Add msg_in filter (new) (#1570)

Closes #1144

AUTHORS.rst

@@ -26,6 +26,7 @@ The following wonderful people contributed directly or indirectly to this projec
 - `d-qoi <https://github.com/d-qoi>`_
 - `daimajia <https://github.com/daimajia>`_
 - `Daniel Reed <https://github.com/nmlorg>`_
+- `Dmitry Grigoryev <https://github.com/icecom-dg>`_
 - `Ehsan Online <https://github.com/ehsanonline>`_
 - `Eli Gao <https://github.com/eligao>`_
 - `Emilio Molinari <https://github.com/xates>`_

telegram/ext/filters.py

@@ -909,6 +909,39 @@ officedocument.wordprocessingml.document")``-
             return message.from_user.language_code and any(
                 [message.from_user.language_code.startswith(x) for x in self.lang])
 
+    class msg_in(BaseFilter):
+        """Filters messages to only allow those whose text/caption appears in a given list.
+
+        Examples:
+            A simple usecase is to allow only messages that were send by a custom
+            :class:`telegram.ReplyKeyboardMarkup`::
+
+                buttons = ['Start', 'Settings', 'Back']
+                markup = ReplyKeyboardMarkup.from_column(buttons)
+                ...
+                MessageHandler(Filters.msg_in(buttons), callback_method)
+
+        Args:
+            list_ (List[:obj:`str`]): Which messages to allow through. Only exact matches
+                are allowed.
+            caption (:obj:`bool`): Optional. Whether the caption should be used instead of text.
+                Default is ``False``.
+
+        """
+
+        def __init__(self, list_, caption=False):
+            self.list_ = list_
+            self.caption = caption
+            self.name = 'Filters.msg_in({!r}, caption={!r})'.format(self.list_, self.caption)
+
+        def filter(self, message):
+            if self.caption:
+                txt = message.caption
+            else:
+                txt = message.text
+
+            return txt in self.list_
+
     class _UpdateType(BaseFilter):
         update_filter = True
 

tests/test_filters.py

@@ -604,6 +604,16 @@ class TestFilters(object):
         update.message.from_user.language_code = 'da'
         assert f(update)
 
+    def test_msg_in_filter(self, update):
+        update.message.text = 'test'
+        update.message.caption = 'caption'
+
+        assert Filters.msg_in(['test'])(update)
+        assert Filters.msg_in(['caption'], caption=True)(update)
+
+        assert not Filters.msg_in(['test'], caption=True)(update)
+        assert not Filters.msg_in(['caption'])(update)
+
     def test_and_filters(self, update):
         update.message.text = 'test'
         update.message.forward_date = datetime.datetime.now()