so this allows us to stabilize them separately from any individual feature. Co-authored-by: Oli Scherer <github35764891676564198441@oli-obk.de> Co-authored-by: Jieyou Xu <jieyouxu@outlook.com> Co-authored-by: Travis Cross <tc@traviscross.com>
33 lines
802 B
Rust
33 lines
802 B
Rust
//@ run-pass
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#![feature(iter_macro, yield_expr)]
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use std::iter::iter;
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fn main() {
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let i = {
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let s = String::new();
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iter! { move || {
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yield s.len();
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for x in 5..10 {
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yield x * 2;
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}
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}}
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};
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test_iterator(i);
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}
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/// Exercise the iterator in a separate function to ensure it's not capturing anything it shoudln't.
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fn test_iterator<I: Iterator<Item = usize>>(i: impl FnOnce() -> I) {
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let mut i = i();
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assert_eq!(i.next(), Some(0));
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assert_eq!(i.next(), Some(10));
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assert_eq!(i.next(), Some(12));
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assert_eq!(i.next(), Some(14));
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assert_eq!(i.next(), Some(16));
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assert_eq!(i.next(), Some(18));
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assert_eq!(i.next(), None);
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assert_eq!(i.next(), None);
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assert_eq!(i.next(), None);
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}
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