pub use enso_shapely_macros::*;
use derivative::Derivative;
use std::ops::Generator;
use std::ops::GeneratorState;
use std::pin::Pin;
use std::marker::PhantomData;
#[derive(Debug)]
pub struct GeneratingIterator<G: Generator>(pub G);
impl<G> Iterator for GeneratingIterator<G>
where G: Generator<Return = ()> + Unpin {
type Item = G::Yield;
fn next(&mut self) -> Option<Self::Item> {
match Pin::new(&mut self.0).resume() {
GeneratorState::Yielded(element) => Some(element),
_ => None,
}
}
}
#[derive(Derivative)]
#[derivative(Debug,Default(bound=""))]
pub struct EmptyIterator<T>(PhantomData<T>);
impl<T> EmptyIterator<T> {
pub fn new() -> Self {
Default::default()
}
}
impl<T> Iterator for EmptyIterator<T> {
type Item = T;
fn next(&mut self) -> Option<Self::Item> {
None
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn empty_iterator_works_for_any_type() {
for elem in EmptyIterator::new() {
elem: i32;
}
for elem in EmptyIterator::new() {
elem: String;
}
}
#[test]
fn generating_iterator_works() {
let generator = || {
yield 0;
yield 1;
yield 2;
};
let expected_numbers = vec!(0, 1, 2);
let generator_iter = GeneratingIterator(generator);
let collected_result: Vec<_> = generator_iter.collect();
assert_eq!(collected_result, expected_numbers);
}
}