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Add docs and debug asserts

This commit is contained in:
MaloJaffre 2018-08-28 15:38:56 +02:00
parent 11e488b64f
commit 1a1a7f6167

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@ -202,10 +202,17 @@ impl<T> VecDeque<T> {
len);
}
/// Copies all values from `src` to `self`, wrapping around if needed.
/// Assumes capacity is sufficient.
/// Copies all values from `src` to the back of `self`, wrapping around if needed.
///
/// # Safety
///
/// The capacity must be sufficient to hold self.len() + src.len() elements.
/// If so, this function never panics.
#[inline]
unsafe fn copy_slice(&mut self, src: &[T]) {
let expected_new_len = self.len() + src.len();
debug_assert!(self.capacity() >= expected_new_len);
let dst_high_ptr = self.ptr().add(self.head);
let dst_high_len = self.cap() - self.head;
@ -216,6 +223,7 @@ impl<T> VecDeque<T> {
ptr::copy_nonoverlapping(src_low.as_ptr(), self.ptr(), src_low.len());
self.head = self.wrap_add(self.head, src.len());
debug_assert!(self.len() == expected_new_len);
}
/// Copies a potentially wrapping block of memory len long from src to dest.
@ -1850,17 +1858,21 @@ impl<T> VecDeque<T> {
#[inline]
#[stable(feature = "append", since = "1.4.0")]
pub fn append(&mut self, other: &mut Self) {
// Guarantees there is space in `self` for `other
self.reserve(other.len());
unsafe {
let (src_high, src_low) = other.as_slices();
self.copy_slice(src_low);
self.copy_slice(src_high);
}
// Guarantees there is space in `self` for `other`.
self.reserve(other.len());
// Some values now exist in both `other` and `self` but are made inaccessible in `other`.
other.tail = other.head;
{
let (src_high, src_low) = other.as_slices();
// This is only safe because copy_slice never panics when capacity is sufficient.
self.copy_slice(src_low);
self.copy_slice(src_high);
}
// Some values now exist in both `other` and `self` but are made inaccessible in `other`.
other.tail = other.head;
}
}
/// Retains only the elements specified by the predicate.