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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 crate::provider::*;
use crate::{LocaleExpander, LocaleTransformError};
use icu_locid::subtags::Script;
use icu_locid::LanguageIdentifier;
use icu_provider::prelude::*;
/// Represents the direction of a script.
///
/// [`LocaleDirectionality`] can be used to get this information.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
#[non_exhaustive]
pub enum Direction {
/// The script is left-to-right.
LeftToRight,
/// The script is right-to-left.
RightToLeft,
}
/// Provides methods to determine the direction of a locale.
///
/// # Examples
///
/// ```
/// use icu::locid::locale;
/// use icu::locid_transform::{Direction, LocaleDirectionality};
///
/// let ld = LocaleDirectionality::new();
///
/// assert_eq!(ld.get(&locale!("en")), Some(Direction::LeftToRight));
/// ```
#[derive(Debug)]
pub struct LocaleDirectionality {
script_direction: DataPayload<ScriptDirectionV1Marker>,
expander: LocaleExpander,
}
#[cfg(feature = "compiled_data")]
impl Default for LocaleDirectionality {
fn default() -> Self {
Self::new()
}
}
impl LocaleDirectionality {
/// Creates a [`LocaleDirectionality`] from compiled data.
///
/// This includes limited likely subtags data, see [`LocaleExpander::new()`].
#[cfg(feature = "compiled_data")]
pub const fn new() -> Self {
Self::new_with_expander(LocaleExpander::new())
}
// Note: This is a custom impl because the bounds on `try_new_unstable` don't suffice
#[doc = icu_provider::gen_any_buffer_unstable_docs!(ANY, Self::new)]
pub fn try_new_with_any_provider(
provider: &(impl AnyProvider + ?Sized),
) -> Result<LocaleDirectionality, LocaleTransformError> {
let expander = LocaleExpander::try_new_with_any_provider(provider)?;
Self::try_new_with_expander_unstable(&provider.as_downcasting(), expander)
}
// Note: This is a custom impl because the bounds on `try_new_unstable` don't suffice
#[doc = icu_provider::gen_any_buffer_unstable_docs!(BUFFER, Self::new)]
#[cfg(feature = "serde")]
pub fn try_new_with_buffer_provider(
provider: &(impl BufferProvider + ?Sized),
) -> Result<LocaleDirectionality, LocaleTransformError> {
let expander = LocaleExpander::try_new_with_buffer_provider(provider)?;
Self::try_new_with_expander_unstable(&provider.as_deserializing(), expander)
}
#[doc = icu_provider::gen_any_buffer_unstable_docs!(UNSTABLE, Self::new)]
pub fn try_new_unstable<P>(provider: &P) -> Result<LocaleDirectionality, LocaleTransformError>
where
P: DataProvider<ScriptDirectionV1Marker>
+ DataProvider<LikelySubtagsForLanguageV1Marker>
+ DataProvider<LikelySubtagsForScriptRegionV1Marker>
+ ?Sized,
{
let expander = LocaleExpander::try_new_unstable(provider)?;
Self::try_new_with_expander_unstable(provider, expander)
}
/// Creates a [`LocaleDirectionality`] with a custom [`LocaleExpander`] and compiled data.
///
/// This allows using [`LocaleExpander::new_extended()`] with data for all locales.
///
/// # Examples
///
/// ```
/// use icu::locid::locale;
/// use icu::locid_transform::{
/// Direction, LocaleDirectionality, LocaleExpander,
/// };
///
/// let ld_default = LocaleDirectionality::new();
///
/// assert_eq!(ld_default.get(&locale!("jbn")), None);
///
/// let expander = LocaleExpander::new_extended();
/// let ld_extended = LocaleDirectionality::new_with_expander(expander);
///
/// assert_eq!(
/// ld_extended.get(&locale!("jbn")),
/// Some(Direction::RightToLeft)
/// );
/// ```
#[cfg(feature = "compiled_data")]
pub const fn new_with_expander(expander: LocaleExpander) -> Self {
LocaleDirectionality {
script_direction: DataPayload::from_static_ref(
crate::provider::Baked::SINGLETON_LOCID_TRANSFORM_SCRIPT_DIR_V1,
),
expander,
}
}
#[doc = icu_provider::gen_any_buffer_unstable_docs!(UNSTABLE, Self::new_with_expander)]
pub fn try_new_with_expander_unstable<P>(
provider: &P,
expander: LocaleExpander,
) -> Result<LocaleDirectionality, LocaleTransformError>
where
P: DataProvider<ScriptDirectionV1Marker> + ?Sized,
{
let script_direction = provider.load(Default::default())?.take_payload()?;
Ok(LocaleDirectionality {
script_direction,
expander,
})
}
/// Returns the script direction of the given locale.
