avoid parsing when setting headers

src/agent.rs

@@ -117,9 +117,10 @@ impl Agent {
         K: Into<String>,
         V: Into<String>,
     {
-        let s = format!("{}: {}", header.into(), value.into());
-        let header = s.parse::<Header>().expect("Failed to parse header");
-        add_header(&mut self.headers, header);
+        add_header(
+            &mut self.headers,
+            Header::new(&header.into(), &value.into()).expect("Failed to parse header"),
+        );
         self
     }
 
@@ -153,9 +154,7 @@ impl Agent {
         I: IntoIterator<Item = (K, V)>,
     {
         for (k, v) in headers.into_iter() {
-            let s = format!("{}: {}", k.into(), v.into());
-            let header = s.parse::<Header>().expect("Failed to parse header");
-            add_header(&mut self.headers, header);
+            self.set(k, v);
         }
         self
     }
@@ -187,6 +186,7 @@ impl Agent {
     /// in all requests using the agent.
     ///
     /// ```
+    /// // sets a header "Authorization: token secret"
     /// let agent = ureq::agent()
     ///     .auth_kind("token", "secret")
     ///     .build();
@@ -200,9 +200,8 @@ impl Agent {
         S: Into<String>,
         T: Into<String>,
     {
-        let s = format!("Authorization: {} {}", kind.into(), pass.into());
-        let header = s.parse::<Header>().expect("Failed to parse header");
-        add_header(&mut self.headers, header);
+        let value = format!("{} {}", kind.into(), pass.into());
+        self.set("Authorization", value);
         self
     }
 

src/header.rs

@@ -16,6 +16,13 @@ impl ::std::fmt::Debug for Header {
 }
 
 impl Header {
+    pub fn new(name: &str, value: &str) -> Result<Self, Error> {
+        let line =
+            AsciiString::from_str(&format!("{}: {}", name, value)).map_err(|_| Error::BadHeader)?;
+        let index = name.len();
+        Ok(Header { line, index })
+    }
+
     /// The header name.
     ///
     /// ```

src/request.rs

@@ -192,9 +192,10 @@ impl Request {
         K: Into<String>,
         V: Into<String>,
     {
-        let s = format!("{}: {}", header.into(), value.into());
-        let header = s.parse::<Header>().expect("Failed to parse header");
-        add_header(&mut self.headers, header);
+        add_header(
+            &mut self.headers,
+            Header::new(&header.into(), &value.into()).expect("Failed to parse header"),
+        );
         self
     }
 
@@ -264,9 +265,7 @@ impl Request {
         I: IntoIterator<Item = (K, V)>,
     {
         for (k, v) in headers.into_iter() {
-            let s = format!("{}: {}", k.into(), v.into());
-            let header = s.parse::<Header>().expect("Failed to parse header");
-            add_header(&mut self.headers, header);
+            self.set(k, v);
         }
         self
     }
@@ -424,9 +423,8 @@ impl Request {
         S: Into<String>,
         T: Into<String>,
     {
-        let s = format!("Authorization: {} {}", kind.into(), pass.into());
-        let header = s.parse::<Header>().expect("Failed to parse header");
-        add_header(&mut self.headers, header);
+        let value = format!("{} {}", kind.into(), pass.into());
+        self.set("Authorization", value);
         self
     }
 

src/unit.rs

@@ -204,8 +204,7 @@ fn match_cookies<'a>(jar: &'a CookieJar, domain: &str, path: &str, is_secure: bo
             let name = c.name().to_string();
             let value = c.value().to_string();
             let nameval = Cookie::new(name, value).encoded().to_string();
-            let head = format!("Cookie: {}", nameval);
-            head.parse::<Header>().ok()
+            Header::new("Cookie", &nameval).ok()
         })
         .filter(|o| o.is_some())
         .map(|o| o.unwrap())