ntex/ntex-bytes/src/buf/buf_impl.rs
2021-06-26 08:38:55 +06:00

939 lines
25 KiB
Rust

use std::{cmp, io::IoSlice, mem, ptr};
macro_rules! buf_get_impl {
($this:ident, $typ:tt::$conv:tt) => {{
const SIZE: usize = mem::size_of::<$typ>();
// try to convert directly from the bytes
// this Option<ret> trick is to avoid keeping a borrow on self
// when advance() is called (mut borrow) and to call bytes() only once
let ret = $this
.chunk()
.get(..SIZE)
.map(|src| unsafe { $typ::$conv(*(src as *const _ as *const [_; SIZE])) });
if let Some(ret) = ret {
// if the direct conversion was possible, advance and return
$this.advance(SIZE);
return ret;
} else {
// if not we copy the bytes in a temp buffer then convert
let mut buf = [0; SIZE];
$this.copy_to_slice(&mut buf); // (do the advance)
return $typ::$conv(buf);
}
}};
(le => $this:ident, $typ:tt, $len_to_read:expr) => {{
debug_assert!(mem::size_of::<$typ>() >= $len_to_read);
// The same trick as above does not improve the best case speed.
// It seems to be linked to the way the method is optimised by the compiler
let mut buf = [0; (mem::size_of::<$typ>())];
$this.copy_to_slice(&mut buf[..($len_to_read)]);
return $typ::from_le_bytes(buf);
}};
(be => $this:ident, $typ:tt, $len_to_read:expr) => {{
debug_assert!(mem::size_of::<$typ>() >= $len_to_read);
let mut buf = [0; (mem::size_of::<$typ>())];
$this.copy_to_slice(&mut buf[mem::size_of::<$typ>() - ($len_to_read)..]);
return $typ::from_be_bytes(buf);
}};
}
/// Read bytes from a buffer.
///
/// A buffer stores bytes in memory such that read operations are infallible.
/// The underlying storage may or may not be in contiguous memory. A `Buf` value
/// is a cursor into the buffer. Reading from `Buf` advances the cursor
/// position. It can be thought of as an efficient `Iterator` for collections of
/// bytes.
///
/// The simplest `Buf` is a `&[u8]`.
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"hello world"[..];
///
/// assert_eq!(b'h', buf.get_u8());
/// assert_eq!(b'e', buf.get_u8());
/// assert_eq!(b'l', buf.get_u8());
///
/// let mut rest = [0; 8];
/// buf.copy_to_slice(&mut rest);
///
/// assert_eq!(&rest[..], &b"lo world"[..]);
/// ```
pub trait Buf {
/// Returns the number of bytes between the current position and the end of
/// the buffer.
///
/// This value is greater than or equal to the length of the slice returned
/// by `bytes`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"hello world"[..];
///
/// assert_eq!(buf.remaining(), 11);
///
/// buf.get_u8();
///
/// assert_eq!(buf.remaining(), 10);
/// ```
///
/// # Implementer notes
///
/// Implementations of `remaining` should ensure that the return value does
/// not change unless a call is made to `advance` or any other function that
/// is documented to change the `Buf`'s current position.
fn remaining(&self) -> usize;
/// Returns a slice starting at the current position and of length between 0
/// and `Buf::remaining()`. Note that this *can* return shorter slice (this allows
/// non-continuous internal representation).
///
/// This is a lower level function. Most operations are done with other
/// functions.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"hello world"[..];
///
/// assert_eq!(buf.chunk(), &b"hello world"[..]);
///
/// buf.advance(6);
///
/// assert_eq!(buf.chunk(), &b"world"[..]);
/// ```
///
/// # Implementer notes
///
/// This function should never panic. Once the end of the buffer is reached,
/// i.e., `Buf::remaining` returns 0, calls to `chunk` should return an
/// empty slice.
fn chunk(&self) -> &[u8];
/// Fills `dst` with potentially multiple slices starting at `self`'s
/// current position.
///
/// If the `Buf` is backed by disjoint slices of bytes, `bytes_vectored` enables
/// fetching more than one slice at once. `dst` is a slice of `IoSlice`
/// references, enabling the slice to be directly used with [`writev`]
/// without any further conversion. The sum of the lengths of all the
/// buffers in `dst` will be less than or equal to `Buf::remaining()`.
///
/// The entries in `dst` will be overwritten, but the data **contained** by
/// the slices **will not** be modified. If `bytes_vectored` does not fill every
/// entry in `dst`, then `dst` is guaranteed to contain all remaining slices
/// in `self.
///
/// This is a lower level function. Most operations are done with other
/// functions.
