use std::fmt::Debug;
pub struct Reader<'a> {
buf: &'a [u8],
offs: usize
}
impl<'a> Reader<'a> {
pub fn init(bytes: &[u8]) -> Reader {
Reader { buf: bytes, offs: 0 }
}
pub fn rest(&self) -> &[u8] {
&self.buf[self.offs ..]
}
pub fn take(&mut self, len: usize) -> Option<&[u8]> {
if self.left() < len {
return None
}
let current = self.offs;
self.offs += len;
Some(&self.buf[current .. current + len])
}
pub fn any_left(&self) -> bool {
self.offs < self.buf.len()
}
pub fn left(&self) -> usize {
self.buf.len() - self.offs
}
pub fn used(&self) -> usize {
self.offs
}
pub fn sub(&mut self, len: usize) -> Option<Reader> {
self.take(len).and_then(|bytes| Some(Reader::init(bytes)))
}
}
pub trait Codec : Debug + Sized {
fn encode(&self, bytes: &mut Vec<u8>);
fn read(&mut Reader) -> Option<Self>;
}
pub fn encode_u8(v: u8, bytes: &mut Vec<u8>) {
bytes.push(v);
}
pub fn decode_u8(bytes: &[u8]) -> Option<u8> {
Some(bytes[0])
}
pub fn read_u8(r: &mut Reader) -> Option<u8> {
r.take(1).and_then(decode_u8)
}
pub fn encode_u16(v: u16, bytes: &mut Vec<u8>) {
bytes.push((v >> 8) as u8);
bytes.push(v as u8);
}
pub fn decode_u16(bytes: &[u8]) -> Option<u16> {
Some(((bytes[0] as u16) << 8) | bytes[1] as u16)
}
pub fn read_u16(r: &mut Reader) -> Option<u16> {
r.take(2).and_then(decode_u16)
}
pub fn encode_u24(v: u32, bytes: &mut Vec<u8>) {
bytes.push((v >> 16) as u8);
bytes.push((v >> 8) as u8);
bytes.push(v as u8);
}
pub fn decode_u24(bytes: &[u8]) -> Option<u32> {
Some(((bytes[0] as u32) << 16) | ((bytes[1] as u32) << 8) | bytes[2] as u32)
}
pub fn read_u24(r: &mut Reader) -> Option<u32> {
r.take(3).and_then(decode_u24)
}
pub fn encode_u32(v: u32, bytes: &mut Vec<u8>) {
bytes.push((v >> 24) as u8);
bytes.push((v >> 16) as u8);
bytes.push((v >> 8) as u8);
bytes.push(v as u8);
}
pub fn decode_u32(bytes: &[u8]) -> Option<u32> {
Some(
((bytes[0] as u32) << 24) |
((bytes[1] as u32) << 16) |
((bytes[2] as u32) << 8) |
bytes[3] as u32
)
}
pub fn read_u32(r: &mut Reader) -> Option<u32> {
r.take(4).and_then(decode_u32)
}
pub fn encode_u64(v: u64, bytes: &mut Vec<u8>) {
let mut b64 = [0u8; 8];
put_u64(v, &mut b64);
bytes.extend_from_slice(&b64);
}
pub fn put_u64(v: u64, bytes: &mut [u8]) {
bytes[0] = (v >> 56) as u8;
bytes[1] = (v >> 48) as u8;
bytes[2] = (v >> 40) as u8;
bytes[3] = (v >> 32) as u8;
bytes[4] = (v >> 24) as u8;
bytes[5] = (v >> 16) as u8;
bytes[6] = (v >> 8) as u8;
bytes[7] = v as u8;
}
pub fn encode_vec_u8<T: Codec>(bytes: &mut Vec<u8>, items: &Vec<T>) {
let mut sub: Vec<u8> = Vec::new();
for i in items {
i.encode(&mut sub);
}
assert!(sub.len() <= 0xff);
encode_u8(sub.len() as u8, bytes);
bytes.append(&mut sub);
}
pub fn encode_vec_u16<T: Codec>(bytes: &mut Vec<u8>, items: &Vec<T>) {
let mut sub: Vec<u8> = Vec::new();
for i in items {
i.encode(&mut sub);
}
assert!(sub.len() <= 0xffff);
encode_u16(sub.len() as u16, bytes);
bytes.append(&mut sub);
}
pub fn encode_vec_u24<T: Codec>(bytes: &mut Vec<u8>, items: &Vec<T>) {
let mut sub: Vec<u8> = Vec::new();
for i in items {
i.encode(&mut sub);
}
assert!(sub.len() <= 0xffffff);
encode_u24(sub.len() as u32, bytes);
bytes.append(&mut sub);
}
pub fn read_vec_u8<T: Codec>(r: &mut Reader) -> Option<Vec<T>> {
let mut ret: Vec<T> = Vec::new();
let len = try_ret!(read_u8(r)) as usize;
let mut sub = try_ret!(r.sub(len));
while sub.any_left() {
ret.push(try_ret!(T::read(&mut sub)));
}
Some(ret)
}
pub fn read_vec_u16<T: Codec>(r: &mut Reader) -> Option<Vec<T>> {
let mut ret: Vec<T> = Vec::new();
let len = try_ret!(read_u16(r)) as usize;
let mut sub = try_ret!(r.sub(len));
while sub.any_left() {
ret.push(try_ret!(T::read(&mut sub)));
}
Some(ret)
}
pub fn read_vec_u24<T: Codec>(r: &mut Reader) -> Option<Vec<T>> {
let mut ret: Vec<T> = Vec::new();
let len = try_ret!(read_u24(r)) as usize;
let mut sub = try_ret!(r.sub(len));
while sub.any_left() {
ret.push(try_ret!(T::read(&mut sub)));
}
Some(ret)
}