First draft for implementing Local Displayname Algorithm #3587
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -7,9 +7,14 @@ | |
| use crate::options::*; | ||
| use crate::provider::*; | ||
| use alloc::borrow::Cow; | ||
| use alloc::string::String; | ||
| use alloc::vec; | ||
| use alloc::vec::Vec; | ||
| use icu_locid::{ | ||
| subtags::Language, subtags::Region, subtags::Script, subtags::Variant, LanguageIdentifier, | ||
| Locale, | ||
| }; | ||
| use icu_provider::prelude::*; | ||
| /// Lookup of the locale-specific display names by region code. | ||
| /// | ||
| /// # Example | ||
|
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@@ -110,7 +115,6 @@ pub struct ScriptDisplayNames { | |
| script_data: DataPayload<ScriptDisplayNamesV1Marker>, | ||
| } | ||
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| impl ScriptDisplayNames { | ||
| icu_provider::gen_any_buffer_data_constructors!( | ||
| locale: include, | ||
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@@ -188,7 +192,6 @@ pub struct VariantDisplayNames { | |
| variant_data: DataPayload<VariantDisplayNamesV1Marker>, | ||
| } | ||
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| impl VariantDisplayNames { | ||
| icu_provider::gen_any_buffer_data_constructors!( | ||
| locale: include, | ||
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@@ -333,9 +336,9 @@ impl LanguageDisplayNames { | |
| /// ) | ||
| /// .expect("Data should load successfully"); | ||
| /// | ||
| /// assert_eq!(display_name.of(&locale!("en-GB")), "British English"); | ||
| /// assert_eq!(display_name.of(&locale!("en")), "English"); | ||
| /// assert_eq!(display_name.of(&locale!("en-MX")), "English (Mexico)"); | ||
| /// assert_eq!(display_name.of(&locale!("xx-YY")), "xx (YY)"); | ||
| /// assert_eq!(display_name.of(&locale!("xx")), "xx"); | ||
| /// ``` | ||
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@@ -345,13 +348,11 @@ pub struct LocaleDisplayNamesFormatter { | |
| locale_data: DataPayload<LocaleDisplayNamesV1Marker>, | ||
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| language_data: DataPayload<LanguageDisplayNamesV1Marker>, | ||
| script_data: DataPayload<ScriptDisplayNamesV1Marker>, | ||
| region_data: DataPayload<RegionDisplayNamesV1Marker>, | ||
| variant_data: DataPayload<VariantDisplayNamesV1Marker>, | ||
| // key_data: DataPayload<KeyDisplayNamesV1Marker>, | ||
| // measurement_data: DataPayload<MeasurementSystemsDisplayNamesV1Marker>, | ||
| // subdivisions_data: DataPayload<SubdivisionsDisplayNamesV1Marker>, | ||
| // transforms_data: DataPayload<TransformsDisplayNamesV1Marker>, | ||
| } | ||
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@@ -404,90 +405,216 @@ impl LocaleDisplayNamesFormatter { | |
| } | ||
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| /// Returns the display name of a locale. | ||
| /// This implementation is based on the algorithm described in | ||
| /// <https://www.unicode.org/reports/tr35/tr35-general.html#locale_display_name_algorithm> | ||
| /// | ||
| // TODO: Make this return a writeable instead of using alloc | ||
| pub fn of<'a, 'b: 'a, 'c: 'a>(&'b self, locale: &'c Locale) -> Cow<'a, str> { | ||
| let longest_matching_identifier = self.find_longest_matching_subtag(locale); | ||
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||
| // Step - 1: Construct a locale display name string (LDN). | ||
| // Find the displayname for the longest_matching_subtag which was derived above. | ||
| let ldn = self.get_locale_display_name(locale, &longest_matching_identifier); | ||
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| // Step - 2: Construct a vector of longest qualifying substrings (LQS). | ||
| // Find the displayname for the remaining locale if exists. | ||
| let lqs = self.get_longest_qualifying_substrings(locale, &longest_matching_identifier); | ||
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| // Step - 3: Return the displayname based on the size of LQS. | ||
| let mut result = Cow::Borrowed(ldn); | ||
| #[allow(clippy::indexing_slicing)] // indexes in range | ||
