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//! # rkyv //! //! rkyv (*archive*) is a zero-copy deserialization framework for Rust. //! //! It's similar to other zero-copy deserialization frameworks such as //! [Cap'n Proto](https://capnproto.org) and //! [FlatBuffers](https://google.github.io/flatbuffers). However, while the //! former have external schemas and heavily restricted data types, rkyv allows //! all serialized types to be defined in code and can serialize a wide variety //! of types that the others cannot. Additionally, rkyv is designed to have //! little to no overhead, and in most cases will perform exactly the same as //! native types. //! //! rkyv has a hashmap implementation that is built for zero-copy //! deserialization, so you can serialize your hashmaps with abandon! The //! implementation is based off of the standard library's `hashbrown` crate and //! should have nearly identical performance. //! //! One of the most impactful features made possible by rkyv is the ability to //! serialize trait objects and use them *as trait objects* without //! deserialization. See the `archive_dyn` crate for more details. //! //! ## Design //! //! Like [serde](https://serde.rs), rkyv uses Rust's powerful trait system to //! serialize data without the need for reflection. Despite having a wide array //! of features, you also only pay for what you use. If your data checks out, //! the serialization process can be as simple as a `memcpy`! Like serde, this //! allows rkyv to perform at speeds similar to handwritten serializers. //! //! Unlike serde, rkyv produces data that is guaranteed deserialization free. If //! you wrote your data to disk, you can just `mmap` your file into memory, cast //! a pointer, and your data is ready to use. This makes it ideal for //! high-performance and IO-limited applications. //! //! ## Tradeoffs //! //! rkyv is designed primarily for loading bulk game data as efficiently as //! possible. While rkyv is a great format for final data, it lacks a full //! schema system and isn't well equipped for data migration. Using a //! serialization library like serde can help fill these gaps, and you can use //! serde with the same types as rkyv conflict-free. //! //! ## Features //! //! - `const_generics`: Improves the implementations for some traits and //! provides an [`Archive`] implementation for slices with elements that //! implement [`ArchiveSelf`]. Ideal for `#![no_std]` environments. //! - `inline_more`: Performs more aggressive function inlining. //! - `long_rel_ptrs`: Increases the size of relative pointers to 64 bits for //! large archive support //! - `more_portable`: Avoids using sse2-optimized intrinsics since they may //! cause alignment issues across machines. This feature may go away once any //! portability bugs are identified and fixed. //! - `nightly`: Enables some nightly features, such as //! [`likely`](std::intrinsics::likely). //! - `specialization`: Enables the unfinished specialization feature and //! provides more efficient implementations of some functions when working //! with [`ArchiveSelf`] types. //! - `std`: Enables standard library support. //! - `strict`: Guarantees that types will have the same representations across //! platforms and compilations. This is already the case in practice, but this //! feature provides a guarantee. //! - `validation`: Enables validation support through `bytecheck`. //! //! By default, the `inline_more` and `std` features are enabled. #![cfg_attr(not(feature = "std"), no_std)] #![cfg_attr( any(feature = "const_generics", feature = "specialization"), allow(incomplete_features) )] #![cfg_attr(feature = "const_generics", feature(const_generics))] #![cfg_attr(feature = "nightly", feature(core_intrinsics))] #![cfg_attr(feature = "specialization", feature(specialization))] pub mod core_impl; #[cfg(feature = "std")] pub mod std_impl; #[cfg(feature = "validation")] pub mod validation; use core::{ marker::PhantomPinned, mem, ops::{Deref, DerefMut}, pin::Pin, ptr, slice, }; #[cfg(feature = "std")] use std::io; pub use memoffset::offset_of; pub use rkyv_derive::Archive; #[cfg(feature = "validation")] pub use validation::{check_archive, ArchiveContext}; /// A `#![no_std]` compliant writer that knows where it is. /// /// A type that is [`io::Write`](std::io::Write) can