Struct icu_locale_core::LanguageIdentifier

pub struct LanguageIdentifier {
    pub language: Language,
    pub script: Option<Script>,
    pub region: Option<Region>,
    pub variants: Variants,
}

A core struct representing a Unicode BCP47 Language Identifier.

Parsing

Unicode recognizes three levels of standard conformance for any language identifier:

• well-formed - syntactically correct
• valid - well-formed and only uses registered language, region, script and variant subtags…
• canonical - valid and no deprecated codes or structure.

At the moment parsing normalizes a well-formed language identifier converting _ separators to - and adjusting casing to conform to the Unicode standard.

Any syntactically invalid subtags will cause the parsing to fail with an error.

This operation normalizes syntax to be well-formed. No legacy subtag replacements is performed. For validation and canonicalization, see LocaleCanonicalizer.

Ordering

This type deliberately does not implement Ord or PartialOrd because there are multiple possible orderings, and the team did not want to favor one over any other.

Instead, there are functions available that return these different orderings:

• LanguageIdentifier::strict_cmp
• LanguageIdentifier::total_cmp

See issue: https://github.com/unicode-org/icu4x/issues/1215

Examples

Simple example:

use icu::locale::{
    langid,
    subtags::{language, region},
};

let li = langid!("en-US");

assert_eq!(li.language, language!("en"));
assert_eq!(li.script, None);
assert_eq!(li.region, Some(region!("US")));
assert_eq!(li.variants.len(), 0);

More complex example:

use icu::locale::{
    langid,
    subtags::{language, region, script, variant},
};

let li = langid!("eN_latn_Us-Valencia");

assert_eq!(li.language, language!("en"));
assert_eq!(li.script, Some(script!("Latn")));
assert_eq!(li.region, Some(region!("US")));
assert_eq!(li.variants.get(0), Some(&variant!("valencia")));

Fields

language: Language

Language subtag of the language identifier.

script: Option<Script>

Script subtag of the language identifier.

region: Option<Region>

Region subtag of the language identifier.

variants: Variants

Variant subtags of the language identifier.

Implementations

impl LanguageIdentifier

pub fn try_from_str(s: &str) -> Result<Self, ParseError>

A constructor which takes a utf8 slice, parses it and produces a well-formed LanguageIdentifier.

Examples

use icu::locale::LanguageIdentifier;

LanguageIdentifier::try_from_str("en-US").expect("Parsing failed");

pub fn try_from_utf8(code_units: &[u8]) -> Result<Self, ParseError>

See Self::try_from_str

pub fn try_from_locale_bytes(v: &[u8]) -> Result<Self, ParseError>

A constructor which takes a utf8 slice which may contain extension keys, parses it and produces a well-formed LanguageIdentifier.

Examples

use icu::locale::{langid, LanguageIdentifier};

let li = LanguageIdentifier::try_from_locale_bytes(b"en-US-x-posix")
    .expect("Parsing failed.");

assert_eq!(li, langid!("en-US"));

This method should be used for input that may be a locale identifier. All extensions will be lost.

pub const fn default() -> Self

Const-friendly version of Default::default.

pub const fn is_default(&self) -> bool

Whether this language identifier equals Self::default.

pub fn normalize_utf8(input: &[u8]) -> Result<Cow<'_, str>, ParseError>

Normalize the language identifier (operating on UTF-8 formatted byte slices)

This operation will normalize casing and the separator.

Examples

use icu::locale::LanguageIdentifier;

assert_eq!(
    LanguageIdentifier::normalize("pL_latn_pl").as_deref(),
    Ok("pl-Latn-PL")
);

pub fn normalize(input: &str) -> Result<Cow<'_, str>, ParseError>

Normalize the language identifier (operating on strings)

This operation will normalize casing and the separator.

Examples

use icu::locale::LanguageIdentifier;

assert_eq!(
    LanguageIdentifier::normalize("pL_latn_pl").as_deref(),
    Ok("pl-Latn-PL")
);

pub fn strict_cmp(&self, other: &[u8]) -> Ordering

Compare this LanguageIdentifier with BCP-47 bytes.

The return value is equivalent to what would happen if you first converted this LanguageIdentifier to a BCP-47 string and then performed a byte comparison.

This function is case-sensitive and results in a total order, so it is appropriate for binary search. The only argument producing Ordering::Equal is self.to_string().

Examples

use icu::locale::LanguageIdentifier;
use std::cmp::Ordering;

let bcp47_strings: &[&str] = &[
    "pl-Latn-PL",
    "und",
    "und-Adlm",
    "und-GB",
    "und-ZA",
    "und-fonipa",
    "zh",
];

for ab in bcp47_strings.windows(2) {
    let a = ab[0];
    let b = ab[1];
    assert!(a.cmp(b) == Ordering::Less);
    let a_langid = a.parse::<LanguageIdentifier>().unwrap();
    assert!(a_langid.strict_cmp(a.as_bytes()) == Ordering::Equal);
    assert!(a_langid.strict_cmp(b.as_bytes()) == Ordering::Less);
}

pub fn total_cmp(&self, other: &Self) -> Ordering

Compare this LanguageIdentifier with another LanguageIdentifier field-by-field. The result is a total ordering sufficient for use in a BTreeSet.

Unlike LanguageIdentifier::strict_cmp, the ordering may or may not be equivalent to string ordering, and it may or may not be stable across ICU4X releases.