| if !lqs.is_empty() { | ||
| let mut output = String::with_capacity( | ||
| result.len() + " (".len() + lqs.iter().map(|s| ", ".len() + s.len()).sum::<usize>() | ||
| - ", ".len() | ||
| + ")".len(), | ||
|
Comment on lines
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There was a problem hiding this comment. These strings should come from locale data. Could be a follow-up but we definitely need this before this goes stable. |
||
| ); | ||
| output.push_str(&result); | ||
| output.push_str(" ("); | ||
| output.push_str(lqs[0]); | ||
| for lqs in &lqs[1..] { | ||
| output.push_str(", "); | ||
| output.push_str(lqs); | ||
| } | ||
| output.push(')'); | ||
| result = Cow::Owned(output); | ||
| } | ||
| result | ||
| } | ||
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| /// For a given locale and the data, find the longest prefix of the string that exists as a key in the CLDR locale data. | ||
| pub fn find_longest_matching_subtag(&self, locale: &Locale) -> LanguageIdentifier { | ||
|
Comment on lines
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There was a problem hiding this comment. Observation: this only ever returns one of the following:
But does the spec allow us to return language-script-region, etc? Consider this in #3913 |
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| // NOTE: The subtag ordering of the canonical locale is `language_script_region + variants + extensions`. | ||
| // The logic to find the longest matching subtag is based on this ordering. | ||
| if let Some(script) = locale.id.script { | ||
|
There was a problem hiding this comment. Don't you technically have to try all these combinations according to the algorithm?
There was a problem hiding this comment. There is no explicit mention in the algorithm for what is covered under LocaleDisplayName (LDN). But because we are looking for the longest matching string in the locale and language data, I couldn't find any example in the data which has any other combinations then what is already covered in this implementation. However, we do need to technically support the other combinations as the data may change in future. I think a better way to implement the support for this is to use the subtag iterator.
There was a problem hiding this comment. If what we have is more efficient than the general solution, I'm okay landing this and fixing the algorithm later if these types of cases come up. The way you've written this, I think old-code-new-data should just ignore the new entries, which is fine. There was a problem hiding this comment. Chopping off subtags will only cover LSRV, LSR, LS, L. |
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| let lang_script_identifier: LanguageIdentifier = | ||
| (locale.id.language, Some(script), None).into(); | ||
| if self | ||
| .locale_data | ||
| .get() | ||
| .names | ||
| .get_by(|uvstr| lang_script_identifier.strict_cmp(uvstr).reverse()) | ||
| .is_some() | ||
| { | ||
| return lang_script_identifier; | ||
| } | ||
| } | ||
| if let Some(region) = locale.id.region { | ||
| if locale.id.script.is_none() { | ||
| let lang_region_identifier: LanguageIdentifier = | ||
| (locale.id.language, None, Some(region)).into(); | ||
| if self | ||
| .locale_data | ||
| .get() | ||
| .names | ||
| .get_by(|uvstr| lang_region_identifier.strict_cmp(uvstr).reverse()) | ||
| .is_some() | ||
| { | ||
| return lang_region_identifier; | ||
| } | ||
| } | ||
| } | ||
| (locale.id.language, None, None).into() | ||
| } | ||
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| fn get_locale_display_name<'a>( | ||
| &'a self, | ||
| locale: &'a Locale, | ||
| longest_matching_identifier: &LanguageIdentifier, | ||
| ) -> &'a str { | ||
| let LocaleDisplayNamesFormatter { | ||
| options, | ||
| locale_data, | ||
| language_data, | ||
| .. | ||
| } = self; | ||
|
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| // Check if the key exists in the locale_data first. | ||
| // Example: "en_GB", "nl_BE". | ||
| let mut ldn = match options.style { | ||
| Some(Style::Short) => locale_data | ||
