Rust Event Emitter

A thread-safe, flexible event emitter implementation in Rust.

Features

• Thread-safe event emission and handling
• Support for multiple event types and handlers
• Typed event arguments
• Asynchronous event processing
• Easy-to-use macros for event emission

Installation

Add this to your Cargo.toml:

[dependencies]
event_emitter = "3.0.0" 

Usage

Here's a more comprehensive example demonstrating various features of the EventEmitter and AsyncEventEmitter:

EventEmitter

The main struct for managing events.

Example

use event_emitter::{EventEmitter, emit};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

fn main() {
    // Create a new EventEmitter
    let emitter = EventEmitter::new();
    
    // Start the event listener in a separate thread
    let listener = emitter.start_listening();

    // Create a shared state to demonstrate thread-safe updates
    let shared_state = Arc::new(Mutex::new(Vec::new()));

    // Handler for a simple greeting event
    emitter.on("greet", |(name,): (String,)| {
        println!("Hello, {}!", name);
    });

    // Handler for an event with multiple arguments
    {
        let state = Arc::clone(&shared_state);
        emitter.on("user_action", move |(user, action, value): (String, String, i32)| {
            println!("User {} performed action: {} with value: {}", user, action, value);
            let mut data = state.lock().unwrap();
            data.push((user, action, value));
        });
    }

    // Handler for a more complex event
    {
        let state = Arc::clone(&shared_state);
        emitter.on("process_data", move |(data, callback): (Vec<i32>, Box<dyn Fn(i32) + Send + 'static>)| {
            let sum: i32 = data.iter().sum();
            callback(sum);
            let mut shared_data = state.lock().unwrap();
            shared_data.push(("System".to_string(), "process_data".to_string(), sum));
        });
    }

    // Emit events
    emit!(emitter, "greet", "Alice".to_string());
    
    emit!(emitter, "user_action", "Bob".to_string(), "click".to_string(), 5);
    
    let callback = Box::new(|result: i32| {
        println!("Processing result: {}", result);
    });
    emit!(emitter, "process_data", vec![1, 2, 3, 4, 5], callback);

    // Demonstrate emitting events from another thread
    let emitter_clone = emitter.clone();
    thread::spawn(move || {
        thread::sleep(Duration::from_millis(100));
        emit!(emitter_clone, "greet", "Thread".to_string());
    });

    // Wait a bit for all events to be processed
    thread::sleep(Duration::from_millis(200));

    // Print the final state
    let final_state = shared_state.lock().unwrap();
    println!("Final state: {:?}", *final_state);

    // Stop the event listener
    emitter.stop_listening();
    listener.join().unwrap();
}

This example demonstrates:

1. Creating and starting an EventEmitter
2. Registering handlers for different event types
3. Handling events with multiple arguments
4. Using shared state across event handlers
5. Emitting events with the emit! macro
6. Passing callbacks as event arguments
7. Cloning and using the EventEmitter in different threads

API

Methods

• new(): Create a new EventEmitter.
• with_thread_pool_size(thread_pool_size: usize): Create a new EventEmitter with a specified capacity.
• on<F, Args>(&self, event: &str, handler: F) -> HandlerId: Register an event handler.
• off(&self, event: &str, handler_id: HandlerId): Remove all handlers for an event.
• emit(&self, event: &str, args: Vec<Param>): Emit an event.
• start_listening(&self) -> JoinHandle<()>: Start the event processing loop.
• stop_listening(&self): Stop the event processing loop.
• clone(&self) -> Self: Create a clone of the EventEmitter.

AsyncEventEmitter

rs-event-emitter = { version = "2.0.2", features = ["async"] }

// or use tokio runtime
rs-event-emitter = { version = "2.0.2", features = ["async", "tokio_runtime"] }

Example

#[tokio::main]
async fn use_tokio_runtime() {
    // use tokio runtime
    let rt = Arc::new(TokioRuntime::new());

    let emitter = AsyncEventEmitter::new(rt);

    let counter = Arc::new(AtomicI32::new(0));

    let counter_clone = counter.clone();

    emitter
        .on("test_event", move |_args: ()| {
            let counter = counter_clone.clone();
            Box::pin(async move {
                counter.fetch_add(1, Ordering::SeqCst);
            })
        })
        .await;

    emitter.emit("test_event", vec![]).await;
    // emitter.emit("test_event", vec![]).await;
    async_emit!(emitter, "test_event").await;

    assert_eq!(counter.load(Ordering::SeqCst), 2);

    println!("done");
}

// or use custom runtime
use rs_event_emitter::runtime::*;

struct CustomRuntime;

impl Runtime for CustomRuntime {
    ...
}

fn use_custom_runtime() {
    // use custom runtime
    let rt = Arc::new(CustomRuntime::new());
    let emitter = AsyncEventEmitter::new(rt);   
}

This example demonstrates:

1. Creating and starting an AsyncEventEmitter
2. Registering asynchronous event handlers
3. Emitting events with typed arguments
4. Using custom async runtimes
5. Handling events with multiple arguments
6. Emitting events with the async_emit! macro

API

Methods

• new(rt: Arc<R>): Create a new AsyncEventEmitter with the given async runtime.
• async on<F, Args>(&self, event: &str, handler: F) -> HandlerId: Register an asynchronous event handler.
• async off(&self, event: &str, handler_id: HandlerId): Remove a specific handler for an event.
• async emit(&self, event: &str, args: Vec<Param>): Emit an event asynchronously.
• clone(&self) -> Self: Create a clone of the AsyncEventEmitter.

Note: All methods on AsyncEventEmitter are asynchronous and return Futures that need to be awaited.

Additional Information

• Event Parameters: Supports up to 16 parameters per event. For more, use structs or collections.
• Macros: emit! for convenient event emission with typed arguments.
• Threading: Designed to be thread-safe with concurrent event processing.
• Testing: Run tests with cargo test.

Macros

• emit!: A convenient macro for emitting events with typed arguments.
• async_emit!: A convenient macro for emitting events with typed arguments.

Testing

The library includes a comprehensive test suite. Run the tests using:

cargo test

License

This project is licensed under [LICENSE NAME]. See the LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.