///
/// # Implementer notes
///
/// This function should never panic. Once the end of the buffer is reached,
/// i.e., `Buf::remaining` returns 0, calls to `bytes_vectored` must return 0
/// without mutating `dst`.
///
/// Implementations should also take care to properly handle being called
/// with `dst` being a zero length slice.
///
/// [`writev`]: http://man7.org/linux/man-pages/man2/readv.2.html
fn bytes_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize {
if dst.is_empty() {
return 0;
}
if self.has_remaining() {
dst[0] = IoSlice::new(self.chunk());
1
} else {
0
}
}
/// Advance the internal cursor of the Buf
///
/// The next call to `bytes` will return a slice starting `cnt` bytes
/// further into the underlying buffer.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"hello world"[..];
///
/// assert_eq!(buf.chunk(), &b"hello world"[..]);
///
/// buf.advance(6);
///
/// assert_eq!(buf.chunk(), &b"world"[..]);
/// ```
///
/// # Panics
///
/// This function **may** panic if `cnt > self.remaining()`.
///
/// # Implementer notes
///
/// It is recommended for implementations of `advance` to panic if `cnt >
/// self.remaining()`. If the implementation does not panic, the call must
/// behave as if `cnt == self.remaining()`.
///
/// A call with `cnt == 0` should never panic and be a no-op.
fn advance(&mut self, cnt: usize);
/// Returns true if there are any more bytes to consume
///
/// This is equivalent to `self.remaining() != 0`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"a"[..];
///
/// assert!(buf.has_remaining());
///
/// buf.get_u8();
///
/// assert!(!buf.has_remaining());
/// ```
fn has_remaining(&self) -> bool {
self.remaining() > 0
}
/// Copies bytes from `self` into `dst`.
///
/// The cursor is advanced by the number of bytes copied. `self` must have
/// enough remaining bytes to fill `dst`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"hello world"[..];
/// let mut dst = [0; 5];
///
/// buf.copy_to_slice(&mut dst);
/// assert_eq!(&b"hello"[..], &dst);
/// assert_eq!(6, buf.remaining());
/// ```
///
/// # Panics
///
/// This function panics if `self.remaining() < dst.len()`
fn copy_to_slice(&mut self, dst: &mut [u8]) {
let mut off = 0;
assert!(self.remaining() >= dst.len());
while off < dst.len() {
let cnt;
unsafe {
let src = self.chunk();
cnt = cmp::min(src.len(), dst.len() - off);
ptr::copy_nonoverlapping(src.as_ptr(), dst[off..].as_mut_ptr(), cnt);
off += cnt;
}
self.advance(cnt);
}
}
/// Gets an unsigned 8 bit integer from `self`.
///
/// The current position is advanced by 1.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08 hello"[..];
/// assert_eq!(8, buf.get_u8());
/// ```
///
/// # Panics
///
/// This function panics if there is no more remaining data in `self`.
fn get_u8(&mut self) -> u8 {
assert!(self.remaining() >= 1);
let ret = self.chunk()[0];
self.advance(1);
ret
}
/// Gets a signed 8 bit integer from `self`.
///
/// The current position is advanced by 1.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08 hello"[..];
/// assert_eq!(8, buf.get_i8());
/// ```
///
/// # Panics
///
/// This function panics if there is no more remaining data in `self`.
fn get_i8(&mut self) -> i8 {
assert!(self.remaining() >= 1);
let ret = self.chunk()[0] as i8;
self.advance(1);
ret
}
/// Gets an unsigned 16 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 2.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x09 hello"[..];
/// assert_eq!(0x0809, buf.get_u16());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u16(&mut self) -> u16 {
buf_get_impl!(self, u16::from_be_bytes);
}
/// Gets an unsigned 16 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 2.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x09\x08 hello"[..];
/// assert_eq!(0x0809, buf.get_u16_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u16_le(&mut self) -> u16 {
buf_get_impl!(self, u16::from_le_bytes);
}
/// Gets a signed 16 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 2.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x09 hello"[..];
/// assert_eq!(0x0809, buf.get_i16());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i16(&mut self) -> i16 {
buf_get_impl!(self, i16::from_be_bytes);
}
/// Gets a signed 16 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 2.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x09\x08 hello"[..];
/// assert_eq!(0x0809, buf.get_i16_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i16_le(&mut self) -> i16 {
buf_get_impl!(self, i16::from_le_bytes);
}
/// Gets an unsigned 32 bit integer from `self` in the big-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x09\xA0\xA1 hello"[..];
/// assert_eq!(0x0809A0A1, buf.get_u32());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u32(&mut self) -> u32 {
buf_get_impl!(self, u32::from_be_bytes);
}
/// Gets an unsigned 32 bit integer from `self` in the little-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\xA1\xA0\x09\x08 hello"[..];
/// assert_eq!(0x0809A0A1, buf.get_u32_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u32_le(&mut self) -> u32 {
buf_get_impl!(self, u32::from_le_bytes);
}
