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trait RefCont<'a, T> {
fn t(&'a self) -> &'a T;
}
impl<'a, T> RefCont<'a, T> for &'a T {
fn t(&'a self) -> &'a T {
self
}
}
impl<'a, T> RefCont<'a, T> for Box<T> {
fn t(&'a self) -> &'a T {
self.as_ref()
}
}
trait MapLike<K, V> {
type VRefCont<'a>: RefCont<'a, V>
where
Self: 'a;
fn get<'a>(&'a self, key: &K) -> Option<Self::VRefCont<'a>>;
}
impl<K: Ord, V: 'static> MapLike<K, V> for std::collections::BTreeMap<K, V> {
type VRefCont<'a>
= &'a V
where
Self: 'a;
fn get<'a>(&'a self, key: &K) -> Option<&'a V> {
std::collections::BTreeMap::get(self, key)
}
}
struct Source;
impl<K, V: Default> MapLike<K, V> for Source {
type VRefCont<'a> = Box<V>;
fn get<'a>(&self, _: &K) -> Option<Box<V>> {
Some(Box::new(V::default()))
}
}
fn main() {
let m = Box::new(std::collections::BTreeMap::<u8, u8>::new())
as Box<dyn MapLike<u8, u8, VRefCont = dyn RefCont<'_, u8>>>;
//~^ ERROR the trait
//~| ERROR missing generics for associated type
}
|
