icu_provider_adapters/fork/
macros.rs

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/// Make a forking data provider with an arbitrary number of inner providers
6/// that are known at build time.
7///
8/// # Examples
9///
10/// ```
11/// use icu_provider_adapters::fork::ForkByKeyProvider;
12///
13/// // Some empty example providers:
14/// #[derive(PartialEq, Debug)]
15/// struct Provider1;
16/// #[derive(PartialEq, Debug)]
17/// struct Provider2;
18/// #[derive(PartialEq, Debug)]
19/// struct Provider3;
20///
21/// // Combine them into one:
22/// let forking1 = icu_provider_adapters::make_forking_provider!(
23///     ForkByKeyProvider::new,
24///     [Provider1, Provider2, Provider3,]
25/// );
26///
27/// // This is equivalent to:
28/// let forking2 = ForkByKeyProvider::new(
29///     Provider1,
30///     ForkByKeyProvider::new(Provider2, Provider3),
31/// );
32///
33/// assert_eq!(forking1, forking2);
34/// ```
35#[macro_export]
36macro_rules! make_forking_provider {
37    // Base case:
38    ($combo_p:path, [ $a:expr, $b:expr, ]) => {
39        $combo_p($a, $b)
40    };
41    // General list:
42    ($combo_p:path, [ $a:expr, $b:expr, $($c:expr),+, ]) => {
43        $combo_p($a, $crate::make_forking_provider!($combo_p, [ $b, $($c),+, ]))
44    };
45}
46
47#[cfg(test)]
48mod test {
49    struct Provider1;
50    struct Provider2;
51    struct Provider3;
52
53    #[test]
54    fn test_make_forking_provider() {
55        make_forking_provider!(
56            crate::fork::ForkByKeyProvider::new,
57            [Provider1, Provider2, Provider3,]
58        );
59    }
60}
icu_provider_adapters/fork/macros.rs

icu_provider_adapters/fork/
macros.rs
