1 files changed, 87 insertions, 0 deletions
diff --git a/components/shared/net/quality.rs b/components/shared/net/quality.rs
new file mode 100644
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--- /dev/null
+++ b/components/shared/net/quality.rs
@@ -0,0 +1,87 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+//TODO(eijebong): Remove this once typed headers figure out quality
+// This is copy pasted from the old hyper headers to avoid hardcoding everything
+// (I would probably also make some silly mistakes while migrating...)
+
+use std::{fmt, str};
+
+use http::header::HeaderValue;
+use mime::Mime;
+
+/// A quality value, as specified in [RFC7231].
+///
+/// Quality values are decimal numbers between 0 and 1 (inclusive) with up to 3 fractional digits of precision.
+///
+/// [RFC7231]: https://tools.ietf.org/html/rfc7231#section-5.3.1
+#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct Quality(u16);
+
+impl Quality {
+    /// Creates a quality value from a value between 0 and 1000 inclusive.
+    ///
+    /// This is semantically divided by 1000 to produce a value between 0 and 1.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the value is greater than 1000.
+    pub fn from_u16(quality: u16) -> Quality {
+        assert!(quality <= 1000);
+        Quality(quality)
+    }
+}
+
+/// A value paired with its "quality" as defined in [RFC7231].
+///
+/// Quality items are used in content negotiation headers such as `Accept` and `Accept-Encoding`.
+///
+/// [RFC7231]: https://tools.ietf.org/html/rfc7231#section-5.3
+#[derive(Clone, Debug, PartialEq)]
+pub struct QualityItem<T> {
+    pub item: T,
+    pub quality: Quality,
+}
+
+impl<T> QualityItem<T> {
+    /// Creates a new quality item.
+    pub fn new(item: T, quality: Quality) -> QualityItem<T> {
+        QualityItem { item, quality }
+    }
+}
+
+impl<T> fmt::Display for QualityItem<T>
+where
+    T: fmt::Display,
+{
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&self.item, fmt)?;
+        match self.quality.0 {
+            1000 => Ok(()),
+            0 => fmt.write_str("; q=0"),
+            mut x => {
+                fmt.write_str("; q=0.")?;
+                let mut digits = *b"000";
+                digits[2] = (x % 10) as u8 + b'0';
+                x /= 10;
+                digits[1] = (x % 10) as u8 + b'0';
+                x /= 10;
+                digits[0] = (x % 10) as u8 + b'0';
+
+                let s = str::from_utf8(&digits[..]).unwrap();
+                fmt.write_str(s.trim_end_matches('0'))
+            },
+        }
+    }
+}
+
+pub fn quality_to_value(q: Vec<QualityItem<Mime>>) -> HeaderValue {
+    HeaderValue::from_str(
+        &q.iter()
+            .map(|q| q.to_string())
+            .collect::<Vec<String>>()
+            .join(", "),
+    )
+    .unwrap()
+}