Restructure modules

Modules are now separated into a fashion where the library can be used
for most use cases, without needing to compile the rest.

The core of serenity, with no features enabled, contains only the
struct (model) definitions, constants, and prelude. Models do not have
most functions compiled in, as that is separated into the `model`
feature.

The `client` module has been split into 3 modules: `client`, `gateway`,
and `http`.

`http` contains functions to interact with the REST API. `gateway`
contains the Shard to interact with the gateway, requiring `http` for
retrieving the gateway URL. `client` requires both of the other features
and acts as an abstracted interface over both the gateway and REST APIs,
handling the event loop.

The `builder` module has been separated from `utils`, and can now be
optionally compiled in. It and the `http` feature are required by the
`model` feature due to a large number of methods requiring access to
them.

`utils` now contains a number of utilities, such as the Colour struct, the
`MessageBuilder`, and mention parsing functions.

Each of the original `ext` modules are still featured, with `cache` not
requiring any feature to be enabled, `framework` requiring the `client`,
`model`, and `utils`, and `voice` requiring `gateway`.

In total the features and their requirements are:

- `builder`: none
- `cache`: none
- `client`: `gateway`, `http`
- `framework`: `client`, `model`, `utils`
- `gateway`: `http`
- `http`: none
- `model`: `builder`, `http`
- `utils`: none
- `voice`: `gateway`

The default features are `builder`, `cache`, `client`, `framework`,
`gateway`, `model`, `http`, and `utils`.

To help with forwards compatibility, modules have been re-exported from
their original locations.

1 files changed, 67 insertions, 29 deletions

diff --git a/src/error.rs b/src/error.rs
index d6fbd63..7795db5 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,17 +1,25 @@
-use hyper::Error as HyperError;
 use serde_json::Error as JsonError;
-use serde_json::Value;
 use std::io::Error as IoError;
 use std::error::Error as StdError;
 use std::fmt::{self, Display, Error as FormatError};
 use std::num::ParseIntError;
-use websocket::result::WebSocketError;
-use ::client::gateway::GatewayError;
-use ::client::ClientError;
+use ::internal::prelude::*;
+use ::model::ModelError;
+
+#[cfg(feature="hyper")]
+use hyper::Error as HyperError;
 #[cfg(feature="voice")]
 use opus::Error as OpusError;
+#[cfg(feature="websocket")]
+use websocket::result::WebSocketError;
+#[cfg(feature="client")]
+use ::client::ClientError;
+#[cfg(feature="gateway")]
+use ::gateway::GatewayError;
+#[cfg(feature="http")]
+use ::http::HttpError;
 #[cfg(feature="voice")]
-use ::ext::voice::VoiceError;
+use ::voice::VoiceError;
 
 /// The common result type between most library functions.
 ///
@@ -21,7 +29,7 @@ use ::ext::voice::VoiceError;
 /// implied, and a "simpler" result is used.
 ///
 /// [`Error`]: enum.Error.html
-pub type Result<T> = ::std::result::Result<T, Error>;
+pub type Result<T> = StdResult<T, Error>;
 
 /// A common error enum returned by most of the library's functionality within a
 /// custom [`Result`].
@@ -33,29 +41,22 @@ pub type Result<T> = ::std::result::Result<T, Error>;
 /// [`Client`]: #variant.Client
 /// [`ClientError`]: client/enum.ClientError.html
 /// [`Gateway`]: #variant.Gateway
-/// [`GatewayError`]: client/gateway/enum.GatewayError.html
+/// [`GatewayError`]: gateway/enum.GatewayError.html
 /// [`Result`]: type.Result.html
 #[derive(Debug)]
 pub enum Error {
-    /// A [rest] or [client] error.
-    ///
-    /// [client]: client/index.html
-    /// [rest]: client/rest/index.html
-    Client(ClientError),
-    /// An error with the WebSocket [`Gateway`].
-    ///
-    /// [`Gateway`]: client/gateway/index.html
-    Gateway(GatewayError),
     /// An error while decoding a payload.
     Decode(&'static str, Value),
     /// There was an error with a format.
     Format(FormatError),
-    /// An error from the `hyper` crate.
-    Hyper(HyperError),
     /// An `std::io` error.
     Io(IoError),
     /// An error from the `serde_json` crate.
     Json(JsonError),
+    /// An error from the [`model`] module.
+    ///
+    /// [`model`]: model/index.html
+    Model(ModelError),
     /// An error occurred while parsing an integer.
     Num(ParseIntError),
     /// Some other error. This is only used for "Expected value <TYPE>" errors,
@@ -66,14 +67,31 @@ pub enum Error {
     Other(&'static str),
     /// An error from the `url` crate.
     Url(String),
+    /// A [client] error.
+    ///
+    /// [client]: client/index.html
+    #[cfg(feature="client")]
+    Client(ClientError),
+    /// An error from the `gateway` module.
+    #[cfg(feature="gateway")]
+    Gateway(GatewayError),
+    /// An error from the [`http`] module.
+    ///
+    /// [`http`]: http/index.html
+    #[cfg(feature="http")]
+    Http(HttpError),
+    /// An error from the `hyper` crate.
+    #[cfg(feature="hyper")]
+    Hyper(HyperError),
     /// An error from the `rust-websocket` crate.
+    #[cfg(feature="gateway")]
     WebSocket(WebSocketError),
     /// An error from the `opus` crate.
     #[cfg(feature="voice")]
     Opus(OpusError),
     /// Indicating an error within the [voice module].
     ///
-    /// [voice module]: ext/voice/index.html
+    /// [voice module]: voice/index.html
     #[cfg(feature="voice")]
     Voice(VoiceError),
 }
@@ -84,18 +102,26 @@ impl From<FormatError> for Error {
     }
 }
 