be wrapped in an /// ArchiveWriter to equip it with `Write`. It's important that the memory for /// archived objects is properly aligned before attempting to read objects out /// of it, use the [`Aligned`] wrapper if it's appropriate. pub trait Write { /// The errors that may occur while writing. type Error: 'static; /// Returns the current position of the writer. fn pos(&self) -> usize; /// Attempts to write the given bytes to the writer. fn write(&mut self, bytes: &[u8]) -> Result<(), Self::Error>; /// Advances the given number of bytes as padding. fn pad(&mut self, mut padding: usize) -> Result<(), Self::Error> { const ZEROES_LEN: usize = 16; const ZEROES: [u8; ZEROES_LEN] = [0; ZEROES_LEN]; while padding > 0 { let len = usize::min(ZEROES_LEN, padding); self.write(&ZEROES[0..len])?; padding -= len; } Ok(()) } } /// Helper functions on [`Write`] objects. pub trait WriteExt: Write { /// Aligns the position of the writer to the given alignment. fn align(&mut self, align: usize) -> Result<usize, Self::Error> { debug_assert!(align & (align - 1) == 0); let offset = self.pos() & (align - 1); if offset != 0 { self.pad(align - offset)?; } Ok(self.pos()) } /// Aligns the position of the writer to be suitable to write the given /// type. fn align_for<T>(&mut self) -> Result<usize, Self::Error> { self.align(mem::align_of::<T>()) } /// Resolves the given resolver and writes its archived type, returning the /// position of the written archived type. /// /// # Safety /// /// This is only safe to call when the writer is already aligned for the /// archived version of the given type. unsafe fn resolve_aligned<T: ?Sized, R: Resolve<T>>( &mut self, value: &T, resolver: R, ) -> Result<usize, Self::Error> { let pos = self.pos(); debug_assert!(pos & (mem::align_of::<R::Archived>() - 1) == 0); let archived = &resolver.resolve(pos, value); let data = (archived as *const R::Archived).cast::<u8>(); let len = mem::size_of::<R::Archived>(); self.write(slice::from_raw_parts(data, len))?; Ok(pos) } /// Archives the given object and returns the position it was archived at. fn archive<T: Archive>(&mut self, value: &T) -> Result<usize, Self::Error> { let resolver = value.archive(self)?; self.align_for::<T::Archived>()?; unsafe { self.resolve_aligned(value, resolver) } } /// Archives a reference to the given object and returns the position it was /// archived at. fn archive_ref<T: ArchiveRef + ?Sized>(&mut self, value: &T) -> Result<usize, Self::Error> { let resolver = value.archive_ref(self)?; self.align_for::<T::Reference>()?; unsafe { self.resolve_aligned(value, resolver) } } } impl<W: Write + ?Sized> WriteExt for W {} /// A writer that can seek to an absolute position. pub trait Seek: Write { /// Seeks the writer to the given absolute position. fn seek(&mut self, pos: usize) -> Result<(), Self::Error>; } /// Helper functions on [`Seek`] objects. pub trait SeekExt: Seek { /// Archives the given value at the nearest available position. If the /// writer is already aligned, it will archive it at the current position. fn archive_root<T: Archive>(&mut self, value: &T) -> Result<usize, Self::Error> { self.align_for::<Archived<T>>()?; let pos = self.pos(); self.seek(pos + mem::size_of::<Archived<T>>())?; let resolver = value.archive(self)?; self.seek(pos)?; unsafe { self.resolve_aligned(value, resolver)?; } Ok(pos) } /// Archives a reference to the given value at the nearest available /// position. If the writer is already aligned, it will archive it at the /// current position. fn archive_ref_root<T: ArchiveRef + ?Sized>( &mut self, value: &T, ) -> Result<usize, Self::Error> { self.align_for::<Reference<T>>()?; let pos = self.pos(); self.seek(pos + mem::size_of::<Reference<T>>())?; let resolver = value.archive_ref(self)?; self.seek(pos)?; unsafe { self.resolve_aligned(value, resolver)?; } Ok(pos) } } impl<W: Seek + ?Sized> SeekExt for W {} /// Creates an archived value when given a value and position. /// /// Resolvers are passed the original value, so any information that is already /// in them doesn't have to be stored in the resolver. pub trait Resolve<T: ?Sized> { /// The type that this resolver resolves to. type Archived; /// Creates the archived version of the given value at the given position. fn resolve(self, pos: usize, value: &T) -> Self::Archived; } /// Writes a type to a [`Writer`](Write) so it can be used without /// deserializing. /// /// Archiving is done depth-first, writing any data owned by a type before /// writing the data for the type itself. The [`Resolver`](Resolve) must be able /// to create the archived type from only its own data and the value being /// archived. /// /// ## Examples /// /// Most of the time, `#[derive(Archive)]` will create an acceptable /// implementation. You can use the `#[archive(...)]