Source code
Revision control
Copy as Markdown
Other Tools
// 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
//! Transform Extensions provide information on content transformations in a given locale.
//!
//! The main struct for this extension is [`Transform`] which contains [`Fields`] and an
//! optional [`LanguageIdentifier`].
//!
//! [`LanguageIdentifier`]: super::super::LanguageIdentifier
//!
//! # Examples
//!
//! ```
//! use icu::locid::extensions::transform::{Fields, Key, Transform, Value};
//! use icu::locid::{LanguageIdentifier, Locale};
//!
//! let mut loc: Locale =
//! "en-US-t-es-ar-h0-hybrid".parse().expect("Parsing failed.");
//!
//! let lang: LanguageIdentifier =
//! "es-AR".parse().expect("Parsing LanguageIdentifier failed.");
//!
//! let key: Key = "h0".parse().expect("Parsing key failed.");
//! let value: Value = "hybrid".parse().expect("Parsing value failed.");
//!
//! assert_eq!(loc.extensions.transform.lang, Some(lang));
//! assert!(loc.extensions.transform.fields.contains_key(&key));
//! assert_eq!(loc.extensions.transform.fields.get(&key), Some(&value));
//!
//! assert_eq!(&loc.extensions.transform.to_string(), "t-es-ar-h0-hybrid");
//! ```
mod fields;
mod key;
mod value;
use core::cmp::Ordering;
pub use fields::Fields;
#[doc(inline)]
pub use key::{key, Key};
pub use value::Value;
use crate::parser::SubtagIterator;
use crate::parser::{parse_language_identifier_from_iter, ParserError, ParserMode};
use crate::shortvec::ShortBoxSlice;
use crate::subtags::{self, Language};
use crate::LanguageIdentifier;
use litemap::LiteMap;
/// A list of [`Unicode BCP47 T Extensions`] as defined in [`Unicode Locale
/// Identifier`] specification.
///
/// Transform extension carries information about source language or script of
/// transformed content, including content that has been transliterated, transcribed,
/// or translated, or in some other way influenced by the source (See [`RFC 6497`] for details).
///
/// # Examples
///
/// ```
/// use icu::locid::extensions::transform::{Key, Value};
/// use icu::locid::{LanguageIdentifier, Locale};
///
/// let mut loc: Locale =
/// "de-t-en-us-h0-hybrid".parse().expect("Parsing failed.");
///
/// let en_us: LanguageIdentifier = "en-US".parse().expect("Parsing failed.");
///
/// assert_eq!(loc.extensions.transform.lang, Some(en_us));
/// let key: Key = "h0".parse().expect("Parsing key failed.");
/// let value: Value = "hybrid".parse().expect("Parsing value failed.");
/// assert_eq!(loc.extensions.transform.fields.get(&key), Some(&value));
/// ```
#[derive(Clone, PartialEq, Eq, Debug, Default, Hash)]
#[allow(clippy::exhaustive_structs)] // spec-backed stable datastructure
pub struct Transform {
/// The [`LanguageIdentifier`] specified with this locale extension, or `None` if not present.
pub lang: Option<LanguageIdentifier>,
/// The key-value pairs present in this locale extension, with each extension key subtag
/// associated to its provided value subtag.
pub fields: Fields,
}
impl Transform {
/// Returns a new empty map of Transform extensions. Same as [`default()`](Default::default()), but is `const`.
///
/// # Examples
///
/// ```
/// use icu::locid::extensions::transform::Transform;
///
/// assert_eq!(Transform::new(), Transform::default());
/// ```
#[inline]
pub const fn new() -> Self {
Self {
lang: None,
fields: Fields::new(),
}
}
/// Returns `true` if there are no tfields and no tlang in the `TransformExtensionList`.
///
/// # Examples
///
/// ```
/// use icu::locid::Locale;
///
/// let mut loc: Locale = "en-US-t-es-ar".parse().expect("Parsing failed.");
///
/// assert!(!loc.extensions.transform.is_empty());
/// ```
pub fn is_empty(&self) -> bool {
self.lang.is_none() && self.fields.is_empty()
}
/// Clears the transform extension, effectively removing it from the locale.
