45 lines
1.1 KiB
Rust
45 lines
1.1 KiB
Rust
#![feature(generators, generator_trait)]
|
|
|
|
use std::{
|
|
ops::{Generator, GeneratorState},
|
|
pin::Pin,
|
|
};
|
|
|
|
fn firstn() -> impl Generator<Yield = u64, Return = ()> {
|
|
static move || {
|
|
let mut num = 0;
|
|
let num = &mut num;
|
|
|
|
yield *num;
|
|
*num += 1; //~ ERROR dereferenced after this allocation got freed
|
|
}
|
|
}
|
|
|
|
struct GeneratorIteratorAdapter<G>(G);
|
|
|
|
impl<G> Iterator for GeneratorIteratorAdapter<G>
|
|
where
|
|
G: Generator<Return = ()>,
|
|
{
|
|
type Item = G::Yield;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
let me = unsafe { Pin::new_unchecked(&mut self.0) };
|
|
match me.resume(()) {
|
|
GeneratorState::Yielded(x) => Some(x),
|
|
GeneratorState::Complete(_) => None,
|
|
}
|
|
}
|
|
}
|
|
|
|
fn main() {
|
|
let mut generator_iterator_2 = {
|
|
let mut generator_iterator = Box::new(GeneratorIteratorAdapter(firstn()));
|
|
generator_iterator.next(); // pin it
|
|
|
|
Box::new(*generator_iterator) // move it
|
|
}; // *deallocate* generator_iterator
|
|
|
|
generator_iterator_2.next(); // and use moved value
|
|
}
|