` attribute to control how /// the implementation is generated. See the [`Archive`](macro@Archive) derive /// macro for more details. /// /// ``` /// use rkyv::{Aligned, Archive, ArchiveBuffer, Archived, archived_value, WriteExt}; /// /// #[derive(Archive)] /// struct Test { /// int: u8, /// string: String, /// option: Option<Vec<i32>>, /// } /// /// let mut writer = ArchiveBuffer::new(Aligned([0u8; 256])); /// let value = Test { /// int: 42, /// string: "hello world".to_string(), /// option: Some(vec![1, 2, 3, 4]), /// }; /// let pos = writer.archive(&value) /// .expect("failed to archive test"); /// let buf = writer.into_inner(); /// let archived = unsafe { archived_value::<Test>(buf.as_ref(), pos) }; /// assert_eq!(archived.int, value.int); /// assert_eq!(archived.string, value.string); /// assert_eq!(archived.option, value.option); /// ``` /// /// Many of the core and standard library types already have Archive /// implementations available, but you may need to implement `Archive` for your /// own types in some cases the derive macro cannot handle. /// /// In this example, we add our own wrapper that serializes a `&'static str` as /// if it's owned. Normally you can lean on the archived version of `String` to /// do most of the work, but this example does everything to demonstrate how to /// implement `Archive` for your own types. /// /// ``` /// use core::{slice, str}; /// use rkyv::{ /// Aligned, /// Archive, /// ArchiveBuffer, /// Archived, /// archived_value, /// offset_of, /// RelPtr, /// Resolve, /// Write, /// WriteExt, /// }; /// /// struct OwnedStr { /// inner: &'static str, /// } /// /// struct ArchivedOwnedStr { /// // This will be a relative pointer to the bytes of our string. /// ptr: RelPtr, /// // The length of the archived version must be explicitly sized for /// // 32/64-bit compatibility. Archive is not implemented for usize and /// // isize to help you avoid making this mistake. /// len: u32, /// } /// /// impl ArchivedOwnedStr { /// // This will help us get the bytes of our type as a str again. /// fn as_str(&self) -> &str { /// unsafe { /// // The as_ptr() function of RelPtr will get a pointer /// // to its memory. /// let bytes = slice::from_raw_parts(self.ptr.as_ptr(), self.len as usize); /// str::from_utf8_unchecked(bytes) /// } /// } /// } /// /// struct OwnedStrResolver { /// // This will be the position that the bytes of our string are stored at. /// // We'll use this to make the relative pointer of our ArchivedOwnedStr. /// bytes_pos: usize, /// } /// /// impl Resolve<OwnedStr> for OwnedStrResolver { /// // This is essentially the output type of the resolver. It must match /// // the Archived associated type in our impl of Archive for OwnedStr. /// type Archived = ArchivedOwnedStr; /// /// // The resolve function consumes the resolver and produces the archived /// // value at the given position. /// fn resolve(self, pos: usize, value: &OwnedStr) -> Self::Archived { /// Self::Archived { /// // We have to be careful to add the offset of the ptr field, /// // otherwise we'll be using the position of the ArchivedOwnedStr /// // instead of the position of the ptr. That's the reason why /// // RelPtr::new is unsafe. /// ptr: unsafe { /// RelPtr::new(pos + offset_of!(ArchivedOwnedStr, ptr), self.bytes_pos) /// }, /// len: value.inner.len() as u32, /// } /// } /// } /// /// impl Archive for OwnedStr { /// type Archived = ArchivedOwnedStr; /// /// This is the resolver we'll return from archive. /// type Resolver = OwnedStrResolver; /// /// fn archive<W: Write + ?Sized>(&self, writer: &mut W) -> Result<Self::Resolver, W::Error> { /// // This is where we want to write the bytes of our string and return /// // a resolver that knows where those bytes were written. /// let bytes_pos = writer.pos(); /// writer.write(self.inner.as_bytes())?; /// Ok(Self::Resolver { bytes_pos }) /// } /// } /// /// let mut writer = ArchiveBuffer::new(Aligned([0u8; 256])); /// const STR_VAL: &'static str = "I'm in an OwnedStr!"; /// let value = OwnedStr { inner: STR_VAL }; /// // It works! /// let pos = writer.archive(&value) /// .expect("failed to archive test"); /// let buf = writer.into_inner(); /// let archived = unsafe { archived_value::<OwnedStr>(buf.as_ref(), pos) }; /// // Let's make sure our data got written correctly /// assert_eq!