Merge actix-http project

actix-http/src/header/shared/charset.rs

@@ -0,0 +1,153 @@
+use std::fmt::{self, Display};
+use std::str::FromStr;
+
+use self::Charset::*;
+
+/// A Mime charset.
+///
+/// The string representation is normalized to upper case.
+///
+/// See [http://www.iana.org/assignments/character-sets/character-sets.xhtml][url].
+///
+/// [url]: http://www.iana.org/assignments/character-sets/character-sets.xhtml
+#[derive(Clone, Debug, PartialEq)]
+#[allow(non_camel_case_types)]
+pub enum Charset {
+    /// US ASCII
+    Us_Ascii,
+    /// ISO-8859-1
+    Iso_8859_1,
+    /// ISO-8859-2
+    Iso_8859_2,
+    /// ISO-8859-3
+    Iso_8859_3,
+    /// ISO-8859-4
+    Iso_8859_4,
+    /// ISO-8859-5
+    Iso_8859_5,
+    /// ISO-8859-6
+    Iso_8859_6,
+    /// ISO-8859-7
+    Iso_8859_7,
+    /// ISO-8859-8
+    Iso_8859_8,
+    /// ISO-8859-9
+    Iso_8859_9,
+    /// ISO-8859-10
+    Iso_8859_10,
+    /// Shift_JIS
+    Shift_Jis,
+    /// EUC-JP
+    Euc_Jp,
+    /// ISO-2022-KR
+    Iso_2022_Kr,
+    /// EUC-KR
+    Euc_Kr,
+    /// ISO-2022-JP
+    Iso_2022_Jp,
+    /// ISO-2022-JP-2
+    Iso_2022_Jp_2,
+    /// ISO-8859-6-E
+    Iso_8859_6_E,
+    /// ISO-8859-6-I
+    Iso_8859_6_I,
+    /// ISO-8859-8-E
+    Iso_8859_8_E,
+    /// ISO-8859-8-I
+    Iso_8859_8_I,
+    /// GB2312
+    Gb2312,
+    /// Big5
+    Big5,
+    /// KOI8-R
+    Koi8_R,
+    /// An arbitrary charset specified as a string
+    Ext(String),
+}
+
+impl Charset {
+    fn label(&self) -> &str {
+        match *self {
+            Us_Ascii => "US-ASCII",
+            Iso_8859_1 => "ISO-8859-1",
+            Iso_8859_2 => "ISO-8859-2",
+            Iso_8859_3 => "ISO-8859-3",
+            Iso_8859_4 => "ISO-8859-4",
+            Iso_8859_5 => "ISO-8859-5",
+            Iso_8859_6 => "ISO-8859-6",
+            Iso_8859_7 => "ISO-8859-7",
+            Iso_8859_8 => "ISO-8859-8",
+            Iso_8859_9 => "ISO-8859-9",
+            Iso_8859_10 => "ISO-8859-10",
+            Shift_Jis => "Shift-JIS",
+            Euc_Jp => "EUC-JP",
+            Iso_2022_Kr => "ISO-2022-KR",
+            Euc_Kr => "EUC-KR",
+            Iso_2022_Jp => "ISO-2022-JP",
+            Iso_2022_Jp_2 => "ISO-2022-JP-2",
+            Iso_8859_6_E => "ISO-8859-6-E",
+            Iso_8859_6_I => "ISO-8859-6-I",
+            Iso_8859_8_E => "ISO-8859-8-E",
+            Iso_8859_8_I => "ISO-8859-8-I",
+            Gb2312 => "GB2312",
+            Big5 => "big5",
+            Koi8_R => "KOI8-R",
+            Ext(ref s) => s,
+        }