-impl From<IoError> for Error {
-    fn from(e: IoError) -> Error {
-        Error::Io(e)
+#[cfg(feature="gateway")]
+impl From<GatewayError> for Error {
+    fn from(e: GatewayError) -> Error {
+        Error::Gateway(e)
     }
 }
 
+#[cfg(feature="hyper")]
 impl From<HyperError> for Error {
     fn from(e: HyperError) -> Error {
         Error::Hyper(e)
     }
 }
 
+impl From<IoError> for Error {
+    fn from(e: IoError) -> Error {
+        Error::Io(e)
+    }
+}
+
 impl From<JsonError> for Error {
     fn from(e: JsonError) -> Error {
         Error::Json(e)
@@ -115,6 +141,7 @@ impl From<OpusError> for Error {
     }
 }
 
+#[cfg(feature="gateway")]
 impl From<WebSocketError> for Error {
     fn from(e: WebSocketError) -> Error {
         Error::WebSocket(e)
@@ -124,9 +151,11 @@ impl From<WebSocketError> for Error {
 impl Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
-            Error::Hyper(ref inner) => inner.fmt(f),
             Error::Io(ref inner) => inner.fmt(f),
             Error::Json(ref inner) => inner.fmt(f),
+            #[cfg(feature="http")]
+            Error::Hyper(ref inner) => inner.fmt(f),
+            #[cfg(feature="gateway")]
             Error::WebSocket(ref inner) => inner.fmt(f),
             #[cfg(feature="voice")]
             Error::Opus(ref inner) => inner.fmt(f),
@@ -138,29 +167,38 @@ impl Display for Error {
 impl StdError for Error {
     fn description(&self) -> &str {
         match *self {
-            Error::Client(_) => "Client refused a request",
             Error::Decode(msg, _) | Error::Other(msg) => msg,
             Error::Format(ref inner) => inner.description(),
-            Error::Gateway(ref _inner) => "Gateway error",
-            Error::Hyper(ref inner) => inner.description(),
             Error::Io(ref inner) => inner.description(),
             Error::Json(ref inner) => inner.description(),
+            Error::Model(ref inner) => inner.description(),
             Error::Num(ref inner) => inner.description(),
             Error::Url(ref inner) => inner,
-            Error::WebSocket(ref inner) => inner.description(),
+            #[cfg(feature="client")]
+            Error::Client(ref inner) => inner.description(),
+            #[cfg(feature="gateway")]
+            Error::Gateway(ref inner) => inner.description(),
+            #[cfg(feature="http")]
+            Error::Http(ref inner) => inner.description(),
+            #[cfg(feature="http")]
+            Error::Hyper(ref inner) => inner.description(),
             #[cfg(feature="voice")]
             Error::Opus(ref inner) => inner.description(),
             #[cfg(feature="voice")]
             Error::Voice(_) => "Voice error",
+            #[cfg(feature="gateway")]
+            Error::WebSocket(ref inner) => inner.description(),
         }
     }
 
     fn cause(&self) -> Option<&StdError> {
         match *self {
+            #[cfg(feature="http")]
             Error::Hyper(ref inner) => Some(inner),
             Error::Json(ref inner) => Some(inner),
-            Error::WebSocket(ref inner) => Some(inner),
             Error::Io(ref inner) => Some(inner),
+            #[cfg(feature="gateway")]
+            Error::WebSocket(ref inner) => Some(inner),
             _ => None,
         }
     }