diff options
Diffstat (limited to 'compiler/rustc_data_structures/src')
-rw-r--r-- | compiler/rustc_data_structures/src/owned_slice.rs | 43 | ||||
-rw-r--r-- | compiler/rustc_data_structures/src/owned_slice/tests.rs | 12 | ||||
-rw-r--r-- | compiler/rustc_data_structures/src/sync.rs | 6 |
3 files changed, 48 insertions, 13 deletions
diff --git a/compiler/rustc_data_structures/src/owned_slice.rs b/compiler/rustc_data_structures/src/owned_slice.rs index 311a42aa42a..cbb3047d884 100644 --- a/compiler/rustc_data_structures/src/owned_slice.rs +++ b/compiler/rustc_data_structures/src/owned_slice.rs @@ -1,5 +1,6 @@ use std::{borrow::Borrow, ops::Deref}; +use crate::sync::Lrc; // Use our fake Send/Sync traits when on not parallel compiler, // so that `OwnedSlice` only implements/requires Send/Sync // for parallel compiler builds. @@ -7,7 +8,7 @@ use crate::sync::{Send, Sync}; /// An owned slice. /// -/// This is similar to `Box<[u8]>` but allows slicing and using anything as the +/// This is similar to `Lrc<[u8]>` but allows slicing and using anything as the /// backing buffer. /// /// See [`slice_owned`] for `OwnedSlice` construction and examples. @@ -16,6 +17,7 @@ use crate::sync::{Send, Sync}; /// /// This is essentially a replacement for `owning_ref` which is a lot simpler /// and even sound! 🌸 +#[derive(Clone)] pub struct OwnedSlice { /// This is conceptually a `&'self.owner [u8]`. bytes: *const [u8], @@ -31,7 +33,7 @@ pub struct OwnedSlice { // \/ // ⊂(´・◡・⊂ )∘˚˳° (I am the phantom remnant of #97770) #[expect(dead_code)] - owner: Box<dyn Send + Sync>, + owner: Lrc<dyn Send + Sync>, } /// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function. @@ -72,10 +74,10 @@ where O: Send + Sync + 'static, F: FnOnce(&O) -> Result<&[u8], E>, { - // We box the owner of the bytes, so it doesn't move. + // We wrap the owner of the bytes in, so it doesn't move. // // Since the owner does not move and we don't access it in any way - // before drop, there is nothing that can invalidate the bytes pointer. + // before dropping, there is nothing that can invalidate the bytes pointer. // // Thus, "extending" the lifetime of the reference returned from `F` is fine. // We pretend that we pass it a reference that lives as long as the returned slice. @@ -83,12 +85,39 @@ where // N.B. the HRTB on the `slicer` is important — without it the caller could provide // a short lived slice, unrelated to the owner. - let owner = Box::new(owner); + let owner = Lrc::new(owner); let bytes = slicer(&*owner)?; Ok(OwnedSlice { bytes, owner }) } +impl OwnedSlice { + /// Slice this slice by `slicer`. + /// + /// # Examples + /// + /// ```rust + /// # use rustc_data_structures::owned_slice::{OwnedSlice, slice_owned}; + /// let vec = vec![1, 2, 3, 4]; + /// + /// // Identical to slicing via `&v[1..3]` but produces an owned slice + /// let slice: OwnedSlice = slice_owned(vec, |v| &v[..]); + /// assert_eq!(&*slice, [1, 2, 3, 4]); + /// + /// let slice = slice.slice(|slice| &slice[1..][..2]); + /// assert_eq!(&*slice, [2, 3]); + /// ``` + /// + pub fn slice(self, slicer: impl FnOnce(&[u8]) -> &[u8]) -> OwnedSlice { + // This is basically identical to `try_slice_owned`, + // `slicer` can only return slices of its argument or some static data, + // both of which are valid while `owner` is alive. + + let bytes = slicer(&self); + OwnedSlice { bytes, ..self } + } +} + impl Deref for OwnedSlice { type Target = [u8]; @@ -108,11 +137,11 @@ impl Borrow<[u8]> for OwnedSlice { } } -// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Send` +// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Send` #[cfg(parallel_compiler)] unsafe impl Send for OwnedSlice {} -// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Box<dyn Send + Sync>)`, which is `Sync` +// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Sync` #[cfg(parallel_compiler)] unsafe impl Sync for OwnedSlice {} diff --git a/compiler/rustc_data_structures/src/owned_slice/tests.rs b/compiler/rustc_data_structures/src/owned_slice/tests.rs index e151b8c2de0..1eb5378cd1a 100644 --- a/compiler/rustc_data_structures/src/owned_slice/tests.rs +++ b/compiler/rustc_data_structures/src/owned_slice/tests.rs @@ -26,7 +26,7 @@ fn static_storage() { } #[test] -fn slice_the_slice() { +fn slice_owned_the_slice() { let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice); let slice = slice_owned(slice, |s| &s[1..][..4]); let slice = slice_owned(slice, |s| s); @@ -36,6 +36,16 @@ fn slice_the_slice() { } #[test] +fn slice_the_slice() { + let slice = slice_owned(vec![1, 2, 3, 4, 5, 6], Vec::as_slice) + .slice(|s| &s[1..][..4]) + .slice(|s| s) + .slice(|s| &s[1..]); + + assert_eq!(&*slice, &[1, 2, 3, 4, 5, 6][1..][..4][1..]); +} + +#[test] fn try_and_fail() { let res = try_slice_owned(vec![0], |v| v.get(12..).ok_or(())); diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs index 8a778866a77..6c3197d8ec2 100644 --- a/compiler/rustc_data_structures/src/sync.rs +++ b/compiler/rustc_data_structures/src/sync.rs @@ -40,7 +40,6 @@ //! [^2] `MTLockRef` is a typedef. pub use crate::marker::*; -use crate::owned_slice::OwnedSlice; use std::collections::HashMap; use std::hash::{BuildHasher, Hash}; use std::ops::{Deref, DerefMut}; @@ -92,6 +91,7 @@ mod mode { } pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode}; + cfg_if! { if #[cfg(not(parallel_compiler))] { pub unsafe auto trait Send {} @@ -244,8 +244,6 @@ cfg_if! { r } - pub type MetadataRef = OwnedSlice; - pub use std::rc::Rc as Lrc; pub use std::rc::Weak as Weak; pub use std::cell::Ref as ReadGuard; @@ -517,8 +515,6 @@ cfg_if! { } } - pub type MetadataRef = OwnedSlice; - /// This makes locks panic if they are already held. /// It is only useful when you are running in a single thread const ERROR_CHECKING: bool = false; |