Struct LocaleFallbackConfig 

#[non_exhaustive]
pub struct LocaleFallbackConfig {
    pub priority: LocaleFallbackPriority,
    pub extension_key: Option<Key>,
    pub fallback_supplement: Option<LocaleFallbackSupplement>,
}

Configuration settings for a particular fallback operation.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

priority: LocaleFallbackPriority

Strategy for choosing which subtags to drop during locale fallback.

Examples

Retain the language and script subtags until the final step:

use icu::locid::locale;
use icu::locid_transform::fallback::LocaleFallbackConfig;
use icu::locid_transform::fallback::LocaleFallbackPriority;
use icu::locid_transform::LocaleFallbacker;

// Set up the fallback iterator.
let fallbacker = LocaleFallbacker::new();
let mut config = LocaleFallbackConfig::default();
config.priority = LocaleFallbackPriority::Language;
let mut fallback_iterator = fallbacker
    .for_config(config)
    .fallback_for(locale!("ca-ES-valencia").into());

// Run the algorithm and check the results.
assert_eq!(fallback_iterator.get(), &locale!("ca-ES-valencia").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ca-ES").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ca-valencia").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ca").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und").into());

Retain the region subtag until the final step:

use icu::locid::locale;
use icu::locid_transform::fallback::LocaleFallbackConfig;
use icu::locid_transform::fallback::LocaleFallbackPriority;
use icu::locid_transform::LocaleFallbacker;

// Set up the fallback iterator.
let fallbacker = LocaleFallbacker::new();
let mut config = LocaleFallbackConfig::default();
config.priority = LocaleFallbackPriority::Region;
let mut fallback_iterator = fallbacker
    .for_config(config)
    .fallback_for(locale!("ca-ES-valencia").into());

// Run the algorithm and check the results.
assert_eq!(fallback_iterator.get(), &locale!("ca-ES-valencia").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ca-ES").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und-ES-valencia").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und-ES").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und").into());

extension_key: Option<Key>

An extension keyword to retain during locale fallback.

Examples

use icu::locid::locale;
use icu::locid_transform::fallback::LocaleFallbackConfig;
use icu::locid_transform::LocaleFallbacker;

// Set up the fallback iterator.
let fallbacker = LocaleFallbacker::new();
let mut config = LocaleFallbackConfig::default();
config.extension_key = Some(icu::locid::extensions::unicode::key!("nu"));
let mut fallback_iterator = fallbacker
    .for_config(config)
    .fallback_for(locale!("ar-EG-u-nu-latn").into());

// Run the algorithm and check the results.
assert_eq!(fallback_iterator.get(), &locale!("ar-EG-u-nu-latn").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ar-EG").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ar-u-nu-latn").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("ar").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und").into());

fallback_supplement: Option<LocaleFallbackSupplement>

Fallback supplement data key to customize fallback rules.

For example, most data keys for collation add additional parent locales, such as “yue” to “zh-Hant”, and data used for the "-u-co" extension keyword fallback.

Currently the only supported fallback supplement is LocaleFallbackSupplement::Collation, but more may be added in the future.

Examples

use icu::locid::locale;
use icu::locid_transform::fallback::LocaleFallbackConfig;
use icu::locid_transform::fallback::LocaleFallbackPriority;
use icu::locid_transform::fallback::LocaleFallbackSupplement;
use icu::locid_transform::LocaleFallbacker;

// Set up the fallback iterator.
let fallbacker = LocaleFallbacker::new();
let mut config = LocaleFallbackConfig::default();
config.priority = LocaleFallbackPriority::Collation;
config.fallback_supplement = Some(LocaleFallbackSupplement::Collation);
let mut fallback_iterator = fallbacker
    .for_config(config)
    .fallback_for(locale!("yue-HK").into());

// Run the algorithm and check the results.
assert_eq!(fallback_iterator.get(), &locale!("yue-HK").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("yue").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("zh-Hant").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("zh").into());
fallback_iterator.step();
assert_eq!(fallback_iterator.get(), &locale!("und").into());

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 4 bytes