+    }
+}
+
+impl Display for Charset {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(self.label())
+    }
+}
+
+impl FromStr for Charset {
+    type Err = crate::Error;
+
+    fn from_str(s: &str) -> crate::Result<Charset> {
+        Ok(match s.to_ascii_uppercase().as_ref() {
+            "US-ASCII" => Us_Ascii,
+            "ISO-8859-1" => Iso_8859_1,
+            "ISO-8859-2" => Iso_8859_2,
+            "ISO-8859-3" => Iso_8859_3,
+            "ISO-8859-4" => Iso_8859_4,
+            "ISO-8859-5" => Iso_8859_5,
+            "ISO-8859-6" => Iso_8859_6,
+            "ISO-8859-7" => Iso_8859_7,
+            "ISO-8859-8" => Iso_8859_8,
+            "ISO-8859-9" => Iso_8859_9,
+            "ISO-8859-10" => Iso_8859_10,
+            "SHIFT-JIS" => Shift_Jis,
+            "EUC-JP" => Euc_Jp,
+            "ISO-2022-KR" => Iso_2022_Kr,
+            "EUC-KR" => Euc_Kr,
+            "ISO-2022-JP" => Iso_2022_Jp,
+            "ISO-2022-JP-2" => Iso_2022_Jp_2,
+            "ISO-8859-6-E" => Iso_8859_6_E,
+            "ISO-8859-6-I" => Iso_8859_6_I,
+            "ISO-8859-8-E" => Iso_8859_8_E,
+            "ISO-8859-8-I" => Iso_8859_8_I,
+            "GB2312" => Gb2312,
+            "big5" => Big5,
+            "KOI8-R" => Koi8_R,
+            s => Ext(s.to_owned()),
+        })
+    }
+}
+
+#[test]
+fn test_parse() {
+    assert_eq!(Us_Ascii, "us-ascii".parse().unwrap());
+    assert_eq!(Us_Ascii, "US-Ascii".parse().unwrap());
+    assert_eq!(Us_Ascii, "US-ASCII".parse().unwrap());
+    assert_eq!(Shift_Jis, "Shift-JIS".parse().unwrap());
+    assert_eq!(Ext("ABCD".to_owned()), "abcd".parse().unwrap());
+}
+
+#[test]
+fn test_display() {
+    assert_eq!("US-ASCII", format!("{}", Us_Ascii));
+    assert_eq!("ABCD", format!("{}", Ext("ABCD".to_owned())));
+}

actix-http/src/header/shared/encoding.rs

@@ -0,0 +1,58 @@
+use std::{fmt, str};
+
+pub use self::Encoding::{
+    Brotli, Chunked, Compress, Deflate, EncodingExt, Gzip, Identity, Trailers,
+};
+
+/// A value to represent an encoding used in `Transfer-Encoding`
+/// or `Accept-Encoding` header.
+#[derive(Clone, PartialEq, Debug)]
+pub enum Encoding {
+    /// The `chunked` encoding.
+    Chunked,
+    /// The `br` encoding.
+    Brotli,
+    /// The `gzip` encoding.
+    Gzip,
+    /// The `deflate` encoding.
+    Deflate,
+    /// The `compress` encoding.
+    Compress,
+    /// The `identity` encoding.
+    Identity,
+    /// The `trailers` encoding.
+    Trailers,
+    /// Some other encoding that is less common, can be any String.
