icu_provider/
dynutil.rs

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1// This file is part of ICU4X. For terms of use, please see the file
2// called LICENSE at the top level of the ICU4X source tree
3// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
4
5//! Utilities for using trait objects with `DataPayload`.
6
7/// Trait to allow conversion from `DataPayload<T>` to `DataPayload<S>`.
8///
9/// This trait can be manually implemented in order to enable [`impl_dynamic_data_provider`].
10pub trait UpcastDataPayload<M>
11where
12    M: crate::DynamicDataMarker,
13    Self: Sized + crate::DynamicDataMarker,
14{
15    /// Upcast a `DataPayload<T>` to a `DataPayload<S>` where `T` implements trait `S`.
16    fn upcast(other: crate::DataPayload<M>) -> crate::DataPayload<Self>;
17}
18
19/// Implements [`UpcastDataPayload`] from several data markers to a single data marker
20/// that all share the same [`DynamicDataMarker::DataStruct`].
21///
22/// # Examples
23///
24/// ```
25/// use icu_provider::prelude::*;
26/// use std::borrow::Cow;
27///
28/// struct FooV1;
29/// impl DynamicDataMarker for FooV1 {
30///     type DataStruct = Foo<'static>;
31/// }
32/// icu_provider::data_marker!(BarV1, Foo<'static>);
33/// icu_provider::data_marker!(BazV1, Foo<'static>);
34///
35/// #[derive(yoke::Yokeable)]
36/// pub struct Foo<'data> {
37///     message: Cow<'data, str>,
38/// };
39///
40/// icu_provider::data_struct!(Foo<'_>);
41///
42/// icu_provider::dynutil::impl_casting_upcast!(FooV1, [BarV1, BazV1,]);
43/// ```
44///
45/// [`DynamicDataMarker::DataStruct`]: crate::DynamicDataMarker::DataStruct
46#[macro_export]
47#[doc(hidden)] // macro
48macro_rules! __impl_casting_upcast {
49    ($dyn_m:path, [ $($struct_m:ident),+, ]) => {
50        $(
51            impl $crate::dynutil::UpcastDataPayload<$struct_m> for $dyn_m {
52                fn upcast(other: $crate::DataPayload<$struct_m>) -> $crate::DataPayload<$dyn_m> {
53                    other.cast()
54                }
55            }
56        )+
57    }
58}
59#[doc(inline)]
60pub use __impl_casting_upcast as impl_casting_upcast;
61
62/// Implements [`DynamicDataProvider`] for a marker type `S` on a type that already implements
63/// [`DynamicDataProvider`] or [`DataProvider`] for one or more `M`, where `M` is a concrete type
64/// that is convertible to `S` via [`UpcastDataPayload`].
65///
66/// ## Wrapping DataProvider
67///
68/// If your type implements [`DataProvider`], pass a list of markers as the second argument.
69/// This results in a `DynamicDataProvider` that delegates to a specific marker if the marker
70/// matches or else returns [`DataErrorKind::MarkerNotFound`].
