Cache parsed ContentType and Accept headers.

This is a breaking change. `Request::content_type` now returns a borrow
to `ContentType`. `FromRequest` for `ContentType` is no longer
implemented. Instead, `FromRequest` for `&ContentType` is implemented.

lib/Cargo.toml

@@ -25,7 +25,7 @@ url = "1"
 hyper = { version = "0.10.4", default-features = false }
 toml = { version = "0.2", default-features = false }
 num_cpus = "1"
-state = "0.2"
+state = "0.2.1"
 time = "0.1"
 memchr = "1"
 base64 = "0.4"

lib/src/data/from_data.rs

@@ -104,7 +104,7 @@ impl<'a, S, E> IntoOutcome<S, (Status, E), Data> for Result<S, E> {
 ///     fn from_data(req: &Request, data: Data) -> data::Outcome<Self, String> {
 ///         // Ensure the content type is correct before opening the data.
 ///         let person_ct = ContentType::new("application", "x-person");
-///         if req.content_type() != Some(person_ct) {
+///         if req.content_type() != Some(&person_ct) {
 ///             return Outcome::Forward(data);
 ///         }
 ///

lib/src/request/from_request.rs

@@ -220,7 +220,7 @@ impl<'a, 'r> FromRequest<'a, 'r> for Session<'a> {
     }
 }
 
-impl<'a, 'r> FromRequest<'a, 'r> for Accept {
+impl<'a, 'r> FromRequest<'a, 'r> for &'a Accept {
     type Error = ();
 
     fn from_request(request: &'a Request<'r>) -> Outcome<Self, Self::Error> {
@@ -231,7 +231,7 @@ impl<'a, 'r> FromRequest<'a, 'r> for Accept {
     }
 }
 
-impl<'a, 'r> FromRequest<'a, 'r> for ContentType {
+impl<'a, 'r> FromRequest<'a, 'r> for &'a ContentType {
     type Error = ();
 
     fn from_request(request: &'a Request<'r>) -> Outcome<Self, Self::Error> {

lib/src/request/request.rs

@@ -6,7 +6,7 @@ use std::str;
 use term_painter::Color::*;
 use term_painter::ToStyle;
 
-use state::Container;
+use state::{Container, Storage};
 
 use error::Error;
 use super::{FromParam, FromSegments};
@@ -15,7 +15,6 @@ use router::Route;
 use http::uri::{URI, Segments};
 use http::{Method, Header, HeaderMap, Cookies, Session, CookieJar, Key};
 use http::{RawStr, ContentType, Accept, MediaType};
-use http::parse::media_type;
 use http::hyper;
 
 struct PresetState<'r> {
@@ -28,6 +27,8 @@ struct RequestState<'r> {
     params: RefCell<Vec<(usize, usize)>>,
     cookies: RefCell<CookieJar>,
     session: RefCell<CookieJar>,
+    accept: Storage<Option<Accept>>,
+    content_type: Storage<Option<ContentType>>,
 }
 
 /// The type of an incoming web request.
@@ -71,6 +72,8 @@ impl<'r> Request<'r> {
                 params: RefCell::new(Vec::new()),
                 cookies: RefCell::new(CookieJar::new()),
                 session: RefCell::new(CookieJar::new()),
+                accept: Storage::new(),
+                content_type: Storage::new(),
             }
         }
     }
@@ -238,11 +241,11 @@ impl<'r> Request<'r> {
     /// let mut request = Request::new(Method::Get, "/uri");
     /// assert!(request.headers().is_empty());
     ///
-    /// request.add_header(ContentType::HTML);
-    /// assert_eq!(request.content_type(), Some(ContentType::HTML));
+    /// request.add_header(ContentType::Any);
+    /// assert_eq!(request.headers().get_one("Content-Type"), Some("*/*"));
     ///
-    /// request.replace_header(ContentType::JSON);
-    /// assert_eq!(request.content_type(), Some(ContentType::JSON));
+    /// request.replace_header(ContentType::PNG);
+    /// assert_eq!(request.headers().get_one("Content-Type"), Some("image/png"));
     /// ```
     #[inline(always)]
     pub fn replace_header<H: Into<Header<'r>>>(&mut self, header: H) {
@@ -307,7 +310,9 @@ impl<'r> Request<'r> {
     }
 
     /// Returns `Some` of the Content-Type header of `self`. If the header is
-    /// not present, returns `None`.
+    /// not present, returns `None`. The Content-Type header is cached after the
+    /// first call to this function. As a result, subsequent calls will always
+    /// return the same value.
     ///
     /// # Example
     ///
@@ -317,38 +322,47 @@ impl<'r> Request<'r> {
     ///
     /// let mut request = Request::new(Method::Get, "/uri");
     /// assert_eq!(request.content_type(), None);
+    /// ```
     ///
-    /// request.replace_header(ContentType::JSON);
-    /// assert_eq!(request.content_type(), Some(ContentType::JSON));
+    /// ```rust
+    /// use rocket::Request;
+    /// use rocket::http::{Method, ContentType};
+    ///
+    /// let mut request = Request::new(Method::Get, "/uri");
+    /// request.add_header(ContentType::JSON);
+    /// assert_eq!(request.content_type(), Some(&ContentType::JSON));
     /// ```
     #[inline(always)]
-    pub fn content_type(&self) -> Option<ContentType> {
-        // FIXME: Don't reparse each time! Use RC? Smarter than that?
-        // Use state::Storage!
-        self.headers().get_one("Content-Type").and_then(|value| value.parse().ok())
+    pub fn content_type(&self) -> Option<&ContentType> {
+        self.extra.content_type.get_or_set(|| {
+            self.headers().get_one("Content-Type").and_then(|v| v.parse().ok())
+        }).as_ref()
     }
 
     #[inline(always)]
-    pub fn accept(&self) -> Option<Accept> {
+    pub fn accept(&self) -> Option<&Accept> {
+        self.extra.accept.get_or_set(|| {
             self.headers().get_one("Accept").and_then(|v| v.parse().ok())
+        }).as_ref()
     }
 
     #[inline(always)]
-    pub fn accept_first(&self) -> Option<MediaType> {
-        self.headers().get_one("Accept").and_then(|mut v| media_type(&mut v).ok())
+    pub fn accept_first(&self) -> Option<&MediaType> {
+        self.accept().and_then(|accept| accept.first()).map(|wmt| wmt.media_type())
     }
 
     #[inline(always)]
-    pub fn format(&self) -> Option<MediaType> {
+    pub fn format(&self) -> Option<&MediaType> {
+        static ANY: MediaType = MediaType::Any;
         if self.method.supports_payload() {
-            self.content_type().map(|ct| ct.into_media_type())
+            self.content_type().map(|ct| ct.media_type())
         } else {
             // FIXME: Should we be using `accept_first` or `preferred`? Or
             // should we be checking neither and instead pass things through
             // where the client accepts the thing at all?
             self.accept()
-                .map(|accept| accept.preferred().media_type().clone())
-                .or(Some(MediaType::Any))
+                .map(|accept| accept.preferred().media_type())
+                .or(Some(&ANY))
         }
     }