+    EncodingExt(String),
+}
+
+impl fmt::Display for Encoding {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(match *self {
+            Chunked => "chunked",
+            Brotli => "br",
+            Gzip => "gzip",
+            Deflate => "deflate",
+            Compress => "compress",
+            Identity => "identity",
+            Trailers => "trailers",
+            EncodingExt(ref s) => s.as_ref(),
+        })
+    }
+}
+
+impl str::FromStr for Encoding {
+    type Err = crate::error::ParseError;
+    fn from_str(s: &str) -> Result<Encoding, crate::error::ParseError> {
+        match s {
+            "chunked" => Ok(Chunked),
+            "br" => Ok(Brotli),
+            "deflate" => Ok(Deflate),
+            "gzip" => Ok(Gzip),
+            "compress" => Ok(Compress),
+            "identity" => Ok(Identity),
+            "trailers" => Ok(Trailers),
+            _ => Ok(EncodingExt(s.to_owned())),
+        }
+    }
+}

actix-http/src/header/shared/entity.rs

@@ -0,0 +1,265 @@
+use std::fmt::{self, Display, Write};
+use std::str::FromStr;
+
+use crate::header::{HeaderValue, IntoHeaderValue, InvalidHeaderValueBytes, Writer};
+
+/// check that each char in the slice is either:
+/// 1. `%x21`, or
+/// 2. in the range `%x23` to `%x7E`, or
+/// 3. above `%x80`
+fn check_slice_validity(slice: &str) -> bool {
+    slice
+        .bytes()
+        .all(|c| c == b'\x21' || (c >= b'\x23' && c <= b'\x7e') | (c >= b'\x80'))
+}
+
+/// An entity tag, defined in [RFC7232](https://tools.ietf.org/html/rfc7232#section-2.3)
+///
+/// An entity tag consists of a string enclosed by two literal double quotes.
+/// Preceding the first double quote is an optional weakness indicator,
+/// which always looks like `W/`. Examples for valid tags are `"xyzzy"` and
+/// `W/"xyzzy"`.
+///
+/// # ABNF
+///
+/// ```text
+/// entity-tag = [ weak ] opaque-tag
+/// weak       = %x57.2F ; "W/", case-sensitive
+/// opaque-tag = DQUOTE *etagc DQUOTE
+/// etagc      = %x21 / %x23-7E / obs-text
+///            ; VCHAR except double quotes, plus obs-text
+/// ```
+///
+/// # Comparison
+/// To check if two entity tags are equivalent in an application always use the
+/// `strong_eq` or `weak_eq` methods based on the context of the Tag. Only use
+/// `==` to check if two tags are identical.
+///
+/// The example below shows the results for a set of entity-tag pairs and
+/// both the weak and strong comparison function results:
+///
+/// | `ETag 1`| `ETag 2`| Strong Comparison | Weak Comparison |
+/// |---------|---------|-------------------|-----------------|
+/// | `W/"1"` | `W/"1"` | no match          | match           |
+/// | `W/"1"` | `W/"2"` | no match          | no match        |
+/// | `W/"1"` | `"1"`   | no match          | match           |
+/// | `"1"`   | `"1"`   | match             | match           |
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct EntityTag {
+    /// Weakness indicator for the tag
+    pub weak: bool,
+    /// The opaque string in between the DQUOTEs
+    tag: String,
+}
+
+impl EntityTag {
+    /// Constructs a new EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn new(weak: bool, tag: String) -> EntityTag {
+        assert!(check_slice_validity(&tag), "Invalid tag: {:?}", tag);
+        EntityTag { weak, tag }
+    }
+
+    /// Constructs a new weak EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn weak(tag: String) -> EntityTag {
+        EntityTag::new(true, tag)
+    }
+
+    /// Constructs a new strong EntityTag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn strong(tag: String) -> EntityTag {
+        EntityTag::new(false, tag)
+    }
+
+    /// Get the tag.
+    pub fn tag(&self) -> &str {
+        self.tag.as_ref()
+    }
+
+    /// Set the tag.
+    /// # Panics
+    /// If the tag contains invalid characters.
+    pub fn set_tag(&mut self, tag: String) {
+        assert!(check_slice_validity(&tag), "Invalid tag: {:?}", tag);
+        self.tag = tag
+    }
+
+    /// For strong comparison two entity-tags are equivalent if both are not
+    /// weak and their opaque-tags match character-by-character.
+    pub fn strong_eq(&self, other: &EntityTag) -> bool {
+        !self.weak && !other.weak && self.tag == other.tag
+    }
+
+    /// For weak comparison two entity-tags are equivalent if their
+    /// opaque-tags match character-by-character, regardless of either or
+    /// both being tagged as "weak".
+    pub fn weak_eq(&self, other: &EntityTag) -> bool {
+        self.tag == other.tag
+    }
+
+    /// The inverse of `EntityTag.strong_eq()`.
+    pub fn strong_ne(&self, other: &EntityTag) -> bool {
+        !self.strong_eq(other)
+    }
+
+    /// The inverse of `EntityTag.weak_eq()`.
+    pub fn weak_ne(&self, other: &EntityTag) -> bool {
+        !self.weak_eq(other)
+    }
+}
+
+impl Display for EntityTag {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.weak {
+            write!(f, "W/\"{}\"", self.tag)
+        } else {
+            write!(f, "\"{}\"", self.tag)
+        }
+    }
+}
+
+impl FromStr for EntityTag {
+    type Err = crate::error::ParseError;
+
+    fn from_str(s: &str) -> Result<EntityTag, crate::error::ParseError> {
+        let length: usize = s.len();
+        let slice = &s[..];
+        // Early exits if it doesn't terminate in a DQUOTE.
+        if !slice.ends_with('"') || slice.len() < 2 {
+            return Err(crate::error::ParseError::Header);
+        }
+        // The etag is weak if its first char is not a DQUOTE.
+        if slice.len() >= 2
+            && slice.starts_with('"')
+            && check_slice_validity(&slice[1..length - 1])
+        {
+            // No need to check if the last char is a DQUOTE,
+            // we already did that above.
+            return Ok(EntityTag {
+                weak: false,
+                tag: slice[1..length - 1].to_owned(),
+            });
+        } else if slice.len() >= 4
+            && slice.starts_with("W/\"")
+            && check_slice_validity(&slice[3..length - 1])
+        {
+            return Ok(EntityTag {
+                weak: true,
+                tag: slice[3..length - 1].to_owned(),
+            });
+        }
+        Err(crate::error::ParseError::Header)
+    }
+}
+
+impl IntoHeaderValue for EntityTag {
+    type Error = InvalidHeaderValueBytes;
+
+    fn try_into(self) -> Result<HeaderValue, Self::Error> {
+        let mut wrt = Writer::new();
+        write!(wrt, "{}", self).unwrap();
+        HeaderValue::from_shared(wrt.take())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::EntityTag;
+
+    #[test]
+    fn test_etag_parse_success() {
+        // Expected success
+        assert_eq!(
+            "\"foobar\"".parse::<EntityTag>().unwrap(),
+            EntityTag::strong("foobar".to_owned())
+        );
+        assert_eq!(
+            "\"\"".parse::<EntityTag>().unwrap(),
+            EntityTag::strong("".to_owned())
+        );
+        assert_eq!(
+            "W/\"weaktag\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("weaktag".to_owned())
+        );
+        assert_eq!(
+            "W/\"\x65\x62\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("\x65\x62".to_owned())
+        );
+        assert_eq!(
+            "W/\"\"".parse::<EntityTag>().unwrap(),
+            EntityTag::weak("".to_owned())
+        );
+    }
+
+    #[test]
+    fn test_etag_parse_failures() {
+        // Expected failures
+        assert!("no-dquotes".parse::<EntityTag>().is_err());
+        assert!("w/\"the-first-w-is-case-sensitive\""
+            .parse::<EntityTag>()
+            .is_err());
+        assert!("".parse::<EntityTag>().is_err());
+        assert!("\"unmatched-dquotes1".parse::<EntityTag>().is_err());
+        assert!("unmatched-dquotes2\"".parse::<EntityTag>().is_err());
+        assert!("matched-\"dquotes\"".parse::<EntityTag>().is_err());
+    }
+
+    #[test]
+    fn test_etag_fmt() {
+        assert_eq!(
