From 094fd71d1aa61e0aa6cefa5ee66b6f598c4f057b Mon Sep 17 00:00:00 2001
From: David Pedersen <david.pdrsn@gmail.com>
Date: Tue, 1 Mar 2022 09:12:45 +0100
Subject: [PATCH] Move `Extension` into root (#804)

---
 axum/src/{extract => }/extension.rs | 35 +++++++++++++++++++++++------
 axum/src/extract/mod.rs             |  5 +++--
 axum/src/lib.rs                     |  3 +++
 axum/src/response/mod.rs            |  3 +++
 4 files changed, 37 insertions(+), 9 deletions(-)
 rename axum/src/{extract => }/extension.rs (81%)

diff --git a/axum/src/extract/extension.rs b/axum/src/extension.rs
similarity index 81%
rename from axum/src/extract/extension.rs
rename to axum/src/extension.rs
index 0a200600..8ca50d88 100644
--- a/axum/src/extract/extension.rs
+++ b/axum/src/extension.rs
@@ -1,20 +1,20 @@
-use super::{rejection::*, FromRequest, RequestParts};
+use crate::extract::{rejection::*, FromRequest, RequestParts};
 use crate::response::IntoResponseParts;
 use async_trait::async_trait;
 use axum_core::response::{IntoResponse, Response, ResponseParts};
 use std::ops::Deref;
 
-/// Extractor that gets a value from request extensions.
+/// Extractor and response for extensions.
+///
+/// # As extractor
 ///
 /// This is commonly used to share state across handlers.
 ///
-/// # Example
-///
 /// ```rust,no_run
 /// use axum::{
-///     extract::Extension,
-///     routing::get,
 ///     Router,
+///     Extension,
+///     routing::get,
 /// };
 /// use std::sync::Arc;
 ///
@@ -40,6 +40,27 @@ use std::ops::Deref;
 ///
 /// If the extension is missing it will reject the request with a `500 Internal
 /// Server Error` response.
+///
+/// # As response
+///
+/// Response extensions can be used to share state with middleware.
+///
+/// ```rust
+/// use axum::{
+///     Extension,
+///     response::IntoResponse,
+/// };
+///
+/// async fn handler() -> impl IntoResponse {
+///     (
+///         Extension(Foo("foo")),
+///         "Hello, World!"
+///     )
+/// }
+///
+/// #[derive(Clone)]
+/// struct Foo(&'static str);
+/// ```
 #[derive(Debug, Clone, Copy)]
 pub struct Extension<T>(pub T);
 
@@ -57,7 +78,7 @@ where
             .get::<T>()
             .ok_or_else(|| {
                 MissingExtension::from_err(format!(
-                    "Extension of type `{}` was not found. Perhaps you forgot to add it? See `axum::extract::Extension`.",
+                    "Extension of type `{}` was not found. Perhaps you forgot to add it? See `axum::Extension`.",
                     std::any::type_name::<T>()
                 ))
             })
diff --git a/axum/src/extract/mod.rs b/axum/src/extract/mod.rs
index e7ccabd7..fcdc08df 100644
--- a/axum/src/extract/mod.rs
+++ b/axum/src/extract/mod.rs
@@ -12,7 +12,6 @@ pub mod rejection;
 pub mod ws;
 
 mod content_length_limit;
-mod extension;
 mod raw_query;
 mod request_parts;
 
@@ -23,7 +22,6 @@ pub use axum_core::extract::{FromRequest, RequestParts};
 pub use self::{
     connect_info::ConnectInfo,
     content_length_limit::ContentLengthLimit,
-    extension::Extension,
     extractor_middleware::extractor_middleware,
     path::Path,
     raw_query::RawQuery,
@@ -34,6 +32,9 @@ pub use self::{
 #[cfg(feature = "json")]
 pub use crate::Json;
 
+#[doc(no_inline)]
+pub use crate::Extension;
+
 #[cfg(feature = "form")]
 mod form;
 
diff --git a/axum/src/lib.rs b/axum/src/lib.rs
index 357c1021..5f0b996a 100644
--- a/axum/src/lib.rs
+++ b/axum/src/lib.rs
@@ -393,6 +393,7 @@
 pub(crate) mod macros;
 
 mod add_extension;
+mod extension;
 #[cfg(feature = "json")]
 mod json;
 mod util;
@@ -419,6 +420,8 @@ pub use http;
 #[doc(no_inline)]
 pub use hyper::Server;
 
+#[doc(inline)]
+pub use self::extension::Extension;
 #[doc(inline)]
 #[cfg(feature = "json")]
 pub use self::json::Json;
diff --git a/axum/src/response/mod.rs b/axum/src/response/mod.rs
index db5a20ea..1cfbdfba 100644
--- a/axum/src/response/mod.rs
+++ b/axum/src/response/mod.rs
@@ -11,6 +11,9 @@ pub mod sse;
 #[cfg(feature = "json")]
 pub use crate::Json;
 
+#[doc(no_inline)]
+pub use crate::Extension;
+
 #[doc(inline)]
 pub use axum_core::response::{IntoResponse, IntoResponseParts, Response, ResponseParts};