vendor/icu_provider_adapters/src/fallback/mod.rs - toolchain/rustc - Git at Google

 // 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 ).

 //! A data provider wrapper that performs locale fallback.

 use crate::helpers::result_is_err_missing_locale;
 use icu_locid_transform::provider::*;
 use icu_provider::prelude::*;

 #[doc(hidden)] // moved
 pub use icu_locid_transform::fallback::{
     LocaleFallbackIterator, LocaleFallbacker, LocaleFallbackerWithConfig,
 };
 #[doc(hidden)] // moved
 pub use icu_provider::fallback::LocaleFallbackConfig;

 /// A data provider wrapper that performs locale fallback. This enables arbitrary locales to be
 /// handled at runtime.
 ///
 /// # Examples
 ///
 /// ```
 /// use icu_locid::locale;
 /// use icu_provider::prelude::*;
 /// use icu_provider::hello_world::*;
 /// use icu_provider_adapters::fallback::LocaleFallbackProvider;
 ///
 /// # let provider = icu_provider_blob::BlobDataProvider::try_new_from_static_blob(include_bytes!("../../tests/data/blob.postcard")).unwrap();
 /// # let provider = provider.as_deserializing();
 ///
 /// let req = DataRequest {
 ///     locale: &locale!("ja-JP").into(),
 ///     metadata: Default::default(),
 /// };
 ///
 /// // The provider does not have data for "ja-JP":
 /// DataProvider::<HelloWorldV1Marker>::load(&provider, req).expect_err("No fallback");
 ///
 /// // But if we wrap the provider in a fallback provider...
 /// let provider = LocaleFallbackProvider::try_new_unstable(provider)
 ///     .expect("Fallback data present");
 ///
 /// // ...then we can load "ja-JP" based on "ja" data
 /// let response =
 ///   DataProvider::<HelloWorldV1Marker>::load(&provider, req).expect("successful with vertical fallback");
 ///
 /// assert_eq!(
 ///     response.metadata.locale.unwrap(),
 ///     locale!("ja").into(),
 /// );
 /// assert_eq!(
 ///     response.payload.unwrap().get().message,
 ///     "こんにちは世界",
 /// );
 /// ```
 #[derive(Clone, Debug)]
 pub struct LocaleFallbackProvider<P> {
     inner: P,
     fallbacker: LocaleFallbacker,
 }

 impl<P> LocaleFallbackProvider<P>
 where
     P: DataProvider<LocaleFallbackLikelySubtagsV1Marker>
         + DataProvider<LocaleFallbackParentsV1Marker>
         + DataProvider<CollationFallbackSupplementV1Marker>,
 {
     /// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
     /// fallback data from it.
     ///
     /// If the data provider being wrapped does not contain fallback data, use
     /// [`LocaleFallbackProvider::new_with_fallbacker`].
     pub fn try_new_unstable(provider: P) -> Result<Self, DataError> {
         let fallbacker = LocaleFallbacker::try_new_unstable(&provider)?;
         Ok(Self {
             inner: provider,
             fallbacker,
         })
     }
 }

 impl<P> LocaleFallbackProvider<P>
 where
     P: AnyProvider,
 {
     /// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
     /// fallback data from it.
     ///
     /// If the data provider being wrapped does not contain fallback data, use
     /// [`LocaleFallbackProvider::new_with_fallbacker`].
     pub fn try_new_with_any_provider(provider: P) -> Result<Self, DataError> {
         let fallbacker = LocaleFallbacker::try_new_with_any_provider(&provider)?;
         Ok(Self {
             inner: provider,
             fallbacker,
         })
     }
 }

 #[cfg(feature = "serde")]
 impl<P> LocaleFallbackProvider<P>
 where
     P: BufferProvider,
 {
     /// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
     /// fallback data from it.
     ///
     /// If the data provider being wrapped does not contain fallback data, use
     /// [`LocaleFallbackProvider::new_with_fallbacker`].
     pub fn try_new_with_buffer_provider(provider: P) -> Result<Self, DataError> {
         let fallbacker = LocaleFallbacker::try_new_with_buffer_provider(&provider)?;
         Ok(Self {
             inner: provider,
             fallbacker,
         })
     }
 }

 impl<P> LocaleFallbackProvider<P> {
     /// Wrap a provider with an arbitrary fallback engine.
     ///
     /// This relaxes the requirement that the wrapped provider contains its own fallback data.
     ///
     /// # Examples
     ///
     /// ```
     /// use icu_locid::locale;
     /// use icu_locid_transform::LocaleFallbacker;
     /// use icu_provider::hello_world::*;
     /// use icu_provider::prelude::*;
     /// use icu_provider_adapters::fallback::LocaleFallbackProvider;
     ///
     /// let provider = HelloWorldProvider;
     ///
     /// let req = DataRequest {
     ///     locale: &locale!("de-CH").into(),
     ///     metadata: Default::default(),
     /// };
     ///
     /// // There is no "de-CH" data in the `HelloWorldProvider`
     /// DataProvider::<HelloWorldV1Marker>::load(&provider, req)
     ///     .expect_err("No data for de-CH");
     ///
     /// // `HelloWorldProvider` does not contain fallback data,
     /// // but we can construct a fallbacker with `icu_locid_transform`'s
     /// // compiled data.
     /// let provider = LocaleFallbackProvider::new_with_fallbacker(
     ///     provider,
     ///     LocaleFallbacker::new().static_to_owned(),
     /// );
     ///
     /// // Now we can load the "de-CH" data via fallback to "de".
     /// let german_hello_world: DataPayload<HelloWorldV1Marker> = provider
     ///     .load(req)
     ///     .expect("Loading should succeed")
     ///     .take_payload()
     ///     .expect("Data should be present");
     ///
     /// assert_eq!("Hallo Welt", german_hello_world.get().message);
     /// ```
     pub fn new_with_fallbacker(provider: P, fallbacker: LocaleFallbacker) -> Self {
         Self {
             inner: provider,
             fallbacker,
         }
     }

     /// Returns a reference to the inner provider, bypassing fallback.
     pub fn inner(&self) -> &P {
         &self.inner
     }

     /// Returns a mutable reference to the inner provider.
     pub fn inner_mut(&mut self) -> &mut P {
         &mut self.inner
     }

     /// Returns ownership of the inner provider to the caller.
     pub fn into_inner(self) -> P {
         self.inner
     }

     /// Run the fallback algorithm with the data request using the inner data provider.
     /// Internal function; external clients should use one of the trait impls below.
     ///
     /// Function arguments:
     ///
     /// - F1 should perform a data load for a single DataRequest and return the result of it
     /// - F2 should map from the provider-specific response type to DataResponseMetadata
     fn run_fallback<F1, F2, R>(
         &self,
         key: DataKey,
         mut base_req: DataRequest,
         mut f1: F1,
         mut f2: F2,
     ) -> Result<R, DataError>
     where
         F1: FnMut(DataRequest) -> Result<R, DataError>,
         F2: FnMut(&mut R) -> &mut DataResponseMetadata,
     {
         if key.metadata().singleton {
             return f1(base_req);
         }
         let mut fallback_iterator = self
             .fallbacker
             .for_config(key.fallback_config())
             .fallback_for(base_req.locale.clone());
         let base_silent = core::mem::replace(&mut base_req.metadata.silent, true);
         loop {
             let result = f1(DataRequest {
                 locale: fallback_iterator.get(),
                 metadata: base_req.metadata,
             });
             if !result_is_err_missing_locale(&result) {
                 return result
                     .map(|mut res| {
                         f2(&mut res).locale = Some(fallback_iterator.take());
                         res
                     })
                     // Log the original request rather than the fallback request
                     .map_err(|e| {
                         base_req.metadata.silent = base_silent;
                         e.with_req(key, base_req)
                     });
             }
             // If we just checked und, break out of the loop.
             if fallback_iterator.get().is_und() {
                 break;
             }
             fallback_iterator.step();
         }
         base_req.metadata.silent = base_silent;
         Err(DataErrorKind::MissingLocale.with_req(key, base_req))
     }
 }

 impl<P> AnyProvider for LocaleFallbackProvider<P>
 where
     P: AnyProvider,
 {
     fn load_any(&self, key: DataKey, base_req: DataRequest) -> Result<AnyResponse, DataError> {
         self.run_fallback(
             key,
             base_req,
             |req| self.inner.load_any(key, req),
             |res| &mut res.metadata,
         )
     }
 }

 impl<P> BufferProvider for LocaleFallbackProvider<P>
 where
     P: BufferProvider,
 {
     fn load_buffer(
         &self,
         key: DataKey,
         base_req: DataRequest,
     ) -> Result<DataResponse<BufferMarker>, DataError> {
         self.run_fallback(
             key,
             base_req,
             |req| self.inner.load_buffer(key, req),
             |res| &mut res.metadata,
         )
     }
 }

 impl<P, M> DynamicDataProvider<M> for LocaleFallbackProvider<P>
 where
     P: DynamicDataProvider<M>,
     M: DataMarker,
 {
     fn load_data(&self, key: DataKey, base_req: DataRequest) -> Result<DataResponse<M>, DataError> {
         self.run_fallback(
             key,
             base_req,
             |req| self.inner.load_data(key, req),
             |res| &mut res.metadata,
         )
     }
 }

 impl<P, M> DataProvider<M> for LocaleFallbackProvider<P>
 where
     P: DataProvider<M>,
     M: KeyedDataMarker,
 {
     fn load(&self, base_req: DataRequest) -> Result<DataResponse<M>, DataError> {
         self.run_fallback(
             M::KEY,
             base_req,
             |req| self.inner.load(req),
             |res| &mut res.metadata,
         )
     }
 }
	// 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 ).

	//! A data provider wrapper that performs locale fallback.

	use crate::helpers::result_is_err_missing_locale;
	use icu_locid_transform::provider::*;
	use icu_provider::prelude::*;

	#[doc(hidden)] // moved
	pub use icu_locid_transform::fallback::{
	LocaleFallbackIterator, LocaleFallbacker, LocaleFallbackerWithConfig,
	};
	#[doc(hidden)] // moved
	pub use icu_provider::fallback::LocaleFallbackConfig;

	/// A data provider wrapper that performs locale fallback. This enables arbitrary locales to be
	/// handled at runtime.
	///
	/// # Examples
	///
	/// ```
	/// use icu_locid::locale;
	/// use icu_provider::prelude::*;
	/// use icu_provider::hello_world::*;
	/// use icu_provider_adapters::fallback::LocaleFallbackProvider;
	///
	/// # let provider = icu_provider_blob::BlobDataProvider::try_new_from_static_blob(include_bytes!("../../tests/data/blob.postcard")).unwrap();
	/// # let provider = provider.as_deserializing();
	///
	/// let req = DataRequest {
	/// locale: &locale!("ja-JP").into(),
	/// metadata: Default::default(),
	/// };
	///
	/// // The provider does not have data for "ja-JP":
	/// DataProvider::<HelloWorldV1Marker>::load(&provider, req).expect_err("No fallback");
	///
	/// // But if we wrap the provider in a fallback provider...
	/// let provider = LocaleFallbackProvider::try_new_unstable(provider)
	/// .expect("Fallback data present");
	///
	/// // ...then we can load "ja-JP" based on "ja" data
	/// let response =
	/// DataProvider::<HelloWorldV1Marker>::load(&provider, req).expect("successful with vertical fallback");
	///
	/// assert_eq!(
	/// response.metadata.locale.unwrap(),
	/// locale!("ja").into(),
	/// );
	/// assert_eq!(
	/// response.payload.unwrap().get().message,
	/// "こんにちは世界",
	/// );
	/// ```
	#[derive(Clone, Debug)]
	pub struct LocaleFallbackProvider<P> {
	inner: P,
	fallbacker: LocaleFallbacker,
	}

	impl<P> LocaleFallbackProvider<P>
	where
	P: DataProvider<LocaleFallbackLikelySubtagsV1Marker>
	+ DataProvider<LocaleFallbackParentsV1Marker>
	+ DataProvider<CollationFallbackSupplementV1Marker>,
	{
	/// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
	/// fallback data from it.
	///
	/// If the data provider being wrapped does not contain fallback data, use
	/// [`LocaleFallbackProvider::new_with_fallbacker`].
	pub fn try_new_unstable(provider: P) -> Result<Self, DataError> {
	let fallbacker = LocaleFallbacker::try_new_unstable(&provider)?;
	Ok(Self {
	inner: provider,
	fallbacker,
	})
	}
	}

	impl<P> LocaleFallbackProvider<P>
	where
	P: AnyProvider,
	{
	/// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
	/// fallback data from it.
	///
	/// If the data provider being wrapped does not contain fallback data, use
	/// [`LocaleFallbackProvider::new_with_fallbacker`].
	pub fn try_new_with_any_provider(provider: P) -> Result<Self, DataError> {
	let fallbacker = LocaleFallbacker::try_new_with_any_provider(&provider)?;
	Ok(Self {
	inner: provider,
	fallbacker,
	})
	}
	}

	#[cfg(feature = "serde")]
	impl<P> LocaleFallbackProvider<P>
	where
	P: BufferProvider,
	{
	/// Create a [`LocaleFallbackProvider`] by wrapping another data provider and then loading
	/// fallback data from it.
	///
	/// If the data provider being wrapped does not contain fallback data, use
	/// [`LocaleFallbackProvider::new_with_fallbacker`].
	pub fn try_new_with_buffer_provider(provider: P) -> Result<Self, DataError> {
	let fallbacker = LocaleFallbacker::try_new_with_buffer_provider(&provider)?;
	Ok(Self {
	inner: provider,
	fallbacker,
	})
	}
	}

	impl<P> LocaleFallbackProvider<P> {
	/// Wrap a provider with an arbitrary fallback engine.
	///
	/// This relaxes the requirement that the wrapped provider contains its own fallback data.
	///
	/// # Examples
	///
	/// ```
	/// use icu_locid::locale;
	/// use icu_locid_transform::LocaleFallbacker;
	/// use icu_provider::hello_world::*;
	/// use icu_provider::prelude::*;
	/// use icu_provider_adapters::fallback::LocaleFallbackProvider;
	///
	/// let provider = HelloWorldProvider;
	///
	/// let req = DataRequest {
	/// locale: &locale!("de-CH").into(),
	/// metadata: Default::default(),
	/// };
	///
	/// // There is no "de-CH" data in the `HelloWorldProvider`
	/// DataProvider::<HelloWorldV1Marker>::load(&provider, req)
	/// .expect_err("No data for de-CH");
	///
	/// // `HelloWorldProvider` does not contain fallback data,
	/// // but we can construct a fallbacker with `icu_locid_transform`'s
	/// // compiled data.
	/// let provider = LocaleFallbackProvider::new_with_fallbacker(
	/// provider,
	/// LocaleFallbacker::new().static_to_owned(),
	/// );
	///
	/// // Now we can load the "de-CH" data via fallback to "de".
	/// let german_hello_world: DataPayload<HelloWorldV1Marker> = provider
	/// .load(req)
	/// .expect("Loading should succeed")
	/// .take_payload()
	/// .expect("Data should be present");
	///
	/// assert_eq!("Hallo Welt", german_hello_world.get().message);
	/// ```
	pub fn new_with_fallbacker(provider: P, fallbacker: LocaleFallbacker) -> Self {
	Self {
	inner: provider,
	fallbacker,
	}
	}

