refactor(body): separate body, payload, and chunk into their own internal mods

src/body/payload.rs

@@ -0,0 +1,97 @@
+use bytes::Buf;
+use futures::{Async, Poll};
+use http::HeaderMap;
+
+use super::internal::{FullDataArg, FullDataRet};
+
+/// This trait represents a streaming body of a `Request` or `Response`.
+///
+/// The built-in implementation of this trait is [`Body`](Body), in case you
+/// don't need to customize a send stream for your own application.
+pub trait Payload: Send + 'static {
+    /// A buffer of bytes representing a single chunk of a body.
+    type Data: Buf + Send;
+
+    /// The error type of this stream.
+    type Error: Into<Box<::std::error::Error + Send + Sync>>;
+
+    /// Poll for a `Data` buffer.
+    ///
+    /// Similar to `Stream::poll_next`, this yields `Some(Data)` until
+    /// the body ends, when it yields `None`.
+    fn poll_data(&mut self) -> Poll<Option<Self::Data>, Self::Error>;
+
+    /// Poll for an optional **single** `HeaderMap` of trailers.
+    ///
+    /// This should **only** be called after `poll_data` has ended.
+    ///
+    /// Note: Trailers aren't currently used for HTTP/1, only for HTTP/2.
+    fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, Self::Error> {
+        Ok(Async::Ready(None))
+    }
+
+    /// A hint that the `Body` is complete, and doesn't need to be polled more.
+    ///
+    /// This can be useful to determine if the there is any body or trailers
+    /// without having to poll. An empty `Body` could return `true` and hyper
+    /// would be able to know that only the headers need to be sent. Or, it can
+    /// also be checked after each `poll_data` call, to allow hyper to try to
+    /// end the underlying stream with the last chunk, instead of needing to
+    /// send an extra `DATA` frame just to mark the stream as finished.
+    ///
+    /// As a hint, it is used to try to optimize, and thus is OK for a default
+    /// implementation to return `false`.
+    fn is_end_stream(&self) -> bool {
+        false
+    }
+
+    /// Return a length of the total bytes that will be streamed, if known.
+    ///
+    /// If an exact size of bytes is known, this would allow hyper to send a
+    /// `Content-Length` header automatically, not needing to fall back to
+    /// `Transfer-Encoding: chunked`.
+    ///
+    /// This does not need to be kept updated after polls, it will only be
+    /// called once to create the headers.
+    fn content_length(&self) -> Option<u64> {
+        None
+    }
+
+    // This API is unstable, and is impossible to use outside of hyper. Some
+    // form of it may become stable in a later version.
+    //
+    // The only thing a user *could* do is reference the method, but DON'T
+    // DO THAT! :)
+    #[doc(hidden)]
+    fn __hyper_full_data(&mut self, FullDataArg) -> FullDataRet<Self::Data> {
+        FullDataRet(None)
+    }
+}
+
+impl<E: Payload> Payload for Box<E> {
+    type Data = E::Data;
+    type Error = E::Error;
+
+    fn poll_data(&mut self) -> Poll<Option<Self::Data>, Self::Error> {
+        (**self).poll_data()
+    }
+
+    fn poll_trailers(&mut self) -> Poll<Option<HeaderMap>, Self::Error> {
+        (**self).poll_trailers()
+    }
+
+    fn is_end_stream(&self) -> bool {
+        (**self).is_end_stream()
+    }
+
+    fn content_length(&self) -> Option<u64> {
+        (**self).content_length()
+    }
+
+    #[doc(hidden)]
+    fn __hyper_full_data(&mut self, arg: FullDataArg) -> FullDataRet<Self::Data> {
+        (**self).__hyper_full_data(arg)
+    }
+}
+
+