1 files changed, 55 insertions, 44 deletions
diff --git a/src/sstream/mod.rs b/src/sstream/mod.rs
index f28875a..83536d0 100644
--- a/src/sstream/mod.rs
+++ b/src/sstream/mod.rs
@@ -19,74 +19,85 @@
 // er General Public License along with bzipper. If
 // not, see <https://www.gnu.org/licenses/>.
 
-use crate::{Dstream, Serialise};
+use crate::{Error, Result};
 
-use std::fmt::{Debug, Formatter};
-use std::mem::size_of;
+use core::fmt::{Debug, Formatter};
 
 /// Byte stream for serialisation.
 ///
-/// The bytes themselves are contained by the type.
-/// The stream may be converted to [`Dstream`] using [`as_dstream`](Sstream::as_dstream)
-#[derive(Clone, Eq, PartialEq)]
-pub struct Sstream(pub(in crate) Vec<u8>);
+/// 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 Sstream {
- /// Constructs a new, empty byte stream.
+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 const fn new() -> Self { Self(Vec::new()) }
+ pub fn new(data: &'a mut [u8]) -> Self { Self { data, len: 0x0 } }
 
 /// Extends the byte stream.
- pub fn append(&mut self, extra: &[u8]) {
- self.0.extend(extra);
+ ///
+ /// # 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.
- pub fn append_byte(&mut self, extra: u8) {
- self.0.push(extra);
+ ///
+ /// # 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])
 }
 
- /// Converts the stream to a `Dstream` object.
+ /// Yields the length of the stream.
 ///
- /// The returned object references the original stream.
+ /// That is, the amount of bytes written so far.
 #[inline(always)]
 #[must_use]
- pub fn as_dstream(&self) -> Dstream { Dstream::new(&self.0) }
-}
+ pub const fn len(&self) -> usize { self.len }
 
-impl AsRef<[u8]> for Sstream {
+ /// Tests if the stream is empty.
 #[inline(always)]
- fn as_ref(&self) -> &[u8] { self.0.as_ref() }
-}
-
-impl Debug for Sstream {
- fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
- write!(f, "[")?;
-
- for v in &self.0 { write!(f, "{v:#02X},")? };
-
- write!(f, "]")?;
+ #[must_use]
+ pub const fn is_empty(&self) -> bool { self.len == 0x0 }
 
- Ok(())
- }
+ /// 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 Default for Sstream {
+impl AsRef<[u8]> for Sstream<'_> {
 #[inline(always)]
- fn default() -> Self { Self::new() }
+ fn as_ref(&self) -> &[u8] { self.as_slice() }
 }
 
-impl<T: Serialise> From<&T> for Sstream {
- fn from(value: &T) -> Self {
- let mut stream = Self(Vec::with_capacity(size_of::<T>()));
- value.serialise(&mut stream);
-
- stream
+impl Debug for Sstream<'_> {
+ fn fmt(&self, f: &mut Formatter) -> core::fmt::Result {
+ self.data.fmt(f)
 }
 }
-
-impl From<Sstream> for Box<[u8]> {
- #[inline(always)]
- fn from(value: Sstream) -> Self { value.0.into_boxed_slice() }
-}