use std::slice;
pub struct Bytes<'a> {
slice: &'a [u8],
pos: usize
}
impl<'a> Bytes<'a> {
#[inline]
pub fn new(slice: &'a [u8]) -> Bytes<'a> {
Bytes {
slice: slice,
pos: 0
}
}
#[inline]
pub fn pos(&self) -> usize {
self.pos
}
#[inline]
pub fn peek(&self) -> Option<u8> {
if self.slice.len() > self.pos {
Some(unsafe { *self.slice.get_unchecked(self.pos) })
} else {
None
}
}
pub fn bump(&mut self) {
self.pos += 1;
}
#[inline]
pub fn len(&self) -> usize {
self.slice.len()
}
#[inline]
pub fn slice(&mut self) -> &'a [u8] {
self.slice_skip(0)
}
#[inline]
pub fn slice_skip(&mut self, skip: usize) -> &'a [u8] {
debug_assert!(self.pos >= skip);
let head_pos = self.pos - skip;
unsafe {
let ptr = self.slice.as_ptr();
let head = slice::from_raw_parts(ptr, head_pos);
let tail = slice::from_raw_parts(ptr.offset(self.pos as isize), self.slice.len() - self.pos);
self.pos = 0;
self.slice = tail;
head
}
}
#[inline]
pub fn next_8<'b>(&'b mut self) -> Option<Bytes8<'b, 'a>> {
if self.slice.len() > self.pos + 8 {
Some(Bytes8 { bytes: self, pos: 0 })
} else {
None
}
}
}
impl<'a> Iterator for Bytes<'a> {
type Item = u8;
#[inline]
fn next(&mut self) -> Option<u8> {
if self.slice.len() > self.pos {
let b = unsafe { *self.slice.get_unchecked(self.pos) };
self.pos += 1;
Some(b)
} else {
None
}
}
}
pub struct Bytes8<'a, 'b: 'a> {
bytes: &'a mut Bytes<'b>,
pos: usize
}
macro_rules! bytes8_methods {
($f:ident, $pos:expr) => {
#[inline]
pub fn $f(&mut self) -> u8 {
debug_assert!(self.assert_pos($pos));
let b = unsafe { *self.bytes.slice.get_unchecked(self.bytes.pos) };
self.bytes.pos += 1;
b
}
};
() => {
bytes8_methods!(_0, 0);
bytes8_methods!(_1, 1);
bytes8_methods!(_2, 2);
bytes8_methods!(_3, 3);
bytes8_methods!(_4, 4);
bytes8_methods!(_5, 5);
bytes8_methods!(_6, 6);
bytes8_methods!(_7, 7);
}
}
impl<'a, 'b: 'a> Bytes8<'a, 'b> {
bytes8_methods! {}
fn assert_pos(&mut self, pos: usize) -> bool {
let ret = self.pos == pos;
self.pos += 1;
ret
}
}