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Diffstat (limited to 'compiler/rustc_data_structures/src/functor.rs')
-rw-r--r-- | compiler/rustc_data_structures/src/functor.rs | 116 |
1 files changed, 0 insertions, 116 deletions
diff --git a/compiler/rustc_data_structures/src/functor.rs b/compiler/rustc_data_structures/src/functor.rs deleted file mode 100644 index e3fcaccb1..000000000 --- a/compiler/rustc_data_structures/src/functor.rs +++ /dev/null @@ -1,116 +0,0 @@ -use rustc_index::{Idx, IndexVec}; -use std::{mem, rc::Rc, sync::Arc}; - -pub trait IdFunctor: Sized { - type Inner; - - fn try_map_id<F, E>(self, f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>; -} - -impl<T> IdFunctor for Box<T> { - type Inner = T; - - #[inline] - fn try_map_id<F, E>(self, mut f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>, - { - let raw = Box::into_raw(self); - Ok(unsafe { - // SAFETY: The raw pointer points to a valid value of type `T`. - let value = raw.read(); - // SAFETY: Converts `Box<T>` to `Box<MaybeUninit<T>>` which is the - // inverse of `Box::assume_init()` and should be safe. - let raw: Box<mem::MaybeUninit<T>> = Box::from_raw(raw.cast()); - // SAFETY: Write the mapped value back into the `Box`. - Box::write(raw, f(value)?) - }) - } -} - -impl<T> IdFunctor for Vec<T> { - type Inner = T; - - #[inline] - fn try_map_id<F, E>(self, f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>, - { - self.into_iter().map(f).collect() - } -} - -impl<T> IdFunctor for Box<[T]> { - type Inner = T; - - #[inline] - fn try_map_id<F, E>(self, f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>, - { - Vec::from(self).try_map_id(f).map(Into::into) - } -} - -impl<I: Idx, T> IdFunctor for IndexVec<I, T> { - type Inner = T; - - #[inline] - fn try_map_id<F, E>(self, f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>, - { - self.raw.try_map_id(f).map(IndexVec::from_raw) - } -} - -macro_rules! rc { - ($($rc:ident),+) => {$( - impl<T: Clone> IdFunctor for $rc<T> { - type Inner = T; - - #[inline] - fn try_map_id<F, E>(mut self, mut f: F) -> Result<Self, E> - where - F: FnMut(Self::Inner) -> Result<Self::Inner, E>, - { - // We merely want to replace the contained `T`, if at all possible, - // so that we don't needlessly allocate a new `$rc` or indeed clone - // the contained type. - unsafe { - // First step is to ensure that we have a unique reference to - // the contained type, which `$rc::make_mut` will accomplish (by - // allocating a new `$rc` and cloning the `T` only if required). - // This is done *before* casting to `$rc<ManuallyDrop<T>>` so that - // panicking during `make_mut` does not leak the `T`. - $rc::make_mut(&mut self); - - // Casting to `$rc<ManuallyDrop<T>>` is safe because `ManuallyDrop` - // is `repr(transparent)`. - let ptr = $rc::into_raw(self).cast::<mem::ManuallyDrop<T>>(); - let mut unique = $rc::from_raw(ptr); - - // Call to `$rc::make_mut` above guarantees that `unique` is the - // sole reference to the contained value, so we can avoid doing - // a checked `get_mut` here. - let slot = $rc::get_mut_unchecked(&mut unique); - - // Semantically move the contained type out from `unique`, fold - // it, then move the folded value back into `unique`. Should - // folding fail, `ManuallyDrop` ensures that the "moved-out" - // value is not re-dropped. - let owned = mem::ManuallyDrop::take(slot); - let folded = f(owned)?; - *slot = mem::ManuallyDrop::new(folded); - - // Cast back to `$rc<T>`. - Ok($rc::from_raw($rc::into_raw(unique).cast())) - } - } - } - )+}; -} - -rc! { Rc, Arc } |