From 09403321710d94abaa3e12a07eb5391490117bd4 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Tue, 23 Jul 2024 18:59:07 +0200 Subject: rust: alloc: implement `IntoIterator` for `Vec` Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as `Iterator` for `IntoIter`. `Vec::into_iter` disassembles the `Vec` into its raw parts; additionally, `IntoIter` keeps track of a separate pointer, which is incremented correspondingsly as the iterator advances, while the length, or the count of elements, is decremented. This also means that `IntoIter` takes the ownership of the backing buffer and is responsible to drop the remaining elements and free the backing buffer, if it's dropped. Reviewed-by: Alice Ryhl Reviewed-by: Benno Lossin Reviewed-by: Gary Guo Signed-off-by: Danilo Krummrich --- rust/kernel/alloc.rs | 1 + rust/kernel/alloc/kvec.rs | 170 ++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 171 insertions(+) diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index a3285416f845..8144934d21af 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -20,6 +20,7 @@ pub use self::kbox::KBox; pub use self::kbox::KVBox; pub use self::kbox::VBox; +pub use self::kvec::IntoIter; pub use self::kvec::KVVec; pub use self::kvec::KVec; pub use self::kvec::VVec; diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index d41353b7653d..86382827f576 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -648,3 +648,173 @@ impl_slice_eq! { [A: Allocator, const N: usize] Vec, [U; N], [A: Allocator, const N: usize] Vec, &[U; N], } + +impl<'a, T, A> IntoIterator for &'a Vec +where + A: Allocator, +{ + type Item = &'a T; + type IntoIter = slice::Iter<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter() + } +} + +impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec +where + A: Allocator, +{ + type Item = &'a mut T; + type IntoIter = slice::IterMut<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter_mut() + } +} + +/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector. +/// +/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the +/// [`IntoIterator`] trait). +/// +/// # Examples +/// +/// ``` +/// let v = kernel::kvec![0, 1, 2]?; +/// let iter = v.into_iter(); +/// +/// # Ok::<(), Error>(()) +/// ``` +pub struct IntoIter { + ptr: *mut T, + buf: NonNull, + len: usize, + layout: ArrayLayout, + _p: PhantomData, +} + +impl Iterator for IntoIter +where + A: Allocator, +{ + type Item = T; + + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2, 3]?; + /// let mut it = v.into_iter(); + /// + /// assert_eq!(it.next(), Some(1)); + /// assert_eq!(it.next(), Some(2)); + /// assert_eq!(it.next(), Some(3)); + /// assert_eq!(it.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn next(&mut self) -> Option { + if self.len == 0 { + return None; + } + + let current = self.ptr; + + // SAFETY: We can't overflow; decreasing `self.len` by one every time we advance `self.ptr` + // by one guarantees that. + unsafe { self.ptr = self.ptr.add(1) }; + + self.len -= 1; + + // SAFETY: `current` is guaranteed to point at a valid element within the buffer. + Some(unsafe { current.read() }) + } + + /// # Examples + /// + /// ``` + /// let v: KVec = kernel::kvec![1, 2, 3]?; + /// let mut iter = v.into_iter(); + /// let size = iter.size_hint().0; + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 1); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 2); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 3); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn size_hint(&self) -> (usize, Option) { + (self.len, Some(self.len)) + } +} + +impl Drop for IntoIter +where + A: Allocator, +{ + fn drop(&mut self) { + // SAFETY: `self.ptr` is guaranteed to be valid by the type invariant. + unsafe { ptr::drop_in_place(ptr::slice_from_raw_parts_mut(self.ptr, self.len)) }; + + // SAFETY: + // - `self.buf` was previously allocated with `A`. + // - `self.layout` matches the `ArrayLayout` of the preceeding allocation. + unsafe { A::free(self.buf.cast(), self.layout.into()) }; + } +} + +impl IntoIterator for Vec +where + A: Allocator, +{ + type Item = T; + type IntoIter = IntoIter; + + /// Consumes the `Vec` and creates an `Iterator`, which moves each value out of the + /// vector (from start to end). + /// + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2]?; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option = v_iter.next(); + /// + /// assert_eq!(first_element, Some(1)); + /// assert_eq!(v_iter.next(), Some(2)); + /// assert_eq!(v_iter.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + /// + /// ``` + /// let v = kernel::kvec![]; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option = v_iter.next(); + /// + /// assert_eq!(first_element, None); + /// + /// # Ok::<(), Error>(()) + /// ``` + #[inline] + fn into_iter(self) -> Self::IntoIter { + let buf = self.ptr; + let layout = self.layout; + let (ptr, len, _) = self.into_raw_parts(); + + IntoIter { + ptr, + buf, + len, + layout, + _p: PhantomData::, + } + } +} -- cgit v1.2.3-58-ga151