Add a plugin infrastructure

jedi/plugins/__init__.py

@@ -0,0 +1,43 @@
+from functools import partial
+
+
+class _PluginManager(object):
+    def __init__(self, registered_plugin_classes=()):
+        self._registered_plugin_classes = list(registered_plugin_classes)
+
+    def register(self, plugin_class):
+        """
+        Makes it possible to register your plugin.
+        """
+        self._registered_plugins.append(plugin_class)
+
+    def _build_chain(self, evaluator):
+        for plugin_class in self._registered_plugin_classes:
+            yield plugin_class(evaluator)
+
+    def get_callbacks(self, evaluator):
+        return _PluginCallbacks(self._build_chain(evaluator))
+
+
+class _PluginCallbacks(object):
+    def __init__(self, plugins):
+        plugins = list(plugins)
+        self.execute = self._wrap(plugins, 'execute')
+
+    def _wrap(self, plugins, name):
+        if not plugins:
+            def default_callback(callback, *args, **kwargs):
+                return callback(*args, **kwargs)
+
+            return default_callback
+
+        func = None
+        for plugin in plugins:
+            if func is None:
+                func = getattr(plugin, name)
+            else:
+                func = partial(getattr(plugin, name), func)
+        return func
+
+
+plugin_manager = _PluginManager()