Struct icu_provider_adapters::fork::predicates::IdentifierNotFoundPredicate

pub struct IdentifierNotFoundPredicate;

A predicate that allows forking providers to search for a provider that supports a particular locale, based on whether it returns [DataErrorKind::IdentifierNotFound].

Examples

use icu_provider_adapters::fork::ForkByErrorProvider;
use icu_provider_adapters::fork::predicates::IdentifierNotFoundPredicate;
use icu_provider::prelude::*;
use icu_provider::hello_world::*;
use icu_locale::langid;

struct SingleLocaleProvider(DataLocale);
impl DataProvider<HelloWorldV1Marker> for SingleLocaleProvider {
    fn load(&self, req: DataRequest) -> Result<DataResponse<HelloWorldV1Marker>, DataError> {
        if *req.id.locale != self.0 {
            return Err(DataErrorKind::IdentifierNotFound.with_req(HelloWorldV1Marker::INFO, req));
        }
        HelloWorldProvider.load(req)
    }
}

let provider_de = SingleLocaleProvider(langid!("de").into());
let provider_ro = SingleLocaleProvider(langid!("ro").into());

// Create the forking provider:
let provider = ForkByErrorProvider::new_with_predicate(
    provider_de,
    provider_ro,
    IdentifierNotFoundPredicate
);

// Test that we can load both "de" and "ro" data:

let german_hello_world: DataResponse<HelloWorldV1Marker> = provider
    .load(DataRequest {
        id: DataIdentifierBorrowed::for_locale(&langid!("de").into()),
        ..Default::default()
    })
    .expect("Loading should succeed");

assert_eq!("Hallo Welt", german_hello_world.payload.get().message);

let romanian_hello_world: DataResponse<HelloWorldV1Marker> = provider
    .load(DataRequest {
        id: DataIdentifierBorrowed::for_locale(&langid!("ro").into()),
        ..Default::default()
    })
    .expect("Loading should succeed");

assert_eq!("Salut, lume", romanian_hello_world.payload.get().message);

// We should not be able to load "en" data because it is not in either provider:

DataProvider::<HelloWorldV1Marker>::load(
    &provider,
    DataRequest {
        id: DataIdentifierBorrowed::for_locale(&langid!("en").into()),
        ..Default::default()
    }
)
.expect_err("No English data");

Trait Implementations

impl Debug for IdentifierNotFoundPredicate

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl ForkByErrorPredicate for IdentifierNotFoundPredicate

const UNIT_ERROR: DataErrorKind = DataErrorKind::IdentifierNotFound

The error to return if there are zero providers.

fn test( &self, _: DataMarkerInfo, _: Option<DataRequest<'_>>, err: DataError, ) -> bool

This function is called when a data request fails and there are additional providers that could possibly fulfill the request.

impl PartialEq for IdentifierNotFoundPredicate

fn eq(&self, other: &IdentifierNotFoundPredicate) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for IdentifierNotFoundPredicate

impl StructuralPartialEq for IdentifierNotFoundPredicate