diff options
| -rw-r--r-- | library/alloc/src/vec/into_iter.rs | 270 | ||||
| -rw-r--r-- | library/alloc/src/vec/mod.rs | 270 |
2 files changed, 276 insertions, 264 deletions
diff --git a/library/alloc/src/vec/into_iter.rs b/library/alloc/src/vec/into_iter.rs new file mode 100644 index 00000000000..623792a6316 --- /dev/null +++ b/library/alloc/src/vec/into_iter.rs @@ -0,0 +1,270 @@ +use crate::alloc::{Allocator, Global}; +use crate::raw_vec::RawVec; +use core::marker::PhantomData; +use core::intrinsics::{arith_offset}; +use core::mem::{self}; +use core::fmt; +use core::ptr::{self, NonNull}; +use core::slice::{self}; +use core::iter::{ + FusedIterator, InPlaceIterable, SourceIter, TrustedLen, TrustedRandomAccess, +}; + +/// An iterator that moves out of a vector. +/// +/// This `struct` is created by the `into_iter` method on [`Vec`] (provided +/// by the [`IntoIterator`] trait). +/// +/// # Example +/// +/// ``` +/// let v = vec![0, 1, 2]; +/// let iter: std::vec::IntoIter<_> = v.into_iter(); +/// ``` +#[stable(feature = "rust1", since = "1.0.0")] +pub struct IntoIter< + T, + #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, +> { + pub(super) buf: NonNull<T>, + pub(super) phantom: PhantomData<T>, + pub(super) cap: usize, + pub(super) alloc: A, + pub(super) ptr: *const T, + pub(super) end: *const T, +} + +#[stable(feature = "vec_intoiter_debug", since = "1.13.0")] +impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<T, A> { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_tuple("IntoIter").field(&self.as_slice()).finish() + } +} + +impl<T, A: Allocator> IntoIter<T, A> { + /// Returns the remaining items of this iterator as a slice. + /// + /// # Examples + /// + /// ``` + /// let vec = vec!['a', 'b', 'c']; + /// let mut into_iter = vec.into_iter(); + /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); + /// let _ = into_iter.next().unwrap(); + /// assert_eq!(into_iter.as_slice(), &['b', 'c']); + /// ``` + #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] + pub fn as_slice(&self) -> &[T] { + unsafe { slice::from_raw_parts(self.ptr, self.len()) } + } + + /// Returns the remaining items of this iterator as a mutable slice. + /// + /// # Examples + /// + /// ``` + /// let vec = vec!['a', 'b', 'c']; + /// let mut into_iter = vec.into_iter(); + /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); + /// into_iter.as_mut_slice()[2] = 'z'; + /// assert_eq!(into_iter.next().unwrap(), 'a'); + /// assert_eq!(into_iter.next().unwrap(), 'b'); + /// assert_eq!(into_iter.next().unwrap(), 'z'); + /// ``` + #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] + pub fn as_mut_slice(&mut self) -> &mut [T] { + unsafe { &mut *self.as_raw_mut_slice() } + } + + /// Returns a reference to the underlying allocator. + #[unstable(feature = "allocator_api", issue = "32838")] + #[inline] + pub fn allocator(&self) -> &A { + &self.alloc + } + + fn as_raw_mut_slice(&mut self) -> *mut [T] { + ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len()) + } + + pub(super) fn drop_remaining(&mut self) { + unsafe { + ptr::drop_in_place(self.as_mut_slice()); + } + self.ptr = self.end; + } + + /// Relinquishes the backing allocation, equivalent to + /// `ptr::write(&mut self, Vec::new().into_iter())` + pub(super) fn forget_allocation(&mut self) { + self.cap = 0; + self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) }; + self.ptr = self.buf.as_ptr(); + self.end = self.buf.as_ptr(); + } +} + +#[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")] +impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> { + fn as_ref(&self) -> &[T] { + self.as_slice() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {} +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<T: Sync, A: Allocator> Sync for IntoIter<T, A> {} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T, A: Allocator> Iterator for IntoIter<T, A> { + type Item = T; + + #[inline] + fn next(&mut self) -> Option<T> { + if self.ptr as *const _ == self.end { + None + } else if mem::size_of::<T>() == 0 { + // purposefully don't