Reactive Rock Paper Scissors with Groovy and RxJava

ReactiveRPS.groovy

@Grab( 'com.netflix.rxjava:rxjava-groovy:0.15.1' )
import groovy.transform.*
import rx.*

@CompileStatic
class RPSRX {
    enum Result {
        WIN, LOSE, DRAW
    }
    
    enum Move {
        ROCK( SCISSORS ),
        PAPER( ROCK ),
        SCISSORS( PAPER )
        Move beats
        Move( Move beats ) {
            this.beats = beats
        }
        boolean beats( Move other ) {
            other == beats
        }
    }
    
    @Immutable
    static class PlayerMove {
        String player
        Move move
        String toString() { "$player:$move" }
    }
    
    final Random rnd = new Random()
    
    private <T> Observable.OnSubscribeFunc<T> subscriptionBuilder( Closure<T> generator ) {
        { Observer<T> observer ->
            boolean running = true
            new Thread( { ->
                while( running ) {
                    observer.onNext( generator() )
                }
                observer.onCompleted();
            } ).start()
            
            return { -> running = false } as Subscription
        }
    }
 
    Observable<Integer> numbers() {
        int n = 1
        Observable.create( subscriptionBuilder( { -> n++ } ) )
    }
        
    Observable<Move> moves() {
        Observable.create( subscriptionBuilder {
            Move.values()[ rnd.nextInt( Move.values().length ) ]
        } )
    }
    
    Observable<PlayerMove> player( String name ) {
        moves().map { Move it -> new PlayerMove( name, it ) }
    }
    
    String message( Integer index, PlayerMove m1, PlayerMove m2 ) {
        "Game $index : $m1 vs $m2 : ${resultMessage( m1, m2, result( m1, m2 ) )}"
    }
    
    Result result( PlayerMove m1, PlayerMove m2 ) {
        m1.move == m2.move ? Result.DRAW : m1.move.beats == m2.move ? Result.WIN : Result.LOSE
    }
    
    String resultMessage( PlayerMove m1, PlayerMove m2, Result r ) {
        r == Result.DRAW ? 'draw' : r == Result.WIN ? "$m1.player wins" : "$m2.player wins"
    }
        
    Observable<String> game( String name1, String name2 ) {
        Observable.zip( numbers(), player( name1 ), player( name2 ) ) { Integer n, PlayerMove a, PlayerMove b ->
            message( n, a, b ) 
        }
    }
}
 
new RPSRX().game( 'tim', 'alice' ).take( 10 ).subscribe { println it }

@tednaleid Cool! Top tip :-) I hadn't noticed that in the rx-java deps, thanks! :-)

Rock Paper Scissors is my new Hello World ;-) Got my groovy-stream version, a Java 8 one, this one and next I might try project reactor ;-)

Doesn't seem to work anymore:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
/Users/rgrinberg/reps/snippets/groovy/rx-rps.groovy: 34: [Static type checking] - Cannot return value of type groovy.lang.Closure <rx.Subscription> on method returning type rx.Observable$OnSubscribeFunc <T>
 @ line 34, column 13.
               { Observer<T> observer ->
               ^

1 error