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extern crate int;
use int::UInt;
pub trait Write {
fn write<V: UInt>(&mut self, v: V) -> std::io::Result<()>;
}
/// Write the given unsigned integer in the LEB128+ format to `std::io::Write` stream.
///
/// ## Examples
///
/// ```
/// let f = || -> std::io::Result<Vec<u8>> {
/// let mut v = vec![];
/// use leb128plus::Write;
/// {
/// let mut c = std::io::Cursor::new(&mut v);
/// c.write(0_u8)?;
/// c.write(127_u16)?;
/// c.write(128_u32)?;
/// c.write(0xFF_u64)?;
/// c.write(0x17F_u128)?;
/// c.write(0x407F_u16)?;
/// c.write(0x4080_u32)?;
/// }
/// Ok(v)
/// };
/// assert_eq!(
/// f().unwrap(),
/// [
/// 0,
/// 127,
/// 128, 0,
/// 0xFF, 0,
/// 0xFF, 1,
/// 0xFF, 0x7F,
/// 0x80, 0x80, 0x00
/// ]
/// );
/// ```
impl<T: std::io::Write> Write for T {
fn write<V: UInt>(&mut self, mut v: V) -> std::io::Result<()> {
loop {
let x = v.as_();
v >>= 7;
if v == V::_0 {
self.write(&[x])?;
break Ok(());
}
self.write(&[0x80 | x])?;
v -= V::_1;
}
}
}
pub trait Read {
fn read<V: UInt>(&mut self) -> std::io::Result<V>;
}
/// Read an unsigned integer in the LEB128+ format from `std::io::Read` stream.
///
/// ## Example
///
/// ```
/// let mut c = std::io::Cursor::new(&[
/// 0,
/// 127,
/// 128, 0,
/// 0xFF, 0,
/// 0xFF, 1,
/// 0xFF, 0x7F,
/// 0x80, 0x80, 0,
/// 128,
/// ]);
/// use leb128plus::Read;
/// assert_eq!(c.read::<u8>().unwrap(), 0);
/// assert_eq!(c.read::<u16>().unwrap(), 127);
/// assert_eq!(c.read::<u32>().unwrap(), 128);
/// assert_eq!(c.read::<u64>().unwrap(), 0xFF);
/// assert_eq!(c.read::<u128>().unwrap(), 0x17F);
/// assert_eq!(c.read::<u16>().unwrap(), 0x407F);
/// assert_eq!(c.read::<u32>().unwrap(), 0x4080);
/// assert!(match c.read::<u64>() {
/// Result::Err(_) => true,
/// _ => false
/// });
/// ```
impl<T: std::io::Read> Read for T {
fn read<V: UInt>(&mut self) -> std::io::Result<V> {
let mut result = V::_0;
let mut shift = 0_u8;
loop {
let x = {
let mut buf = [0];
self.read_exact(&mut buf)?;
buf[0]
};
result += V::from_u8(x) << shift;
if x < 128 {
break Ok(result);
}
shift += 7;
}
}
}