| use crate::fmt; |
| use crate::ops::{Generator, GeneratorState}; |
| use crate::pin::Pin; |
| |
| /// Creates a new iterator where each iteration calls the provided generator. |
| /// |
| /// Similar to [`iter::from_fn`]. |
| /// |
| /// [`iter::from_fn`]: crate::iter::from_fn |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// #![feature(generators)] |
| /// #![feature(iter_from_generator)] |
| /// |
| /// let it = std::iter::from_generator(|| { |
| /// yield 1; |
| /// yield 2; |
| /// yield 3; |
| /// }); |
| /// let v: Vec<_> = it.collect(); |
| /// assert_eq!(v, [1, 2, 3]); |
| /// ``` |
| #[inline] |
| #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] |
| pub fn from_generator<G: Generator<Return = ()> + Unpin>(generator: G) -> FromGenerator<G> { |
| FromGenerator(generator) |
| } |
| |
| /// An iterator over the values yielded by an underlying generator. |
| /// |
| /// This `struct` is created by the [`iter::from_generator()`] function. See its documentation for |
| /// more. |
| /// |
| /// [`iter::from_generator()`]: from_generator |
| #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] |
| #[derive(Clone)] |
| pub struct FromGenerator<G>(G); |
| |
| #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] |
| impl<G: Generator<Return = ()> + Unpin> Iterator for FromGenerator<G> { |
| type Item = G::Yield; |
| |
| fn next(&mut self) -> Option<Self::Item> { |
| match Pin::new(&mut self.0).resume(()) { |
| GeneratorState::Yielded(n) => Some(n), |
| GeneratorState::Complete(()) => None, |
| } |
| } |
| } |
| |
| #[unstable(feature = "iter_from_generator", issue = "43122", reason = "generators are unstable")] |
| impl<G> fmt::Debug for FromGenerator<G> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| f.debug_struct("FromGenerator").finish() |
| } |
| } |