Made the YouTubeIE regex verbose/commented

diff --git a/youtube_dl/InfoExtractors.py b/youtube_dl/InfoExtractors.py
index ddb4aa16b9af9c8f6a24b5ed922639392f48ca54..3875e7fd8c7560e58cf0da7ee619579bfd04d1da 100644 (file)
--- a/youtube_dl/InfoExtractors.py
+++ b/youtube_dl/InfoExtractors.py
@@ -95,7 +95,24 @@ class InfoExtractor(object):
 class YoutubeIE(InfoExtractor):
        """Information extractor for youtube.com."""
 
-       _VALID_URL = r'^((?:https?://)?(?:youtu\.be/|(?:\w+\.)?youtube(?:-nocookie)?\.com/)(?!view_play_list|my_playlists|artist|playlist)(?:(?:(?:v|embed|e)/)|(?:(?:watch(?:_popup)?(?:\.php)?)?(?:\?|#!?)(?:.+&)?v=))?)?([0-9A-Za-z_-]+)(?(1).+)?$'
+       _VALID_URL = r"""^
+                        (
+                            (?:https?://)?                                       # http(s):// (optional)
+                            (?:youtu\.be/|(?:\w+\.)?youtube(?:-nocookie)?\.com/) # the various hostnames, with wildcard subdomains
+                            (?!view_play_list|my_playlists|artist|playlist)      # ignore playlist URLs
+                            (?:                                                  # the various things that can precede the ID:
+                                (?:(?:v|embed|e)/)                               # v/ or embed/ or e/
+                                |(?:                                             # or the v= param in all its forms
+                                    (?:watch(?:_popup)?(?:\.php)?)?              # preceding watch(_popup|.php) or nothing (like /?v=xxxx)
+                                    (?:\?|\#!?)                                  # the params delimiter ? or # or #!
+                                    (?:.+&)?                                     # any other preceding param (like /?s=tuff&v=xxxx)
+                                    v=
+                                )
+                            )?                                                   # optional -> youtube.com/xxxx is OK
+                        )?                                                       # all until now is optional -> you can pass the naked ID
+                        ([0-9A-Za-z_-]+)                                         # here is it! the YouTube video ID
+                        (?(1).+)?                                                # if we found the ID, everything can follow
+                        $"""
        _LANG_URL = r'http://www.youtube.com/?hl=en&persist_hl=1&gl=US&persist_gl=1&opt_out_ackd=1'
        _LOGIN_URL = 'https://www.youtube.com/signup?next=/&gl=US&hl=en'
        _AGE_URL = 'http://www.youtube.com/verify_age?next_url=/&gl=US&hl=en'
@@ -134,6 +151,10 @@ class YoutubeIE(InfoExtractor):
        }       
        IE_NAME = u'youtube'
 
+       def suitable(self, url):
+               """Receives a URL and returns True if suitable for this IE."""
+               return re.match(self._VALID_URL, url, re.VERBOSE) is not None
+
        def report_lang(self):
                """Report attempt to set language."""
                self._downloader.to_screen(u'[youtube] Setting language')
@@ -268,7 +289,7 @@ class YoutubeIE(InfoExtractor):
                        url = 'http://www.youtube.com/' + urllib.unquote(mobj.group(1)).lstrip('/')
 
                # Extract video id from URL
-               mobj = re.match(self._VALID_URL, url)
+               mobj = re.match(self._VALID_URL, url, re.VERBOSE)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
                        return