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use crate :: { Filter, Events }; /// Indicate that a type is observable. You can call [`observe`](Observable::observe) to get a /// stream of events. /// /// Generally used with a [Pharos](crate::Pharos) object which manages the observers for you. /// /// ``` /// use pharos::*; /// use futures::stream::StreamExt; /// /// // The event we want to broadcast /// // /// #[ derive( Debug, Clone ) ] /// // /// enum Steps /// { /// Step1 , /// Step2 , /// Done , /// /// // Data is possible, but it has to be clone and will be cloned for each observer /// // except observers that filter this event out. /// // /// Error(u8) , /// } /// /// /// impl Steps /// { /// fn is_err( &self ) -> bool /// { /// match self /// { /// Self::Error(_) => true , /// _ => false , /// } /// } /// } /// /// /// // The object we want to be observable /// // /// struct Foo { pharos: Pharos<Steps> }; /// /// impl Observable<Steps> for Foo /// { /// // Pharos implements observable, so we just forward the call. /// // /// fn observe( &mut self, options: ObserveConfig<Steps> ) -> Events<Steps> /// { /// self.pharos.observe( options ) /// } /// } /// /// /// // use in async context /// // /// async fn task() /// { /// let mut foo = Foo { pharos: Pharos::default() }; /// let mut errors = foo.observe( Filter::Pointer( Steps::is_err ).into() ); /// /// // will only be notified on errors now /// // /// let next_error = errors.next().await; /// } /// ``` // pub trait Observable<Event> where Event: Clone + 'static + Send , { /// Add an observer to the observable. Options can be in order to choose channel type and /// to filter events with a predicate. // fn observe( &mut self, options: ObserveConfig<Event> ) -> Events<Event>; } /// Choose the type of channel that will be used for your event stream. Used in [ObserveConfig]. // #[ derive( Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord )] // pub enum Channel { /// A channel with a limited buffer (the usize parameter). Creates back pressure when the buffer is full. /// This means that producer tasks may block if consumers can't process fast enough. // Bounded(usize), /// A channel with unbounded capacity. Note that this may lead to unbouded memory consumption if producers /// outpace consumers. // Unbounded, /// This enum might grow in the future, thanks to this that won't be a breaking change. // __NonExhaustive__ } impl Default for Channel { fn default() -> Self { Channel::Unbounded } } /// Configuration for your event stream, passed to [Observable::observe] when subscribing. /// This let's you choose the type of [channel](Channel) and let's /// you set a [filter](Filter) to ignore certain events. /// /// ``` /// use pharos::*; /// /// // We choose event type usize for simplicity. You choose whatever type you want here, /// // see the bounds on the Event type parameter throughout this library. /// // /// let mut pharos = Pharos::<usize>::default(); /// /// // Use defaults, unbounded channel and no filter. /// // /// pharos.observe( ObserveConfig::default() ); /// /// // Use bounded channel and defaults for other options. /// // /// pharos.observe( Channel::Bounded(5).into() ); /// /// // Use a filter and defaults for other options. /// // Will only receive events if they are bigger than three. /// // /// pharos.observe( Filter::Pointer( |evt| *evt > 3 ).into() ); /// /// // Set both channel and filter. Note you can only set one filter per observable. /// // /// let opts = ObserveConfig::default() /// /// .channel( Channel::Bounded( 5 ) ) /// .filter ( |evt| *evt > 3 ) /// ; /// /// pharos.observe( opts ); /// ``` // #[ derive( Debug ) ] // pub struct ObserveConfig<Event> where Event: Clone + 'static + Send { pub(crate) channel: Channel, pub(crate) filter : Option<Filter<Event>>, } /// Create a default configuration: /// - no filter /// - an unbounded channel // impl<Event> Default for ObserveConfig<Event> where Event: Clone + 'static + Send { fn default() -> Self { Self { channel: Channel::default(), filter : None , } } } impl<Event> ObserveConfig<Event> where Event: Clone + 'static + Send { /// Choose which channel implementation to use for your event stream. // pub fn channel( mut self, channel: Channel ) -> Self { self.channel = channel; self } /// Filter your event stream with a predicate that is a fn pointer. /// You can only set one filter per observable. // pub fn filter( mut self, filter: fn(&Event) -> bool ) -> Self { debug_assert!( self.filter.is_none(), "You can only set one filter on ObserveConfig" ); self.filter = Some( Filter::Pointer(filter) ); self } /// Filter your event stream with a predicate that is a closure that captures environment. /// It is preferred to use [filter](ObserveConfig::filter) if you can as this will box the closure. /// You can only set one filter per observable. // pub fn filter_boxed( mut self, filter: impl FnMut(&Event) -> bool + Send + 'static ) -> Self { debug_assert!( self.filter.is_none(), "You can only set one filter on ObserveConfig" ); self.filter = Some( Filter::Closure( Box::new(filter) ) ); self } } /// Create a ObserveConfig from a [Channel], getting default values for other options. // impl<Event> From<Channel> for ObserveConfig<Event> where Event: Clone + 'static + Send { fn from( channel: Channel ) -> Self { Self::default().channel( channel ) } } /// Create a ObserveConfig from a [Filter], getting default values for other options. // impl<Event> From<Filter<Event>> for ObserveConfig<Event> where Event: Clone + 'static + Send { fn from( filter: Filter<Event> ) -> Self { let mut s = Self::default(); s.filter = Some( filter ); s } }