97 lines
1.8 KiB
Rust
97 lines
1.8 KiB
Rust
#![feature(generators, generator_trait, never_type)]
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use std::ops::{GeneratorState, Generator};
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use std::pin::Pin;
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fn finish<T>(mut amt: usize, mut t: T) -> T::Return
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where T: Generator<Yield = usize>
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{
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// We are not moving the `t` around until it gets dropped, so this is okay.
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let mut t = unsafe { Pin::new_unchecked(&mut t) };
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loop {
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match t.as_mut().resume() {
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GeneratorState::Yielded(y) => amt -= y,
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GeneratorState::Complete(ret) => {
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assert_eq!(amt, 0);
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return ret
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}
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}
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}
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}
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enum Never {}
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fn never() -> Never {
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panic!()
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}
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fn main() {
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finish(1, || yield 1);
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finish(3, || {
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let mut x = 0;
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yield 1;
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x += 1;
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yield 1;
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x += 1;
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yield 1;
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assert_eq!(x, 2);
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});
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finish(7*8/2, || {
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for i in 0..8 {
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yield i;
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}
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});
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finish(1, || {
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if true {
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yield 1;
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} else {
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}
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});
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finish(1, || {
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if false {
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} else {
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yield 1;
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}
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});
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finish(2, || {
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if { yield 1; false } {
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yield 1;
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panic!()
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}
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yield 1;
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});
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// also test a self-referential generator
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assert_eq!(
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finish(5, || {
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let mut x = Box::new(5);
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let y = &mut *x;
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*y = 5;
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yield *y;
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*y = 10;
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*x
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}),
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10
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);
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let b = true;
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finish(1, || {
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yield 1;
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if b { return; }
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#[allow(unused)]
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let x = never();
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yield 2;
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drop(x);
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});
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finish(3, || {
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yield 1;
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#[allow(unreachable_code)]
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let _x: (String, !) = (String::new(), { yield 2; return });
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});
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}
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