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