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SASLprep implementation
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‎Cargo.toml

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@@ -4,3 +4,5 @@ version = "0.1.0"
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authors = ["Steven Fackler <sfackler@gmail.com>"]
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[dependencies]
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unicode-bidi = "0.3"
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unicode-normalization = "0.1"

‎src/lib.rs

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//! An implementation of the "stringprep" algorithm defined in [RFC 3454][].
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//!
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//! [RFC 3454]: https://tools.ietf.org/html/rfc3454
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#![warn(missing_docs)]
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extern crate unicode_bidi;
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extern crate unicode_normalization;
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use std::ascii::AsciiExt;
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use std::borrow::Cow;
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use std::error;
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use std::fmt;
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use unicode_normalization::UnicodeNormalization;
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pub mod tables;
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#[derive(Debug)]
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enum ErrorCause {
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ProhibitedCharacter(char),
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ProhibitedBidirectionalText,
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}
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/// An error performing the stringprep algorithm.
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#[derive(Debug)]
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pub struct Error(ErrorCause);
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impl fmt::Display for Error {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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match self.0 {
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ErrorCause::ProhibitedCharacter(c) => write!(fmt, "prohibited character `{}`", c),
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ErrorCause::ProhibitedBidirectionalText => write!(fmt, "prohibited bidirectional text"),
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}
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}
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}
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impl error::Error for Error {
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fn description(&self) -> &str {
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"error performing stringprep algorithm"
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}
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}
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/// Prepares a string with the SASLprep profile of the stringprep algorithm.
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///
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/// SASLprep is defined in [RFC 4013][].
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///
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/// [RFC 4013]: https://tools.ietf.org/html/rfc4013
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pub fn saslprep<'a>(s: &'a str) -> Result<Cow<'a, str>, Error> {
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// fast path for ascii text
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if s.chars()
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.all(|c| c.is_ascii() && !tables::ascii_control_character(c)) {
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return Ok(Cow::Borrowed(s));
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}
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let mapped = s.chars()
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.map(|c| if tables::non_ascii_space_character(c) {
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' '
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} else {
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c
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})
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.filter(|&c| !tables::commonly_mapped_to_nothing(c));
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let normalized = mapped.nfkc().collect::<String>();
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let prohibited = normalized
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.chars()
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.filter(|&c| {
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tables::non_ascii_space_character(c) || tables::ascii_control_character(c) ||
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tables::non_ascii_control_character(c) || tables::private_use(c) ||
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tables::non_character_code_point(c) ||
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tables::surrogate_code(c) || tables::inappropriate_for_plain_text(c) ||
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tables::inappropriate_for_canonical_representation(c) ||
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tables::change_display_properties_or_deprecated(c) ||
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tables::tagging_character(c)
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})
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.next();
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if let Some(c) = prohibited {
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return Err(Error(ErrorCause::ProhibitedCharacter(c)));
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}
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if normalized.contains(tables::bidi_r_or_al) {
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if normalized.contains(tables::bidi_l) {
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return Err(Error(ErrorCause::ProhibitedBidirectionalText));
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}
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if !tables::bidi_r_or_al(normalized.chars().next().unwrap()) ||
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!tables::bidi_r_or_al(normalized.chars().next_back().unwrap()) {
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return Err(Error(ErrorCause::ProhibitedBidirectionalText));
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}
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}
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Ok(Cow::Owned(normalized))
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}
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#[cfg(test)]
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mod tests {
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mod test {
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use super::*;
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#[test]
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fn it_works() {
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fn saslprep_examples() {
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assert_eq!(saslprep("I\u{00AD}X").unwrap(), "IX");
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assert_eq!(saslprep("user").unwrap(), "user");
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assert_eq!(saslprep("USER").unwrap(), "USER");
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assert_eq!(saslprep("\u{00AA}").unwrap(), "a");
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assert_eq!(saslprep("\u{2168}").unwrap(), "IX");
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assert!(saslprep("\u{0007}").is_err());
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assert!(saslprep("\u{0627}\u{0031}").is_err());
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}
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}

