bp3d_util/

extension.rs

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//! Helper macro for writing extensions to any foreign type using sealed traits.

/// Generate a sealed trait with a given name and content.
#[macro_export]
macro_rules! extension {
    (
        $(
            $(#[$meta: meta])*
            pub extension $name: ident $(<$($generic: ident),*>)?: $ty: ty {
                $($tokens: tt)*
            }
        )*
    ) => {
        mod sealing {
            pub trait Sealed {}
        }
        $(
            impl$(<$($generic),*>)? sealing::Sealed for $ty {}

            $(#[$meta])*
            pub trait $name $(<$($generic),*>)? : sealing::Sealed {
                $($tokens)*
            }
        )*
    };
}