use std::fmt::Debug;
use std::ops::Range;
pub trait Source {
type Slice: ?Sized + PartialEq + Eq + Debug;
fn len(&self) -> usize;
fn read<'a, Chunk>(&'a self, offset: usize) -> Option<Chunk>
where
Chunk: self::Chunk<'a>;
unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
where
Chunk: self::Chunk<'a>;
fn slice(&self, range: Range<usize>) -> Option<&Self::Slice>;
unsafe fn slice_unchecked(&self, range: Range<usize>) -> &Self::Slice;
#[inline]
fn find_boundary(&self, index: usize) -> usize {
index
}
fn is_boundary(&self, index: usize) -> bool;
}
impl Source for str {
type Slice = str;
#[inline]
fn len(&self) -> usize {
self.len()
}
#[inline]
fn read<'a, Chunk>(&'a self, offset: usize) -> Option<Chunk>
where
Chunk: self::Chunk<'a>,
{
if offset + (Chunk::SIZE - 1) < self.len() {
Some(unsafe { Chunk::from_ptr(self.as_ptr().add(offset)) })
} else {
None
}
}
#[inline]
unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
where
Chunk: self::Chunk<'a>,
{
Chunk::from_ptr(self.as_ptr().add(offset))
}
#[inline]
fn slice(&self, range: Range<usize>) -> Option<&str> {
self.get(range)
}
#[inline]
unsafe fn slice_unchecked(&self, range: Range<usize>) -> &str {
debug_assert!(
range.start <= self.len() && range.end <= self.len(),
"Reading out of bounds {:?} for {}!",
range,
self.len()
);
self.get_unchecked(range)
}
#[inline]
fn find_boundary(&self, mut index: usize) -> usize {
while !self.is_char_boundary(index) {
index += 1;
}
index
}
#[inline]
fn is_boundary(&self, index: usize) -> bool {
self.is_char_boundary(index)
}
}
impl Source for [u8] {
type Slice = [u8];
#[inline]
fn len(&self) -> usize {
self.len()
}
#[inline]
fn read<'a, Chunk>(&'a self, offset: usize) -> Option<Chunk>
where
Chunk: self::Chunk<'a>,
{
if offset + (Chunk::SIZE - 1) < self.len() {
Some(unsafe { Chunk::from_ptr(self.as_ptr().add(offset)) })
} else {
None
}
}
#[inline]
unsafe fn read_unchecked<'a, Chunk>(&'a self, offset: usize) -> Chunk
where
Chunk: self::Chunk<'a>,
{
Chunk::from_ptr(self.as_ptr().add(offset))
}
#[inline]
fn slice(&self, range: Range<usize>) -> Option<&[u8]> {
self.get(range)
}
#[inline]
unsafe fn slice_unchecked(&self, range: Range<usize>) -> &[u8] {
debug_assert!(
range.start <= self.len() && range.end <= self.len(),
"Reading out of bounds {:?} for {}!",
range,
self.len()
);
self.get_unchecked(range)
}
#[inline]
fn is_boundary(&self, index: usize) -> bool {
index <= self.len()
}
}
pub trait Chunk<'source>: Sized + Copy + PartialEq + Eq {
const SIZE: usize;
unsafe fn from_ptr(ptr: *const u8) -> Self;
}
impl<'source> Chunk<'source> for u8 {
const SIZE: usize = 1;
#[inline]
unsafe fn from_ptr(ptr: *const u8) -> Self {
*ptr
}
}
macro_rules! impl_array {
($($size:expr),*) => ($(
impl<'source> Chunk<'source> for &'source [u8; $size] {
const SIZE: usize = $size;
#[inline]
unsafe fn from_ptr(ptr: *const u8) -> Self {
&*(ptr as *const [u8; $size])
}
}
)*);
}
impl_array!(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16);