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// Copyright 2024 Gabriel Bjørnager Jensen.
//
// This file is part of bzipper.
//
// bzipper is free software: you can redistribute
// it and/or modify it under the terms of the GNU
// Lesser General Public License as published by
// the Free Software Foundation, either version 3
// of the License, or (at your option) any later
// version.
//
// bzipper is distributed in the hope that it will
// be useful, but WITHOUT ANY WARRANTY; without
// even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Less-
// er General Public License along with bzipper. If
// not, see <https://www.gnu.org/licenses/>.
#[cfg(test)]
mod test;
use crate::{DStream, Error};
use std::convert::Infallible;
use std::error::Error as StdError;
use std::mem::size_of;
use std::num::NonZero;
/// Denotes a type capable of being deserialised.
pub trait Deserialise: Sized {
type Error;
/// Deserialises the byte stream to an object.
///
/// # Errors
///
/// If deserialisation failed, e.g. by an invalid value being found, an error is returned.
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error>;
}
macro_rules! impl_float {
($type:ty) => {
impl Deserialise for $type {
type Error = Error;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let data = stream
.take(size_of::<Self>())?
.try_into()
.unwrap();
Ok(Self::from_be_bytes(data))
}
}
};
}
macro_rules! impl_int {
($type:ty) => {
impl Deserialise for $type {
type Error = Error;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let data = stream
.take(size_of::<Self>())?
.try_into()
.unwrap();
Ok(Self::from_be_bytes(data))
}
}
impl Deserialise for NonZero<$type> {
type Error = Error;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let value = <$type>::deserialise(stream)?;
NonZero::new(value)
.ok_or(Error::NullInteger)
}
}
};
}
impl<T: Deserialise<Error: StdError + 'static>, const N: usize> Deserialise for [T; N] {
type Error = Box<dyn StdError>;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let len = usize::try_from(u64::deserialise(stream)?).unwrap();
if len != N { return Err(Box::new(Error::ArrayLengthMismatch { len, ok_len: N })) };
let mut buf = Vec::with_capacity(len);
for _ in 0x0..len { buf.push(Deserialise::deserialise(stream)?); }
// If we had used the checked unwrap, we would also
// have to require `T: Debug`.
Ok(unsafe { buf.try_into().unwrap_unchecked() })
}
}
impl Deserialise for () {
type Error = Error;
fn deserialise(_stream: &mut DStream) -> Result<Self, Self::Error> { Ok(()) }
}
impl Deserialise for bool {
type Error = Error;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let value = u8::deserialise(stream)?;
match value {
0x00 => Ok(false),
0x01 => Ok(true),
_ => Err(Error::InvalidBoolean { value })
}
}
}
impl Deserialise for char {
type Error = Error;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let value = u32::deserialise(stream)?;
Self::from_u32(value)
.ok_or(Error::InvalidCodePoint { value })
}
}
impl Deserialise for Infallible {
type Error = Error;
fn deserialise(_stream: &mut DStream) -> Result<Self, Self::Error> { unreachable!() }
}
impl<T: Deserialise<Error: StdError + 'static>> Deserialise for Option<T> {
type Error = Box<dyn StdError>;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let sign = bool::deserialise(stream)?;
if sign {
Ok(Some(T::deserialise(stream)?))
} else {
Ok(None)
}
}
}
impl<T: Deserialise, E: Deserialise> Deserialise for Result<T, E>
where
<T as Deserialise>::Error: StdError + 'static,
<E as Deserialise>::Error: StdError + 'static, {
type Error = Box<dyn StdError>;
fn deserialise(stream: &mut DStream) -> Result<Self, Self::Error> {
let sign = bool::deserialise(stream)?;
let value = if sign {
Err(E::deserialise(stream)?)
} else {
Ok(T::deserialise(stream)?)
};
Ok(value)
}
}
impl_float!(f32);
impl_float!(f64);
impl_int!(i128);
impl_int!(i16);
impl_int!(i32);
impl_int!(i64);
impl_int!(i8);
impl_int!(u128);
impl_int!(u16);
impl_int!(u32);
impl_int!(u64);
impl_int!(u8);
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