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use std::io::{Read, Seek, SeekFrom};
use crate::Result;
pub trait Tape: Read + Seek + Sized {
#[inline]
fn take<T: Value>(&mut self) -> Result<T> {
Value::read(self)
}
#[inline]
fn take_given<T: Walue>(&mut self, parameter: T::Parameter) -> Result<T> {
Walue::read(self, parameter)
}
#[doc(hidden)]
#[inline]
fn jump(&mut self, position: u64) -> Result<u64> {
self.seek(SeekFrom::Start(position))
}
#[doc(hidden)]
fn peek<T: Value>(&mut self) -> Result<T> {
let current = self.position()?;
let result = Value::read(self);
self.jump(current)?;
result
}
#[doc(hidden)]
#[inline]
fn position(&mut self) -> Result<u64> {
self.seek(SeekFrom::Current(0))
}
}
pub trait Value: Sized {
fn read<T: Tape>(tape: &mut T) -> Result<Self>;
}
pub trait Walue: Sized {
type Parameter;
fn read<T: Tape>(tape: &mut T, parameter: Self::Parameter) -> Result<Self>;
}
impl<T: Read + Seek> Tape for T {}
macro_rules! read(
($tape:ident, $size:expr) => (unsafe {
let mut buffer: [u8; $size] = ::std::mem::zeroed();
::std::io::Read::read_exact($tape, &mut buffer)?;
::std::mem::transmute(buffer)
});
);
macro_rules! value {
([$kind:ident; $count:expr], 1) => {
impl Value for [$kind; $count] {
#[inline]
fn read<T: Tape>(tape: &mut T) -> Result<Self> {
Ok(read!(tape, $count))
}
}
};
($kind:ident, 1) => {
impl Value for $kind {
#[inline]
fn read<T: Tape>(tape: &mut T) -> Result<Self> {
Ok(read!(tape, 1))
}
}
};
($kind:ident, $size:expr) => {
impl Value for $kind {
#[inline]
fn read<T: Tape>(tape: &mut T) -> Result<Self> {
Ok($kind::from_be(read!(tape, $size)))
}
}
};
}
value!(u8, 1);
value!(u16, 2);
value!(u32, 4);
value!([u8; 3], 1);
macro_rules! walue {
($kind:ty, 1) => {
impl Walue for $kind {
type Parameter = usize;
fn read<T: Tape>(tape: &mut T, count: usize) -> Result<Self> {
let mut buffer = vec![0; count];
::std::io::Read::read_exact(tape, &mut buffer)?;
Ok(buffer)
}
}
};
}
walue!(Vec<u8>, 1);