src/test/run-pass/generator/control-flow.rs

   1 // run-pass
   2
   3 #![feature(generators, generator_trait)]
   4
   5 use std::marker::Unpin;
   6 use std::ops::{GeneratorState, Generator};
   7 use std::pin::Pin;
   8
   9 fn finish<T>(mut amt: usize, mut t: T) -> T::Return
  10     where T: Generator<Yield = ()> + Unpin,
  11 {
  12     loop {
  13         match Pin::new(&mut t).resume() {
  14             GeneratorState::Yielded(()) => amt = amt.checked_sub(1).unwrap(),
  15             GeneratorState::Complete(ret) => {
  16                 assert_eq!(amt, 0);
  17                 return ret
  18             }
  19         }
  20     }
  21
  22 }
  23
  24 fn main() {
  25     finish(1, || yield);
  26     finish(8, || {
  27         for _ in 0..8 {
  28             yield;
  29         }
  30     });
  31     finish(1, || {
  32         if true {
  33             yield;
  34         } else {
  35         }
  36     });
  37     finish(1, || {
  38         if false {
  39         } else {
  40             yield;
  41         }
  42     });
  43     finish(2, || {
  44         if { yield; false } {
  45             yield;
  46             panic!()
  47         }
  48         yield
  49     });
  50 }