(archived.as_str(), STR_VAL); /// ``` pub trait Archive { /// The archived version of this type. type Archived; /// The resolver for this type. It must contain all the information needed /// to make the archived type from the unarchived type. type Resolver: Resolve<Self, Archived = Self::Archived>; /// Writes the dependencies for the object and returns a resolver that can /// create the archived type. fn archive<W: Write + ?Sized>(&self, writer: &mut W) -> Result<Self::Resolver, W::Error>; } /// This trait is a counterpart of [`Archive`] that's suitable for unsized /// types. /// /// Instead of archiving its value directly, `ArchiveRef` archives a type that /// dereferences to its archived type. As a consequence, its `Resolver` resolves /// to a `Reference` instead of the archived type. /// /// `ArchiveRef` is automatically implemented for all types that implement /// [`Archive`], and uses a [`RelPtr`] as the reference type. /// /// `ArchiveRef` is already implemented for slices and string slices. Use the /// `rkyv_dyn` crate to archive trait objects. Unfortunately, you'll have to /// manually implement `ArchiveRef` for your other unsized types. pub trait ArchiveRef { /// The archived version of this type. type Archived: ?Sized; /// The reference to the archived version of this type. type Reference: Deref<Target = Self::Archived> + DerefMut<Target = Self::Archived>; /// The resolver for the reference of this type. type Resolver: Resolve<Self, Archived = Self::Reference>; /// Writes the object and returns a resolver that can create the reference /// to the archived type. fn archive_ref<W: Write + ?Sized>(&self, writer: &mut W) -> Result<Self::Resolver, W::Error>; } /// A trait that indicates that some [`Archive`] type can be copied directly to /// an archive without additional processing. /// /// You can derive an implementation of `ArchiveSelf` by adding /// `#[archive(self)]` to the struct or enum. Types that implement `ArchiveSelf` /// must also implement [`Copy`](core::marker::Copy). /// /// Types that implement `ArchiveSelf` are not guaranteed to have `archive` /// called on them to archive their value. Most or all implementations that /// leverage `ArchiveSelf` will require the `specialization` feature. /// /// `ArchiveSelf` must be manually implemented even if a type implements /// [`Archive`] and [`Copy`](core::marker::Copy) because some types may /// transform their data when writing to an archive. /// /// ## Examples /// ``` /// use rkyv::{Aligned, Archive, ArchiveBuffer, archived_value, Write, WriteExt}; /// /// #[derive(Archive, Clone, Copy, Debug, PartialEq)] /// #[archive(self)] /// struct Vector4<T>(T, T, T, T); /// /// let mut writer = ArchiveBuffer::new(Aligned([0u8; 256])); /// let value = Vector4(1f32, 2f32, 3f32, 4f32); /// let pos = writer.archive(&value) /// .expect("failed to archive Vector4"); /// let buf = writer.into_inner(); /// let archived_value = unsafe { archived_value::<Vector4<f32>>(buf.as_ref(), pos) }; /// assert_eq!(&value, archived_value); /// ``` pub unsafe trait ArchiveSelf: Archive<Archived = Self> + Copy {} /// A resolver that always resolves to the unarchived value. This can be useful /// while implementing [`ArchiveSelf`]. pub struct SelfResolver; impl<T: ArchiveSelf> Resolve<T> for SelfResolver { type Archived = T; fn resolve(self, _pos: usize, value: &T) -> T { *value } } /// The type used for offsets in relative pointers. #[cfg(not(feature = "long_rel_ptrs"))] pub type Offset = i32; /// The type used for offsets in relative pointers. #[cfg(feature = "long_rel_ptrs")] pub type Offset = i64; /// A pointer which resolves to relative to its position in memory. /// /// See [`Archive`] for an example of creating one. #[repr(transparent)] #[derive(Debug)] pub struct RelPtr { offset: Offset, _phantom: PhantomPinned, } impl RelPtr { /// Creates