Decode URLs from Sage single cell server into Sage code

singlecelldecode.py

"""
Permalinks from the Sage cell server [1] include the Sage code in the URL,
and sometimes you may want to get that Sage code without loading the URL
in a browser.

The get_sage_code function does exactly that. It's basically copied from
web_server.py [2]. Just feed it the full URL and it returns the Sage
code.

The get_urls function is the inverse. It is essentially stolen from line
158 in the same file. It returns a list of URLs: the first is the
base64-encoded one, and if your code is short enough, there will be a
second "quoted" URL.

[1]: https://github.com/sagemath/sagecell/
[2]: https://github.com/sagemath/sagecell/blob/master/web_server.py#L87

--Dan Drake
"""

from base64 import urlsafe_b64decode as decode
from zlib import decompress
from urlparse import urlparse
from urllib import unquote

def get_sage_code(url):
    return decompress(
             decode(
               unquote(
                 urlparse(url).query.split('=')[1])))

from base64 import urlsafe_b64encode as encode
from zlib import compress
from urllib import urlencode

def get_urls(s_, server='aleph.sagemath.org'):
    """
    If your input is not pure ASCII, you will need to give this function
    a real Unicode string, or else encoding will give you a
    UnicodeDecodeError (yes, really: [1]). Just using u"..." in the
    Python/Sage interpreter does not always seem to work; my
    recommendation is to put your code into a file (so your editor does
    the work of proper encoding) and then use the codecs module.

    >>> get_urls(codecs.open('filename', 'r', 'utf8').read())

    Presumably this all goes away in Python 3, where all strings are
    Unicode.

    [1]: http://wiki.python.org/moin/UnicodeDecodeError
    """
    s = s_.encode('utf8')
    code = encode(
             compress(s))
    ret = ['http://{0}/?{1}'.format(server, urlencode({'z': code}))]
    quoted = urlencode({'c': s})
    if len(quoted) < 100:
        ret.append('http://{0}/?{1}'.format(server, quoted))
    return ret

if __name__ == '__main__':
    import sys
    print get_sage_code(sys.argv[1])