Struct icu_provider_adapters::filter::RequestFilterDataProvider

pub struct RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool,{
    pub inner: D,
    pub predicate: F,
    pub filter_name: &'static str,
}

A data provider that selectively filters out data requests.

Data requests that are rejected by the filter will return a DataError with kind FilteredResource, and they will not be returned by [datagen::IterableDynamicDataProvider::supported_locales_for_key].

Although this struct can be created directly, the traits in this module provide helper functions for common filtering patterns.

Fields

inner: D

The data provider to which we delegate requests.

predicate: F

The predicate function. A return value of true indicates that the request should proceed as normal; a return value of false will reject the request.

filter_name: &'static str

A name for this filter, used in error messages.

Implementations

impl<D, F> RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool + Sync,

pub fn filter_by_langid<'a>(
    self,
    predicate: impl Fn(&LanguageIdentifier) -> bool + Sync + 'a
) -> RequestFilterDataProvider<D, Box<dyn Fn(DataRequest<'_>) -> bool + Sync + 'a>>where
    F: 'a,

Filter out data requests with certain langids according to the predicate function. The predicate should return true to allow a langid and false to reject a langid.

Data requests with no langid will be allowed. To reject data requests without a langid, chain this with Self::require_langid.

Examples

use icu_locid::LanguageIdentifier;
use icu_locid::{langid, locale, subtags_language as language};
use icu_provider::datagen::*;
use icu_provider::hello_world::*;
use icu_provider::prelude::*;
use icu_provider_adapters::filter::Filterable;

let provider = HelloWorldProvider
    .filterable("Demo no-English filter")
    .filter_by_langid(|langid| langid.language != language!("en"));

// German requests should succeed:
let req_de = DataRequest {
    locale: &locale!("de").into(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_de);
assert!(matches!(response, Ok(_)));

// English requests should fail:
let req_en = DataRequest {
    locale: &locale!("en-US").into(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_en);
assert!(matches!(
    response,
    Err(DataError {
        kind: DataErrorKind::FilteredResource,
        ..
    })
));

// English should not appear in the iterator result:
let supported_langids = provider
    .supported_locales()
    .expect("Should successfully make an iterator of supported locales")
    .into_iter()
    .map(|options| options.get_langid())
    .collect::<Vec<LanguageIdentifier>>();
assert!(supported_langids.contains(&langid!("de")));
assert!(!supported_langids.contains(&langid!("en")));

pub fn filter_by_langid_allowlist_strict<'a>(
    self,
    allowlist: &'a [LanguageIdentifier]
) -> RequestFilterDataProvider<D, Box<dyn Fn(DataRequest<'_>) -> bool + Sync + 'a>>where
    F: 'a,

Filter out data request except those having a language identifier that exactly matches one in the allowlist.

This will be replaced with a smarter algorithm for locale filtering; see https://github.com/unicode-org/icu4x/issues/834

Data requests with no langid will be allowed. To reject data requests without a langid, chain this with Self::require_langid.

Examples

use icu_locid::{langid, locale};
use icu_provider::hello_world::*;
use icu_provider::prelude::*;
use icu_provider_adapters::filter::Filterable;

let allowlist = vec![langid!("de"), langid!("zh")];
let provider = HelloWorldProvider
    .filterable("Demo German+Chinese filter")
    .filter_by_langid_allowlist_strict(&allowlist);

// German requests should succeed:
let req_de = DataRequest {
    locale: &locale!("de").into(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_de);
assert!(matches!(response, Ok(_)));

// English requests should fail:
let req_en = DataRequest {
    locale: &locale!("en-US").into(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_en);
assert!(matches!(
    response,
    Err(DataError {
        kind: DataErrorKind::FilteredResource,
        ..
    })
));
assert_eq!(
    response.unwrap_err().str_context,
    Some("Demo German+Chinese filter")
);

pub fn require_langid<'a>(
    self
) -> RequestFilterDataProvider<D, Box<dyn Fn(DataRequest<'_>) -> bool + Sync + 'a>>where
    F: 'a,

Require that data requests contain a langid.

Examples

use icu_locid::locale;
use icu_provider::hello_world::*;
use icu_provider::prelude::*;
use icu_provider_adapters::filter::Filterable;

let provider = HelloWorldProvider
    .filterable("Demo require-langid filter")
    .require_langid();

// Requests with a langid should succeed:
let req_with_langid = DataRequest {
    locale: &locale!("de").into(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_with_langid);
assert!(matches!(response, Ok(_)));

// Requests without a langid should fail:
let req_no_langid = DataRequest {
    locale: Default::default(),
    metadata: Default::default(),
};
let response: Result<DataResponse<HelloWorldV1Marker>, _> =
    provider.load(req_no_langid);
assert!(matches!(
    response,
    Err(DataError {
        kind: DataErrorKind::FilteredResource,
        ..
    })
));

Trait Implementations

impl<D, F> AnyProvider for RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool,
    D: AnyProvider,

fn load_any(
    &self,
    key: DataKey,
    req: DataRequest<'_>
) -> Result<AnyResponse, DataError>

Loads an AnyPayload according to the key and request.

impl<D, F> BufferProvider for RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool,
    D: BufferProvider,

fn load_buffer(
    &self,
    key: DataKey,
    req: DataRequest<'_>
) -> Result<DataResponse<BufferMarker>, DataError>

Loads a DataPayload<BufferMarker> according to the key and request.

impl<D, F, M> DataProvider<M> for RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool,
    M: KeyedDataMarker,
    D: DataProvider<M>,

fn load(&self, req: DataRequest<'_>) -> Result<DataResponse<M>, DataError>

Query the provider for data, returning the result.

impl<D, F, M> DynamicDataProvider<M> for RequestFilterDataProvider<D, F>where
    F: Fn(DataRequest<'_>) -> bool,
    M: DataMarker,
    D: DynamicDataProvider<M>,

fn load_data(
    &self,
    key: DataKey,
    req: DataRequest<'_>
) -> Result<DataResponse<M>, DataError>

Query the provider for data, returning the result.