add zstd stream stubs

Author: fairingrey

Cargo.toml

@@ -11,6 +11,7 @@ bytes = "0.4.12"
 flate2 = "1.0.7"
 futures-preview = "0.3.0-alpha.15"
 pin-project = "0.3.2"
+zstd = "0.4"
 
 [dev-dependencies]
 proptest = "0.9.3"

src/stream/mod.rs

@@ -4,3 +4,4 @@ pub mod brotli;
 pub mod deflate;
 pub mod gzip;
 pub mod zlib;
+pub mod zstd;

src/stream/zstd.rs

@@ -0,0 +1,55 @@
+use std::{
+    io::Result,
+    mem,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
+use bytes::{Bytes, BytesMut};
+use futures::{ready, stream::Stream};
+use pin_project::unsafe_project;
+use zstd::stream::raw::{Decoder, Encoder, Operation, Status};
+
+#[derive(Debug)]
+enum State {
+    Reading,
+    Writing(Bytes),
+    Flushing,
+    Done,
+    Invalid,
+}
+
+#[unsafe_project(Unpin)]
+pub struct ZstdStream<S: Stream<Item = Result<Bytes>>> {
+    #[pin]
+    inner: S,
+    state: State,
+    output: BytesMut,
+    encoder: Encoder,
+}
+
+impl<S: Stream<Item = Result<Bytes>>> Stream for ZstdStream<S> {
+    type Item = Result<Bytes>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>> {
+        unimplemented!()
+    }
+}
+
+
+#[unsafe_project(Unpin)]
+pub struct DecompressedZstdStream<S: Stream<Item = Result<Bytes>>> {
+    #[pin]
+    inner: S,
+    state: State,
+    output: BytesMut,
+    decoder: Decoder,
+}
+
+impl<S: Stream<Item = Result<Bytes>>> Stream for DecompressedZstdStream<S> {
+    type Item = Result<Bytes>;
+
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Result<Bytes>>> {
+        unimplemented!()
+    }
+}