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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use std::marker::PhantomData;
use std::ops;
use super::smallvec::VecLike;
// TODO(pcwalton): Speed up with SIMD, or better yet, find some way to not do this.
pub fn byte_swap(data: &mut [u8]) {
let length = data.len();
for i in (0..length).step_by(4) {
let r = data[i + 2];
data[i + 2] = data[i + 0];
data[i + 0] = r;
}
}
/// A `VecLike` that only tracks whether or not something was ever pushed to it.
pub struct ForgetfulSink<T> {
empty: bool,
_data: PhantomData<T>,
}
impl<T> ForgetfulSink<T> {
pub fn new() -> ForgetfulSink<T> {
ForgetfulSink {
empty: true,
_data: PhantomData,
}
}
pub fn is_empty(&self) -> bool {
self.empty
}
}
impl<T> ops::Deref for ForgetfulSink<T> {
type Target = [T];
fn deref(&self) -> &[T] {
unreachable!()
}
}
impl<T> ops::DerefMut for ForgetfulSink<T> {
fn deref_mut(&mut self) -> &mut [T] {
unreachable!()
}
}
macro_rules! impl_index {
($index_type: ty, $output_type: ty) => {
impl<T> ops::Index<$index_type> for ForgetfulSink<T> {
type Output = $output_type;
fn index(&self, _index: $index_type) -> &$output_type {
unreachable!()
}
}
impl<T> ops::IndexMut<$index_type> for ForgetfulSink<T> {
fn index_mut(&mut self, _index: $index_type) -> &mut $output_type {
unreachable!()
}
}
}
}
impl_index!(usize, T);
impl_index!(ops::Range<usize>, [T]);
impl_index!(ops::RangeFrom<usize>, [T]);
impl_index!(ops::RangeTo<usize>, [T]);
impl_index!(ops::RangeFull, [T]);
impl<T> VecLike<T> for ForgetfulSink<T> {
#[inline]
fn len(&self) -> usize {
unreachable!()
}
#[inline]
fn push(&mut self, _value: T) {
self.empty = false;
}
}
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