| .get() | ||
| .short_names | ||
| .get_by(|uvstr| longest_matching_identifier.strict_cmp(uvstr).reverse()), | ||
| Some(Style::Long) => locale_data | ||
| .get() | ||
| .long_names | ||
| .get_by(|uvstr| longest_matching_identifier.strict_cmp(uvstr).reverse()), | ||
| Some(Style::Menu) => locale_data | ||
| .get() | ||
| .menu_names | ||
| .get_by(|uvstr| longest_matching_identifier.strict_cmp(uvstr).reverse()), | ||
| _ => None, | ||
| } | ||
| .or_else(|| { | ||
| locale_data | ||
| .get() | ||
| .names | ||
| .get_by(|uvstr| longest_matching_identifier.strict_cmp(uvstr).reverse()) | ||
| }); | ||
|
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||
| // At this point the key should exist in the language_data. | ||
| // Example: "en", "nl", "zh". | ||
| if ldn.is_none() { | ||
| ldn = match options.style { | ||
| Some(Style::Short) => language_data.get().short_names.get( | ||
| &longest_matching_identifier | ||
| .language | ||
| .into_tinystr() | ||
| .to_unvalidated(), | ||
| ), | ||
| Some(Style::Long) => language_data.get().long_names.get( | ||
| &longest_matching_identifier | ||
| .language | ||
| .into_tinystr() | ||
| .to_unvalidated(), | ||
| ), | ||
| Some(Style::Menu) => language_data.get().menu_names.get( | ||
| &longest_matching_identifier | ||
| .language | ||
| .into_tinystr() | ||
| .to_unvalidated(), | ||
| ), | ||
| _ => None, | ||
| } | ||
| .or_else(|| { | ||
| language_data.get().names.get( | ||
| &longest_matching_identifier | ||
| .language | ||
| .into_tinystr() | ||
| .to_unvalidated(), | ||
| ) | ||
| }); | ||
| } | ||
| // Fallback on language subtag in LanguageIdentifier id the key is not found in CLDR data. | ||
| return ldn.unwrap_or(locale.id.language.as_str()); | ||
| } | ||
|
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||
| fn get_longest_qualifying_substrings<'a>( | ||
| &'a self, | ||
| locale: &'a Locale, | ||
| longest_matching_identifier: &'a LanguageIdentifier, | ||
| ) -> Vec<&'a str> { | ||
| let LocaleDisplayNamesFormatter { | ||
| options, | ||
| region_data, | ||
| script_data, | ||
| variant_data, | ||
| .. | ||
| } = self; | ||
|
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| let mut lqs: Vec<&'a str> = vec![]; | ||
|
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| if let Some(script) = &locale.id.script { | ||
| // Ignore if the script was used to derive LDN. | ||
| if longest_matching_identifier.script.is_none() { | ||
| let scriptdisplay = match options.style { | ||
| Some(Style::Short) => script_data | ||
| .get() | ||
| .short_names | ||
| .get(&script.into_tinystr().to_unvalidated()), | ||
| _ => None, | ||
| } | ||
| .or_else(|| { | ||
| script_data | ||
| .get() | ||
| .names | ||
| .get(&script.into_tinystr().to_unvalidated()) | ||
| }); | ||
| lqs.push(scriptdisplay.unwrap_or(script.as_str())); | ||
| } | ||
| } | ||
|
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| if let Some(region) = &locale.id.region { | ||
| // Ignore if the region was used to derive LDN. | ||
| if longest_matching_identifier.region.is_none() { | ||
| let regiondisplay = match options.style { | ||
| Some(Style::Short) => region_data | ||
| .get() | ||
| .short_names | ||
| .get(®ion.into_tinystr().to_unvalidated()), | ||
| _ => None, | ||
| } | ||
| .or_else(|| { | ||
| region_data | ||
| .get() | ||
| .names | ||
| .get(®ion.into_tinystr().to_unvalidated()) | ||
| }); | ||
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| lqs.push(regiondisplay.unwrap_or(region.as_str())); | ||
| } | ||
| } | ||
|
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| for variant_key in locale.id.variants.iter() { | ||
| lqs.push( | ||
| variant_data | ||
| .get() | ||
| .names | ||
| .get(&variant_key.into_tinystr().to_unvalidated()) | ||
| .unwrap_or(variant_key.as_str()), | ||
| ); | ||
| } | ||
| lqs | ||
| } | ||
| } | ||
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Suggestion (optional): you can use
split_firstto avoid the need to unwrap.split_firstreturns anOption<&T>with the first and anOption<&[T]>with the remainder.