1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124
use std::{marker::PhantomData, sync::Arc}; /// Handle for manipulating a signal owned elsewhere /// /// Handle types are typically verbose. Consider using type aliases or newtypes as shorthand for /// those that arise commonly in your application. pub struct Handle<T: ?Sized> { shared: Arc<T>, } impl<T: ?Sized> Handle<T> { /// Construct a handle enclosing `signal` /// /// Used to implement signals like [`Mixer`](crate::Mixer). /// /// # Safety /// /// There must never be more than one other `Arc` referencing the same `T`. pub unsafe fn from_arc(signal: Arc<T>) -> Self { Self { shared: signal } } /// Get the control for [`Controlled`] signal `S` in a chain of signals /// /// `Index` can usually be inferred. /// /// # Example /// ``` /// # use oddio::*; /// fn quiet(signal: &mut Handle<Spatial<Gain<FramesSignal<Sample>>>>) { /// signal.control::<Gain<_>, _>().set_gain(0.5); /// } /// ``` pub fn control<'a, S, Index>(&'a mut self) -> S::Control where T: FilterHaving<S, Index>, S: Controlled<'a>, { let signal: &S = (*self.shared).get(); unsafe { S::make_control(signal) } } } // Sound because `T` is not accessible except via `unsafe trait Controlled` unsafe impl<T> Send for Handle<T> {} unsafe impl<T> Sync for Handle<T> {} /// A wrapper which transforms a [`Signal`](crate::Signal) /// /// Allows [`Handle::control`] to expose the transformed signal as well as the transformer. For /// example, a `Handle<Spatial<Gain<_>>>` allows both gain and motion state to be updated. pub trait Filter { /// Type of signal transformed by this filter type Inner: ?Sized; /// Access the inner signal fn inner(&self) -> &Self::Inner; } /// A [`Signal`] or transformer that can be safely controlled from another thread /// /// # Safety /// /// `make_control` and `Control` must not permit access to `&Self` that constitutes a data race with /// concurrent invocation of any [`Signal`] method even if `Self: !Sync`. For example, an /// implementation could restrict itself to atomic operations. /// /// [`Signal`]: crate::Signal pub unsafe trait Controlled<'a>: Sized + 'a { /// The interface through which this signal can be safely controlled type Control; /// Construct a `Control` for `signal` /// /// # Safety /// /// Must not be invoked while another `Control` for this signal exists unsafe fn make_control(signal: &'a Self) -> Self::Control; } /// Filter chains that contain a `T` at any position /// /// Helper trait for [`Handle::control()`]. `Index` is [`Here`] or [`There`], and can generally be /// inferred. pub trait FilterHaving<T, Index> { /// Get the `T` element of a filter chain fn get(&self) -> &T; } /// `Index` value for [`FilterHaving`] representing the first filter in the chain pub struct Here(()); /// `Index` value for [`FilterHaving`] representing the filter at position `T+1` pub struct There<T>(PhantomData<T>); impl<T> FilterHaving<T, Here> for T { fn get(&self) -> &T { self } } impl<T: Filter, U, I> FilterHaving<U, There<I>> for T where T::Inner: FilterHaving<U, I>, { fn get(&self) -> &U { self.inner().get() } } #[cfg(test)] mod tests { use super::*; fn _foo<A, B, C>(x: &A) where A: Filter<Inner = B>, B: Filter<Inner = C>, { let _: &A = x.get(); let _: &B = x.get(); let _: &C = x.get(); } }