The `header::Formatter` ensures that a formatted header is written to a
line, and allows for headers that require multiple lines. The only
header to specifically require this is `Set-Cookie`.
BREAKING CHANGE: The `fmt_header` method has changed to take a different
formatter. In most cases, if your header also implements
`fmt::Display`, you can just call `f.fmt_line(self)`.
The Raw type repesents the raw bytes of a header-value.
Having a special type allows a couple of benefits:
- The exact representation has become private, allowing "uglier"
internals. Specifically, since the common case is for a header to only
have 1 line of bytes, an enum is used to skip allocating a Vec for only
1 line. Additionally, a Cow<'static, [u8]> is used, so static bytes
don't require a copy. Finally, since we can use static bytes, when
parsing, we can compare the incoming bytes against a couple of the most
common header-values, and possibly remove another copy.
- As its own type, the `Headers.set_raw` method can be generic over
`Into<Raw>`, which allows for more ergnomic method calls.
BREAKING CHANGE: `Header::parse_header` now receives `&Raw`, instead of
a `&[Vec<u8>]`. `Raw` provides several methods to ease using it, but
may require some changes to existing code.
Header::parse_header() returns now a hyper Result instead of an option
this will enable more precise Error messages in the future, currently
most failures are reported as ::Error::Header.
BREAKING CHANGE: parse_header returns Result instead of Option, related
code did also change
A single value header value can't be "", so `from_one_raw_str()` now
returns `None` on empty values. This makes custom checks in headers
obsolete.
BREAKING CHANGE: `from_one_raw_str()` returns `None` on empty values.
Add the HTTP/1.0 `Pragma` header field used to prevent older Caches, that
do not understand the `Cache-Control` header field from caching the ressource.
Closes#237
