feat(client): add HttpMessage trait

src/lib.rs

@@ -185,6 +185,7 @@ pub mod server;
 pub mod status;
 pub mod uri;
 pub mod version;
+pub mod message;
 
 
 /// Re-exporting the mime crate, for convenience.

src/message.rs

@@ -0,0 +1,114 @@
+//! Defines the `HttpMessage` trait that serves to encapsulate the operations of a single
+//! request-response cycle on any HTTP connection.
+
+use std::fmt::Debug;
+use std::any::{Any, TypeId};
+use std::io::{Read, Write};
+
+use std::mem;
+
+use typeable::Typeable;
+
+use header::Headers;
+use http::RawStatus;
+use url::Url;
+
+use method;
+use version;
+use traitobject;
+
+/// Describes a request.
+#[derive(Clone, Debug)]
+pub struct RequestHead {
+    /// The headers of the request
+    pub headers: Headers,
+    /// The method of the request
+    pub method: method::Method,
+    /// The URL of the request
+    pub url: Url,
+}
+
+/// Describes a response.
+#[derive(Clone, Debug)]
+pub struct ResponseHead {
+    /// The headers of the reponse
+    pub headers: Headers,
+    /// The raw status line of the response
+    pub raw_status: RawStatus,
+    /// The HTTP/2 version which generated the response
+    pub version: version::HttpVersion,
+}
+
+/// The trait provides an API for sending an receiving HTTP messages.
+pub trait HttpMessage: Write + Read + Send + Any + Typeable + Debug {
+    /// Initiates a new outgoing request.
+    ///
+    /// Only the request's head is provided (in terms of the `RequestHead` struct).
+    ///
+    /// After this, the `HttpMessage` instance can be used as an `io::Write` in order to write the
+    /// body of the request.
+    fn set_outgoing(&mut self, head: RequestHead) -> ::Result<RequestHead>;
+    /// Obtains the incoming response and returns its head (i.e. the `ResponseHead` struct)
+    ///
+    /// After this, the `HttpMessage` instance can be used as an `io::Read` in order to read out
+    /// the response body.
+    fn get_incoming(&mut self) -> ::Result<ResponseHead>;
+
+    /// Closes the underlying HTTP connection.
+    fn close_connection(&mut self) -> ::Result<()>;
+}
+
+impl HttpMessage {
+    unsafe fn downcast_ref_unchecked<T: 'static>(&self) -> &T {
+        mem::transmute(traitobject::data(self))
+    }
+
+    unsafe fn downcast_mut_unchecked<T: 'static>(&mut self) -> &mut T {
+        mem::transmute(traitobject::data_mut(self))
+    }
+
+    unsafe fn downcast_unchecked<T: 'static>(self: Box<HttpMessage>) -> Box<T>  {
+        let raw: *mut HttpMessage = mem::transmute(self);
+        mem::transmute(traitobject::data_mut(raw))
+    }
+}
+
+impl HttpMessage {
+    /// Is the underlying type in this trait object a T?
+    #[inline]
+    pub fn is<T: Any>(&self) -> bool {
+        (*self).get_type() == TypeId::of::<T>()
+    }
+
+    /// If the underlying type is T, get a reference to the contained data.
+    #[inline]
+    pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
+        if self.is::<T>() {
+            Some(unsafe { self.downcast_ref_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// If the underlying type is T, get a mutable reference to the contained
+    /// data.
+    #[inline]
+    pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
+        if self.is::<T>() {
+            Some(unsafe { self.downcast_mut_unchecked() })
+        } else {
+            None
+        }
+    }
+
+    /// If the underlying type is T, extract it.
+    #[inline]
+    pub fn downcast<T: Any>(self: Box<HttpMessage>)
+            -> Result<Box<T>, Box<HttpMessage>> {
+        if self.is::<T>() {
+            Ok(unsafe { self.downcast_unchecked() })
+        } else {
+            Err(self)
+        }
+    }
+}