+            format!("{}", EntityTag::strong("foobar".to_owned())),
+            "\"foobar\""
+        );
+        assert_eq!(format!("{}", EntityTag::strong("".to_owned())), "\"\"");
+        assert_eq!(
+            format!("{}", EntityTag::weak("weak-etag".to_owned())),
+            "W/\"weak-etag\""
+        );
+        assert_eq!(
+            format!("{}", EntityTag::weak("\u{0065}".to_owned())),
+            "W/\"\x65\""
+        );
+        assert_eq!(format!("{}", EntityTag::weak("".to_owned())), "W/\"\"");
+    }
+
+    #[test]
+    fn test_cmp() {
+        // | ETag 1  | ETag 2  | Strong Comparison | Weak Comparison |
+        // |---------|---------|-------------------|-----------------|
+        // | `W/"1"` | `W/"1"` | no match          | match           |
+        // | `W/"1"` | `W/"2"` | no match          | no match        |
+        // | `W/"1"` | `"1"`   | no match          | match           |
+        // | `"1"`   | `"1"`   | match             | match           |
+        let mut etag1 = EntityTag::weak("1".to_owned());
+        let mut etag2 = EntityTag::weak("1".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::weak("1".to_owned());
+        etag2 = EntityTag::weak("2".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(!etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::weak("1".to_owned());
+        etag2 = EntityTag::strong("1".to_owned());
+        assert!(!etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+
+        etag1 = EntityTag::strong("1".to_owned());
+        etag2 = EntityTag::strong("1".to_owned());
+        assert!(etag1.strong_eq(&etag2));
+        assert!(etag1.weak_eq(&etag2));
+        assert!(!etag1.strong_ne(&etag2));
+        assert!(!etag1.weak_ne(&etag2));
+    }
+}

actix-http/src/header/shared/httpdate.rs

@@ -0,0 +1,118 @@
+use std::fmt::{self, Display};
+use std::io::Write;
+use std::str::FromStr;
+use std::time::{Duration, SystemTime, UNIX_EPOCH};
+
+use bytes::{BufMut, BytesMut};
+use http::header::{HeaderValue, InvalidHeaderValueBytes};
+
+use crate::error::ParseError;
+use crate::header::IntoHeaderValue;
+
+/// A timestamp with HTTP formatting and parsing
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub struct HttpDate(time::Tm);
+
+impl FromStr for HttpDate {
+    type Err = ParseError;
+
+    fn from_str(s: &str) -> Result<HttpDate, ParseError> {
+        match time::strptime(s, "%a, %d %b %Y %T %Z")
+            .or_else(|_| time::strptime(s, "%A, %d-%b-%y %T %Z"))
+            .or_else(|_| time::strptime(s, "%c"))
+        {
+            Ok(t) => Ok(HttpDate(t)),
+            Err(_) => Err(ParseError::Header),
+        }
+    }
+}
+
+impl Display for HttpDate {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&self.0.to_utc().rfc822(), f)
+    }
+}
+
+impl From<time::Tm> for HttpDate {
+    fn from(tm: time::Tm) -> HttpDate {
+        HttpDate(tm)
+    }
+}
+
+impl From<SystemTime> for HttpDate {
+    fn from(sys: SystemTime) -> HttpDate {
+        let tmspec = match sys.duration_since(UNIX_EPOCH) {
+            Ok(dur) => {
+                time::Timespec::new(dur.as_secs() as i64, dur.subsec_nanos() as i32)
+            }
+            Err(err) => {
+                let neg = err.duration();
+                time::Timespec::new(
+                    -(neg.as_secs() as i64),
+                    -(neg.subsec_nanos() as i32),
+                )
+            }
+        };
+        HttpDate(time::at_utc(tmspec))
+    }
+}
+
+impl IntoHeaderValue for HttpDate {
+    type Error = InvalidHeaderValueBytes;
+
+    fn try_into(self) -> Result<HeaderValue, Self::Error> {
+        let mut wrt = BytesMut::with_capacity(29).writer();
+        write!(wrt, "{}", self.0.rfc822()).unwrap();
+        HeaderValue::from_shared(wrt.get_mut().take().freeze())
+    }
+}
+
+impl From<HttpDate> for SystemTime {
+    fn from(date: HttpDate) -> SystemTime {
+        let spec = date.0.to_timespec();
+        if spec.sec >= 0 {
+            UNIX_EPOCH + Duration::new(spec.sec as u64, spec.nsec as u32)
+        } else {
+            UNIX_EPOCH - Duration::new(spec.sec as u64, spec.nsec as u32)
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::HttpDate;
+    use time::Tm;
+
+    const NOV_07: HttpDate = HttpDate(Tm {
+        tm_nsec: 0,
+        tm_sec: 37,
+        tm_min: 48,
+        tm_hour: 8,
+        tm_mday: 7,
+        tm_mon: 10,
+        tm_year: 94,
+        tm_wday: 0,
+        tm_isdst: 0,
+        tm_yday: 0,
+        tm_utcoff: 0,
+    });
+
+    #[test]
+    fn test_date() {
+        assert_eq!(
+            "Sun, 07 Nov 1994 08:48:37 GMT".parse::<HttpDate>().unwrap(),
+            NOV_07
+        );
+        assert_eq!(
+            "Sunday, 07-Nov-94 08:48:37 GMT"
+                .parse::<HttpDate>()
+                .unwrap(),
+            NOV_07
+        );
+        assert_eq!(
+            "Sun Nov  7 08:48:37 1994".parse::<HttpDate>().unwrap(),
+            NOV_07
+        );
+        assert!("this-is-no-date".parse::<HttpDate>().is_err());
+    }
+}

actix-http/src/header/shared/mod.rs

@@ -0,0 +1,14 @@
+//! Copied for `hyper::header::shared`;
+
+pub use self::charset::Charset;
+pub use self::encoding::Encoding;
+pub use self::entity::EntityTag;
+pub use self::httpdate::HttpDate;
+pub use self::quality_item::{q, qitem, Quality, QualityItem};
+pub use language_tags::LanguageTag;
+
+mod charset;
+mod encoding;
+mod entity;
+mod httpdate;
+mod quality_item;

actix-http/src/header/shared/quality_item.rs

@@ -0,0 +1,291 @@
+use std::{cmp, fmt, str};
+
+use self::internal::IntoQuality;
+
+/// Represents a quality used in quality values.
+///
+/// Can be created with the `q` function.
+///
+/// # Implementation notes
+///
+/// The quality value is defined as a number between 0 and 1 with three decimal
+/// places. This means there are 1001 possible values. Since floating point
+/// numbers are not exact and the smallest floating point data type (`f32`)
+/// consumes four bytes, hyper uses an `u16` value to store the
+/// quality internally. For performance reasons you may set quality directly to
+/// a value between 0 and 1000 e.g. `Quality(532)` matches the quality
+/// `q=0.532`.
+///
+/// [RFC7231 Section 5.3.1](https://tools.ietf.org/html/rfc7231#section-5.3.1)
+/// gives more information on quality values in HTTP header fields.
+#[derive(Copy, Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+pub struct Quality(u16);
+
+impl Default for Quality {
+    fn default() -> Quality {
+        Quality(1000)
+    }
+}
+
+/// Represents an item with a quality value as defined in
+/// [RFC7231](https://tools.ietf.org/html/rfc7231#section-5.3.1).
+#[derive(Clone, PartialEq, Debug)]
+pub struct QualityItem<T> {
+    /// The actual contents of the field.
+    pub item: T,
+    /// The quality (client or server preference) for the value.
+    pub quality: Quality,
+}
+
+impl<T> QualityItem<T> {
+    /// Creates a new `QualityItem` from an item and a quality.
+    /// The item can be of any type.
+    /// The quality should be a value in the range [0, 1].
