Crate icu_providersource · [−]
icu_provider is one of the
Unicode’s experience with ICU4X’s parent projects, ICU4C and ICU4J, led the team to realize that data management is the most critical aspect of deploying internationalization, and that it requires a high level of customization for the needs of the platform it is embedded in. As a result ICU4X comes with a selection of providers that should allow for ICU4X to naturally fit into different business and technological needs of customers.
icu_provider defines traits and structs for transmitting data through the ICU4X locale
data pipeline. The primary trait is
DataProvider. It is parameterized by a
KeyedDataMarker, which contains the data type and a
DataKey. It has one method,
DataProvider::load, which transforms a
DataKeyis a fixed identifier for the data type, such as
DataRequestcontains additional annotations to choose a specific variant of the key, such as a locale.
DataResponsecontains the data if the request was successful.
In addition, there are three other traits which are widely implemented:
AnyProviderreturns data as
dyn Anytrait objects.
BufferProviderreturns data as
DynamicDataProviderreturns structured data but is not specific to a key.
The most common types required for this crate are included via the prelude:
Types of Data Providers
All nontrivial data providers can fit into one of two classes.
AnyProvider: Those whose data originates as structured Rust objects
BufferProvider: Those whose data originates as unstructured
✨ Key Insight: A given data provider is generally either an
AnyProvider or a
BufferProvider. Which type depends on the data source, and it is not generally possible
to convert one to the other.
See also crate::constructors.
These providers are able to return structured data cast into
dyn Any trait objects. Users
as_downcasting() to get an object implementing
DataProvider by downcasting
the trait objects.
Examples of AnyProviders:
CldrJsonDataProviderreads structured data from CLDR JSON source files and returns structured Rust objects.
AnyPayloadProviderwraps a specific data struct and returns it.
BakedDataProviderwhich encodes structured data directly in Rust source
These providers are able to return unstructured data typically represented as
serde-serialized buffers. Users can call
as_deserializing() to get an object
DataProvider by invoking Serde Deserialize.
Examples of BufferProviders:
FsDataProviderreads individual buffers from the filesystem.
BlobDataProviderreads buffers from a large in-memory blob.
ICU4X offers several built-in modules to combine providers in interesting ways.
These can be found in the
This crate also contains a concrete provider for testing purposes:
HelloWorldProviderreturns “hello world” strings in several languages.
If you need a testing provider that contains the actual resource keys used by ICU4X features,
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
Data structs should generally have one lifetime argument:
'data. This lifetime allows data
structs to borrow zero-copy data.
Data generation API
This functionality is enabled with the “datagen” Cargo feature
datagen module contains several APIs for data generation. See
icu_datagen for the reference
data generation implementation.
pub use prelude::*;
pub use crate::any::MaybeSendSync;
Traits for data providers that produce
Traits for data providers that produce opaque buffers.
📚 This module documents ICU4X constructor signatures.
This module contains various utilities required to generate ICU4X data files, typically
icu_datagen reference crate. End users should not need to consume anything in
this module as a library unless defining new types that integrate with
Utilities for using trait objects with
Data provider returning multilingual “Hello World” strings for testing.
Marker types and traits for DataProvider.
Core selection of APIs and structures for the ICU4X data provider.
DeserializingBufferProvider wrapper, which deserializes data using Serde.
UpcastDataPayload from several data markers to a single data marker
that all share the same
DynamicDataProvider for a marker type
S on a type that already implements
DataProvider for one or more
M is a concrete type
that is convertible to
This macro can be used on a data provider to allow it to be used for data generation.
The type of the “cart” that is used by
Metadata statically associated with a particular
The string path of a data key. For example, “foo@1”
Metadata for data requests. This is currently empty, but it may be extended with options for tuning locale fallback, buffer layout, and so forth.
Hint for what to prioritize during fallback when data is unavailable.
What additional data to load when performing fallback.
#[data_struct] attribute should be applied to all types intended
for use in a