	/// Returns a reference to the inner provider, bypassing fallback.
	pub fn inner(&self) -> &P {
	&self.inner
	}

	/// Returns a mutable reference to the inner provider.
	pub fn inner_mut(&mut self) -> &mut P {
	&mut self.inner
	}

	/// Returns ownership of the inner provider to the caller.
	pub fn into_inner(self) -> P {
	self.inner
	}

	/// Run the fallback algorithm with the data request using the inner data provider.
	/// Internal function; external clients should use one of the trait impls below.
	///
	/// Function arguments:
	///
	/// - F1 should perform a data load for a single DataRequest and return the result of it
	/// - F2 should map from the provider-specific response type to DataResponseMetadata
	fn run_fallback<F1, F2, R>(
	&self,
	key: DataKey,
	mut base_req: DataRequest,
	mut f1: F1,
	mut f2: F2,
	) -> Result<R, DataError>
	where
	F1: FnMut(DataRequest) -> Result<R, DataError>,
	F2: FnMut(&mut R) -> &mut DataResponseMetadata,
	{
	if key.metadata().singleton {
	return f1(base_req);
	}
	let mut fallback_iterator = self
	.fallbacker
	.for_config(key.fallback_config())
	.fallback_for(base_req.locale.clone());
	let base_silent = core::mem::replace(&mut base_req.metadata.silent, true);
	loop {
	let result = f1(DataRequest {
	locale: fallback_iterator.get(),
	metadata: base_req.metadata,
	});
	if !result_is_err_missing_locale(&result) {
	return result
	.map(\|mut res\| {
	f2(&mut res).locale = Some(fallback_iterator.take());
	res
	})
	// Log the original request rather than the fallback request
	.map_err(\|e\| {
	base_req.metadata.silent = base_silent;
	e.with_req(key, base_req)
	});
	}
	// If we just checked und, break out of the loop.
	if fallback_iterator.get().is_und() {
	break;
	}
	fallback_iterator.step();
	}
	base_req.metadata.silent = base_silent;
	Err(DataErrorKind::MissingLocale.with_req(key, base_req))
	}
	}

	impl<P> AnyProvider for LocaleFallbackProvider<P>
	where
	P: AnyProvider,
	{
	fn load_any(&self, key: DataKey, base_req: DataRequest) -> Result<AnyResponse, DataError> {
	self.run_fallback(
	key,
	base_req,
	\|req\| self.inner.load_any(key, req),
	\|res\| &mut res.metadata,
	)
	}
	}

	impl<P> BufferProvider for LocaleFallbackProvider<P>
	where
	P: BufferProvider,
	{
	fn load_buffer(
	&self,
	key: DataKey,
	base_req: DataRequest,
	) -> Result<DataResponse<BufferMarker>, DataError> {
	self.run_fallback(
	key,
	base_req,
	\|req\| self.inner.load_buffer(key, req),
	\|res\| &mut res.metadata,
	)
	}
	}

	impl<P, M> DynamicDataProvider<M> for LocaleFallbackProvider<P>
	where
	P: DynamicDataProvider<M>,
	M: DataMarker,
	{
	fn load_data(&self, key: DataKey, base_req: DataRequest) -> Result<DataResponse<M>, DataError> {
	self.run_fallback(
	key,
	base_req,
	\|req\| self.inner.load_data(key, req),
	\|res\| &mut res.metadata,
	)
	}
	}

	impl<P, M> DataProvider<M> for LocaleFallbackProvider<P>
	where
	P: DataProvider<M>,
	M: KeyedDataMarker,
	{
	fn load(&self, base_req: DataRequest) -> Result<DataResponse<M>, DataError> {
	self.run_fallback(
	M::KEY,
	base_req,
	\|req\| self.inner.load(req),
	\|res\| &mut res.metadata,
	)
	}
	}