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Add VecDeque::extend from vec::IntoIter and slice::Iter specializations
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,73 @@ | ||
use crate::alloc::Allocator; | ||
use crate::vec; | ||
use core::slice; | ||
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use super::VecDeque; | ||
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// Specialization trait used for VecDeque::extend | ||
pub(super) trait SpecExtend<T, I> { | ||
fn spec_extend(&mut self, iter: I); | ||
} | ||
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impl<T, I, A: Allocator> SpecExtend<T, I> for VecDeque<T, A> | ||
where | ||
I: Iterator<Item = T>, | ||
{ | ||
default fn spec_extend(&mut self, mut iter: I) { | ||
// This function should be the moral equivalent of: | ||
// | ||
// for item in iter { | ||
// self.push_back(item); | ||
// } | ||
while let Some(element) = iter.next() { | ||
if self.len() == self.capacity() { | ||
let (lower, _) = iter.size_hint(); | ||
self.reserve(lower.saturating_add(1)); | ||
} | ||
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let head = self.head; | ||
self.head = self.wrap_add(self.head, 1); | ||
unsafe { | ||
self.buffer_write(head, element); | ||
} | ||
} | ||
} | ||
} | ||
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impl<T, A: Allocator> SpecExtend<T, vec::IntoIter<T>> for VecDeque<T, A> { | ||
fn spec_extend(&mut self, mut iterator: vec::IntoIter<T>) { | ||
let slice = iterator.as_slice(); | ||
self.reserve(slice.len()); | ||
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unsafe { | ||
self.copy_slice(self.head, slice); | ||
self.head = self.wrap_add(self.head, slice.len()); | ||
} | ||
iterator.forget_remaining_elements(); | ||
} | ||
} | ||
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impl<'a, T: 'a, I, A: Allocator> SpecExtend<&'a T, I> for VecDeque<T, A> | ||
where | ||
I: Iterator<Item = &'a T>, | ||
T: Copy, | ||
{ | ||
default fn spec_extend(&mut self, iterator: I) { | ||
self.spec_extend(iterator.copied()) | ||
} | ||
} | ||
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impl<'a, T: 'a, A: Allocator> SpecExtend<&'a T, slice::Iter<'a, T>> for VecDeque<T, A> | ||
where | ||
T: Copy, | ||
{ | ||
fn spec_extend(&mut self, iterator: slice::Iter<'a, T>) { | ||
let slice = iterator.as_slice(); | ||
self.reserve(slice.len()); | ||
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unsafe { | ||
self.copy_slice(self.head, slice); | ||
self.head = self.wrap_add(self.head, slice.len()); | ||
} | ||
} | ||
} |
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