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# inspired by toy-rx: https://github.com/staltz/toy-rx
class Subscriber
attr_writer :subscription
def initialize(observer)
@observer = observer
end
def next(value)
@observer.next(value)
end
def error(error)
@observer.error(error)
end
def complete
@observer.complete
end
def unsubscribe
@subscription.unsubscribe unless @subscription.nil?
end
end
class Observable
def initialize(&subscribe)
@subscribe = subscribe
end
def self.create(&subscribe)
fail ArgumentError, "`create` needs a subscribe block" unless block_given?
new do |observer|
subscriber = Subscriber.new(observer)
subscription = subscribe.call(subscriber);
subscriber.subscription = subscription
subscription
end
end
# XXX probably nicer to define operators in another file
def map(&tx)
inobservable = self
Observable.create do |out|
observer = {
next: -> (x) {
begin
out.next(tx.call(x))
rescue => e
out.error(e)
end
},
error: -> (e) { out.error(e) },
complete: -> (e) { out.complete },
};
inobservable.subscribe(observer)
end
end
def subscribe(callbacks = {}, &nextcb)
callbacks[:next] = nextcb if block_given?
noop = -> () {}
klass = Class.new do
define_method(:next, callbacks.fetch(:next, noop))
define_method(:error, callbacks.fetch(:error, noop))
define_method(:complete, callbacks.fetch(:complete, noop))
end
observer = klass.new
@subscribe.call(observer)
end
end
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