+    pub fn new(item: T, quality: Quality) -> QualityItem<T> {
+        QualityItem { item, quality }
+    }
+}
+
+impl<T: PartialEq> cmp::PartialOrd for QualityItem<T> {
+    fn partial_cmp(&self, other: &QualityItem<T>) -> Option<cmp::Ordering> {
+        self.quality.partial_cmp(&other.quality)
+    }
+}
+
+impl<T: fmt::Display> fmt::Display for QualityItem<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Display::fmt(&self.item, f)?;
+        match self.quality.0 {
+            1000 => Ok(()),
+            0 => f.write_str("; q=0"),
+            x => write!(f, "; q=0.{}", format!("{:03}", x).trim_end_matches('0')),
+        }
+    }
+}
+
+impl<T: str::FromStr> str::FromStr for QualityItem<T> {
+    type Err = crate::error::ParseError;
+
+    fn from_str(s: &str) -> Result<QualityItem<T>, crate::error::ParseError> {
+        if !s.is_ascii() {
+            return Err(crate::error::ParseError::Header);
+        }
+        // Set defaults used if parsing fails.
+        let mut raw_item = s;
+        let mut quality = 1f32;
+
+        let parts: Vec<&str> = s.rsplitn(2, ';').map(|x| x.trim()).collect();
+        if parts.len() == 2 {
+            if parts[0].len() < 2 {
+                return Err(crate::error::ParseError::Header);
+            }
+            let start = &parts[0][0..2];
+            if start == "q=" || start == "Q=" {
+                let q_part = &parts[0][2..parts[0].len()];
+                if q_part.len() > 5 {
+                    return Err(crate::error::ParseError::Header);
+                }
+                match q_part.parse::<f32>() {
+                    Ok(q_value) => {
+                        if 0f32 <= q_value && q_value <= 1f32 {
+                            quality = q_value;
+                            raw_item = parts[1];
+                        } else {
+                            return Err(crate::error::ParseError::Header);
+                        }
+                    }
+                    Err(_) => return Err(crate::error::ParseError::Header),
+                }
+            }
+        }
+        match raw_item.parse::<T>() {
+            // we already checked above that the quality is within range
+            Ok(item) => Ok(QualityItem::new(item, from_f32(quality))),
+            Err(_) => Err(crate::error::ParseError::Header),
+        }
+    }
+}
+
+#[inline]
+fn from_f32(f: f32) -> Quality {
+    // this function is only used internally. A check that `f` is within range
+    // should be done before calling this method. Just in case, this
+    // debug_assert should catch if we were forgetful
+    debug_assert!(
+        f >= 0f32 && f <= 1f32,
+        "q value must be between 0.0 and 1.0"
+    );
+    Quality((f * 1000f32) as u16)
+}
+
+/// Convenience function to wrap a value in a `QualityItem`
+/// Sets `q` to the default 1.0
+pub fn qitem<T>(item: T) -> QualityItem<T> {
+    QualityItem::new(item, Default::default())
+}
+
+/// Convenience function to create a `Quality` from a float or integer.
+///
+/// Implemented for `u16` and `f32`. Panics if value is out of range.
+pub fn q<T: IntoQuality>(val: T) -> Quality {
+    val.into_quality()
+}
+
+mod internal {
+    use super::Quality;
+
+    // TryFrom is probably better, but it's not stable. For now, we want to
+    // keep the functionality of the `q` function, while allowing it to be
+    // generic over `f32` and `u16`.
+    //
+    // `q` would panic before, so keep that behavior. `TryFrom` can be
+    // introduced later for a non-panicking conversion.
