bpo-29976: urllib.parse clarify '' in scheme values. (GH-984)
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 5d33159..1af2906 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -38,29 +38,37 @@
"DefragResult", "ParseResult", "SplitResult",
"DefragResultBytes", "ParseResultBytes", "SplitResultBytes"]
-# A classification of schemes ('' means apply by default)
-uses_relative = ['ftp', 'http', 'gopher', 'nntp', 'imap',
+# A classification of schemes.
+# The empty string classifies URLs with no scheme specified,
+# being the default value returned by “urlsplit” and “urlparse”.
+
+uses_relative = ['', 'ftp', 'http', 'gopher', 'nntp', 'imap',
'wais', 'file', 'https', 'shttp', 'mms',
- 'prospero', 'rtsp', 'rtspu', '', 'sftp',
+ 'prospero', 'rtsp', 'rtspu', 'sftp',
'svn', 'svn+ssh', 'ws', 'wss']
-uses_netloc = ['ftp', 'http', 'gopher', 'nntp', 'telnet',
+
+uses_netloc = ['', 'ftp', 'http', 'gopher', 'nntp', 'telnet',
'imap', 'wais', 'file', 'mms', 'https', 'shttp',
- 'snews', 'prospero', 'rtsp', 'rtspu', 'rsync', '',
+ 'snews', 'prospero', 'rtsp', 'rtspu', 'rsync',
'svn', 'svn+ssh', 'sftp', 'nfs', 'git', 'git+ssh',
'ws', 'wss']
-uses_params = ['ftp', 'hdl', 'prospero', 'http', 'imap',
+
+uses_params = ['', 'ftp', 'hdl', 'prospero', 'http', 'imap',
'https', 'shttp', 'rtsp', 'rtspu', 'sip', 'sips',
- 'mms', '', 'sftp', 'tel']
+ 'mms', 'sftp', 'tel']
# These are not actually used anymore, but should stay for backwards
# compatibility. (They are undocumented, but have a public-looking name.)
+
non_hierarchical = ['gopher', 'hdl', 'mailto', 'news',
'telnet', 'wais', 'imap', 'snews', 'sip', 'sips']
-uses_query = ['http', 'wais', 'imap', 'https', 'shttp', 'mms',
- 'gopher', 'rtsp', 'rtspu', 'sip', 'sips', '']
-uses_fragment = ['ftp', 'hdl', 'http', 'gopher', 'news',
+
+uses_query = ['', 'http', 'wais', 'imap', 'https', 'shttp', 'mms',
+ 'gopher', 'rtsp', 'rtspu', 'sip', 'sips']
+
+uses_fragment = ['', 'ftp', 'hdl', 'http', 'gopher', 'news',
'nntp', 'wais', 'https', 'shttp', 'snews',
- 'file', 'prospero', '']
+ 'file', 'prospero']
# Characters valid in scheme names
scheme_chars = ('abcdefghijklmnopqrstuvwxyz'