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ccn/Packages/Localization/Sources/Internal/Protocols/CatalogResolving.swift
T
2026-08-19 23:19:08 +02:00

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Swift

import Foundation
/// A backend that resolves localized strings for an explicit locale and reports the languages it serves.
///
/// This is the seam that decouples ``Localize`` and ``LanguageList`` from *how* localizations are stored and resolved. The shipping implementation,
/// ``StringCatalog``, reads a raw `.xcstrings` catalog so it behaves identically on Darwin and Linux. A future backend — for example one built on
/// `String(localized:)` for a native Apple app that needs plural and device variations — can conform without changing any caller.
///
/// Resolution never fails: an implementation returns the key itself when it has no localization for it, mirroring Foundation's `String(localized:)`.
/// This is the contract both a dictionary lookup and the native API can honour, since the native API cannot distinguish a missing key from a translation that
/// happens to equal the key.
protocol CatalogResolving: Sendable {
// MARK: Properties
/// The source (development) language, used as the final fallback when a locale has no localization and as the default language a ``LanguageList``
/// serves.
var sourceLanguage: String { get }
/// The outcome of reading the backing catalog, for consumers to surface at startup.
var state: CatalogState { get }
/// Every language the backend can resolve strings for, including the source language.
var languages: Set<String> { get }
// MARK: Methods
/// Resolves a catalog key in the given locale.
/// - Parameters:
/// - key: the catalog key to look up.
/// - locale: the locale to resolve the key in.
/// - Returns: the localized string, falling back to the source language, then to the key itself.
func string(
for key: String,
in locale: Locale
) -> String
}