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another-boids-in-rust/vendor/bevy_reflect/src/func/macros.rs

113 lines
2.8 KiB
Rust

/// Helper macro to implement the necessary traits for function reflection.
///
/// This macro calls the following macros:
/// - [`impl_get_ownership`](crate::func::args::impl_get_ownership)
/// - [`impl_from_arg`](crate::func::args::impl_from_arg)
/// - [`impl_into_return`](crate::func::impl_into_return)
///
/// # Syntax
///
/// For non-generic types, the macro simply expects the type:
///
/// ```ignore
/// impl_function_traits!(foo::bar::Baz);
/// ```
///
/// For generic types, however, the generic type parameters must also be given in angle brackets (`<` and `>`):
///
/// ```ignore
/// impl_function_traits!(foo::bar::Baz<T, U>; <T: Clone, U>);
/// ```
///
/// For generic const parameters, they must be given in square brackets (`[` and `]`):
///
/// ```ignore
/// impl_function_traits!(foo::bar::Baz<T, N>; <T> [const N: usize]);
/// ```
macro_rules! impl_function_traits {
(
$ty: ty
$(;
<
$($T: ident $(: $T1: tt $(+ $T2: tt)*)?),*
>
)?
$(
[
$(const $N: ident : $size: ident),*
]
)?
$(
where
$($U: ty $(: $U1: tt $(+ $U2: tt)*)?),*
)?
) => {
$crate::func::args::impl_get_ownership!(
$ty
$(;
<
$($T $(: $T1 $(+ $T2)*)?),*
>
)?
$(
[
$(const $N : $size),*
]
)?
$(
where
$($U $(: $U1 $(+ $U2)*)?),*
)?
);
$crate::func::args::impl_from_arg!(
$ty
$(;
<
$($T $(: $T1 $(+ $T2)*)?),*
>
)?
$(
[
$(const $N : $size),*
]
)?
$(
where
$($U $(: $U1 $(+ $U2)*)?),*
)?
);
$crate::func::impl_into_return!(
$ty
$(;
<
$($T $(: $T1 $(+ $T2)*)?),*
>
)?
$(
[
$(const $N : $size),*
]
)?
$(
where
$($U $(: $U1 $(+ $U2)*)?),*
)?
);
};
}
pub(crate) use impl_function_traits;
/// Helper macro that returns the number of tokens it receives.
///
/// See [here] for details.
///
/// [here]: https://veykril.github.io/tlborm/decl-macros/building-blocks/counting.html#bit-twiddling
macro_rules! count_tokens {
() => { 0 };
($odd:tt $($a:tt $b:tt)*) => { ($crate::func::macros::count_tokens!($($a)*) << 1) | 1 };
($($a:tt $even:tt)*) => { $crate::func::macros::count_tokens!($($a)*) << 1 };
}
pub(crate) use count_tokens;