Fixed subjects

src/cpl_reactive_extensions/subject.py

@@ -1,9 +1,100 @@
+from typing import Any, Optional
+
 from cpl_core.type import T
+from cpl_reactive_extensions.abc.observer import Observer
 from cpl_reactive_extensions.observable import Observable
+from cpl_reactive_extensions.subscriber import Subscriber
+from cpl_reactive_extensions.subscription import Subscription
 
 
-class Subject(Observable):
+class Subject(Observable, Observer):
     def __init__(self, _t: type):
         Observable.__init__(self)
 
+        self.is_closed = False
         self._t = _t
+        self._current_observers: Optional[list[Observer]] = None
+
+        self.closed = False
+        self.observers: list[Observer] = []
+        self.is_stopped = False
+        self.has_error = False
+        self.raised_error: Any = None
+
+    @property
+    def observed(self) -> bool:
+        return len(self.observers) > 0
+
+    def _raise_if_closed(self):
+        if not self.closed:
+            return
+        raise Exception("Subject is unsubscribed!")
+
+    def next(self, value: T):
+        self._raise_if_closed()
+
+        if not isinstance(value, self._t):
+            raise TypeError()
+
+        if self.is_stopped:
+            return
+
+        if self._current_observers is None:
+            self._current_observers = self.observers
+
+        for observer in self._current_observers:
+            observer.next(value)
+
+    def error(self, error: Exception):
+        self._raise_if_closed()
+        if self.is_stopped:
+            return
+
+        self.is_stopped = True
+        self.has_error = self.is_stopped
+        for observer in self.observers:
+            observer.error(error)
+
+    def complete(self):
+        self._raise_if_closed()
+
+        if self.is_stopped:
+            return
+
+        self.is_stopped = True
+        for observer in self.observers:
+            observer.complete()
+
+    def unsubscribe(self):
+        self.is_stopped = True
+        self.is_closed = True
+        self._current_observers = None
+        self.observers = []
+
+    def _try_subscribe(self, subscriber: Subscriber):
+        self._raise_if_closed()
+        return super()._try_subscribe(subscriber)
+
+    def _subscribe(self, subscriber: Subscriber) -> Subscription:
+        self._raise_if_closed()
+        self._check_finalized_statuses(subscriber)
+        return self._inner_subscribe(subscriber)
+
+    def _check_finalized_statuses(self, subscriber: Subscriber):
+        if self.has_error:
+            subscriber.error(self.raised_error)
+        elif self.is_stopped:
+            subscriber.complete()
+
+    def _inner_subscribe(self, subscriber: Subscriber) -> Optional[Subscription]:
+        if self.has_error or self.is_stopped:
+            return Subscription.empty()
+
+        self._current_observers = None
+        self.observers.append(subscriber)
+
+        def _initial():
+            self._current_observers = None
+            self.observers.remove(subscriber)
+
+        return Subscription(_initial)