294 lines
9.4 KiB
Rust
294 lines
9.4 KiB
Rust
//! Localization (L10n).
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//!
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//! PageTop uses the [Fluent](https://www.projectfluent.org/) set of specifications for application
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//! localization.
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//!
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//! # Fluent Syntax (FTL)
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//!
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//! The format used to describe the translation resources used by Fluent is called
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//! [FTL](https://www.projectfluent.org/fluent/guide/). FTL is designed to be easy to read while
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//! simultaneously allowing the representation of complex natural language concepts to address
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//! gender, plurals, conjugations, and others.
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//!
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//! # Fluent Resources
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//!
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//! PageTop utilizes [fluent-templates](https://docs.rs/fluent-templates/) to integrate localization
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//! resources into the application binary. The following example groups files and subfolders from
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//! *src/locale* that have a valid [Unicode Language Identifier](https://docs.rs/unic-langid/) and
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//! assigns them to their corresponding identifier:
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//!
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//! ```text
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//! src/locale/
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//! ├── common.ftl
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//! ├── en-US/
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//! │ ├── default.ftl
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//! │ └── main.ftl
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//! ├── es-ES/
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//! │ ├── default.ftl
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//! │ └── main.ftl
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//! ├── es-MX/
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//! │ ├── default.ftl
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//! │ └── main.ftl
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//! └── fr/
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//! ├── default.ftl
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//! └── main.ftl
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//! ```
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//!
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//! Example of a file *src/locale/en-US/main.ftl*:
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//!
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//! ```text
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//! hello-world = Hello world!
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//! hello-user = Hello, {$userName}!
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//! shared-photos =
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//! {$userName} {$photoCount ->
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//! [one] added a new photo
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//! *[other] added {$photoCount} new photos
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//! } of {$userGender ->
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//! [male] him and his family
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//! [female] her and her family
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//! *[other] the family
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//! }.
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//! ```
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//!
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//! Example of the equivalent file *src/locale/es-ES/main.ftl*:
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//!
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//! ```text
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//! hello-world = Hola mundo!
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//! hello-user = ¡Hola, {$userName}!
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//! shared-photos =
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//! {$userName} {$photoCount ->
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//! [one] ha añadido una nueva foto
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//! *[other] ha añadido {$photoCount} nuevas fotos
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//! } de {$userGender ->
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//! [male] él y su familia
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//! [female] ella y su familia
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//! *[other] la familia
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//! }.
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//! ```
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//!
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//! # How to apply localization in your code
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//!
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//! Once you have created your FTL resource directory, use the
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//! [`static_locales!`](crate::static_locales) macro to integrate them into your module or
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//! application. If your resources are located in the `"src/locale"` directory, simply declare:
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//!
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//! ```
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//! use pagetop::prelude::*;
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//!
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//! static_locales!(LOCALES_SAMPLE);
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//! ```
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//!
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//! But if they are in another directory, then you can use:
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//!
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//! ```
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//! use pagetop::prelude::*;
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//!
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//! static_locales!(LOCALES_SAMPLE in "path/to/locale");
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//! ```
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use crate::html::{Markup, PreEscaped};
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use crate::{global, kv, AutoDefault, LOCALES_PAGETOP};
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pub use fluent_templates;
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pub use unic_langid::LanguageIdentifier;
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use fluent_templates::Loader;
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use fluent_templates::StaticLoader as Locales;
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use unic_langid::langid;
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use std::collections::HashMap;
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use std::sync::LazyLock;
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use std::fmt;
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const LANGUAGE_SET_FAILURE: &str = "language_set_failure";
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static LANGUAGES: LazyLock<HashMap<String, (LanguageIdentifier, &str)>> = LazyLock::new(|| {
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kv![
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"en" => (langid!("en-US"), "English"),
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"en-GB" => (langid!("en-GB"), "English (British)"),
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"en-US" => (langid!("en-US"), "English (United States)"),
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"es" => (langid!("es-ES"), "Spanish"),
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"es-ES" => (langid!("es-ES"), "Spanish (Spain)"),
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]
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});
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static FALLBACK_LANGID: LazyLock<LanguageIdentifier> = LazyLock::new(|| langid!("en-US"));
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/// Sets the application's default
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/// [Unicode Language Identifier](https://unicode.org/reports/tr35/tr35.html#Unicode_language_identifier)
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/// through `SETTINGS.app.language`.
