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// This file is part of ICU4X. For terms of use, please see the file
// called LICENSE at the top level of the ICU4X source tree
use core::cmp::Ordering;
#[cfg(feature = "alloc")]
use core::str::FromStr;
use crate::parser;
use crate::subtags;
use crate::ParseError;
#[cfg(feature = "alloc")]
use alloc::borrow::Cow;
/// A core struct representing a [`Unicode BCP47 Language Identifier`].
///
/// # Ordering
///
/// This type deliberately does not implement `Ord` or `PartialOrd` because there are
/// multiple possible orderings. Depending on your use case, two orderings are available:
///
/// 1. A string ordering, suitable for stable serialization: [`LanguageIdentifier::strict_cmp`]
/// 2. A struct ordering, suitable for use with a BTreeSet: [`LanguageIdentifier::total_cmp`]
///
///
/// # 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`.
///
/// # 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")));
/// ```
///
/// [`Unicode BCP47 Language Identifier`]: https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier
#[derive(PartialEq, Eq, Clone, Hash)] // no Ord or PartialOrd: see docs
#[allow(clippy::exhaustive_structs)] // This struct is stable (and invoked by a macro)
pub struct LanguageIdentifier {
/// Language subtag of the language identifier.
pub language: subtags::Language,
/// Script subtag of the language identifier.
pub script: Option<subtags::Script>,
/// Region subtag of the language identifier.
pub region: Option<subtags::Region>,
/// Variant subtags of the language identifier.
pub variants: subtags::Variants,
}
impl LanguageIdentifier {
/// The unknown language identifier "und".
pub const UNKNOWN: Self = crate::langid!("und");
/// 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");
/// ```
#[inline]
#[cfg(feature = "alloc")]
pub fn try_from_str(s: &str) -> Result<Self, ParseError> {
Self::try_from_utf8(s.as_bytes())
}
/// See [`Self::try_from_str`]
#[cfg(feature = "alloc")]
pub fn try_from_utf8(code_units: &[u8]) -> Result<Self, ParseError> {
crate::parser::parse_language_identifier(code_units, parser::ParserMode::LanguageIdentifier)
}
#[doc(hidden)] // macro use
#[allow(clippy::type_complexity)]
// The return type should be `Result<Self, ParseError>` once the `const_precise_live_drops`
pub const fn try_from_utf8_with_single_variant(
code_units: &[u8],
) -> Result<
(
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
Option<subtags::Variant>,
),
ParseError,
> {
crate::parser::parse_language_identifier_with_single_variant(
code_units,
parser::ParserMode::LanguageIdentifier,
)
}
/// 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.
#[cfg(feature = "alloc")]
pub fn try_from_locale_bytes(v: &[u8]) -> Result<Self, ParseError> {
parser::parse_language_identifier(v, parser::ParserMode::Locale)
}
/// Whether this [`LanguageIdentifier`] equals [`LanguageIdentifier::UNKNOWN`].
pub const fn is_unknown(&self) -> bool {
self.language.is_unknown()
&& self.script.is_none()
&& self.region.is_none()
&& self.variants.is_empty()
}
/// 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")
/// );
/// ```
#[cfg(feature = "alloc")]
pub fn normalize_utf8(input: &[u8]) -> Result<Cow<str>, ParseError> {
let lang_id = Self::try_from_utf8(input)?;
Ok(writeable::to_string_or_borrow(&lang_id, input))
}
/// 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")
/// );
/// ```
#[cfg(feature = "alloc")]
pub fn normalize(input: &str) -> Result<Cow<str>, ParseError> {
Self::normalize_utf8(input.as_bytes())
}
/// 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
///
/// Sorting a list of langids with this method requires converting one of them to a string:
///
/// ```
/// use icu::locale::LanguageIdentifier;
/// use std::cmp::Ordering;
/// use writeable::Writeable;
///
/// // Random input order:
/// let bcp47_strings: &[&str] = &[
/// "ar-Latn",
/// "zh-Hant-TW",
/// "zh-TW",
/// "und-fonipa",
/// "zh-Hant",
/// "ar-SA",
/// ];
///
/// let mut langids = bcp47_strings
/// .iter()
/// .map(|s| s.parse().unwrap())
/// .collect::<Vec<LanguageIdentifier>>();
/// langids.sort_by(|a, b| {
/// let b = b.write_to_string();
/// a.strict_cmp(b.as_bytes())
/// });
/// let strict_cmp_strings = langids
/// .iter()
/// .map(|l| l.to_string())
/// .collect::<Vec<String>>();
///
/// // Output ordering, sorted alphabetically
