Crate icu_provider
source ·Expand description
icu_provider
is one of the ICU4X
components.
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 DataRequest
into a DataResponse
.
DataKey
is a fixed identifier for the data type, such as"plurals/cardinal@1"
.DataRequest
contains additional annotations to choose a specific variant of the key, such as a locale.DataResponse
contains the data if the request was successful.
In addition, there are three other traits which are widely implemented:
AnyProvider
returns data asdyn Any
trait objects.BufferProvider
returns data as[u8]
buffers.DynamicDataProvider
returns structured data but is not specific to a key.
The most common types required for this crate are included via the prelude:
use icu_provider::prelude::*;
§Types of Data Providers
All nontrivial data providers can fit into one of two classes.
AnyProvider
: Those whose data originates as structured Rust objectsBufferProvider
: Those whose data originates as unstructured[u8]
buffers
✨ 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.
§AnyProvider
These providers are able to return structured data cast into dyn Any
trait objects. Users
can call as_downcasting()
to get an object implementing DataProvider
by downcasting
the trait objects.
Examples of AnyProviders:
DatagenProvider
reads structured data from CLDR source files and returns ICU4X data structs.AnyPayloadProvider
wraps a specific data struct and returns it.- The
BakedDataProvider
which encodes structured data directly in Rust source
§BufferProvider
These providers are able to return unstructured data typically represented as
[serde
]-serialized buffers. Users can call as_deserializing()
to get an object
implementing DataProvider
by invoking Serde Deserialize.
Examples of BufferProviders:
FsDataProvider
reads individual buffers from the filesystem.BlobDataProvider
reads buffers from a large in-memory blob.
§Provider Adapters
ICU4X offers several built-in modules to combine providers in interesting ways.
These can be found in the icu_provider_adapters
crate.
§Testing Provider
This crate also contains a concrete provider for demonstration purposes:
HelloWorldProvider
returns “hello world” strings in several languages.
§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
.
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
The [datagen
] module contains several APIs for data generation. See icu_datagen
for the reference
data generation implementation.
Re-exports§
pub use crate::response::DataPayloadOr;
pub use crate::any::AnyMarker;
pub use crate::any::AnyPayload;
pub use crate::any::AnyProvider;
pub use crate::any::AnyResponse;
pub use crate::any::AsDowncastingAnyProvider;
pub use crate::any::AsDynamicDataProviderAnyMarkerWrap;
pub use crate::any::MaybeSendSync;
pub use crate::buf::BufferMarker;
pub use crate::buf::BufferProvider;
pub use crate::marker::DataMarker;
pub use crate::marker::KeyedDataMarker;
pub use crate::marker::NeverMarker;
Modules§
- Traits for data providers that produce
Any
objects. - Traits for data providers that produce opaque buffers.
- 📚 This module documents ICU4X constructor signatures.
- Utilities for using trait objects with
DataPayload
. - 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.
Macros§
- See
DataKey
. - Implements
UpcastDataPayload
from several data markers to a single data marker that all share the sameDataMarker::Yokeable
. - Implements
DataProvider<NeverMarker<Y>>
on a struct. - Implements
DynamicDataProvider
for a marker typeS
on a type that already implementsDynamicDataProvider
orDataProvider
for one or moreM
, whereM
is a concrete type that is convertible toS
viaUpcastDataPayload
.
Structs§
- The type of the “cart” that is used by
DataPayload
. - The error type for ICU4X data provider operations.
- Used for loading data from an ICU4X data provider.
- A compact hash of a
DataKey
. Useful for keys in maps. - Metadata statically associated with a particular
DataKey
. - The string path of a data key. For example, “foo@1”
- A locale type optimized for use in fallbacking and the ICU4X data pipeline.
- A container for data payloads returned from a data provider.
- A
DataProvider
associated with a specific key. - The request type passed into all data provider implementations.
- Metadata for data requests. This is currently empty, but it may be extended with options for tuning locale fallback, buffer layout, and so forth.
- A response object containing an object as payload and metadata about it.
- A response object containing metadata about the returned data.
Enums§
- A list specifying general categories of data provider error.
Traits§
- A data provider that loads data for a specific data type.
- A data provider that loads data for a specific
DataKey
. - A data provider that loads data for a specific data type.
Attribute Macros§
- The
#[data_struct]
attribute should be applied to all types intended for use in aDataStruct
.