[common] Add new helper function _match_id

1 files changed, 8 insertions, 0 deletions

diff --git a/youtube_dl/extractor/common.py b/youtube_dl/extractor/common.py
index 403791e6b..8d6a6f601 100644
--- a/youtube_dl/extractor/common.py
+++ b/youtube_dl/extractor/common.py
@@ -166,6 +166,14 @@ class InfoExtractor(object):
         return cls._VALID_URL_RE.match(url) is not None
 
     @classmethod
+    def _match_id(cls, url):
+        if '_VALID_URL_RE' not in cls.__dict__:
+            cls._VALID_URL_RE = re.compile(cls._VALID_URL)
+        m = cls._VALID_URL_RE.match(url)
+        assert m
+        return m.group('id')
+
+    @classmethod
     def working(cls):
         """Getter method for _WORKING."""
         return cls._WORKING