/rust/registry/src/index.crates.io-1949cf8c6b5b557f/icu_provider-2.0.0/src/fallback.rs

Source
// 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
// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).

//! Options to define fallback behaviour.
//!
//! These options are consumed by the `LocaleFallbacker` in the `icu_locales` crate
//! (or the `icu::locales` module), but are defined here because they are used by `DataMarkerInfo`.

/// Hint for which subtag to prioritize during fallback.
///
/// For example, `"en-US"` might fall back to either `"en"` or `"und-US"` depending
/// on this enum.
#[derive(Debug, PartialEq, Eq, Copy, Clone, PartialOrd, Ord)]
#[non_exhaustive]
pub enum LocaleFallbackPriority {
    /// Prioritize the language. This is the default behavior.
    ///
    /// For example, `"en-US"` should go to `"en"` and then `"und"`.
    Language,
    /// Prioritize the script.
    ///
    /// For example, `"en-US"` should go to `"en"` and then `"und-Latn"` and then `"und"`.
    Script,
    /// Prioritize the region.
    ///
    /// For example, `"en-US"` should go to `"und-US"` and then `"und"`.
    Region,
}

impl LocaleFallbackPriority {
    /// Const-friendly version of [`Default::default`].
    pub const fn default() -> Self {
        Self::Language
    }
}

impl Default for LocaleFallbackPriority {
    fn default() -> Self {
        Self::default()
    }
}

/// Configuration settings for a particular fallback operation.
#[derive(Debug, Clone, PartialEq, Eq, Copy)]
#[non_exhaustive]
pub struct LocaleFallbackConfig {
    /// Strategy for choosing which subtags to drop during locale fallback.
    ///
    /// # Examples
    ///
    /// Retain the language and script subtags until the final step:
    ///
    /// ```
    /// use icu::locale::fallback::LocaleFallbackConfig;
    /// use icu::locale::fallback::LocaleFallbackPriority;
    /// use icu::locale::locale;
    /// use icu::locale::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::locale::fallback::LocaleFallbackConfig;
    /// use icu::locale::fallback::LocaleFallbackPriority;
    /// use icu::locale::locale;
    /// use icu::locale::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());
    /// ```
    pub priority: LocaleFallbackPriority,
}

impl LocaleFallbackConfig {
    /// Const version of [`Default::default`].
    pub const fn default() -> Self {
        Self {
            priority: LocaleFallbackPriority::default(),
        }
    }
}

impl Default for LocaleFallbackConfig {
    fn default() -> Self {
        Self::default()
    }
}

Coverage Report

Created: 2025-10-10 06:28

Line	Count	Source
1		// This file is part of ICU4X. For terms of use, please see the file
2		// called LICENSE at the top level of the ICU4X source tree
3		// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5		//! Options to define fallback behaviour.
6		//!
7		//! These options are consumed by the `LocaleFallbacker` in the `icu_locales` crate
8		//! (or the `icu::locales` module), but are defined here because they are used by `DataMarkerInfo`.
9
10		/// Hint for which subtag to prioritize during fallback.
11		///
12		/// For example, `"en-US"` might fall back to either `"en"` or `"und-US"` depending
13		/// on this enum.
14		#[derive(Debug, PartialEq, Eq, Copy, Clone, PartialOrd, Ord)]
15		#[non_exhaustive]
16		pub enum LocaleFallbackPriority {
17		/// Prioritize the language. This is the default behavior.
18		///
19		/// For example, `"en-US"` should go to `"en"` and then `"und"`.
20		Language,
21		/// Prioritize the script.
22		///
23		/// For example, `"en-US"` should go to `"en"` and then `"und-Latn"` and then `"und"`.
24		Script,
25		/// Prioritize the region.
26		///
27		/// For example, `"en-US"` should go to `"und-US"` and then `"und"`.
28		Region,
29		}
30
31		impl LocaleFallbackPriority {
32		/// Const-friendly version of [`Default::default`].
33	0	pub const fn default() -> Self {
34	0	Self::Language
35	0	}
36		}
37
38		impl Default for LocaleFallbackPriority {
39	0	fn default() -> Self {
40	0	Self::default()
41	0	}
42		}
43
44		/// Configuration settings for a particular fallback operation.
45		#[derive(Debug, Clone, PartialEq, Eq, Copy)]
46		#[non_exhaustive]
47		pub struct LocaleFallbackConfig {
48		/// Strategy for choosing which subtags to drop during locale fallback.
49		///
50		/// # Examples
51		///
52		/// Retain the language and script subtags until the final step:
53		///
54		/// ```
55		/// use icu::locale::fallback::LocaleFallbackConfig;
56		/// use icu::locale::fallback::LocaleFallbackPriority;
57		/// use icu::locale::locale;
58		/// use icu::locale::LocaleFallbacker;
59		///
60		/// // Set up the fallback iterator.
61		/// let fallbacker = LocaleFallbacker::new();
62		/// let mut config = LocaleFallbackConfig::default();
63		/// config.priority = LocaleFallbackPriority::Language;
64		/// let mut fallback_iterator = fallbacker
65		/// .for_config(config)
66		/// .fallback_for(locale!("ca-ES-valencia").into());
67		///
68		/// // Run the algorithm and check the results.
69		/// assert_eq!(fallback_iterator.get(), &locale!("ca-ES-valencia").into());
70		/// fallback_iterator.step();
71		/// assert_eq!(fallback_iterator.get(), &locale!("ca-ES").into());
72		/// fallback_iterator.step();
73		/// assert_eq!(fallback_iterator.get(), &locale!("ca-valencia").into());
74		/// fallback_iterator.step();
75		/// assert_eq!(fallback_iterator.get(), &locale!("ca").into());
76		/// fallback_iterator.step();
77		/// assert_eq!(fallback_iterator.get(), &locale!("und").into());
78		/// ```
79		///
80		/// Retain the region subtag until the final step:
81		///
82		/// ```
83		/// use icu::locale::fallback::LocaleFallbackConfig;
84		/// use icu::locale::fallback::LocaleFallbackPriority;
85		/// use icu::locale::locale;
86		/// use icu::locale::LocaleFallbacker;
87		///
88		/// // Set up the fallback iterator.
89		/// let fallbacker = LocaleFallbacker::new();
90		/// let mut config = LocaleFallbackConfig::default();
91		/// config.priority = LocaleFallbackPriority::Region;
92		/// let mut fallback_iterator = fallbacker
93		/// .for_config(config)
94		/// .fallback_for(locale!("ca-ES-valencia").into());
95		///
96		/// // Run the algorithm and check the results.
97		/// assert_eq!(fallback_iterator.get(), &locale!("ca-ES-valencia").into());
98		/// fallback_iterator.step();
99		/// assert_eq!(fallback_iterator.get(), &locale!("ca-ES").into());
100		/// fallback_iterator.step();
101		/// assert_eq!(fallback_iterator.get(), &locale!("und-ES-valencia").into());
102		/// fallback_iterator.step();
103		/// assert_eq!(fallback_iterator.get(), &locale!("und-ES").into());
104		/// fallback_iterator.step();
105		/// assert_eq!(fallback_iterator.get(), &locale!("und").into());
106		/// ```
107		pub priority: LocaleFallbackPriority,
108		}
109
110		impl LocaleFallbackConfig {
111		/// Const version of [`Default::default`].
112	0	pub const fn default() -> Self {
113	0	Self {
114	0	priority: LocaleFallbackPriority::default(),
115	0	}
116	0	}
117		}
118
119		impl Default for LocaleFallbackConfig {
120	0	fn default() -> Self {
121	0	Self::default()
122	0	}
123		}