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#![no_std]
mod sealed {
pub trait Sealed {}
}
use sealed::Sealed;
pub trait Unflatten: Sealed + Sized {
fn unflatten(self) -> Option<Self> {
Some(self)
}
}
impl<T> Sealed for Option<T> {}
impl<T> Unflatten for Option<T> {}
#[cfg(test)]
mod tests {
use super::Unflatten;
#[test]
fn unflattening_some_works() {
let x: Option<i32> = Some(1);
assert_eq!(x.unflatten(), Some(Some(1)));
}
#[test]
fn unflattening_none_works() {
let x: Option<i32> = None;
assert_eq!(x.unflatten(), Some(None));
}
#[test]
fn flattening_unflattened_some_returns_same() {
let x: Option<i32> = Some(1);
assert_eq!(x.unflatten().flatten(), x);
}
#[test]
fn flattening_unflattened_none_returns_same() {
let x: Option<i32> = None;
assert_eq!(x.unflatten().flatten(), x);
}
#[test]
fn unflattening_flattened_some_returns_same() {
let x: Option<Option<i32>> = Some(Some(1));
assert_eq!(x.flatten().unflatten(), x);
}
}