Changed de_singleton_inner() buffer to be generic

Fortune for transfer's current commit: Half curse − 半凶

src/enc.rs

@@ -117,12 +117,15 @@ where F: AsyncRead + Unpin + ?Sized,
     Ok((written, read))
 }
 
-async fn de_singleton_inner<T: DeserializeOwned>(mut from: &[u8], how: &RecvOpt) -> Result<T, TransformErrorKind>
+async fn de_singleton_inner<T: DeserializeOwned, B, F>(buf: F, mut from: &[u8], how: &RecvOpt) -> Result<T, TransformErrorKind>
+where B: AsRef<[u8]> + AsyncWrite + Unpin,
+F: FnOnce(&[u8]) -> B
 {
     // Decompressor
     // The output is written to this (through writer)
     let mut is_spec = false; //TODO: Determine this before allocating `buf`.
-    let mut buf = Vec::with_capacity(from.len()); // The `spec` output buffer. Used if there are transformations that need to be done to the data before deserialisation
+    let mut buf = buf(from);
+    //let mut buf = Vec::with_capacity(from.len()); // The `spec` output buffer. Used if there are transformations that need to be done to the data before deserialisation
     from = {
 	let mut b;
 	let writer: &mut (dyn AsyncWrite + Unpin) =
@@ -147,11 +150,11 @@ async fn de_singleton_inner<T: DeserializeOwned>(mut from: &[u8], how: &RecvOpt)
 		    self::cha_copy::<_, _, DEFAULT_BUFSIZE, true>(&mut &from[..], writer, k, iv).await?;
 		},
 	    }
-	    &buf[..]
+	    &buf.as_ref()[..]
 	} else if is_spec {
 	    // There is decompression to be done through `writer`. Return its output buffer
 	    writer.write_all(from).await?;
-	    &buf[..]
+	    &buf.as_ref()[..]
 	} else {
 	    // There is neither decompression nor decryption to be done, return the input reference itself
 	    from
@@ -207,7 +210,7 @@ where F: FnOnce(&Vec<u8>) -> V
 #[inline(always)] pub fn de_singleton<'a, T: DeserializeOwned + 'a, B: ?Sized + AsRef<[u8]> + 'a>(from: &'a B, how: &'a RecvOpt) -> impl Future<Output = Result<T, RecvError>> + 'a
 {
     use futures::prelude::*;
-    de_singleton_inner(from.as_ref(), how)
+    de_singleton_inner(|from| Vec::with_capacity(from.as_ref().len()), from.as_ref(), how)
 	.map_err(|k| RecvError(Box::new((k, how.clone()))))
 }
 
@@ -277,6 +280,30 @@ pub enum TransformErrorKind
 #[derive(Debug)]
 pub struct RecvError(Box<(TransformErrorKind, RecvOpt)>);
 
+impl error::Error for RecvError
+{
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+	Some(match &self.0.0
+	     {
+		 TransformErrorKind::IO(io) => io,
+		 _ => return None,
+	     })
+    }
+}
+impl fmt::Display for RecvError
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result
+    {
+	write!(f, "error when deserialising object with params {:?}: ", self.0.1)?;
+	match self.0.0 {
+	    TransformErrorKind::Format => write!(f, "failed to deserialise object to data"),
+	    TransformErrorKind::Compress => write!(f, "failed to decompress data"),
+	    TransformErrorKind::Encrypt => write!(f, "failed to decrypt data"),
+	    TransformErrorKind::IO(_) => write!(f, "i/o failure"),
+	}
+    }
+}
+
 
 /// An error when sending / serialising an object.
 #[derive(Debug)]