1use std::marker::PhantomData;
2
3use crate::{conversion::IntoPyObject, Py};
4#[allow(deprecated)]
5use crate::{IntoPy, ToPyObject};
6
7/// Trait used to combine with zero-sized types to calculate at compile time
8/// some property of a type.
9///
10/// The trick uses the fact that an associated constant has higher priority
11/// than a trait constant, so we can use the trait to define the false case.
12///
13/// The true case is defined in the zero-sized type's impl block, which is
14/// gated on some property like trait bound or only being implemented
15/// for fixed concrete types.
16pub trait Probe {
17 const VALUE: bool = false;
18}
19
20macro_rules! probe {
21 ($name:ident) => {
22 pub struct $name<T>(PhantomData<T>);
23 impl<T> Probe for $name<T> {}
24 };
25}
26
27probe!(IsPyT);
28
29impl<T> IsPyT<Py<T>> {
30 pub const VALUE: bool = true;
31}
32
33probe!(IsToPyObject);
34
35#[allow(deprecated)]
36impl<T: ToPyObject> IsToPyObject<T> {
37 pub const VALUE: bool = true;
38}
39
40probe!(IsIntoPy);
41
42#[allow(deprecated)]
43impl<T: IntoPy<crate::PyObject>> IsIntoPy<T> {
44 pub const VALUE: bool = true;
45}
46
47probe!(IsIntoPyObjectRef);
48
49// Possible clippy beta regression,
50// see https://github.com/rust-lang/rust-clippy/issues/13578
51#[allow(clippy::extra_unused_lifetimes)]
52impl<'a, 'py, T: 'a> IsIntoPyObjectRef<T>
53where
54 &'a T: IntoPyObject<'py>,
55{
56 pub const VALUE: bool = true;
57}
58
59probe!(IsIntoPyObject);
60
61impl<'py, T> IsIntoPyObject<T>
62where
63 T: IntoPyObject<'py>,
64{
65 pub const VALUE: bool = true;
66}
67
68probe!(IsSync);
69
70impl<T: Sync> IsSync<T> {
71 pub const VALUE: bool = true;
72}
73
74probe!(IsOption);
75
76impl<T> IsOption<Option<T>> {
77 pub const VALUE: bool = true;
78}
79