Alyssa Haroldsen
2 years ago
committed by
Copybara-Service
parent
066465c978
commit
d5d207f099
5 changed files with 114 additions and 64 deletions
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// Protocol Buffers - Google's data interchange format
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// Copyright 2023 Google LLC. All rights reserved.
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// https://developers.google.com/protocol-buffers/
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google LLC. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//! Runtime-internal macros
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/// Defines a set of opaque pointers and a unique non-accessible pointees.
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///
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/// This provides a type safety benefit over using `NonNull<u8>` everywhere.
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/// The [Rustonomicon][nomicon] currently recommends a zero-sized struct,
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/// though this should use [`extern type`] when that is stabilized.
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///
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/// Because this defines a new private module, it can only be called once per
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/// module.
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///
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/// [nomicon]: https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs
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/// [`extern type`]: https://github.com/rust-lang/rust/issues/43467
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macro_rules! define_opaque_nonnulls { |
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($($(#[$meta:meta])* $vis:vis type $name:ident = NonNull<$raw_name:ident>;)*) => { |
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mod _opaque_pointees { |
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$( |
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#[doc = concat!("Opaque pointee for [`", stringify!($name), "`][pointer]")] |
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///
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/// This type is not meant to be dereferenced in Rust code.
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/// It is only meant to provide type safety for raw pointers
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/// which are manipulated behind FFI.
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#[doc = concat!("[pointer]: super::", stringify!($name))] |
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#[repr(C)] |
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pub struct $raw_name { |
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_data: [u8; 0], |
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_marker: ::std::marker::PhantomData<(*mut u8, ::std::marker::PhantomPinned)>, |
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} |
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)* |
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} |
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$( |
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$(#[$meta])* |
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///
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/// This is an opaque pointer used for FFI:
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/// do not dereference this type in Rust code.
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$vis type $name = ::std::ptr::NonNull<_opaque_pointees::$raw_name>; |
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)* |
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}; |
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} |
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pub(crate) use define_opaque_nonnulls; |
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/// Defines a `impl SettableValue<$proxied> for SomeType` body that forwards to
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/// another implementation.
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///
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/// # Example
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/// ```ignore
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/// impl<'a, const N: usize> SettableValue<[u8]> for &'a [u8; N] {
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/// // Use the `SettableValue<[u8]>` implementation for `&[u8]`:
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/// impl_forwarding_settable_value!([u8], self => &self[..]);
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/// }
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/// ```
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macro_rules! impl_forwarding_settable_value { |
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($proxied:ty, $self:ident => $self_forwarding_expr:expr) => { |
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fn set_on( |
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$self, |
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_private: $crate::__internal::Private, |
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mutator: $crate::Mut<'_, $proxied>, |
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) { |
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($self_forwarding_expr).set_on(Private, mutator) |
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} |
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fn set_on_absent( |
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$self, |
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_private: $crate::__internal::Private, |
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absent_mutator: <$proxied as $crate::ProxiedWithPresence>::AbsentMutData<'_>, |
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) -> <$proxied as $crate::ProxiedWithPresence>::PresentMutData<'_> { |
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($self_forwarding_expr).set_on_absent($crate::__internal::Private, absent_mutator) |
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} |
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fn set_on_present( |
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$self, |
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_private: $crate::__internal::Private, |
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present_mutator: <$proxied as $crate::ProxiedWithPresence>::PresentMutData<'_>, |
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) { |
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($self_forwarding_expr).set_on_present($crate::__internal::Private, present_mutator) |
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} |
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}; |
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} |
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pub(crate) use impl_forwarding_settable_value; |
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