Examples

Using a wrapper to add one of these to a BTreeSet:

use icu::locale::LanguageIdentifier;
use std::cmp::Ordering;
use std::collections::BTreeSet;

#[derive(PartialEq, Eq)]
struct LanguageIdentifierTotalOrd(LanguageIdentifier);

impl Ord for LanguageIdentifierTotalOrd {
    fn cmp(&self, other: &Self) -> Ordering {
        self.0.total_cmp(&other.0)
    }
}

impl PartialOrd for LanguageIdentifierTotalOrd {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}

let _: BTreeSet<LanguageIdentifierTotalOrd> = unimplemented!();

pub fn normalizing_eq(&self, other: &str) -> bool

Compare this LanguageIdentifier with a potentially unnormalized BCP-47 string.

The return value is equivalent to what would happen if you first parsed the BCP-47 string to a LanguageIdentifier and then performed a structural comparison.

Examples

use icu::locale::LanguageIdentifier;

let bcp47_strings: &[&str] = &[
    "pl-LaTn-pL",
    "uNd",
    "UnD-adlm",
    "uNd-GB",
    "UND-FONIPA",
    "ZH",
];

for a in bcp47_strings {
    assert!(a.parse::<LanguageIdentifier>().unwrap().normalizing_eq(a));
}

Trait Implementations

impl Bake for LanguageIdentifier

fn bake(&self, env: &CrateEnv) -> TokenStream

Returns a TokenStream that would evaluate to self.

impl Clone for LanguageIdentifier

fn clone(&self) -> LanguageIdentifier

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LanguageIdentifier

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for LanguageIdentifier

fn default() -> LanguageIdentifier

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for LanguageIdentifier

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for LanguageIdentifier

This trait is implemented for compatibility with fmt!. To create a string, [Writeable::write_to_string] is usually more efficient.

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<&LanguageIdentifier> for (Language, Option<Script>, Option<Region>)

Convert from a LanguageIdentifier to an LSR tuple.

Examples

use icu::locale::{
    langid,
    subtags::{language, region, script},
};

let lid = langid!("en-Latn-US");
let (lang, script, region) = (&lid).into();

assert_eq!(lang, language!("en"));
assert_eq!(script, Some(script!("Latn")));
assert_eq!(region, Some(region!("US")));

fn from(langid: &LanguageIdentifier) -> Self

Converts to this type from the input type.

impl From<&LanguageIdentifier> for LocalePreferences

fn from(lid: &LanguageIdentifier) -> Self

Converts to this type from the input type.

impl From<(Language, Option<Script>, Option<Region>)> for LanguageIdentifier

Convert from an LSR tuple to a LanguageIdentifier.

Examples

use icu::locale::{
    langid,
    subtags::{language, region, script},
    LanguageIdentifier,
};

let lang = language!("en");
let script = script!("Latn");
let region = region!("US");
assert_eq!(
    LanguageIdentifier::from((lang, Some(script), Some(region))),
    langid!("en-Latn-US")
);

fn from(lsr: (Language, Option<Script>, Option<Region>)) -> Self

Converts to this type from the input type.

impl From<Language> for LanguageIdentifier

Examples

use icu::locale::{langid, subtags::language, LanguageIdentifier};

assert_eq!(LanguageIdentifier::from(language!("en")), langid!("en"));

fn from(language: Language) -> Self

Converts to this type from the input type.

impl From<LanguageIdentifier> for Locale

fn from(id: LanguageIdentifier) -> Self

Converts to this type from the input type.

impl From<Locale> for LanguageIdentifier

fn from(loc: Locale) -> Self

Converts to this type from the input type.

impl From<Option<Region>> for LanguageIdentifier

Examples

use icu::locale::{langid, subtags::region, LanguageIdentifier};

assert_eq!(
    LanguageIdentifier::from(Some(region!("US"))),
    langid!("und-US")
);

fn from(region: Option<Region>) -> Self

Converts to this type from the input type.

impl From<Option<Script>> for LanguageIdentifier

Examples

use icu::locale::{langid, subtags::script, LanguageIdentifier};

assert_eq!(
    LanguageIdentifier::from(Some(script!("latn"))),
    langid!("und-Latn")
);

fn from(script: Option<Script>) -> Self

Converts to this type from the input type.

impl FromStr for LanguageIdentifier

type Err = ParseError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for LanguageIdentifier

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for LanguageIdentifier

fn eq(&self, other: &LanguageIdentifier) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for LanguageIdentifier

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl Writeable for LanguageIdentifier

fn write_to<W: Write + ?Sized>(&self, sink: &mut W) -> Result

Writes a string to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to_parts, and discards any Part annotations.

fn writeable_length_hint(&self) -> LengthHint

Returns a hint for the number of UTF-8 bytes that will be written to the sink.

fn write_to_string(&self) -> Cow<'_, str>

Creates a new String with the data from this Writeable. Like ToString, but smaller and faster.

fn write_to_parts<S>(&self, sink: &mut S) -> Result<(), Error>

where S: PartsWrite + ?Sized,

Write bytes and Part annotations to the given sink. Errors from the sink are bubbled up. The default implementation delegates to write_to, and doesn’t produce any Part annotations.

impl Eq for LanguageIdentifier

impl StructuralPartialEq for LanguageIdentifier