mail-parse library is an abstraction over the actual
low-level libraries that are described in the next chapter.
Standards change, and so programs have to change to fit in the new
mold. For instance, RFC2045 describes a syntax for the
Content-Type header that only allows ASCII characters in the
parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
for continuation headers and non-ASCII characters.
The traditional way to deal with this is just to update the library functions to parse the new syntax. However, this is sometimes the wrong thing to do. In some instances it may be vital to be able to understand both the old syntax as well as the new syntax, and if there is only one library, one must choose between the old version of the library and the new version of the library.
The Emacs MIME library takes a different tack. It defines a
series of low-level libraries (rfc2047.el, rfc2231.el
and so on) that parses strictly according to the corresponding
standard. However, normal programs would not use the functions
provided by these libraries directly, but instead use the functions
provided by the
mail-parse library. The functions in this
library are just aliases to the corresponding functions in the latest
low-level libraries. Using this scheme, programs get a consistent
interface they can use, and library developers are free to create
write code that handles new standards.
The following functions are defined by this library:
Content-Typeheader and return a list on the following format:
("type/subtype" (attribute1 . value1) (attribute2 . value2) ...)
Here's an example:
(mail-header-parse-content-type "image/gif; name=\"b980912.gif\"") ⇒ ("image/gif" (name . "b980912.gif"))
Content-Dispositionheader and return a list on the same format as the function above.
(mail-content-type-get '("image/gif" (name . "b980912.gif")) 'name) ⇒ "b980912.gif"
(mail-header-remove-comments "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") ⇒ "Gnus/5.070027 "
(mail-header-remove-whitespace "image/gif; name=\"Name with spaces\"") ⇒ "image/gif;name=\"Name with spaces\""
(mail-header-get-comment "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)") ⇒ "Finnish Landrace"
(mail-header-parse-address "Hrvoje Niksic <email@example.com>") ⇒ ("firstname.lastname@example.org" . "Hrvoje Niksic")
(mail-header-parse-addresses "Hrvoje Niksic <email@example.com>, Steinar Bang <firstname.lastname@example.org>") ⇒ (("email@example.com" . "Hrvoje Niksic") ("firstname.lastname@example.org" . "Steinar Bang"))
(mail-encode-encoded-word-string "This is naïve, baby") ⇒ "This is =?iso-8859-1?q?na=EFve,?= baby"
(mail-decode-encoded-word-string "This is =?iso-8859-1?q?na=EFve,?= baby") ⇒ "This is naïve, baby"
mail-parse is an abstraction over
rfc2231. These are documented
in the subsequent sections.