icu_provider
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
:
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.
A Response
contains a [DataPayload
] along with other metadata.
The most common types required for ICU4X DataProvider
are included via the prelude:
use *;
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:
InvariantDataProvider
returns fixed data that does not vary by locale.StructProvider
wraps a particular instance of a struct and returns it.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
].
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
IterableDataProvider
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.
SerdeDeDataProvider
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.
More Information
For more information on development, authorship, contributing etc. please visit ICU4X home page
.