| lib.rs |
`unic-langid` is a core API for parsing, manipulating, and serializing Unicode Language
Identifiers.
The crate provides algorithms for parsing a string into a well-formed language identifier
as defined by [`UTS #35: Unicode LDML 3.1 Unicode Language Identifier`].
# Examples
```
use unic_langid::LanguageIdentifier;
use unic_langid::subtags::{Language, Script, Region};
let mut li: LanguageIdentifier = "en-US".parse()
.expect("Parsing failed.");
let lang: Language = "en".parse().expect("Parsing failed.");
let region: Region = "US".parse().expect("Parsing failed.");
assert_eq!(li.language, lang);
assert_eq!(li.script, None);
assert_eq!(li.region, Some(region));
assert_eq!(li.variants().len(), 0);
let region: Region = "GB".parse().expect("Parsing failed.");
li.region = Some(region);
assert_eq!(li.to_string(), "en-GB");
```
For more details, see [`LanguageIdentifier`].
# Optional features
## `langid!`, `langids!`, and `langid_slice!` macros
If `feature = "macros"` is selected, the crate provides a procedural macro
which allows to construct build-time well-formed language identifiers with zero-cost at runtime.
``` ignore
use unic_langid::{langid, langid_slice, langids, lang, region, script, variant, LanguageIdentifier};
use unic_langid::subtags::{Language, Script, Region, Variant};
use std::str::FromStr;
let es_ar = langid!("es-AR");
let en_us = langid!("en-US");
assert_eq!(&es_ar.to_string(), "es-AR");
assert_eq!(&en_us.to_string(), "en-US");
let lang_ids = langids!("es-AR", "en-US", "de");
assert_eq!(lang_ids[0], "es-AR");
assert_eq!(lang_ids[1], "en-US");
assert_eq!(lang_ids[2], "de");
const LANGUAGES: &[LanguageIdentifier] = langid_slice!["en-GB", "fr"];
assert_eq!(lang!("pl"), "pl");
assert_eq!(lang!("pl"), Language::from_str("pl").unwrap());
assert_eq!(script!("latn"), "Latn");
assert_eq!(script!("latn"), Script::from_str("Latn").unwrap());
assert_eq!(region!("us"), "US");
assert_eq!(region!("us"), Region::from_str("us").unwrap());
assert_eq!(variant!("macos"), "macos");
assert_eq!(variant!("macos"), Variant::from_str("macos").unwrap());
```
The macros produce instances of `LanguageIdentifier` the same way as parsing from `&str` does,
but since the parsing is performed at build time, it doesn't need a `Result`.
At the moment `langid!` can also be used for const variables, but only if no variants are used.
The macros are optional to reduce the dependency chain and compilation time of `unic-langid`.
## Likely Subtags
If `feature = "likelysubtags"` is selected, the `LanguageIdentifier` gains two more methods:
* add_likely_subtags
* remove_likely_subtags
Both of them operate in place updating the existing `LanguageIdentifier` by either extending
subtags to most likely values, or removing the subtags that are not needed.
Both methods return a `bool` that indicates if the identifier has been modified.
``` ignore
use unic_langid::LanuageIdentifier;
let mut li: LanguageIdentifier = "fr-FR".parse()
.expect("Parsing failed.");
assert_eq!(li.add_likely_subtags(), true);
assert_eq!(li, "fr-Latn-FR");
assert_eq!(li.remove_likely_subtags(), true);
assert_eq!(li, "fr");
```
The feature is optional because it increases the binary size of the library by including
a data table for CLDR likelySubtags.
[`UTS #35: Unicode LDML 3.1 Unicode Language Identifier`]: https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier
[`LanguageIdentifier`]: ./struct.LanguageIdentifier.html |
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