Add compat_map/filter and use the former

youtube_dl/compat.py

@@ -2962,6 +2962,25 @@ def unpack(self, string):
         compat_Struct = struct.Struct
 
 
+# compat_map/filter() returning an iterator, supposedly the
+# same versioning as for zip below
+try:
+    from future_builtins import map as compat_map
+except ImportError:
+    try:
+        from itertools import imap as compat_map
+    except ImportError:
+        compat_map = map
+
+try:
+    from future_builtins import filter as compat_filter
+except ImportError:
+    try:
+        from itertools import ifilter as compat_filter
+    except ImportError:
+        compat_filter = filter
+
+
 try:
     from future_builtins import zip as compat_zip
 except ImportError:  # not 2.6+ or is 3.x
@@ -3015,6 +3034,7 @@ def compat_ctypes_WINFUNCTYPE(*args, **kwargs):
     'compat_etree_fromstring',
     'compat_etree_register_namespace',
     'compat_expanduser',
+    'compat_filter',
     'compat_get_terminal_size',
     'compat_getenv',
     'compat_getpass',
@@ -3026,6 +3046,7 @@ def compat_ctypes_WINFUNCTYPE(*args, **kwargs):
     'compat_integer_types',
     'compat_itertools_count',
     'compat_kwargs',
+    'compat_map',
     'compat_numeric_types',
     'compat_ord',
     'compat_os_name',

youtube_dl/extractor/youtube.py

@@ -2,12 +2,6 @@
 
 from __future__ import unicode_literals
 
-# should probably have been in compat.py
-try:
-    from future_builtins import map
-except ImportError:
-    pass
-
 import itertools
 import json
 import os.path
@@ -19,6 +13,7 @@
 from ..compat import (
     compat_chr,
     compat_HTTPError,
+    compat_map as map,
     compat_parse_qs,
     compat_str,
     compat_urllib_parse_unquote_plus,