Crate icu_provider[][src]

Expand description

icu_provider is one of the ICU4X components.

It defines traits and structs for transmitting data through the ICU4X locale data pipeline. The primary trait is DataProvider. It has one method, which transforms a Request into a Response:

fn load_payload(&self, req: &DataRequest) -> Result<DataResponse<'data>, DataError>

A Request contains a ResourceKey (a composition of a Category and sub-category, e.g., “plurals/cardinal@1”) and ResourceOptions (a language identifier and optional variant, e.g., “fr”) being requested. The Response contains the data payload corresponding to the Request.

The most common types required for ICU4X DataProvider are included via the prelude:

use icu_provider::prelude::*;

Concrete Implementations of Data Providers

Any object implementing DataProvider can be used to supply ICU4X with locale data. ICU4X ships with some pre-built data providers:

  • CldrJsonDataProvider reads structured data directly from CLDR source files.
  • FsDataProvider reads structured data from the filesystem. It can also write out that filesystem structure. More efficient than CldrJsonDataProvider.

This crate also contains some concrete implementations for testing purposes:

Types and Lifetimes

Types compatible with Yokeable can be passed through the data provider, so long as they are associated with a marker type implementing DataMarker.

Most DataProvider traits take one lifetime argument: 'data. This lifetime allows data structs to borrow zero-copy data. In practice, it also represents the lifetime of data that the Cart of the Yoke of the DataPayload borrows; for more information on carts and yokes, see yoke.

Additional Traits


Data providers can implement IterableDataProvider, allowing iteration over all ResourceOptions instances supported for a certain key in the data provider.

For more information, see the iter module.


Enabled with the “provider_serde” feature

The trait SerdeDeDataProvider removes the type argument from DataProvider and requires that all data structs be deserializable via Serde. This allows for a Serde-enabled provider to be saved as a trait object without being specific to a data struct type.

DataProvider<dyn SerdeSeDataStruct>

Enabled with the “provider_serde” feature

Data providers capable of returning opaque SerdeSeDataStruct trait objects can be used as input to a data exporter, such as when writing data to the filesystem.

This trait is normally implemented using the impl_dyn_provider! macro.

DataProvider<dyn ErasedDataStruct>

The trait ErasedDataProvider removes the type argument from DataProvider and requires that all data structs be convertible to the Any type. This enables the processing of data without the caller knowing the underlying data struct.

Since ErasedDataProvider is not specific to a single type, it can be useful for caches or other bulk data operations.

This trait is normally implemented using the impl_dyn_provider! macro.


pub use yoke;
pub use prelude::*;


Utilities for using trait objects with DataPayload.

Collection of traits for providers that support type erasure of data structs.

Types having to do with the exporting of data.

Providers that filter resource requests.

Data provider returning multilingual “Hello World” strings for testing.

Macro dependencies; not intended to be used directly.

Locale-invariant data provider that requires no I/O.

Collection of iteration APIs for DataProvider.

Marker types and traits for DataProvider.

Core selection of APIs and structures for DataProvider.

Collection of traits for providers that support serializing or deserializing data.

Data provider always serving the same struct.


Implement DataProvider for a trait object S on a type that already implements DataProvider for one or more M, where M is a concrete type that implements the trait S.

Shortcut to construct a const resource identifier.


Error enumeration for DataProvider.

Attribute Macros

The #[data_struct] attribute should be applied to all types intended for use in a DataStruct. It does the following things: