1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
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)
}
}
|