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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/>.
use crate::{Error, Result};
use core::fmt::{Debug, Formatter};
/// Byte stream for serialisation.
///
/// This type borrows a byte slice (hence [`new`](Sstream::new)), keeping track internally of the used bytes.
#[derive(Eq, PartialEq)]
pub struct Sstream<'a> {
data: &'a mut [u8],
len: usize
}
impl<'a> Sstream<'a> {
/// Constructs a new byte stream.
///
/// If the borrowed slice already contains data, this may overwritten by subsequent serialisations.
#[inline(always)]
#[must_use]
pub fn new(data: &'a mut [u8]) -> Self { Self { data, len: 0x0 } }
/// Extends the byte stream.
///
/// # Errors
///
/// If the stream cannot hold the requested bytes, an [`EndOfStream`](Error::EndOfStream) instance is returned.
pub fn add(&mut self, extra: &[u8]) -> Result<usize> {
let rem = self.data.len() - self.len;
let req = extra.len();
if rem.checked_sub(req).is_none() {
return Err(Error::EndOfStream { req, rem });
}
let start = self.len;
let stop = self.len + req;
self.len += req;
self.data[start..stop].copy_from_slice(extra);
Ok(req)
}
/// Extends the byte stream by a single byte.
///
/// # Errors
///
/// If the stream cannot hold the byte, an [`EndOfStream`](Error::EndOfStream) instance is returned.
pub fn add_byte(&mut self, extra: u8) -> Result<usize> {
self.add(&[extra])
}
/// Yields the length of the stream.
///
/// That is, the amount of bytes written so far.
#[inline(always)]
#[must_use]
pub const fn len(&self) -> usize { self.len }
/// Tests if the stream is empty.
#[inline(always)]
#[must_use]
pub const fn is_empty(&self) -> bool { self.len == 0x0 }
/// Returns a slice to the stream contents.
///
/// This includes all previously written bytes.
#[inline(always)]
#[must_use]
pub fn as_slice(&self) -> &[u8] { &self.data[0x0..self.len] }
}
impl AsRef<[u8]> for Sstream<'_> {
#[inline(always)]
fn as_ref(&self) -> &[u8] { self.as_slice() }
}
impl Debug for Sstream<'_> {
fn fmt(&self, f: &mut Formatter) -> core::fmt::Result {
self.data.fmt(f)
}
}
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