use 'ptr.offset' because for + // vectors with 0-size elements this would return the + // same pointer. + self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T }; + + // Make up a value of this ZST. + Some(unsafe { mem::zeroed() }) + } else { + let old = self.ptr; + self.ptr = unsafe { self.ptr.offset(1) }; + + Some(unsafe { ptr::read(old) }) + } + } + + #[inline] + fn size_hint(&self) -> (usize, Option<usize>) { + let exact = if mem::size_of::<T>() == 0 { + (self.end as usize).wrapping_sub(self.ptr as usize) + } else { + unsafe { self.end.offset_from(self.ptr) as usize } + }; + (exact, Some(exact)) + } + + #[inline] + fn count(self) -> usize { + self.len() + } + + unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item + where + Self: TrustedRandomAccess, + { + // SAFETY: the caller must guarantee that `i` is in bounds of the + // `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)` + // is guaranteed to pointer to an element of the `Vec<T>` and + // thus guaranteed to be valid to dereference. + // + // Also note the implementation of `Self: TrustedRandomAccess` requires + // that `T: Copy` so reading elements from the buffer doesn't invalidate + // them for `Drop`. + unsafe { + if mem::size_of::<T>() == 0 { mem::zeroed() } else { ptr::read(self.ptr.add(i)) } + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> { + #[inline] + fn next_back(&mut self) -> Option<T> { + if self.end == self.ptr { + None + } else if mem::size_of::<T>() == 0 { + // See above for why 'ptr.offset' isn't used + self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T }; + + // Make up a value of this ZST. + Some(unsafe { mem::zeroed() }) + } else { + self.end = unsafe { self.end.offset(-1) }; + + Some(unsafe { ptr::read(self.end) }) + } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> { + fn is_empty(&self) -> bool { + self.ptr == self.end + } +} + +#[stable(feature = "fused", since = "1.26.0")] +impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {} + +#[unstable(feature = "trusted_len", issue = "37572")] +unsafe impl<T, A: Allocator> TrustedLen for IntoIter<T, A> {} + +#[doc(hidden)] +#[unstable(issue = "none", feature = "std_internals")] +// T: Copy as approximation for !Drop since get_unchecked does not advance self.ptr +// and thus we can't implement drop-handling +unsafe impl<T, A: Allocator> TrustedRandomAccess for IntoIter<T, A> + where + T: Copy, +{ + fn may_have_side_effect() -> bool { + false + } +} + +#[stable(feature = "vec_into_iter_clone", since = "1.8.0")] +impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> { + #[cfg(not(test))] + fn clone(&self) -> Self { + self.as_slice().to_vec_in(self.alloc.clone()).into_iter() + } + #[cfg(test)] + fn clone(&self) -> Self { + crate::slice::to_vec(self.as_slice(), self.alloc.clone()).into_iter() + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter<T, A> { + fn drop(&mut self) { + struct DropGuard<'a, T, A: Allocator>(&'a mut IntoIter<T, A>); + + impl<T, A: Allocator> Drop for DropGuard<'_, T, A> { + fn drop(&mut self) { + unsafe { + // `IntoIter::alloc` is not used anymore after this + let alloc = ptr::read(&self.0.alloc); + // RawVec handles deallocation + let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc); + } + } + } + + let guard = DropGuard(self); + // destroy the remaining elements + unsafe { + ptr::drop_in_place(guard.0.as_raw_mut_slice()); + } + // now `guard` will be dropped and do the rest + } +} + +#[unstable(issue = "none", feature = "inplace_iteration")] +unsafe impl<T, A: Allocator> InPlaceIterable for IntoIter<T, A> {} + +#[unstable(issue = "none", feature = "inplace_iteration")] +unsafe impl<T, A: Allocator> SourceIter for IntoIter<T, A> { + type Source = Self; + + #[inline] + unsafe fn as_inner(&mut self) -> &mut Self::Source { + self + } +} diff --git a/library/alloc/src/vec/mod.rs b/library/alloc/src/vec/mod.rs index 8d3f8b0bfd8..b6508bfea08 100644 --- a/library/alloc/src/vec/mod.rs +++ b/library/alloc/src/vec/mod.rs @@ -60,7 +60,7 @@ use core::fmt; use core::hash::{Hash, Hasher}; use