evtc/
extract.rs

1//! Interfaces for extracting information from events.
2
3use crate::Event;
4
5/// Forcefully extracts information from a combat event.
6pub trait Extract: Sized {
7    /// Extracts [`Self`] from the combat event.
8    ///
9    /// # Safety
10    /// This is safe when the given event is a valid event to extract [`Self`] from.
11    unsafe fn extract(event: &Event) -> Self;
12}
13
14/// Attempts to extract information from a combat event.
15pub trait TryExtract: Sized + Extract {
16    /// Attempts to extract [`Self`] from the combat event.
17    #[inline]
18    fn try_extract(event: &Event) -> Option<Self> {
19        Self::can_extract(event).then(|| unsafe { Self::extract(event) })
20    }
21
22    /// Checks whether [`Self`] can be extracted from the event.
23    fn can_extract(event: &Event) -> bool;
24}
25
26/// Helper to transmute [`Event`] fields.
27///
28/// # Usage
29/// ```ignore
30/// let value = transmute_field!(event.src_agent as [f32; 3]);
31/// ```
32macro_rules! transmute_field {
33    ( $event: ident . $field: ident as $ty: tt ) => {{
34        const _: () = {
35            let end = ::memoffset::offset_of!($crate::Event, $field) + ::std::mem::size_of::<$ty>();
36            assert!(
37                end <= ::std::mem::size_of::<$crate::Event>(),
38                "transmute field outside of event",
39            );
40        };
41
42        let event: &$crate::Event = ::std::borrow::Borrow::borrow($event);
43        let field_ptr = ::std::ptr::addr_of!(event.$field);
44        (*field_ptr.cast::<$ty>()).clone()
45    }};
46}
47
48pub(crate) use transmute_field;