/// Gets a signed 32 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x09\xA0\xA1 hello"[..];
/// assert_eq!(0x0809A0A1, buf.get_i32());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i32(&mut self) -> i32 {
buf_get_impl!(self, i32::from_be_bytes);
}
/// Gets a signed 32 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\xA1\xA0\x09\x08 hello"[..];
/// assert_eq!(0x0809A0A1, buf.get_i32_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i32_le(&mut self) -> i32 {
buf_get_impl!(self, i32::from_le_bytes);
}
/// Gets an unsigned 64 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"[..];
/// assert_eq!(0x0102030405060708, buf.get_u64());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u64(&mut self) -> u64 {
buf_get_impl!(self, u64::from_be_bytes);
}
/// Gets an unsigned 64 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
/// assert_eq!(0x0102030405060708, buf.get_u64_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u64_le(&mut self) -> u64 {
buf_get_impl!(self, u64::from_le_bytes);
}
/// Gets a signed 64 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08 hello"[..];
/// assert_eq!(0x0102030405060708, buf.get_i64());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i64(&mut self) -> i64 {
buf_get_impl!(self, i64::from_be_bytes);
}
/// Gets a signed 64 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
/// assert_eq!(0x0102030405060708, buf.get_i64_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i64_le(&mut self) -> i64 {
buf_get_impl!(self, i64::from_le_bytes);
}
/// Gets an unsigned 128 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 16.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16 hello"[..];
/// assert_eq!(0x01020304050607080910111213141516, buf.get_u128());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u128(&mut self) -> u128 {
buf_get_impl!(self, u128::from_be_bytes);
}
/// Gets an unsigned 128 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 16.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x16\x15\x14\x13\x12\x11\x10\x09\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
/// assert_eq!(0x01020304050607080910111213141516, buf.get_u128_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_u128_le(&mut self) -> u128 {
buf_get_impl!(self, u128::from_le_bytes);
}
/// Gets a signed 128 bit integer from `self` in big-endian byte order.
///
/// The current position is advanced by 16.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03\x04\x05\x06\x07\x08\x09\x10\x11\x12\x13\x14\x15\x16 hello"[..];
/// assert_eq!(0x01020304050607080910111213141516, buf.get_i128());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i128(&mut self) -> i128 {
buf_get_impl!(self, i128::from_be_bytes);
}
/// Gets a signed 128 bit integer from `self` in little-endian byte order.
///
/// The current position is advanced by 16.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x16\x15\x14\x13\x12\x11\x10\x09\x08\x07\x06\x05\x04\x03\x02\x01 hello"[..];
/// assert_eq!(0x01020304050607080910111213141516, buf.get_i128_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_i128_le(&mut self) -> i128 {
buf_get_impl!(self, i128::from_le_bytes);
}
/// Gets an unsigned n-byte integer from `self` in big-endian byte order.
///
/// The current position is advanced by `nbytes`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03 hello"[..];
/// assert_eq!(0x010203, buf.get_uint(3));
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_uint(&mut self, nbytes: usize) -> u64 {
buf_get_impl!(be => self, u64, nbytes);
}
/// Gets an unsigned n-byte integer from `self` in little-endian byte order.
///
/// The current position is advanced by `nbytes`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x03\x02\x01 hello"[..];
/// assert_eq!(0x010203, buf.get_uint_le(3));
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_uint_le(&mut self, nbytes: usize) -> u64 {
buf_get_impl!(le => self, u64, nbytes);
}
/// Gets a signed n-byte integer from `self` in big-endian byte order.
///
/// The current position is advanced by `nbytes`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x01\x02\x03 hello"[..];
/// assert_eq!(0x010203, buf.get_int(3));
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_int(&mut self, nbytes: usize) -> i64 {
buf_get_impl!(be => self, i64, nbytes);
}
/// Gets a signed n-byte integer from `self` in little-endian byte order.
///
/// The current position is advanced by `nbytes`.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x03\x02\x01 hello"[..];
/// assert_eq!(0x010203, buf.get_int_le(3));
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_int_le(&mut self, nbytes: usize) -> i64 {
buf_get_impl!(le => self, i64, nbytes);
}
/// Gets an IEEE754 single-precision (4 bytes) floating point number from
/// `self` in big-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x3F\x99\x99\x9A hello"[..];
/// assert_eq!(1.2f32, buf.get_f32());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_f32(&mut self) -> f32 {
f32::from_bits(Self::get_u32(self))
}
/// Gets an IEEE754 single-precision (4 bytes) floating point number from
/// `self` in little-endian byte order.
