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gen_utils.rs
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#![feature(generators, generator_trait, conservative_impl_trait)] | |
use std::ops::{Generator, State}; | |
pub fn gen_to_iter<A, G: Generator<Return = (), Yield = A>>(gen: G) -> impl Iterator<Item = A> { | |
GeneratorIter { | |
state: GeneratorIterState::Pending, | |
gen, | |
} | |
} | |
#[derive(Debug, PartialEq, Eq)] | |
pub struct GeneratorIter<G> { | |
state: GeneratorIterState, | |
gen: G, | |
} | |
#[derive(Debug, PartialEq, Eq)] | |
enum GeneratorIterState { | |
Pending, | |
Empty, | |
} | |
impl<G: Generator<Return = ()>> Iterator for GeneratorIter<G> { | |
type Item = G::Yield; | |
fn next(&mut self) -> Option<Self::Item> { | |
match self.state { | |
GeneratorIterState::Empty => None, | |
GeneratorIterState::Pending => { | |
match self.gen.resume() { | |
State::Yielded(value) => Some(value), | |
State::Complete(_) => { | |
self.state = GeneratorIterState::Empty; | |
None | |
} | |
} | |
} | |
} | |
} | |
} |
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