a relative pointer from one position to another. /// /// # Safety /// /// `from` must be the position of the relative pointer and `to` must be the /// position of some valid memory. pub unsafe fn new(from: usize, to: usize) -> Self { Self { offset: (to as isize - from as isize) as Offset, _phantom: PhantomPinned, } } /// Gets the offset of the relative pointer. pub fn offset(&self) -> isize { self.offset as isize } /// Calculates the memory address being pointed to by this relative pointer. pub fn as_ptr<T>(&self) -> *const T { unsafe { (self as *const Self) .cast::<u8>() .offset(self.offset as isize) .cast::<T>() } } /// Returns an unsafe mutable pointer to the memory address being pointed to /// by this relative pointer. pub fn as_mut_ptr<T>(&mut self) -> *mut T { unsafe { (self as *mut Self) .cast::<u8>() .offset(self.offset as isize) .cast::<T>() } } } /// Alias for the archived version of some [`Archive`] type. pub type Archived<T> = <T as Archive>::Archived; /// Alias for the resolver for some [`Archive`] type. pub type Resolver<T> = <T as Archive>::Resolver; /// Alias for the resolver of the reference for some [`ArchiveRef`] type. pub type ReferenceResolver<T> = <T as ArchiveRef>::Resolver; /// Alias for the reference for some [`ArchiveRef`] type. pub type Reference<T> = <T as ArchiveRef>::Reference; /// Wraps a type and aligns it to at least 16 bytes. Mainly used to align byte /// buffers for [ArchiveBuffer]. /// /// ## Examples /// ``` /// use core::mem; /// use rkyv::Aligned; /// /// assert_eq!(mem::align_of::<u8>(), 1); /// assert_eq!(mem::align_of::<Aligned<u8>>(), 16); /// ``` #[repr(align(16))] pub struct Aligned<T>(pub T); impl<T: Deref> Deref for Aligned<T> { type Target = T::Target; fn deref(&self) -> &Self::Target { &*self.0 } } impl<T: DerefMut> DerefMut for Aligned<T> { fn deref_mut(&mut self) -> &mut Self::Target { &mut *self.0 } } impl<T: AsRef<[U]>, U> AsRef<[U]> for Aligned<T> { fn as_ref(&self) -> &[U] { self.0.as_ref() } } impl<T: AsMut<[U]>, U> AsMut<[U]> for Aligned<T> { fn as_mut(&mut self) -> &mut [U] { self.0.as_mut() } } /// Wraps a byte buffer and writes into it. /// /// Common uses include archiving in `#![no_std]` environments and archiving /// small objects without allocating. /// /// ## Examples /// ``` /// use rkyv::{Aligned, Archive, ArchiveBuffer, Archived, archived_value, WriteExt}; /// /// #[derive(Archive)] /// enum Event { /// Spawn, /// Speak(String), /// Die, /// } /// /// let mut writer = ArchiveBuffer::new(Aligned([0u8; 256])); /// let pos = writer.archive(&Event::Speak("Help me!".to_string())) /// .expect("failed to archive event"); /// let buf = writer.into_inner(); /// let archived = unsafe { archived_value::<Event>(buf.as_ref(), pos) }; /// if let Archived::<Event>::Speak(message) = archived { /// assert_eq!(message.as_str(), "Help me!"); /// } else { /// panic!("archived event was of the wrong type"); /// } /// ``` pub struct ArchiveBuffer<T> { inner: T, pos: usize, } impl<T> ArchiveBuffer<T> { /// Creates a new archive buffer from a byte buffer. pub fn new(inner: T) -> Self { Self::with_pos(inner, 0) } /// Creates a new archive buffer from a byte buffer. The buffer will start /// writing at the given position, but the buffer must contain all bytes /// (otherwise the alignments of types may not be correct). pub fn with_pos(inner: T, pos: usize) -> Self { Self { inner, pos } } /// Consumes the buffer and returns the internal buffer used to create it. pub fn into_inner(self) -> T { self.inner } } /// The error type returned by an [`ArchiveBuffer`]. #[derive(Debug)] pub enum ArchiveBufferError { /// Writing has overflowed the internal buffer. Overflow { pos: usize, bytes_needed: usize, archive_len: usize, }, /// The writer sought past the end of the internal buffer. SoughtPastEnd { seek_position: usize, archive_len: usize, }, } impl<T: AsRef<[u8]> + AsMut<[u8]>> Write for ArchiveBuffer<T> { type Error = ArchiveBufferError; fn pos(&self) -> usize { self.pos } fn write(&mut self, bytes: &[u8]) -> Result<(), Self::Error> { let end_pos = self.pos + bytes.len(); let archive_len = self.inner.as_ref().len(); if end_pos > archive_len { Err(ArchiveBufferError::Overflow { pos: self.pos, bytes_needed: bytes.len(), archive_len, }) } else { unsafe { ptr::copy_nonoverlapping( bytes.as_ptr(), self.inner.as_mut().as_mut_ptr().add(self.pos), bytes.len(), ); } self.pos = end_pos; Ok(()) } } fn pad(&mut self, padding: usize) -> Result<(), Self::Error> { let end_pos = self.pos + padding; let archive_len = self.inner.as_ref().len(); if end_pos > archive_len { Err(ArchiveBufferError::Overflow { pos: self.pos, bytes_needed: padding, archive_len, }) } else { self.pos = end_pos; Ok(()) } } } impl<T: AsRef<[u8]> + AsMut<[u8]>> Seek for ArchiveBuffer<T> { fn seek(&mut self, pos: usize) -> Result<(), Self::Error> { let len = self.inner.as_ref().len(); if pos > len { Err(ArchiveBufferError::SoughtPastEnd { seek_position: pos, archive_len: len, }) } else { self.pos = pos; Ok(()) } } } /// Wraps a type that implements [`io::Write`](std::io::Write) and equips it /// with [`Write`]. /// /// ## Examples /// ``` /// use rkyv::{ArchiveWriter, Write}; /// /// let mut writer = ArchiveWriter::new(Vec::new()); /// assert_eq!(writer.pos(), 0); /// writer.write(&[0u8, 1u8, 2u8, 3u8]); /// assert_eq!(writer.pos(), 4); /// let buf = writer.into_inner(); /// assert_eq!(buf.len(), 4); /// assert_eq!(buf, vec![0u8, 1u8, 2u8, 3u8]); /// ``` #[cfg(feature = "std")] pub struct ArchiveWriter<W: io::Write> { inner: W, pos: usize, } #[cfg(feature = "std")] impl<W: io::Write> ArchiveWriter<W> { /// Creates a new archive writer from a writer. pub fn new(inner: W) -> Self { Self::with_pos(inner, 0) } /// Creates a new archive writer from a writer, and assumes that the /// underlying writer is currently at the given position. pub fn with_pos(inner: W, pos: usize) -> Self { Self { inner, pos } } /// Consumes the writer and returns the internal writer used to create it. pub fn into_inner(self) -> W { self.inner } } #[cfg(feature = "std")] impl<W: io::Write> Write for ArchiveWriter<W> { type Error = io::Error; fn pos(&self) -> usize { self.pos } fn write(&mut self, bytes: &[u8]) -> Result<(), Self::Error> { self.pos += self.inner.write(bytes)?; Ok(()) } } #[cfg(feature = "std")] impl<W: io::Write + io::Seek> Seek for ArchiveWriter<W> { fn seek(&mut self, offset: usize) -> Result<(), Self::Error> { self.inner.seek(io::SeekFrom::Start(offset as u64))?; self.pos = offset; Ok(()) } } /// Casts an archived value from the given byte array at the given position. /// /// This helps avoid situations where lifetimes get inappropriately assigned and /// allow buffer mutation after getting archived value references. /// /// # Safety /// /// This is only safe to call if the value is archived at the given position in /// the byte array. #[inline] pub unsafe fn archived_value<T: Archive + ?Sized>(bytes: &[u8], pos: usize) -> &Archived<T> { &*bytes.as_ptr().add(pos).cast() } /// Casts a mutable archived value from the given byte array at the given /// position. /// /// This helps avoid situations where lifetimes get inappropriately assigned and /// allow buffer mutation after getting archived value references. /// /// # Safety /// /// This is only safe to call if the value is archived at the given position in /// the byte array. #[inline] pub unsafe fn archived_value_mut<T: Archive + ?Sized>( bytes: Pin<&mut [u8]>, pos: usize, ) -> Pin<&mut Archived<T>> { Pin::new_unchecked(&mut *bytes.get_unchecked_mut().as_mut_ptr().add(pos).cast()) } /// Casts an archived reference from the given byte array at the given position. /// /// This helps avoid situations where lifetimes get inappropriately assigned and /// allow buffer mutation after getting archived value references. /// /// # Safety /// /// This is only safe to call if the reference is archived at the given position /// in the byte array. #[inline] pub unsafe fn archived_ref<T: ArchiveRef + ?Sized>(bytes: &[u8], pos: usize) -> &Reference<T> { &*bytes.as_ptr().add(pos).cast() } /// Casts a mutable archived reference from the given byte array at the given /// position. /// /// This helps avoid situations where lifetimes get inappropriately assigned and /// allow buffer mutation after getting archived value references. /// /// # Safety /// /// This is only safe to call if the reference is archived at the given position /// in the byte array. #[inline] pub unsafe fn archived_ref_mut<T: ArchiveRef + ?Sized>( bytes: Pin<&mut [u8]>, pos: usize, ) -> Pin<&mut Reference<T>> { Pin::new_unchecked(&mut *bytes.get_unchecked_mut().as_mut_ptr().add(pos).cast()) }