61 lines
1.7 KiB
Rust
61 lines
1.7 KiB
Rust
use crate::alloc::Allocator;
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use crate::raw_vec::RawVec;
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use core::ptr::{self};
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use super::{ExtendElement, IsZero, Vec};
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// Specialization trait used for Vec::from_elem
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pub(super) trait SpecFromElem: Sized {
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fn from_elem<A: Allocator>(elem: Self, n: usize, alloc: A) -> Vec<Self, A>;
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}
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impl<T: Clone> SpecFromElem for T {
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default fn from_elem<A: Allocator>(elem: Self, n: usize, alloc: A) -> Vec<Self, A> {
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let mut v = Vec::with_capacity_in(n, alloc);
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v.extend_with(n, ExtendElement(elem));
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v
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}
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}
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impl SpecFromElem for i8 {
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#[inline]
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fn from_elem<A: Allocator>(elem: i8, n: usize, alloc: A) -> Vec<i8, A> {
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if elem == 0 {
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return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
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}
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unsafe {
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let mut v = Vec::with_capacity_in(n, alloc);
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ptr::write_bytes(v.as_mut_ptr(), elem as u8, n);
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v.set_len(n);
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v
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}
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}
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}
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impl SpecFromElem for u8 {
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#[inline]
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fn from_elem<A: Allocator>(elem: u8, n: usize, alloc: A) -> Vec<u8, A> {
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if elem == 0 {
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return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
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}
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unsafe {
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let mut v = Vec::with_capacity_in(n, alloc);
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ptr::write_bytes(v.as_mut_ptr(), elem, n);
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v.set_len(n);
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v
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}
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}
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}
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impl<T: Clone + IsZero> SpecFromElem for T {
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#[inline]
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fn from_elem<A: Allocator>(elem: T, n: usize, alloc: A) -> Vec<T, A> {
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if elem.is_zero() {
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return Vec { buf: RawVec::with_capacity_zeroed_in(n, alloc), len: n };
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}
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let mut v = Vec::with_capacity_in(n, alloc);
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v.extend_with(n, ExtendElement(elem));
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v
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}
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}
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