/// let expected_ordering: &[&str] = &[
/// "ar-Latn",
/// "ar-SA",
/// "und-fonipa",
/// "zh-Hant",
/// "zh-Hant-TW",
/// "zh-TW",
/// ];
///
/// assert_eq!(expected_ordering, strict_cmp_strings);
/// ```
pub fn strict_cmp(&self, other: &[u8]) -> Ordering {
writeable::cmp_utf8(self, other)
}
pub(crate) fn as_tuple(
&self,
) -> (
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
&subtags::Variants,
) {
(self.language, self.script, self.region, &self.variants)
}
/// 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
///
/// This method returns a nonsensical ordering derived from the fields of the struct:
///
/// ```
/// use icu::locale::LanguageIdentifier;
/// use std::cmp::Ordering;
///
/// // Input strings, sorted alphabetically
/// let bcp47_strings: &[&str] = &[
/// "ar-Latn",
/// "ar-SA",
/// "und-fonipa",
/// "zh-Hant",
/// "zh-Hant-TW",
/// "zh-TW",
/// ];
/// assert!(bcp47_strings.windows(2).all(|w| w[0] < w[1]));
///
/// let mut langids = bcp47_strings
/// .iter()
/// .map(|s| s.parse().unwrap())
/// .collect::<Vec<LanguageIdentifier>>();
/// langids.sort_by(LanguageIdentifier::total_cmp);
/// let total_cmp_strings = langids
/// .iter()
/// .map(|l| l.to_string())
/// .collect::<Vec<String>>();
///
/// // Output ordering, sorted arbitrarily
/// let expected_ordering: &[&str] = &[
/// "ar-SA",
/// "ar-Latn",
/// "und-fonipa",
/// "zh-TW",
/// "zh-Hant",
/// "zh-Hant-TW",
/// ];
///
/// assert_eq!(expected_ordering, total_cmp_strings);
/// ```
///
/// Use a wrapper to add a [`LanguageIdentifier`] to a [`BTreeSet`]:
///
/// ```no_run
/// 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!();
/// ```
///
/// [`BTreeSet`]: alloc::collections::BTreeSet
pub fn total_cmp(&self, other: &Self) -> Ordering {
self.as_tuple().cmp(&other.as_tuple())
}
/// 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));
/// }
/// ```
pub fn normalizing_eq(&self, other: &str) -> bool {
macro_rules! subtag_matches {
($T:ty, $iter:ident, $expected:expr) => {
$iter
.next()
.map(|b| <$T>::try_from_utf8(b) == Ok($expected))
.unwrap_or(false)
};
}
let mut iter = parser::SubtagIterator::new(other.as_bytes());
if !subtag_matches!(subtags::Language, iter, self.language) {
return false;
}
if let Some(ref script) = self.script {
if !subtag_matches!(subtags::Script, iter, *script) {
return false;
}
}
if let Some(ref region) = self.region {
if !subtag_matches!(subtags::Region, iter, *region) {
return false;
}
}
for variant in self.variants.iter() {
if !subtag_matches!(subtags::Variant, iter, *variant) {
return false;
}
}
iter.next().is_none()
}
pub(crate) fn for_each_subtag_str<E, F>(&self, f: &mut F) -> Result<(), E>
where
F: FnMut(&str) -> Result<(), E>,
{
f(self.language.as_str())?;
if let Some(ref script) = self.script {
f(script.as_str())?;
}
if let Some(ref region) = self.region {
f(region.as_str())?;
}
for variant in self.variants.iter() {
f(variant.as_str())?;
}
Ok(())
}
/// Executes `f` on each subtag string of this `LanguageIdentifier`, with every string in
/// lowercase ascii form.
///
/// The default normalization of language identifiers uses titlecase scripts and uppercase
/// regions. However, this differs from [RFC6497 (BCP 47 Extension T)], which specifies:
///
/// > _The canonical form for all subtags in the extension is lowercase, with the fields
/// > ordered by the separators, alphabetically._
///
/// Hence, this method is used inside [`Transform Extensions`] to be able to get the correct
/// normalization of the language identifier.
///
/// As an example, the canonical form of locale **EN-LATN-CA-T-EN-LATN-CA** is
/// **en-Latn-CA-t-en-latn-ca**, with the script and region parts lowercased inside T extensions,
/// but titlecased and uppercased outside T extensions respectively.
///
/// [`Transform extensions`]: crate::extensions::transform
pub(crate) fn for_each_subtag_str_lowercased<E, F>(&self, f: &mut F) -> Result<(), E>
where
F: FnMut(&str) -> Result<(), E>,
{
f(self.language.as_str())?;
if let Some(ref script) = self.script {
f(script.to_tinystr().to_ascii_lowercase().as_str())?;
}
if let Some(ref region) = self.region {
f(region.to_tinystr().to_ascii_lowercase().as_str())?;
}
for variant in self.variants.iter() {
f(variant.as_str())?;
}
Ok(())
}
/// Writes this `LanguageIdentifier` to a sink, replacing uppercase ascii chars with
/// lowercase ascii chars.
