Added interval

src/cpl_reactive_extensions/interval.py

@@ -0,0 +1,47 @@
+import sched
+import threading
+import time
+from typing import Callable
+
+from cpl_reactive_extensions.observable import Observable
+from cpl_reactive_extensions.subscriber import Subscriber
+
+
+class Interval(Observable):
+    def __init__(self, interval: float, callback: Callable = None):
+        self._interval = interval
+        callback = callback if callback is not None else self._default_callback
+
+        def schedule(x: Subscriber):
+            scheduler = sched.scheduler(time.time, time.sleep)
+            scheduler.enter(
+                self._interval,
+                1,
+                self._run,
+                (scheduler, x, callback),
+            )
+            scheduler.run()
+
+        def thread(x: Subscriber):
+            t = threading.Thread(target=schedule, args=(x,))
+            t.start()
+
+        Observable.__init__(self, thread)
+        self._i = 0
+
+    def _run(self, scheduler, x: Subscriber, callback: Callable):
+        if x.closed:
+            x.complete()
+            return
+
+        scheduler.enter(
+            self._interval,
+            1,
+            self._run,
+            (scheduler, x, callback),
+        )
+        callback(x)
+
+    def _default_callback(self, x: Subscriber):
+        x.next(self._i)
+        self._i += 1