71///
72/// [`DynamicDataProvider`]: crate::DynamicDataProvider
73/// [`DataProvider`]: crate::DataProvider
74/// [`DataErrorKind::MarkerNotFound`]: (crate::DataErrorKind::MarkerNotFound)
75/// [`SerializeMarker`]: (crate::buf::SerializeMarker)
76#[doc(hidden)] // macro
77#[macro_export]
78macro_rules! __impl_dynamic_data_provider {
79    // allow passing in multiple things to do and get dispatched
80    ($provider:ty, $arms:tt, $one:path, $($rest:path),+) => {
81        $crate::dynutil::impl_dynamic_data_provider!(
82            $provider,
83            $arms,
84            $one
85        );
86
87        $crate::dynutil::impl_dynamic_data_provider!(
88            $provider,
89            $arms,
90            $($rest),+
91        );
92    };
93
94    ($provider:ty, { $($ident:ident = $marker:path => $struct_m:ty),+, $(_ => $struct_d:ty,)?}, $dyn_m:ty) => {
95        impl $crate::DynamicDataProvider<$dyn_m> for $provider
96        {
97            fn load_data(
98                &self,
99                marker: $crate::DataMarkerInfo,
100                req: $crate::DataRequest,
101            ) -> Result<
102                $crate::DataResponse<$dyn_m>,
103                $crate::DataError,
104            > {
105                match marker.id.hashed() {
106                    $(
107                        h if h == $marker.id.hashed() => {
108                            let result: $crate::DataResponse<$struct_m> =
109                                $crate::DynamicDataProvider::<$struct_m>::load_data(self, marker, req)?;
110                            Ok($crate::DataResponse {
111                                metadata: result.metadata,
112                                payload: $crate::dynutil::UpcastDataPayload::<$struct_m>::upcast(result.payload),
113                            })
114                        }
115                    )+,
116                    $(
117                        _ => {
118                            let result: $crate::DataResponse<$struct_d> =
119                                $crate::DynamicDataProvider::<$struct_d>::load_data(self, marker, req)?;
120                            Ok($crate::DataResponse {
121                                metadata: result.metadata,
122                                payload: $crate::dynutil::UpcastDataPayload::<$struct_d>::upcast(result.payload),
123                            })
124                        }
125                    )?
126                    _ => Err($crate::DataErrorKind::MarkerNotFound.with_req(marker, req))
127                }
128            }
129        }
130
131    };
132    ($provider:ty, [ $($(#[$cfg:meta])? $struct_m:ty),+, ], $dyn_m:path) => {
133        impl $crate::DynamicDataProvider<$dyn_m> for $provider
134        {
135            fn load_data(
136                &self,
137                marker: $crate::DataMarkerInfo,
138                req: $crate::DataRequest,
139            ) -> Result<
140                $crate::DataResponse<$dyn_m>,
141                $crate::DataError,
142            > {
143                match marker.id.hashed() {
144                    $(
145                        $(#[$cfg])?
146                        h if h == <$struct_m as $crate::DataMarker>::INFO.id.hashed() => {
147                            let result: $crate::DataResponse<$struct_m> =
148                                $crate::DataProvider::load(self, req)?;
149                            Ok($crate::DataResponse {
150                                metadata: result.metadata,
151                                payload: $crate::dynutil::UpcastDataPayload::<$struct_m>::upcast(result.payload),
152                            })
153                        }
154                    )+,
155                    _ => Err($crate::DataErrorKind::MarkerNotFound.with_req(marker, req))
156                }
157            }
158        }
159    };
160}
161#[doc(inline)]
162pub use __impl_dynamic_data_provider as impl_dynamic_data_provider;
163
164#[doc(hidden)] // macro
165#[macro_export]
166macro_rules! __impl_iterable_dynamic_data_provider {
167    ($provider:ty, [ $($(#[$cfg:meta])? $struct_m:ty),+, ], $dyn_m:path) => {
168        impl $crate::IterableDynamicDataProvider<$dyn_m> for $provider {
169            fn iter_ids_for_marker(&self, marker: $crate::DataMarkerInfo) -> Result<alloc::collections::BTreeSet<$crate::DataIdentifierCow>, $crate::DataError> {
170                match marker.id.hashed() {
171                    $(
172                        $(#[$cfg])?
173                        h if h == <$struct_m as $crate::DataMarker>::INFO.id.hashed() => {
174                            $crate::IterableDataProvider::<$struct_m>::iter_ids(self)
175                        }
176                    )+,
177                    _ => Err($crate::DataErrorKind::MarkerNotFound.with_marker(marker))
178                }
179            }
180        }
181    }
182}
183#[doc(inline)]
184pub use __impl_iterable_dynamic_data_provider as impl_iterable_dynamic_data_provider;
icu_provider/dynutil.rs

icu_provider/
dynutil.rs
