use crate::alloc::Allocator;
-use core::iter::TrustedLen;
+use core::iter::{TrustedLen, TrustedRandomAccess};
use core::ptr::{self};
use core::slice::{self};
}
impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
+where
+ I: Iterator<Item = T>,
+{
+ default fn spec_extend(&mut self, iter: I) {
+ SpecExtendInner::spec_extend(self, iter);
+ }
+}
+
+impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
+ fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
+ unsafe {
+ self.append_elements(iterator.as_slice() as _);
+ }
+ iterator.ptr = iterator.end;
+ }
+}
+
+impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec<T, A>
+where
+ I: Iterator<Item = &'a T>,
+ T: Clone,
+{
+ default fn spec_extend(&mut self, iterator: I) {
+ SpecExtend::spec_extend(self, iterator.cloned())
+ }
+}
+
+impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
+where
+ T: Copy,
+{
+ fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
+ let slice = iterator.as_slice();
+ unsafe { self.append_elements(slice) };
+ }
+}
+
+// Helper trait to disambiguate overlapping specializations
+trait SpecExtendInner<T, I> {
+ fn spec_extend(&mut self, iter: I);
+}
+
+impl<T, I, A: Allocator> SpecExtendInner<T, I> for Vec<T, A>
where
I: Iterator<Item = T>,
{
}
}
-impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
+impl<T, I, A: Allocator> SpecExtendInner<T, I> for Vec<T, A>
where
I: TrustedLen<Item = T>,
{
}
}
-impl<T, A: Allocator> SpecExtend<T, IntoIter<T>> for Vec<T, A> {
- fn spec_extend(&mut self, mut iterator: IntoIter<T>) {
- unsafe {
- self.append_elements(iterator.as_slice() as _);
- }
- iterator.ptr = iterator.end;
- }
-}
-
-impl<'a, T: 'a, I, A: Allocator + 'a> SpecExtend<&'a T, I> for Vec<T, A>
+impl<T, I, A: Allocator> SpecExtendInner<T, I> for Vec<T, A>
where
- I: Iterator<Item = &'a T>,
- T: Clone,
+ I: TrustedLen<Item = T> + TrustedRandomAccess,
{
- default fn spec_extend(&mut self, iterator: I) {
- self.spec_extend(iterator.cloned())
- }
-}
+ default fn spec_extend(&mut self, mut iterator: I) {
+ let size = iterator.size();
+ self.reserve(size);
-impl<'a, T: 'a, A: Allocator + 'a> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
-where
- T: Copy,
-{
- fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
- let slice = iterator.as_slice();
- unsafe { self.append_elements(slice) };
+ // SAFETY: reserve ensured that there is sufficient capacity for the additional items.
+ // The loop upholds the TRA requirements by accessing each element only once.
+ unsafe {
+ let sink = self.as_mut_ptr().add(self.len());
+ for i in 0..size {
+ ptr::write(sink.add(i), iterator.__iterator_get_unchecked(i));
+ self.set_len(self.len() + 1);
+ }
+ }
}
}