eventbus_tiny/
macros.rs

1//! Useful macros
2
3/// Creates a filter-map clause that maps any event of type `$source` into `Some(T)`
4#[macro_export]
5macro_rules! where_into {
6    ($($source:ty),+ => $target:ty) => {{
7        // Create mapper function
8        fn convert(event: &dyn ::std::any::Any) -> ::std::option::Option<$target> {
9            // Try to downcast events
10            $(
11                // Downcast event if possible
12                if let Some(event) = event.downcast_ref::<$source>() {
13                    let cloned = event.clone();
14                    return Some(cloned.into());
15                }
16            )+
17
18            // No downcast successful
19            return None;
20        }
21
22        // Return mapper function
23        convert
24    }};
25}
26
27/// Creates a filter-map clause that tries to map any event of type `$source` into `Some(T)`
28#[macro_export]
29macro_rules! where_try_into {
30    ($($source:ty),+ => $target:ty) => {{
31        // Create mapper function
32        fn convert(event: &dyn ::std::any::Any) -> ::std::option::Option<$target> {
33            // Try to downcast events
34            $(
35                // Downcast and map event if possible
36                if let Some(event) = event.downcast_ref::<$source>() {
37                    let cloned = event.clone();
38                    if let Ok(mapped) = cloned.try_into() {
39                        // Return mapped event
40                        return Some(mapped);
41                    }
42                }
43            )+
44
45            // No downcast+mapping successful
46            return None;
47        }
48
49        // Return mapper function
50        convert
51    }};
52}
53
54/// Implements `From` to convert `$source` into `$enum::$variant($source)`
55#[macro_export]
56macro_rules! enum_from {
57    ($($source:ty => $enum:tt :: $variant:tt),+) => {
58        $(
59            // Enum conversion
60            impl ::std::convert::From<$source> for $enum {
61                fn from(source: $source) -> Self {
62                    // Do conversion
63                    <$enum>::$variant(source)
64                }
65            }
66        )+
67    };
68}
eventbus_tiny/macros.rs

eventbus_tiny/
macros.rs
