1 files changed, 48 insertions, 0 deletions
diff --git a/vendor/icu_provider/src/datagen/data_conversion.rs b/vendor/icu_provider/src/datagen/data_conversion.rs
new file mode 100644
index 000000000..59146352a
--- /dev/null
+++ b/vendor/icu_provider/src/datagen/data_conversion.rs
@@ -0,0 +1,48 @@
+// This file is part of ICU4X. For terms of use, please see the file
+// called LICENSE at the top level of the ICU4X source tree
+// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
+
+use crate::prelude::*;
+use crate::DataKey;
+use alloc::boxed::Box;
+
+/// A trait that allows for converting between data payloads of different types.
+///
+/// These payloads will typically be some kind of erased payload, either with
+/// AnyMarker, BufferMarker, or SerializeMarker, where converting requires reifying the type.
+/// A type implementing [`DataConverter`] will essentially have a "registry" mapping keys to
+/// concrete marker types M, and reifying the input to a `DataPayload<M>`, performing some conversion
+/// or computation, and erasing the result to `DataPayload<MTo>`.
+///
+/// It will typically be implemented on data providers used in datagen.
+///
+/// The [`make_exportable_provider!`] macro is able to automatically implement this trait.
+///
+/// [`make_exportable_provider!`]: crate::make_exportable_provider
+pub trait DataConverter<MFrom: DataMarker, MTo: DataMarker> {
+    /// Attempt to convert a payload corresponding to the given data key
+    /// from one marker type to another marker type.
+    ///
+    /// If this is not possible (for example, if the provider does not know about the key),
+    /// the original payload is returned back to the caller.
+    fn convert(
+        &self,
+        key: DataKey,
+        from: DataPayload<MFrom>,
+    ) -> Result<DataPayload<MTo>, (DataPayload<MFrom>, DataError)>;
+}
+
+impl<MFrom, MTo, P> DataConverter<MFrom, MTo> for Box<P>
+where
+    MFrom: DataMarker,
+    MTo: DataMarker,
+    P: DataConverter<MFrom, MTo> + ?Sized,
+{
+    fn convert(
+        &self,
+        key: DataKey,
+        from: DataPayload<MFrom>,
+    ) -> Result<DataPayload<MTo>, (DataPayload<MFrom>, DataError)> {
+        (**self).convert(key, from)
+    }
+}