+
+    pub trait IntoQuality: Sealed + Sized {
+        fn into_quality(self) -> Quality;
+    }
+
+    impl IntoQuality for f32 {
+        fn into_quality(self) -> Quality {
+            assert!(
+                self >= 0f32 && self <= 1f32,
+                "float must be between 0.0 and 1.0"
+            );
+            super::from_f32(self)
+        }
+    }
+
+    impl IntoQuality for u16 {
+        fn into_quality(self) -> Quality {
+            assert!(self <= 1000, "u16 must be between 0 and 1000");
+            Quality(self)
+        }
+    }
+
+    pub trait Sealed {}
+    impl Sealed for u16 {}
+    impl Sealed for f32 {}
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::encoding::*;
+    use super::*;
+
+    #[test]
+    fn test_quality_item_fmt_q_1() {
+        let x = qitem(Chunked);
+        assert_eq!(format!("{}", x), "chunked");
+    }
+    #[test]
+    fn test_quality_item_fmt_q_0001() {
+        let x = QualityItem::new(Chunked, Quality(1));
+        assert_eq!(format!("{}", x), "chunked; q=0.001");
+    }
+    #[test]
+    fn test_quality_item_fmt_q_05() {
+        // Custom value
+        let x = QualityItem {
+            item: EncodingExt("identity".to_owned()),
+            quality: Quality(500),
+        };
+        assert_eq!(format!("{}", x), "identity; q=0.5");
+    }
+
+    #[test]
+    fn test_quality_item_fmt_q_0() {
+        // Custom value
+        let x = QualityItem {
+            item: EncodingExt("identity".to_owned()),
+            quality: Quality(0),
+        };
+        assert_eq!(x.to_string(), "identity; q=0");
+    }
+
+    #[test]
+    fn test_quality_item_from_str1() {
+        let x: Result<QualityItem<Encoding>, _> = "chunked".parse();
+        assert_eq!(
+            x.unwrap(),
+            QualityItem {
+                item: Chunked,
+                quality: Quality(1000),
+            }
+        );
+    }
+    #[test]
+    fn test_quality_item_from_str2() {
+        let x: Result<QualityItem<Encoding>, _> = "chunked; q=1".parse();
+        assert_eq!(
+            x.unwrap(),
+            QualityItem {
+                item: Chunked,
+                quality: Quality(1000),
+            }
+        );
+    }
+    #[test]
+    fn test_quality_item_from_str3() {
+        let x: Result<QualityItem<Encoding>, _> = "gzip; q=0.5".parse();
+        assert_eq!(
+            x.unwrap(),
+            QualityItem {
+                item: Gzip,
+                quality: Quality(500),
+            }
+        );
+    }
+    #[test]
+    fn test_quality_item_from_str4() {
+        let x: Result<QualityItem<Encoding>, _> = "gzip; q=0.273".parse();
+        assert_eq!(
+            x.unwrap(),
+            QualityItem {
+                item: Gzip,
+                quality: Quality(273),
+            }
+        );
+    }
+    #[test]
+    fn test_quality_item_from_str5() {
+        let x: Result<QualityItem<Encoding>, _> = "gzip; q=0.2739999".parse();
+        assert!(x.is_err());
+    }
+    #[test]
+    fn test_quality_item_from_str6() {
+        let x: Result<QualityItem<Encoding>, _> = "gzip; q=2".parse();
+        assert!(x.is_err());
+    }
+    #[test]
+    fn test_quality_item_ordering() {
+        let x: QualityItem<Encoding> = "gzip; q=0.5".parse().ok().unwrap();
+        let y: QualityItem<Encoding> = "gzip; q=0.273".parse().ok().unwrap();
+        let comparision_result: bool = x.gt(&y);
+        assert!(comparision_result)
+    }
+
+    #[test]
+    fn test_quality() {
+        assert_eq!(q(0.5), Quality(500));
+    }
+
+    #[test]
+    #[should_panic] // FIXME - 32-bit msvc unwinding broken
+    #[cfg_attr(all(target_arch = "x86", target_env = "msvc"), ignore)]
+    fn test_quality_invalid() {
+        q(-1.0);
+    }
+
+    #[test]
+    #[should_panic] // FIXME - 32-bit msvc unwinding broken
+    #[cfg_attr(all(target_arch = "x86", target_env = "msvc"), ignore)]
+    fn test_quality_invalid2() {
+        q(2.0);
+    }
+
+    #[test]
+    fn test_fuzzing_bugs() {
+        assert!("99999;".parse::<QualityItem<String>>().is_err());
+        assert!("\x0d;;;=\u{d6aa}==".parse::<QualityItem<String>>().is_err())
+    }
+}