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Diffstat (limited to 'vendor/bitflags/src/external.rs')
-rw-r--r-- | vendor/bitflags/src/external.rs | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/vendor/bitflags/src/external.rs b/vendor/bitflags/src/external.rs new file mode 100644 index 0000000..efeaa82 --- /dev/null +++ b/vendor/bitflags/src/external.rs @@ -0,0 +1,262 @@ +//! Conditional trait implementations for external libraries. + +/* +How do I support a new external library? + +Let's say we want to add support for `my_library`. + +First, we create a module under `external`, like `serde` with any specialized code. +Ideally, any utilities in here should just work off the `Flags` trait and maybe a +few other assumed bounds. + +Next, re-export the library from the `__private` module here. + +Next, define a macro like so: + +```rust +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(feature = "serde")] +macro_rules! __impl_external_bitflags_my_library { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => { + // Implementation goes here + }; +} + +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(not(feature = "my_library"))] +macro_rules! __impl_external_bitflags_my_library { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => {}; +} +``` + +Note that the macro is actually defined twice; once for when the `my_library` feature +is available, and once for when it's not. This is because the `__impl_external_bitflags_my_library` +macro is called in an end-user's library, not in `bitflags`. In an end-user's library we don't +know whether or not a particular feature of `bitflags` is enabled, so we unconditionally call +the macro, where the body of that macro depends on the feature flag. + +Now, we add our macro call to the `__impl_external_bitflags` macro body: + +```rust +__impl_external_bitflags_my_library! { + $InternalBitFlags: $T, $PublicBitFlags { + $( + $(#[$inner $($args)*])* + const $Flag; + )* + } +} +``` +*/ + +pub(crate) mod __private { + #[cfg(feature = "serde")] + pub use serde; + + #[cfg(feature = "arbitrary")] + pub use arbitrary; + + #[cfg(feature = "bytemuck")] + pub use bytemuck; +} + +/// Implements traits from external libraries for the internal bitflags type. +#[macro_export(local_inner_macros)] +#[doc(hidden)] +macro_rules! __impl_external_bitflags { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => { + // Any new library traits impls should be added here + // Use `serde` as an example: generate code when the feature is available, + // and a no-op when it isn't + + __impl_external_bitflags_serde! { + $InternalBitFlags: $T, $PublicBitFlags { + $( + $(#[$inner $($args)*])* + const $Flag; + )* + } + } + + __impl_external_bitflags_arbitrary! { + $InternalBitFlags: $T, $PublicBitFlags { + $( + $(#[$inner $($args)*])* + const $Flag; + )* + } + } + + __impl_external_bitflags_bytemuck! { + $InternalBitFlags: $T, $PublicBitFlags { + $( + $(#[$inner $($args)*])* + const $Flag; + )* + } + } + }; +} + +#[cfg(feature = "serde")] +pub mod serde; + +/// Implement `Serialize` and `Deserialize` for the internal bitflags type. +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(feature = "serde")] +macro_rules! __impl_external_bitflags_serde { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => { + impl $crate::__private::serde::Serialize for $InternalBitFlags { + fn serialize<S: $crate::__private::serde::Serializer>( + &self, + serializer: S, + ) -> $crate::__private::core::result::Result<S::Ok, S::Error> { + $crate::serde::serialize( + &$PublicBitFlags::from_bits_retain(self.bits()), + serializer, + ) + } + } + + impl<'de> $crate::__private::serde::Deserialize<'de> for $InternalBitFlags { + fn deserialize<D: $crate::__private::serde::Deserializer<'de>>( + deserializer: D, + ) -> $crate::__private::core::result::Result<Self, D::Error> { + let flags: $PublicBitFlags = $crate::serde::deserialize(deserializer)?; + + Ok(flags.0) + } + } + }; +} + +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(not(feature = "serde"))] +macro_rules! __impl_external_bitflags_serde { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => {}; +} + +#[cfg(feature = "arbitrary")] +pub mod arbitrary; + +#[cfg(feature = "bytemuck")] +mod bytemuck; + +/// Implement `Arbitrary` for the internal bitflags type. +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(feature = "arbitrary")] +macro_rules! __impl_external_bitflags_arbitrary { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => { + impl<'a> $crate::__private::arbitrary::Arbitrary<'a> for $InternalBitFlags { + fn arbitrary( + u: &mut $crate::__private::arbitrary::Unstructured<'a>, + ) -> $crate::__private::arbitrary::Result<Self> { + $crate::arbitrary::arbitrary::<$PublicBitFlags>(u).map(|flags| flags.0) + } + } + }; +} + +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(not(feature = "arbitrary"))] +macro_rules! __impl_external_bitflags_arbitrary { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => {}; +} + +/// Implement `Pod` and `Zeroable` for the internal bitflags type. +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(feature = "bytemuck")] +macro_rules! __impl_external_bitflags_bytemuck { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => { + // SAFETY: $InternalBitFlags is guaranteed to have the same ABI as $T, + // and $T implements Pod + unsafe impl $crate::__private::bytemuck::Pod for $InternalBitFlags where + $T: $crate::__private::bytemuck::Pod + { + } + + // SAFETY: $InternalBitFlags is guaranteed to have the same ABI as $T, + // and $T implements Zeroable + unsafe impl $crate::__private::bytemuck::Zeroable for $InternalBitFlags where + $T: $crate::__private::bytemuck::Zeroable + { + } + }; +} + +#[macro_export(local_inner_macros)] +#[doc(hidden)] +#[cfg(not(feature = "bytemuck"))] +macro_rules! __impl_external_bitflags_bytemuck { + ( + $InternalBitFlags:ident: $T:ty, $PublicBitFlags:ident { + $( + $(#[$inner:ident $($args:tt)*])* + const $Flag:tt; + )* + } + ) => {}; +} |