1 files changed, 30 insertions, 0 deletions
diff --git a/intl/l10n/rust/l10nregistry-rs/src/source/fetcher.rs b/intl/l10n/rust/l10nregistry-rs/src/source/fetcher.rs
new file mode 100644
index 0000000000..3a022990a6
--- /dev/null
+++ b/intl/l10n/rust/l10nregistry-rs/src/source/fetcher.rs
@@ -0,0 +1,30 @@
+use async_trait::async_trait;
+use fluent_fallback::types::ResourceId;
+use std::io;
+
+/// The users of [`FileSource`] implement this trait to provide loading of
+/// resources, returning the contents of a resource as a
+/// `String`. [`FileSource`] handles the conversion from string representation
+/// into `FluentResource`.
+///
+/// [`FileSource`]: source/struct.FileSource.html
+#[async_trait(?Send)]
+pub trait FileFetcher {
+    /// Return the `String` representation for `path`. This version is
+    /// blocking.
+    ///
+    /// See [`fetch`](#tymethod.fetch).
+    fn fetch_sync(&self, resource_id: &ResourceId) -> io::Result<String>;
+
+    /// Return the `String` representation for `path`.
+    ///
+    /// On success, returns `Poll::Ready(Ok(..))`.
+    ///
+    /// If no resource is available to be fetched, the method returns
+    /// `Poll::Pending` and arranges for the current task (via
+    /// `cx.waker().wake_by_ref()`) to receive a notification when the resource
+    /// is available.
+    ///
+    /// See [`fetch_sync`](#tymethod.fetch_sync)
+    async fn fetch(&self, path: &ResourceId) -> io::Result<String>;
+}