ixa/macros/
define_global_property.rs

1/// Defines a global property with the following parameters:
2/// * `$global_property`: Name for the identifier type of the global property
3/// * `$value`: The type of the property's value
4/// * `$validate`: A function (or closure) that checks the validity of the property and returns
5///   `Result<(), Box<dyn std::error::Error + Send + Sync + 'static>>` (optional)
6///
7/// Validator code is client code, so it should create and box its own error values.
8/// Ixa wraps any returned error in
9/// [`IxaError::IllegalGlobalPropertyValue`](crate::error::IxaError::IllegalGlobalPropertyValue)
10/// when the property is set or loaded.
11#[macro_export]
12macro_rules! define_global_property {
13    ($global_property:ident, $value:ty, $validate: expr) => {
14        #[derive(Copy, Clone)]
15        pub struct $global_property;
16
17        impl $crate::global_properties::GlobalProperty for $global_property {
18            type Value = $value;
19
20            fn id() -> usize {
21                // This static must be initialized with a compile-time constant expression.
22                // We use `usize::MAX` as a sentinel to mean "uninitialized". This
23                // static variable is shared among all instances of this concrete item type.
24                static INDEX: std::sync::atomic::AtomicUsize =
25                    std::sync::atomic::AtomicUsize::new(usize::MAX);
26
27                // Fast path: already initialized.
28                let index = INDEX.load(std::sync::atomic::Ordering::Relaxed);
29                if index != usize::MAX {
30                    return index;
31                }
32
33                // Slow path: initialize it.
34                $crate::global_properties::initialize_global_property_id(&INDEX)
35            }
36
37            fn new() -> Self {
38                $global_property
39            }
40
41            fn name() -> &'static str {
42                let full = std::any::type_name::<Self>();
43                // Splitting any string, including an empty one, always yields at least one segment.
44                full.rsplit("::").next().unwrap()
45            }
46
47            fn validate(
48                val: &$value,
49            ) -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
50                $validate(val)
51            }
52        }
53
54        $crate::paste::paste! {
55            $crate::ctor::declarative::ctor!{
56                #[ctor(unsafe)]
57                fn [<$global_property:snake _register>]() {
58                    let module = module_path!();
59                    // Splitting any module path always yields at least one segment.
60                    let mut name = module.split("::").next().unwrap().to_string();
61                    name += ".";
62                    name += stringify!($global_property);
63                    let _ = <$global_property as $crate::global_properties::GlobalProperty>::id();
64                    $crate::global_properties::add_global_property::<$global_property>(&name);
65                }
66            }
67        }
68    };
69
70    ($global_property: ident, $value: ty) => {
71        $crate::define_global_property!($global_property, $value, |_| { Ok(()) });
72    };
73}
ixa/macros/define_global_property.rs

ixa/macros/
define_global_property.rs
