# actix_web::http::header::parse_extended_value - Rust
API documentation for the Rust `parse_extended_value` fn in crate `actix_web`.
Keywords: rust, rustlang, rust-lang, parse_extended_value

# Function actix_web::http::header::parse_extended_value [−] [src]

    pub fn parse_extended_value(val: &str) -> Result<ExtendedValue, ParseError>

Parses extended header parameter values (`ext-value`), as defined in RFC 5987.

Extended values are denoted by parameter names that end with `*`.

## ABNF

    ext-value     = charset  "'" [ language ] "'" value-chars
                  ; like RFC 2231's <extended-initial-value>
                  ; (see [RFC2231], Section 7)

    charset       = "UTF-8" / "ISO-8859-1" / mime-charset

    mime-charset  = 1*mime-charsetc
    mime-charsetc = ALPHA / DIGIT
                  / "!" / "#" / "$" / "%" / "&"
                  / "+" / "-" / "^" / "_" / "`"
                  / "{" / "}" / "~"
                  ; as <mime-charset> in Section 2.3 of [RFC2978]
                  ; except that the single quote is not included
                  ; SHOULD be registered in the IANA charset registry

    language      = <Language-Tag, defined in [RFC5646], Section 2.1>

    value-chars   = *( pct-encoded / attr-char )

    pct-encoded   = "%" HEXDIG HEXDIG
                  ; see [RFC3986], Section 2.1

    attr-char     = ALPHA / DIGIT
                  / "!" / "#" / "$" / "&" / "+" / "-" / "."
                  / "^" / "_" / "`" / "|" / "~"
                  ; token except ( "*" / "'" / "%" )

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