///
/// The default normalization of language identifiers uses titlecase scripts and uppercase
/// regions. However, this differs from [RFC6497 (BCP 47 Extension T)], which specifies:
///
/// > _The canonical form for all subtags in the extension is lowercase, with the fields
/// > ordered by the separators, alphabetically._
///
/// Hence, this method is used inside [`Transform Extensions`] to be able to get the correct
/// normalization of the language identifier.
///
/// As an example, the canonical form of locale **EN-LATN-CA-T-EN-LATN-CA** is
/// **en-Latn-CA-t-en-latn-ca**, with the script and region parts lowercased inside T extensions,
/// but titlecased and uppercased outside T extensions respectively.
///
/// [`Transform extensions`]: crate::extensions::transform
pub(crate) fn write_lowercased_to<W: core::fmt::Write + ?Sized>(
&self,
sink: &mut W,
) -> core::fmt::Result {
let mut initial = true;
self.for_each_subtag_str_lowercased(&mut |subtag| {
if initial {
initial = false;
} else {
sink.write_char('-')?;
}
sink.write_str(subtag)
})
}
}
impl core::fmt::Debug for LanguageIdentifier {
fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
core::fmt::Display::fmt(&self, f)
}
}
#[cfg(feature = "alloc")]
impl FromStr for LanguageIdentifier {
type Err = ParseError;
#[inline]
fn from_str(s: &str) -> Result<Self, Self::Err> {
Self::try_from_str(s)
}
}
impl_writeable_for_each_subtag_str_no_test!(LanguageIdentifier, selff, selff.script.is_none() && selff.region.is_none() && selff.variants.is_empty() => selff.language.write_to_string());
#[test]
fn test_writeable() {
use writeable::assert_writeable_eq;
assert_writeable_eq!(LanguageIdentifier::UNKNOWN, "und");
assert_writeable_eq!("und-001".parse::<LanguageIdentifier>().unwrap(), "und-001");
assert_writeable_eq!(
"und-Mymr".parse::<LanguageIdentifier>().unwrap(),
"und-Mymr",
);
assert_writeable_eq!(
"my-Mymr-MM".parse::<LanguageIdentifier>().unwrap(),
"my-Mymr-MM",
);
assert_writeable_eq!(
"my-Mymr-MM-posix".parse::<LanguageIdentifier>().unwrap(),
"my-Mymr-MM-posix",
);
assert_writeable_eq!(
"zh-macos-posix".parse::<LanguageIdentifier>().unwrap(),
"zh-macos-posix",
);
}
/// # Examples
///
/// ```
/// use icu::locale::{langid, subtags::language, LanguageIdentifier};
///
/// assert_eq!(LanguageIdentifier::from(language!("en")), langid!("en"));
/// ```
impl From<subtags::Language> for LanguageIdentifier {
fn from(language: subtags::Language) -> Self {
Self {
language,
script: None,
region: None,
variants: subtags::Variants::new(),
}
}
}
/// # Examples
///
/// ```
/// use icu::locale::{langid, subtags::script, LanguageIdentifier};
///
/// assert_eq!(
/// LanguageIdentifier::from(Some(script!("latn"))),
/// langid!("und-Latn")
/// );
/// ```
impl From<Option<subtags::Script>> for LanguageIdentifier {
fn from(script: Option<subtags::Script>) -> Self {
Self {
language: subtags::Language::UNKNOWN,
script,
region: None,
variants: subtags::Variants::new(),
}
}
}
/// # Examples
///
/// ```
/// use icu::locale::{langid, subtags::region, LanguageIdentifier};
///
/// assert_eq!(
/// LanguageIdentifier::from(Some(region!("US"))),
/// langid!("und-US")
/// );
/// ```
impl From<Option<subtags::Region>> for LanguageIdentifier {
fn from(region: Option<subtags::Region>) -> Self {
Self {
language: subtags::Language::UNKNOWN,
script: None,
region,
variants: subtags::Variants::new(),
}
}
}
/// 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")
/// );
/// ```
impl
From<(
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
)> for LanguageIdentifier
{
fn from(
lsr: (
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
),
) -> Self {
Self {
language: lsr.0,
script: lsr.1,
region: lsr.2,
variants: subtags::Variants::new(),
}
}
}
/// 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")));
/// ```
impl From<&LanguageIdentifier>
for (
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
)
{
fn from(langid: &LanguageIdentifier) -> Self {
(langid.language, langid.script, langid.region)
}
}