1use core::clone::TrivialClone;
2use core::iter::TrustedLen;
3use core::slice::{self};
4
5use super::{IntoIter, Vec};
6use crate::alloc::Allocator;
7
8// Specialization trait used for Vec::extend
9pub(super) trait SpecExtend<T, I> {
10 fn spec_extend(&mut self, iter: I);
11}
12
13impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
14where
15 I: Iterator<Item = T>,
16{
17 default fn spec_extend(&mut self, iter: I) {
18 self.extend_desugared(iterator:iter)
19 }
20}
21
22impl<T, I, A: Allocator> SpecExtend<T, I> for Vec<T, A>
23where
24 I: TrustedLen<Item = T>,
25{
26 default fn spec_extend(&mut self, iterator: I) {
27 self.extend_trusted(iterator)
28 }
29}
30
31impl<T, A1: Allocator, A2: Allocator> SpecExtend<T, IntoIter<T, A2>> for Vec<T, A1> {
32 fn spec_extend(&mut self, mut iterator: IntoIter<T, A2>) {
33 unsafe {
34 self.append_elements(iterator.as_slice() as _);
35 }
36 iterator.forget_remaining_elements();
37 }
38}
39
40impl<'a, T: 'a, I, A: Allocator> SpecExtend<&'a T, I> for Vec<T, A>
41where
42 I: Iterator<Item = &'a T>,
43 T: Clone,
44{
45 default fn spec_extend(&mut self, iterator: I) {
46 self.spec_extend(iter:iterator.cloned())
47 }
48}
49
50impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for Vec<T, A>
51where
52 T: TrivialClone,
53{
54 fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) {
55 let slice: *const [T] = iterator.as_slice();
56 unsafe { self.append_elements(slice) };
57 }
58}
59