///
/// The current position is advanced by 4.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x9A\x99\x99\x3F hello"[..];
/// assert_eq!(1.2f32, buf.get_f32_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_f32_le(&mut self) -> f32 {
f32::from_bits(Self::get_u32_le(self))
}
/// Gets an IEEE754 double-precision (8 bytes) floating point number from
/// `self` in big-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x3F\xF3\x33\x33\x33\x33\x33\x33 hello"[..];
/// assert_eq!(1.2f64, buf.get_f64());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_f64(&mut self) -> f64 {
f64::from_bits(Self::get_u64(self))
}
/// Gets an IEEE754 double-precision (8 bytes) floating point number from
/// `self` in little-endian byte order.
///
/// The current position is advanced by 8.
///
/// # Examples
///
/// ```
/// use ntex_bytes::Buf;
///
/// let mut buf = &b"\x33\x33\x33\x33\x33\x33\xF3\x3F hello"[..];
/// assert_eq!(1.2f64, buf.get_f64_le());
/// ```
///
/// # Panics
///
/// This function panics if there is not enough remaining data in `self`.
fn get_f64_le(&mut self) -> f64 {
f64::from_bits(Self::get_u64_le(self))
}
/// Consumes remaining bytes inside self and returns new instance of `Bytes`
///
/// # Examples
///
/// ```
/// use ntex_bytes::{Buf};
///
/// let bytes = "hello world".to_bytes();
/// assert_eq!(&bytes[..], &b"hello world"[..]);
/// ```
fn to_bytes(&mut self) -> crate::Bytes {
use super::BufMut;
let mut ret = crate::BytesMut::with_capacity(self.remaining());
ret.put(self);
ret.freeze()
}
}
impl<T: Buf + ?Sized> Buf for &mut T {
fn remaining(&self) -> usize {
(**self).remaining()
}
fn chunk(&self) -> &[u8] {
(**self).chunk()
}
fn bytes_vectored<'b>(&'b self, dst: &mut [IoSlice<'b>]) -> usize {
(**self).bytes_vectored(dst)
}
fn advance(&mut self, cnt: usize) {
(**self).advance(cnt)
}
}
impl<T: Buf + ?Sized> Buf for Box<T> {
fn remaining(&self) -> usize {
(**self).remaining()
}
fn chunk(&self) -> &[u8] {
(**self).chunk()
}
fn bytes_vectored<'b>(&'b self, dst: &mut [IoSlice<'b>]) -> usize {
(**self).bytes_vectored(dst)
}
fn advance(&mut self, cnt: usize) {
(**self).advance(cnt)
}
}
impl Buf for &[u8] {
#[inline]
fn remaining(&self) -> usize {
self.len()
}
#[inline]
fn chunk(&self) -> &[u8] {
self
}
#[inline]
fn advance(&mut self, cnt: usize) {
*self = &self[cnt..];
}
}
impl Buf for &str {
#[inline]
fn remaining(&self) -> usize {
self.len()
}
#[inline]
fn chunk(&self) -> &[u8] {
self.as_bytes()
}
#[inline]
fn advance(&mut self, cnt: usize) {
*self = &self[cnt..];
}
}
impl Buf for Option<[u8; 1]> {
fn remaining(&self) -> usize {
if self.is_some() {
1
} else {
0
}
}
fn chunk(&self) -> &[u8] {
self.as_ref()
.map(AsRef::as_ref)
.unwrap_or(Default::default())
}
fn advance(&mut self, cnt: usize) {
if cnt == 0 {
return;
}
if self.is_none() {
panic!("overflow");
} else {
assert_eq!(1, cnt);
*self = None;
}
}
}
impl<T: AsRef<[u8]>> Buf for std::io::Cursor<T> {
fn remaining(&self) -> usize {
let len = self.get_ref().as_ref().len();
let pos = self.position();
if pos >= len as u64 {
return 0;
}
len - pos as usize
}
fn chunk(&self) -> &[u8] {
let len = self.get_ref().as_ref().len();
let pos = self.position();
if pos >= len as u64 {
return &[];
}
&self.get_ref().as_ref()[pos as usize..]
}
fn advance(&mut self, cnt: usize) {
let pos = (self.position() as usize)
.checked_add(cnt)
.expect("overflow");
assert!(pos <= self.get_ref().as_ref().len());
self.set_position(pos as u64);
}
}
// The existence of this function makes the compiler catch if the Buf
// trait is "object-safe" or not.
fn _assert_trait_object(_b: &dyn Buf) {}