diff options
Diffstat (limited to 'third_party/rust/bumpalo/src/collections/vec.rs')
| -rw-r--r-- | third_party/rust/bumpalo/src/collections/vec.rs | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/third_party/rust/bumpalo/src/collections/vec.rs b/third_party/rust/bumpalo/src/collections/vec.rs index 312aa055b9..0dab700727 100644 --- a/third_party/rust/bumpalo/src/collections/vec.rs +++ b/third_party/rust/bumpalo/src/collections/vec.rs @@ -104,6 +104,8 @@ use core::ops::{Index, IndexMut, RangeBounds}; use core::ptr; use core::ptr::NonNull; use core::slice; +#[cfg(feature = "std")] +use std::io; unsafe fn arith_offset<T>(p: *const T, offset: isize) -> *const T { p.offset(offset) @@ -1775,6 +1777,132 @@ impl<'bump, T: 'bump + Clone> Vec<'bump, T> { } } +impl<'bump, T: 'bump + Copy> Vec<'bump, T> { + /// Helper method to copy all of the items in `other` and append them to the end of `self`. + /// + /// SAFETY: + /// * The caller is responsible for: + /// * calling [`reserve`](Self::reserve) beforehand to guarantee that there is enough + /// capacity to store `other.len()` more items. + /// * guaranteeing that `self` and `other` do not overlap. + unsafe fn extend_from_slice_copy_unchecked(&mut self, other: &[T]) { + let old_len = self.len(); + debug_assert!(old_len + other.len() <= self.capacity()); + + // SAFETY: + // * `src` is valid for reads of `other.len()` values by virtue of being a `&[T]`. + // * `dst` is valid for writes of `other.len()` bytes because the caller of this + // method is required to `reserve` capacity to store at least `other.len()` items + // beforehand. + // * Because `src` is a `&[T]` and dst is a `&[T]` within the `Vec<T>`, + // `copy_nonoverlapping`'s alignment requirements are met. + // * Caller is required to guarantee that the source and destination ranges cannot overlap + unsafe { + let src = other.as_ptr(); + let dst = self.as_mut_ptr().add(old_len); + ptr::copy_nonoverlapping(src, dst, other.len()); + self.set_len(old_len + other.len()); + } + } + + + /// Copies all elements in the slice `other` and appends them to the `Vec`. + /// + /// Note that this function is same as [`extend_from_slice`] except that it is optimized for + /// slices of types that implement the `Copy` trait. If and when Rust gets specialization + /// this function will likely be deprecated (but still available). + /// + /// To copy and append the data from multiple source slices at once, see + /// [`extend_from_slices_copy`]. + /// + /// # Examples + /// + /// ``` + /// use bumpalo::{Bump, collections::Vec}; + /// + /// let b = Bump::new(); + /// + /// let mut vec = bumpalo::vec![in &b; 1]; + /// vec.extend_from_slice_copy(&[2, 3, 4]); + /// assert_eq!(vec, [1, 2, 3, 4]); + /// ``` + /// + /// ``` + /// use bumpalo::{Bump, collections::Vec}; + /// + /// let b = Bump::new(); + /// + /// let mut vec = bumpalo::vec![in &b; 'H' as u8]; + /// vec.extend_from_slice_copy("ello, world!".as_bytes()); + /// assert_eq!(vec, "Hello, world!".as_bytes()); + /// ``` + /// + /// [`extend_from_slice`]: #method.extend_from_slice + /// [`extend_from_slices`]: #method.extend_from_slices + pub fn extend_from_slice_copy(&mut self, other: &[T]) { + // Reserve space in the Vec for the values to be added + self.reserve(other.len()); + + // Copy values into the space that was just reserved + // SAFETY: + // * `self` has enough capacity to store `other.len()` more items as `self.reserve(other.len())` + // above guarantees that. + // * Source and destination data ranges cannot overlap as we just reserved the destination + // range from the bump. + unsafe { + self.extend_from_slice_copy_unchecked(other); + } + } + + /// For each slice in `slices`, copies all elements in the slice and appends them to the `Vec`. + /// + /// This method is equivalent to calling [`extend_from_slice_copy`] in a loop, but is able + /// to precompute the total amount of space to reserve in advance. This reduces the potential + /// maximum number of reallocations needed from one-per-slice to just one. + /// + /// # Examples + /// + /// ``` + /// use bumpalo::{Bump, collections::Vec}; + /// + /// let b = Bump::new(); + /// + /// let mut vec = bumpalo::vec![in &b; 1]; + /// vec.extend_from_slices_copy(&[&[2, 3], &[], &[4]]); + /// assert_eq!(vec, [1, 2, 3, 4]); + /// ``` + /// + /// ``` + /// use bumpalo::{Bump, collections::Vec}; + /// + /// let b = Bump::new(); + /// + /// let mut vec = bumpalo::vec![in &b; 'H' as u8]; + /// vec.extend_from_slices_copy(&["ello,".as_bytes(), &[], " world!".as_bytes()]); + /// assert_eq!(vec, "Hello, world!".as_bytes()); + /// ``` + /// + /// [`extend_from_slice_copy`]: #method.extend_from_slice_copy + pub fn extend_from_slices_copy(&mut self, slices: &[&[T]]) { + // Reserve the total amount of capacity we'll need to safely append the aggregated contents + // of each slice in `slices`. + let capacity_to_reserve: usize = slices.iter().map(|slice| slice.len()).sum(); + self.reserve(capacity_to_reserve); + + // SAFETY: + // * `dst` is valid for writes of `capacity_to_reserve` items as + // `self.reserve(capacity_to_reserve)` above guarantees that. + // * Source and destination ranges cannot overlap as we just reserved the destination + // range from the bump. + unsafe { + // Copy the contents of each slice onto the end of `self` + slices.iter().for_each(|slice| { + self.extend_from_slice_copy_unchecked(slice); + }); + } + } +} + // This code generalises `extend_with_{element,default}`. trait ExtendWith<T> { fn next(&mut self) -> T; @@ -2612,3 +2740,23 @@ where } } } + +#[cfg(feature = "std")] +impl<'bump> io::Write for Vec<'bump, u8> { + #[inline] + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + self.extend_from_slice_copy(buf); + Ok(buf.len()) + } + + #[inline] + fn write_all(&mut self, buf: &[u8]) -> io::Result<()> { + self.extend_from_slice_copy(buf); + Ok(()) + } + + #[inline] + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } +} |