‎src/tables.rs

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//! Character Tables
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use unicode_bidi::{bidi_class, BidiClass};
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/// B.1 Commonly mapped to nothing
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pub fn commonly_mapped_to_nothing(c: char) -> bool {
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match c {
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'\u{00AD}' | '\u{034F}' | '\u{1806}' | '\u{180B}' | '\u{180C}' | '\u{180D}' |
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'\u{200B}' | '\u{200C}' | '\u{200D}' | '\u{2060}' | '\u{FE00}' | '\u{FE01}' |
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'\u{FE02}' | '\u{FE03}' | '\u{FE04}' | '\u{FE05}' | '\u{FE06}' | '\u{FE07}' |
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'\u{FE08}' | '\u{FE09}' | '\u{FE0A}' | '\u{FE0B}' | '\u{FE0C}' | '\u{FE0D}' |
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'\u{FE0E}' | '\u{FE0F}' | '\u{FEFF}' => true,
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_ => false,
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}
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}
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/// C.1.2 Non-ASCII space characters
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pub fn non_ascii_space_character(c: char) -> bool {
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match c {
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'\u{00A0}' | '\u{1680}' | '\u{2000}' | '\u{2001}' | '\u{2002}' | '\u{2003}' |
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'\u{2004}' | '\u{2005}' | '\u{2006}' | '\u{2007}' | '\u{2008}' | '\u{2009}' |
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'\u{200A}' | '\u{200B}' | '\u{202F}' | '\u{205F}' | '\u{3000}' => true,
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_ => false,
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}
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}
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/// C.2.1 ASCII control characters
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pub fn ascii_control_character(c: char) -> bool {
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match c {
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'\u{0000}'...'\u{001F}' |
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'\u{007F}' => true,
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_ => false,
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}
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}
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/// C.2.2 Non-ASCII control characters
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pub fn non_ascii_control_character(c: char) -> bool {
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match c {
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'\u{0080}'...'\u{009F}' |
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'\u{06DD}' |
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'\u{070F}' |
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'\u{180E}' |
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'\u{200C}' |
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'\u{200D}' |
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'\u{2028}' |
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'\u{2029}' |
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'\u{2060}' |
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'\u{2061}' |
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'\u{2062}' |
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'\u{2063}' |
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'\u{206A}'...'\u{206F}' |
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'\u{FEFF}' |
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'\u{FFF9}'...'\u{FFFC}' |
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'\u{1D173}'...'\u{1D17A}' => true,
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_ => false,
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}
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}
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/// C.3 Private use
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pub fn private_use(c: char) -> bool {
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match c {
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'\u{E000}'...'\u{F8FF}' |
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'\u{F0000}'...'\u{FFFFD}' |
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'\u{100000}'...'\u{10FFFD}' => true,
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_ => false,
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}
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}
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/// C.4 Non-character code points
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pub fn non_character_code_point(c: char) -> bool {
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match c {
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'\u{FDD0}'...'\u{FDEF}' |
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'\u{FFFE}'...'\u{FFFF}' |
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'\u{1FFFE}'...'\u{1FFFF}' |
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'\u{2FFFE}'...'\u{2FFFF}' |
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'\u{3FFFE}'...'\u{3FFFF}' |
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'\u{4FFFE}'...'\u{4FFFF}' |
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'\u{5FFFE}'...'\u{5FFFF}' |
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'\u{6FFFE}'...'\u{6FFFF}' |
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'\u{7FFFE}'...'\u{7FFFF}' |
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'\u{8FFFE}'...'\u{8FFFF}' |
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'\u{9FFFE}'...'\u{9FFFF}' |
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'\u{AFFFE}'...'\u{AFFFF}' |
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'\u{BFFFE}'...'\u{BFFFF}' |
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'\u{CFFFE}'...'\u{CFFFF}' |
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'\u{DFFFE}'...'\u{DFFFF}' |
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'\u{EFFFE}'...'\u{EFFFF}' |
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'\u{FFFFE}'...'\u{FFFFF}' |
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'\u{10FFFE}'...'\u{10FFFF}' => true,
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_ => false,
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}
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}
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/// C.5 Surrogate codes
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pub fn surrogate_code(c: char) -> bool {
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match c {
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// forbidden by rust
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/*'\u{D800}'...'\u{DFFF}' => true,*/
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_ => false,
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}
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}
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/// C.6 Inappropriate for plain text
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pub fn inappropriate_for_plain_text(c: char) -> bool {
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match c {
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'\u{FFF9}' | '\u{FFFA}' | '\u{FFFB}' | '\u{FFFC}' | '\u{FFFD}' => true,
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_ => false,
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}
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}
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/// C.7 Inappropriate for canonical representation
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pub fn inappropriate_for_canonical_representation(c: char) -> bool {
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match c {
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'\u{2FF0}'...'\u{2FFB}' => true,
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_ => false,
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}
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}
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/// C.8 Change display properties or are deprecated
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pub fn change_display_properties_or_deprecated(c: char) -> bool {
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match c {
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'\u{0340}' | '\u{0341}' | '\u{200E}' | '\u{200F}' | '\u{202A}' | '\u{202B}' |
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'\u{202C}' | '\u{202D}' | '\u{202E}' | '\u{206A}' | '\u{206B}' | '\u{206C}' |
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'\u{206D}' | '\u{206E}' | '\u{206F}' => true,
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_ => false,
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}
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}
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/// C.9 Tagging characters
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pub fn tagging_character(c: char) -> bool {
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match c {
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'\u{E0001}' |
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'\u{E0020}'...'\u{E007F}' => true,
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_ => false,
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}
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}
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/// D.1 Characters with bidirectional property "R" or "AL"
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pub fn bidi_r_or_al(c: char) -> bool {
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match bidi_class(c) {
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BidiClass::R | BidiClass::AL => true,
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_ => false,
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}
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}
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/// D.2 Characters with bidirectional property "L"
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pub fn bidi_l(c: char) -> bool {
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match bidi_class(c) {
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BidiClass::L => true,
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_ => false,
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}
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}

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