1 files changed, 46 insertions, 0 deletions
diff --git a/pygerrit/events.py b/pygerrit/events.py
index c07979a..4a7200d 100644
--- a/pygerrit/events.py
+++ b/pygerrit/events.py
@@ -4,6 +4,45 @@ from pygerrit.error import GerritError
 from pygerrit.models import Account, Approval, Change, Patchset, RefUpdate
 
 
+class GerritEventFactory(object):
+
+    """ Gerrit event factory. """
+
+    _events = {}
+
+    @classmethod
+    def register(cls, name):
+        """ Decorator to register the event identified by `name`.
+
+        Raise GerritError if the event is already registered.
+
+        """
+
+        def decorate(klazz):
+            if name in cls._events:
+                raise GerritError("Duplicate event: %s" % name)
+            cls._events[name] = klazz.__name__
+            return klazz
+        return decorate
+
+    @classmethod
+    def create(cls, json_data):
+        """ Create a new event instance.
+
+        Return an instance of the `GerritEvent` subclass from `json_data`
+        Raise GerritError if `json_data` does not contain a `type` key, or
+        no corresponding event is registered.
+
+        """
+        if not "type" in json_data:
+            raise GerritError("`type` not in json_data")
+        name = json_data["type"]
+        if not name in cls._events:
+            raise GerritError("Unknown event: %s" % name)
+        classname = cls._events[name]
+        return globals()[classname](json_data)
+
+
 class GerritEvent(object):
 
     """ Gerrit event base class. """
@@ -12,6 +51,7 @@ class GerritEvent(object):
         pass
 
 
+@GerritEventFactory.register("patchset-created")
 class PatchsetCreatedEvent(GerritEvent):
 
     """ Gerrit "patchset-created" event. """
@@ -26,6 +66,7 @@ class PatchsetCreatedEvent(GerritEvent):
             raise GerritError("PatchsetCreatedEvent: %s" % e)
 
 
+@GerritEventFactory.register("draft-published")
 class DraftPublishedEvent(GerritEvent):
 
     """ Gerrit "draft-published" event. """
@@ -40,6 +81,7 @@ class DraftPublishedEvent(GerritEvent):
             raise GerritError("DraftPublishedEvent: %s" % e)
 
 
+@GerritEventFactory.register("comment-added")
 class CommentAddedEvent(GerritEvent):
 
     """ Gerrit "comment-added" event. """
@@ -59,6 +101,7 @@ class CommentAddedEvent(GerritEvent):
             raise GerritError("CommentAddedEvent: %s" % e)
 
 
+@GerritEventFactory.register("change-merged")
 class ChangeMergedEvent(GerritEvent):
 
     """ Gerrit "change-merged" event. """
@@ -73,6 +116,7 @@ class ChangeMergedEvent(GerritEvent):
             raise GerritError("ChangeMergedEvent: %s" % e)
 
 
+@GerritEventFactory.register("change-abandoned")
 class ChangeAbandonedEvent(GerritEvent):
 
     """ Gerrit "change-abandoned" event. """
@@ -88,6 +132,7 @@ class ChangeAbandonedEvent(GerritEvent):
             raise GerritError("ChangeAbandonedEvent: %s" % e)
 
 
+@GerritEventFactory.register("change-restored")
 class ChangeRestoredEvent(GerritEvent):
 
     """ Gerrit "change-restored" event. """
@@ -103,6 +148,7 @@ class ChangeRestoredEvent(GerritEvent):
             raise GerritError("ChangeRestoredEvent: %s" % e)
 
 
+@GerritEventFactory.register("ref-updated")
 class RefUpdatedEvent(GerritEvent):
 
     """ Gerrit "ref-updated" event. """