quoted-string

This crate provides utilities to handle quoted strings as they appear in multiple mail and web related RFCs. While it is mainly based on RFC5322 (Internet Message Format). It also supports Utf8 based on RFC6532 (optional) and is compatible with quoted-strings as they appear in mime types (including in HTTP/1.1 context).

What it currently does not support are soft-line breaks of RFC5322 and the obsolete parts of the syntax.

Grammar

no-rust quoted-string = DQUOTE *( *WSP qcontent) *WSP DQUOTE WSP = ' ' / '\t' qcontent = qtext / quoted-pair qtext = %d33 / %d35-91 / %d93-126 ; printable us-ascii chars not including '\\' and '"' quoted-pair = ("\" (VCHAR / WSP)) ; VCHAR are printable us-ascii chars

The obsolete syntax is currently not supported. Differences would be:

1. it would allow CTL's in qtext
2. it would allow quoted pairs to escape CTL's, '\0', '\n', '\r'

Nevertheless this part of the syntax is obsolete and should not be generated at all. Adding opt-in support for parts parsing quoted-string is in consideration.

Available functionality contains

• quote/quote_if_needed: quotes content (if needed) allowing the usage of a custom context to define when quoting is needed (e.g. in some places a empty quoted-string is ok but no empty unquoted-string). For optimization quote_if_needed returns a Cow<'a, str>.

• unquote: retrieve the content of a quoted string by unquoting it, also returns a Cow<'a, str> as simple string slicing can be used as long as no quoted-pair appears.

• ContentChars: an iterator over the chars of the content of a quoted-string, i.e. it will strip the surrounding DQUOTEs and will on the fly unquote quoted-pais not needing any extra memory allocations. This can be used to semantically compare two quoted strings regardless of how they used quoted-pairs, it implements Eq.

• CharType: classifies chars using a lookup table, mainly used to determine which chars can be represented in a quoted-string and how, but can also be used to e.g. determine if a string is a valid token (RFC2045)

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.