diesel/macros/
internal.rs

1/// This will implement `SelectableExpression` and `AppearsOnTable` for "simple"
2/// composite nodes where the where clause is roughly `AllTyParams:
3/// SelectableExpression<QS>, Self: Expression`.
4///
5/// This macro is exported because we want to be able to call it from other
6/// macros that are exported, but it is not part of our public API.
7#[macro_export]
8#[doc(hidden)]
9macro_rules! impl_selectable_expression {
10    ($struct_name:ident) => {
11        $crate::impl_selectable_expression!(ty_params = (), struct_ty = $struct_name,);
12    };
13
14    ($struct_name:ident<$($ty_params:ident),+>) => {
15        $crate::impl_selectable_expression!(
16            ty_params = ($($ty_params),+),
17            struct_ty = $struct_name<$($ty_params),+>,
18        );
19    };
20
21    (ty_params = ($($ty_params:ident),*), struct_ty = $struct_ty:ty,) => {
22        impl<$($ty_params,)* QS> $crate::expression::SelectableExpression<QS>
23            for $struct_ty where
24                $struct_ty: $crate::expression::AppearsOnTable<QS>,
25                $($ty_params: $crate::expression::SelectableExpression<QS>,)*
26        {
27        }
28
29        impl<$($ty_params,)* QS> $crate::expression::AppearsOnTable<QS>
30            for $struct_ty where
31                $struct_ty: $crate::expression::Expression,
32                $($ty_params: $crate::expression::AppearsOnTable<QS>,)*
33        {
34        }
35    };
36}