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// check-pass
use std::marker::PhantomData;
pub trait Scalar: 'static {
type RefType<'a>: ScalarRef<'a>;
}
pub trait ScalarRef<'a>: 'a {}
impl Scalar for i32 {
type RefType<'a> = i32;
}
impl Scalar for String {
type RefType<'a> = &'a str;
}
impl Scalar for bool {
type RefType<'a> = i32;
}
impl<'a> ScalarRef<'a> for bool {}
impl<'a> ScalarRef<'a> for i32 {}
impl<'a> ScalarRef<'a> for &'a str {}
fn str_contains(a: &str, b: &str) -> bool {
a.contains(b)
}
pub struct BinaryExpression<A: Scalar, B: Scalar, O: Scalar, F>
where
F: Fn(A::RefType<'_>, B::RefType<'_>) -> O,
{
f: F,
_phantom: PhantomData<(A, B, O)>,
}
impl<A: Scalar, B: Scalar, O: Scalar, F> BinaryExpression<A, B, O, F>
where
F: Fn(A::RefType<'_>, B::RefType<'_>) -> O,
{
pub fn new(f: F) -> Self {
Self {
f,
_phantom: PhantomData,
}
}
}
fn main() {
BinaryExpression::<String, String, bool, _>::new(str_contains);
}
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