core::intrinsics::{arith_offset, assume}; use core::iter::{ - FromIterator, FusedIterator, InPlaceIterable, SourceIter, TrustedLen, TrustedRandomAccess, + FromIterator, InPlaceIterable, SourceIter, TrustedLen, }; use core::marker::PhantomData; use core::mem::{self, ManuallyDrop, MaybeUninit}; @@ -91,6 +91,11 @@ mod drain; mod cow; +#[stable(feature = "rust1", since = "1.0.0")] +pub use self::into_iter::IntoIter; + +mod into_iter; + /// A contiguous growable array type, written `Vec<T>` but pronounced 'vector'. /// /// # Examples @@ -3015,269 +3020,6 @@ impl<T, A: Allocator, const N: usize> TryFrom<Vec<T, A>> for [T; N] { } } -//////////////////////////////////////////////////////////////////////////////// -// Iterators -//////////////////////////////////////////////////////////////////////////////// - -/// An iterator that moves out of a vector. -/// -/// This `struct` is created by the `into_iter` method on [`Vec`] (provided -/// by the [`IntoIterator`] trait). -/// -/// # Example -/// -/// ``` -/// let v = vec![0, 1, 2]; -/// let iter: std::vec::IntoIter<_> = v.into_iter(); -/// ``` -#[stable(feature = "rust1", since = "1.0.0")] -pub struct IntoIter< - T, - #[unstable(feature = "allocator_api", issue = "32838")] A: Allocator = Global, -> { - buf: NonNull<T>, - phantom: PhantomData<T>, - cap: usize, - alloc: A, - ptr: *const T, - end: *const T, -} - -#[stable(feature = "vec_intoiter_debug", since = "1.13.0")] -impl<T: fmt::Debug, A: Allocator> fmt::Debug for IntoIter<T, A> { - fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { - f.debug_tuple("IntoIter").field(&self.as_slice()).finish() - } -} - -impl<T, A: Allocator> IntoIter<T, A> { - /// Returns the remaining items of this iterator as a slice. - /// - /// # Examples - /// - /// ``` - /// let vec = vec!['a', 'b', 'c']; - /// let mut into_iter = vec.into_iter(); - /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); - /// let _ = into_iter.next().unwrap(); - /// assert_eq!(into_iter.as_slice(), &['b', 'c']); - /// ``` - #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] - pub fn as_slice(&self) -> &[T] { - unsafe { slice::from_raw_parts(self.ptr, self.len()) } - } - - /// Returns the remaining items of this iterator as a mutable slice. - /// - /// # Examples - /// - /// ``` - /// let vec = vec!['a', 'b', 'c']; - /// let mut into_iter = vec.into_iter(); - /// assert_eq!(into_iter.as_slice(), &['a', 'b', 'c']); - /// into_iter.as_mut_slice()[2] = 'z'; - /// assert_eq!(into_iter.next().unwrap(), 'a'); - /// assert_eq!(into_iter.next().unwrap(), 'b'); - /// assert_eq!(into_iter.next().unwrap(), 'z'); - /// ``` - #[stable(feature = "vec_into_iter_as_slice", since = "1.15.0")] - pub fn as_mut_slice(&mut self) -> &mut [T] { - unsafe { &mut *self.as_raw_mut_slice() } - } - - /// Returns a reference to the underlying allocator. - #[unstable(feature = "allocator_api", issue = "32838")] - #[inline] - pub fn allocator(&self) -> &A { - &self.alloc - } - - fn as_raw_mut_slice(&mut self) -> *mut [T] { - ptr::slice_from_raw_parts_mut(self.ptr as *mut T, self.len()) - } - - fn drop_remaining(&mut self) { - unsafe { - ptr::drop_in_place(self.as_mut_slice()); - } - self.ptr = self.end; - } - - /// Relinquishes the backing allocation, equivalent to - /// `ptr::write(&mut self, Vec::new().into_iter())` - fn forget_allocation(&mut self) { - self.cap = 0; - self.buf = unsafe { NonNull::new_unchecked(RawVec::NEW.ptr()) }; - self.ptr = self.buf.as_ptr(); - self.end = self.buf.as_ptr(); - } -} - -#[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")] -impl<T, A: Allocator> AsRef<[T]> for IntoIter<T, A> { - fn as_ref(&self) -> &[T] { - self.as_slice() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {} -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<T: Sync, A: Allocator> Sync for IntoIter<T, A> {} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> Iterator for IntoIter<T, A> { - type Item = T; - - #[inline] - fn next(&mut self) -> Option<T> { - if self.ptr as *const _ == self.end { - None - } else if mem::size_of::<T>() == 0 { - // purposefully don't use 'ptr.offset' because for - // vectors with 0-size elements this would return the - // same pointer. - self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T }; - - // Make up a value of this ZST. - Some(unsafe { mem::zeroed() }) - } else { - let old = self.ptr; - self.ptr = unsafe { self.ptr.offset(1) }; - - Some(unsafe { ptr::read(old) }) - } - } - - #[inline] - fn size_hint(&self) -> (usize, Option<usize>) { - let exact = if mem::size_of::<T>() == 0 { - (self.end as usize).wrapping_sub(self.ptr as usize) - } else { - unsafe { self.end.offset_from(self.ptr) as usize } - }; - (exact, Some(exact)) - } - - #[inline] - fn count(self) -> usize { - self.len() - } - - unsafe fn __iterator_get_unchecked(&mut self, i: usize) -> Self::Item - where - Self: TrustedRandomAccess, - { - // SAFETY: the caller must guarantee that `i` is in bounds of the - // `Vec<T>`, so `i` cannot overflow an `isize`, and the `self.ptr.add(i)` - // is guaranteed to pointer to an element of the `Vec<T>` and - // thus guaranteed to be valid to dereference. - // - // Also note the implementation of `Self: TrustedRandomAccess` requires - // that `T: Copy` so reading elements from the buffer doesn't invalidate - // them for `Drop`. - unsafe { - if mem::size_of::<T>() == 0 { mem::zeroed() } else { ptr::read(self.ptr.add(i)) } - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> { - #[inline] - fn next_back(&mut self) -> Option<T> { - if self.end == self.ptr { - None - } else if mem::size_of::<T>() == 0 { - // See above for why 'ptr.offset' isn't used - self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T }; - - // Make up a value of this ZST. - Some(unsafe { mem::zeroed() }) - } else { - self.end = unsafe { self.end.offset(-1) }; - - Some(unsafe { ptr::read(self.end) }) - } - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> { - fn is_empty(&self) -> bool { - self.ptr == self.end - } -} - -#[stable(feature = "fused", since = "1.26.0")] -impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {} - -#[unstable(feature = "trusted_len", issue = "37572")] -unsafe impl<T, A: Allocator> TrustedLen for IntoIter<T, A> {} - -#[doc(hidden)] -#[unstable(issue = "none", feature = "std_internals")] -// T: Copy as approximation for !Drop since get_unchecked does not advance self.ptr -// and thus we can't implement drop-handling -unsafe impl<T, A: Allocator> TrustedRandomAccess for IntoIter<T, A> -where - T: Copy, -{ - fn may_have_side_effect() -> bool { - false - } -} - -#[stable(feature = "vec_into_iter_clone", since = "1.8.0")] -impl<T: Clone, A: Allocator + Clone> Clone for IntoIter<T, A> { - #[cfg(not(test))] - fn clone(&self) -> Self { - self.as_slice().to_vec_in(self.alloc.clone()).into_iter() - } - #[cfg(test)] - fn clone(&self) -> Self { - crate::slice::to_vec(self.as_slice(), self.alloc.clone()).into_iter() - } -} - -#[stable(feature = "rust1", since = "1.0.0")] -unsafe impl<#[may_dangle] T, A: Allocator> Drop for IntoIter<T, A> { - fn drop(&mut self) { - struct DropGuard<'a, T, A: Allocator>(&'a mut IntoIter<T, A>); - - impl<T, A: Allocator> Drop for DropGuard<'_, T, A> { - fn drop(&mut self) { - unsafe { - // `IntoIter::alloc` is not used anymore after this - let alloc = ptr::read(&self.0.alloc); - // RawVec handles deallocation - let _ = RawVec::from_raw_parts_in(self.0.buf.as_ptr(), self.0.cap, alloc); - } - } - } - - let guard = DropGuard(self); - // destroy the remaining elements - unsafe { - ptr::drop_in_place(guard.0.as_raw_mut_slice()); - } - // now `guard` will be dropped and do the rest - } -} - -#[unstable(issue = "none", feature = "inplace_iteration")] -unsafe impl<T, A: Allocator> InPlaceIterable for IntoIter<T, A> {} - -#[unstable(issue = "none", feature = "inplace_iteration")] -unsafe impl<T, A: Allocator> SourceIter for IntoIter<T, A> { - type Source = Self; - - #[inline] - unsafe fn as_inner(&mut self) -> &mut Self::Source { - self - } -} - // internal helper trait for in-place iteration specialization. #[rustc_specialization_trait] pub(crate) trait AsIntoIter { |