///
/// Note that the direction is a property of the script of a locale, not of the language. As such,
/// when given a locale without an associated script tag (i.e., `locale!("en")` vs. `locale!("en-Latn")`),
/// this method first tries to infer the script using the language and region before returning its direction.
///
/// If you already have a script struct and want to get its direction, you should use
/// `Locale::from(Some(my_script))` and call this method.
///
/// This method will return `None` if either a locale's script cannot be determined, or there is no information
/// for the script.
///
/// # Examples
///
/// Using an existing locale:
///
/// ```
/// use icu::locid::locale;
/// use icu::locid_transform::{Direction, LocaleDirectionality};
///
/// let ld = LocaleDirectionality::new();
///
/// assert_eq!(ld.get(&locale!("en-US")), Some(Direction::LeftToRight));
///
/// assert_eq!(ld.get(&locale!("ar")), Some(Direction::RightToLeft));
///
/// assert_eq!(ld.get(&locale!("en-Arab")), Some(Direction::RightToLeft));
///
/// assert_eq!(ld.get(&locale!("foo")), None);
/// ```
///
/// Using a script directly:
///
/// ```
/// use icu::locid::subtags::script;
/// use icu::locid::Locale;
/// use icu::locid_transform::{Direction, LocaleDirectionality};
///
/// let ld = LocaleDirectionality::new();
///
/// assert_eq!(
/// ld.get(&Locale::from(Some(script!("Latn")))),
/// Some(Direction::LeftToRight)
/// );
/// ```
pub fn get(&self, locale: impl AsRef<LanguageIdentifier>) -> Option<Direction> {
let script = self.expander.get_likely_script(locale.as_ref())?;
if self.script_in_ltr(script) {
Some(Direction::LeftToRight)
} else if self.script_in_rtl(script) {
Some(Direction::RightToLeft)
} else {
None
}
}
/// Returns whether the given locale is right-to-left.
///
/// Note that if this method returns `false`, the locale is either left-to-right or
/// the [`LocaleDirectionality`] does not include data for the locale.
/// You should use [`LocaleDirectionality::get`] if you need to differentiate between these cases.
///
/// See [`LocaleDirectionality::get`] for more information.
pub fn is_right_to_left(&self, locale: impl AsRef<LanguageIdentifier>) -> bool {
self.expander
.get_likely_script(locale.as_ref())
.map(|s| self.script_in_rtl(s))
.unwrap_or(false)
}
/// Returns whether the given locale is left-to-right.
///
/// Note that if this method returns `false`, the locale is either right-to-left or
/// the [`LocaleDirectionality`] does not include data for the locale.
/// You should use [`LocaleDirectionality::get`] if you need to differentiate between these cases.
///
/// See [`LocaleDirectionality::get`] for more information.
pub fn is_left_to_right(&self, locale: impl AsRef<LanguageIdentifier>) -> bool {
self.expander
.get_likely_script(locale.as_ref())
.map(|s| self.script_in_ltr(s))
.unwrap_or(false)
}
fn script_in_rtl(&self, script: Script) -> bool {
self.script_direction
.get()
.rtl
.binary_search(&script.into_tinystr().to_unvalidated())
.is_ok()
}
fn script_in_ltr(&self, script: Script) -> bool {
self.script_direction
.get()
.ltr
.binary_search(&script.into_tinystr().to_unvalidated())
.is_ok()
}
}