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use async_recursion::async_recursion;
use futures_executor::block_on;
pub struct Empty {}
impl Empty {
#[async_recursion]
pub async fn fib(&self, n: u32) -> u64 {
match n {
0 => panic!("zero is not a valid argument to fib()!"),
1 | 2 => 1,
3 => 2,
_ => self.fib(n - 1).await + self.fib(n - 2).await,
}
}
#[async_recursion]
pub async fn empty_string<'a>(&self, some_str: &'a str) -> &'a str {
if some_str.is_empty() {
""
} else {
self.empty_string(&some_str[1..]).await
}
}
#[async_recursion]
pub async fn generic_parameter<T>(&self, _something: &T) -> u64 {
0
}
#[async_recursion]
pub async fn all_of_the_above<'a, 'b, S, T>(
&self,
// Some references with / without lifetimes to generic parameters
_x: &S,
_y: &'b T,
// Some generic parameters passed by value
_w: S,
_z: T,
// A reference to a concrete type without a lifetime
_p: &usize,
// A reference to a concrete type with a lifetime
_q: &'a u64,
) {
}
}
#[test]
fn struct_method_fib_works() {
block_on(async move {
let e = Empty {};
assert_eq!(e.fib(6).await, 8);
assert_eq!(e.fib(5).await, 5);
assert_eq!(e.fib(7).await, 13);
});
}
#[test]
fn struct_method_empty_string_works() {
block_on(async move {
let e = Empty {};
assert_eq!(e.empty_string("hello world").await, "");
assert_eq!(e.empty_string("something else").await, "");
});
}
#[test]
fn struct_method_with_generic_parameter_works() {
block_on(async move {
let e = Empty {};
assert_eq!(
e.generic_parameter::<*const u64>(&(0 as *const u64)).await,
0
);
})
}
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