///
/// # Examples
///
/// ```
/// use icu::locid::Locale;
///
/// let mut loc: Locale = "en-US-t-es-ar".parse().unwrap();
/// loc.extensions.transform.clear();
/// assert_eq!(loc, "en-US".parse().unwrap());
/// ```
pub fn clear(&mut self) {
self.lang = None;
self.fields.clear();
}
#[allow(clippy::type_complexity)]
pub(crate) fn as_tuple(
&self,
) -> (
Option<(
subtags::Language,
Option<subtags::Script>,
Option<subtags::Region>,
&subtags::Variants,
)>,
&Fields,
) {
(self.lang.as_ref().map(|l| l.as_tuple()), &self.fields)
}
/// Returns an ordering suitable for use in [`BTreeSet`].
///
/// The ordering may or may not be equivalent to string ordering, and it
/// may or may not be stable across ICU4X releases.
///
/// [`BTreeSet`]: alloc::collections::BTreeSet
pub fn total_cmp(&self, other: &Self) -> Ordering {
self.as_tuple().cmp(&other.as_tuple())
}
pub(crate) fn try_from_iter(iter: &mut SubtagIterator) -> Result<Self, ParserError> {
let mut tlang = None;
let mut tfields = LiteMap::new();
if let Some(subtag) = iter.peek() {
if Language::try_from_bytes(subtag).is_ok() {
tlang = Some(parse_language_identifier_from_iter(
iter,
ParserMode::Partial,
)?);
}
}
let mut current_tkey = None;
let mut current_tvalue = ShortBoxSlice::new();
let mut has_current_tvalue = false;
while let Some(subtag) = iter.peek() {
if let Some(tkey) = current_tkey {
if let Ok(val) = Value::parse_subtag(subtag) {
has_current_tvalue = true;
if let Some(val) = val {
current_tvalue.push(val);
}
} else {
if !has_current_tvalue {
return Err(ParserError::InvalidExtension);
}
tfields.try_insert(tkey, Value::from_short_slice_unchecked(current_tvalue));
current_tkey = None;
current_tvalue = ShortBoxSlice::new();
has_current_tvalue = false;
continue;
}
} else if let Ok(tkey) = Key::try_from_bytes(subtag) {
current_tkey = Some(tkey);
} else {
break;
}
iter.next();
}
if let Some(tkey) = current_tkey {
if !has_current_tvalue {
return Err(ParserError::InvalidExtension);
}
tfields.try_insert(tkey, Value::from_short_slice_unchecked(current_tvalue));
}
Ok(Self {
lang: tlang,
fields: tfields.into(),
})
}
pub(crate) fn for_each_subtag_str<E, F>(&self, f: &mut F) -> Result<(), E>
where
F: FnMut(&str) -> Result<(), E>,
{
if self.is_empty() {
return Ok(());
}
f("t")?;
if let Some(lang) = &self.lang {
lang.for_each_subtag_str_lowercased(f)?;
}
self.fields.for_each_subtag_str(f)
}
}
writeable::impl_display_with_writeable!(Transform);
impl writeable::Writeable for Transform {
fn write_to<W: core::fmt::Write + ?Sized>(&self, sink: &mut W) -> core::fmt::Result {
if self.is_empty() {
return Ok(());
}
sink.write_str("t")?;
if let Some(lang) = &self.lang {
sink.write_char('-')?;
lang.write_lowercased_to(sink)?;
}
if !self.fields.is_empty() {
sink.write_char('-')?;
writeable::Writeable::write_to(&self.fields, sink)?;
}
Ok(())
}
fn writeable_length_hint(&self) -> writeable::LengthHint {
if self.is_empty() {
return writeable::LengthHint::exact(0);
}
let mut result = writeable::LengthHint::exact(1);
if let Some(lang) = &self.lang {
result += writeable::Writeable::writeable_length_hint(lang) + 1;
}
if !self.fields.is_empty() {
result += writeable::Writeable::writeable_length_hint(&self.fields) + 1;
}
result
}
}