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pub static DEFAULT_LANGID: LazyLock<&LanguageIdentifier> = LazyLock::new(|| {
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langid_for(global::SETTINGS.app.language.as_str()).unwrap_or(&FALLBACK_LANGID)
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});
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pub fn langid_for(language: impl Into<String>) -> Result<&'static LanguageIdentifier, String> {
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let language = language.into();
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match LANGUAGES.get(language.as_str()) {
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Some((langid, _)) => Ok(langid),
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None => {
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if language.is_empty() {
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Ok(&FALLBACK_LANGID)
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} else {
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Err(format!(
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"No langid for Unicode Language Identifier \"{language}\".",
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))
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}
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}
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}
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}
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#[macro_export]
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/// Defines a set of localization elements and local translation texts.
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macro_rules! include_locales {
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( $LOCALES:ident $(, $core_locales:literal)? ) => {
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$crate::locale::fluent_templates::static_loader! {
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static $LOCALES = {
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locales: "src/locale",
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$( core_locales: $core_locales, )?
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fallback_language: "en-US",
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// Removes unicode isolating marks around arguments.
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customise: |bundle| bundle.set_use_isolating(false),
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};
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}
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};
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( $LOCALES:ident in $dir_locales:literal $(, $core_locales:literal)? ) => {
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$crate::locale::fluent_templates::static_loader! {
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static $LOCALES = {
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locales: $dir_locales,
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$( core_locales: $core_locales, )?
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fallback_language: "en-US",
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// Removes unicode isolating marks around arguments.
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customise: |bundle| bundle.set_use_isolating(false),
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};
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}
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};
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}
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#[derive(AutoDefault)]
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enum L10nOp {
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#[default]
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None,
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Text(String),
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Translate(String),
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}
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#[derive(AutoDefault)]
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pub struct L10n {
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op: L10nOp,
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locales: Option<&'static Locales>,
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args: HashMap<String, String>,
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}
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impl L10n {
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pub fn none() -> Self {
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L10n::default()
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}
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pub fn n(text: impl Into<String>) -> Self {
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L10n {
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op: L10nOp::Text(text.into()),
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..Default::default()
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}
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}
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pub fn l(key: impl Into<String>) -> Self {
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L10n {
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op: L10nOp::Translate(key.into()),
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locales: Some(&LOCALES_PAGETOP),
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..Default::default()
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}
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}
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pub fn t(key: impl Into<String>, locales: &'static Locales) -> Self {
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L10n {
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op: L10nOp::Translate(key.into()),
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locales: Some(locales),
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..Default::default()
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}
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}
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pub fn with_arg(mut self, arg: impl Into<String>, value: impl Into<String>) -> Self {
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self.args.insert(arg.into(), value.into());
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self
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}
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pub fn using(&self, langid: &LanguageIdentifier) -> Option<String> {
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match &self.op {
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L10nOp::None => None,
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L10nOp::Text(text) => Some(text.to_owned()),
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L10nOp::Translate(key) => match self.locales {
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Some(locales) => {
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if self.args.is_empty() {
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locales.try_lookup(langid, key)
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} else {
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locales.try_lookup_with_args(
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langid,
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key,
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&self
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.args
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.iter()
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.fold(HashMap::new(), |mut args, (key, value)| {
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args.insert(key.to_string(), value.to_owned().into());
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args
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}),
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)
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}
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}
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None => None,
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},
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}
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}
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pub fn markup(&self) -> Markup {
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PreEscaped(self.using(&DEFAULT_LANGID).unwrap_or_default())
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}
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pub fn escaped(&self, langid: &LanguageIdentifier) -> Markup {
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PreEscaped(self.using(langid).unwrap_or_default())
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}
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}
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impl fmt::Display for L10n {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match &self.op {
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L10nOp::None => write!(f, ""),
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L10nOp::Text(text) => write!(f, "{text}"),
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L10nOp::Translate(key) => {
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if let Some(locales) = self.locales {
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write!(
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f,
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"{}",
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if self.args.is_empty() {
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locales.lookup(
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match key.as_str() {
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LANGUAGE_SET_FAILURE => &FALLBACK_LANGID,
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_ => &DEFAULT_LANGID,
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},
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key,
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)
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} else {
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locales.lookup_with_args(
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match key.as_str() {
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LANGUAGE_SET_FAILURE => &FALLBACK_LANGID,
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_ => &DEFAULT_LANGID,
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},
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key,
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&self
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.args
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.iter()
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.fold(HashMap::new(), |mut args, (key, value)| {
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args.insert(key.to_string(), value.to_owned().into());
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args
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}),
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)
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}
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)
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} else {
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write!(f, "Unknown localization {key}")
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}
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}
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}
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}
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}
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