trickle 0.0.1

Simple message bus library
Documentation 
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use std::marker::PhantomData;

use crate::{Receiver, Sender};

/***
 * A node is the default implementation of the event system
 * It can receive events and dispatch them to other nodes
 */
#[derive(Clone)]
pub struct Node<TEvent, TEntity>
where
    TEntity: Receiver<TEvent>,
{
    children: Vec<Node<TEvent, TEntity>>,
    entity: TEntity,
    phantom: PhantomData<TEvent>,
}

impl<TEvent, TEntity> Node<TEvent, TEntity>
where
    TEntity: Receiver<TEvent>,
{
    pub fn new(entity: TEntity, children: Vec<Node<TEvent, TEntity>>) -> Self {
        Self {
            entity,
            children,
            phantom: PhantomData::default(),
        }
    }
}

impl<TEvent, TEntity> Sender<TEvent> for Node<TEvent, TEntity>
where
    TEntity: Receiver<TEvent>,
{
    fn emit(&self, event: TEvent, target: &mut dyn Receiver<TEvent>) -> bool {
        target.handle(&event)
    }
}

impl<TEvent, TEntity> Receiver<TEvent> for Node<TEvent, TEntity>
where
    TEntity: Receiver<TEvent>,
{
    fn handle(&mut self, event: &TEvent) -> bool {
        if !self.entity.handle(event) {
            let mut handeled = false;
            for child in &mut self.children {
                handeled |= child.handle(event);
            }
            handeled
        } else {
            true
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    enum Event {
        HandleInParent,
        HandleInChild,
    }

    enum Entities {
        Parent(ParentEntity),
        Child(ChildEntity),
    }

    impl Receiver<Event> for Entities {
        fn handle(&mut self, event: &Event) -> bool {
            match self {
                Self::Parent(e) => e.handle(event),
                Self::Child(e) => e.handle(event),
            }
        }
    }

    struct ParentEntity;

    impl Receiver<Event> for ParentEntity {
        fn handle(&mut self, event: &Event) -> bool {
            match event {
                Event::HandleInParent => true,
                _ => false,
            }
        }
    }

    struct ChildEntity;

    impl Receiver<Event> for ChildEntity {
        fn handle(&mut self, event: &Event) -> bool {
            match event {
                Event::HandleInChild => true,
                _ => false,
            }
        }
    }

    #[test]
    fn it_trigger_event_in_parent() {
        let mut r = Node::new(Entities::Parent(ParentEntity), vec![]);

        let s = Node::new(Entities::Parent(ParentEntity), vec![]);
        assert!(s.emit(Event::HandleInParent, &mut r));
        assert!(!s.emit(Event::HandleInChild, &mut r));
    }

    #[test]
    fn it_trigger_event_in_child() {
        let mut r = Node::new(Entities::Child(ChildEntity), vec![]);

        let s = Node::new(Entities::Parent(ParentEntity), vec![]);
        assert!(!s.emit(Event::HandleInParent, &mut r));
        assert!(s.emit(Event::HandleInChild, &mut r));
    }

    #[test]
    fn it_trigger_event_in_tree() {
        let mut r = Node::new(
            Entities::Parent(ParentEntity),
            vec![Node::new(Entities::Child(ChildEntity), vec![])],
        );

        let s = Node::new(Entities::Parent(ParentEntity), vec![]);
        assert!(s.emit(Event::HandleInParent, &mut r));
        assert!(s.emit(Event::HandleInChild, &mut r));
    }
}