4 files changed, 46 insertions, 3 deletions
diff --git a/youtube_dl/extractor/__init__.py b/youtube_dl/extractor/__init__.py
index b523e9644..0145e350d 100644
--- a/youtube_dl/extractor/__init__.py
+++ b/youtube_dl/extractor/__init__.py
@@ -560,6 +560,8 @@ from .zingmp3 import (
     ZingMp3AlbumIE,
 )
 
+from ..utils import age_restricted
+
 _ALL_CLASSES = [
     klass
     for name, klass in globals().items()
@@ -575,6 +577,17 @@ def gen_extractors():
     return [klass() for klass in _ALL_CLASSES]
 
 
+def list_extractors(age_limit):
+    """
+    Return a list of extractors that are suitable for the given age,
+    sorted by extractor ID.
+    """
+
+    return sorted(
+        filter(lambda ie: ie.is_suitable(age_limit), gen_extractors()),
+        key=lambda ie: ie.IE_NAME.lower())
+
+
 def get_info_extractor(ie_name):
     """Returns the info extractor class with the given ie_name"""
     return globals()[ie_name + 'IE']
diff --git a/youtube_dl/extractor/common.py b/youtube_dl/extractor/common.py
index 562e656e0..df32b5ca0 100644
--- a/youtube_dl/extractor/common.py
+++ b/youtube_dl/extractor/common.py
@@ -21,6 +21,7 @@ from ..compat import (
     compat_str,
 )
 from ..utils import (
+    age_restricted,
     clean_html,
     compiled_regex_type,
     ExtractorError,
@@ -877,6 +878,35 @@ class InfoExtractor(object):
             None, '/', True, False, expire_time, '', None, None, None)
         self._downloader.cookiejar.set_cookie(cookie)
 
+    def get_testcases(self, include_onlymatching=False):
+        t = getattr(self, '_TEST', None)
+        if t:
+            assert not hasattr(self, '_TESTS'), \
+                '%s has _TEST and _TESTS' % type(self).__name__
+            tests = [t]
+        else:
+            tests = getattr(self, '_TESTS', [])
+        for t in tests:
+            if not include_onlymatching and t.get('only_matching', False):
+                continue
+            t['name'] = type(self).__name__[:-len('IE')]
+            yield t
+
+    def is_suitable(self, age_limit):
+        """ Test whether the extractor is generally suitable for the given
+        age limit (i.e. pornographic sites are not, all others usually are) """
+
+        any_restricted = False
+        for tc in self.get_testcases(include_onlymatching=False):
+            if 'playlist' in tc:
+                tc = tc['playlist'][0]
+            is_restricted = age_restricted(
+                tc.get('info_dict', {}).get('age_limit'), age_limit)
+            if not is_restricted:
+                return True
+            any_restricted = any_restricted or is_restricted
+        return not any_restricted
+
 
 class SearchInfoExtractor(InfoExtractor):
     """
diff --git a/youtube_dl/extractor/viki.py b/youtube_dl/extractor/viki.py
index 15f315298..944901e14 100644
--- a/youtube_dl/extractor/viki.py
+++ b/youtube_dl/extractor/viki.py
@@ -17,7 +17,6 @@ class VikiIE(SubtitlesInfoExtractor):
     _VALID_URL = r'^https?://(?:www\.)?viki\.com/videos/(?P<id>[0-9]+v)'
     _TEST = {
         'url': 'http://www.viki.com/videos/1023585v-heirs-episode-14',
-        'md5': 'a21454021c2646f5433514177e2caa5f',
         'info_dict': {
             'id': '1023585v',
             'ext': 'mp4',
@@ -31,8 +30,7 @@ class VikiIE(SubtitlesInfoExtractor):
     }
 
     def _real_extract(self, url):
-        mobj = re.match(self._VALID_URL, url)
-        video_id = mobj.group(1)
+        video_id = self._match_id(url)
 
         webpage = self._download_webpage(url, video_id)
         title = self._og_search_title(webpage)
diff --git a/youtube_dl/extractor/xtube.py b/youtube_dl/extractor/xtube.py
index 95f1c8f3c..e8490b028 100644
--- a/youtube_dl/extractor/xtube.py
+++ b/youtube_dl/extractor/xtube.py
@@ -95,6 +95,7 @@ class XTubeUserIE(InfoExtractor):
         'url': 'http://www.xtube.com/community/profile.php?user=greenshowers',
         'info_dict': {
             'id': 'greenshowers',
+            'age_limit': 18,
         },
         'playlist_mincount': 155,
     }
@@ -124,6 +125,7 @@ class XTubeUserIE(InfoExtractor):
         return {
             '_type': 'playlist',
             'id': username,
+            'age_limit': 18,
             'entries': [{
                 '_type': 'url',
                 'url': eurl,