test.rs

pub trait UnaryPredicate<T> {
    #[doc(hidden)]
    fn call(&self, val: &T) -> bool;
}

impl<T: PartialEq> UnaryPredicate<T> for T {
    #[inline(always)]
    fn call(&self, val: &T) -> bool {
        self == val
    }
}

impl<T: PartialEq> UnaryPredicate<T> for &T {
    #[inline(always)]
    fn call(&self, val: &T) -> bool {
        *self == val
    }
}


impl<T, F: Fn(&T) -> bool> UnaryPredicate<T> for F {
    #[inline(always)]
    fn call(&self, val: &T) -> bool {
        self(val)
    }
}