iri2uri.py

"""
iri2uri

Converts an IRI to a URI.

"""
__author__ = "Joe Gregorio (joe@bitworking.org)"
__copyright__ = "Copyright 2006, Joe Gregorio"
__contributors__ = []
__version__ = "1.0.0"
__license__ = "MIT"
__history__ = """
"""

import urlparse


# Convert an IRI to a URI following the rules in RFC 3987
#
# The characters we need to enocde and escape are defined in the spec:
#
# iprivate =  %xE000-F8FF / %xF0000-FFFFD / %x100000-10FFFD
# ucschar = %xA0-D7FF / %xF900-FDCF / %xFDF0-FFEF
#         / %x10000-1FFFD / %x20000-2FFFD / %x30000-3FFFD
#         / %x40000-4FFFD / %x50000-5FFFD / %x60000-6FFFD
#         / %x70000-7FFFD / %x80000-8FFFD / %x90000-9FFFD
#         / %xA0000-AFFFD / %xB0000-BFFFD / %xC0000-CFFFD
#         / %xD0000-DFFFD / %xE1000-EFFFD

escape_range = [
    (0xA0, 0xD7FF),
    (0xE000, 0xF8FF),
    (0xF900, 0xFDCF),
    (0xFDF0, 0xFFEF),
    (0x10000, 0x1FFFD),
    (0x20000, 0x2FFFD),
    (0x30000, 0x3FFFD),
    (0x40000, 0x4FFFD),
    (0x50000, 0x5FFFD),
    (0x60000, 0x6FFFD),
    (0x70000, 0x7FFFD),
    (0x80000, 0x8FFFD),
    (0x90000, 0x9FFFD),
    (0xA0000, 0xAFFFD),
    (0xB0000, 0xBFFFD),
    (0xC0000, 0xCFFFD),
    (0xD0000, 0xDFFFD),
    (0xE1000, 0xEFFFD),
    (0xF0000, 0xFFFFD),
    (0x100000, 0x10FFFD),
]

def encode(c):
    retval = c
    i = ord(c)
    for low, high in escape_range:
        if i < low:
            break
        if i >= low and i <= high:
            retval = "".join(["%%%2X" % ord(o) for o in c.encode('utf-8')])
            break
    return retval


def iri2uri(uri):
    """Convert an IRI to a URI. Note that IRIs must be
    passed in a unicode strings. That is, do not utf-8 encode
    the IRI before passing it into the function."""
    if isinstance(uri ,unicode):
        (scheme, authority, path, query, fragment) = urlparse.urlsplit(uri)
        authority = authority.encode('idna')
        # For each character in 'ucschar' or 'iprivate'
        #  1. encode as utf-8
        #  2. then %-encode each octet of that utf-8
        uri = urlparse.urlunsplit((scheme, authority, path, query, fragment))
        uri = "".join([encode(c) for c in uri])
    return uri

if __name__ == "__main__":
    import unittest

    class Test(unittest.TestCase):

        def test_uris(self):
            """Test that URIs are invariant under the transformation."""
            invariant = [
                u"ftp://ftp.is.co.za/rfc/rfc1808.txt",
                u"http://www.ietf.org/rfc/rfc2396.txt",
                u"ldap://[2001:db8::7]/c=GB?objectClass?one",
                u"mailto:John.Doe@example.com",
                u"news:comp.infosystems.www.servers.unix",
                u"tel:+1-816-555-1212",
                u"telnet://192.0.2.16:80/",
                u"urn:oasis:names:specification:docbook:dtd:xml:4.1.2" ]
            for uri in invariant:
                self.assertEqual(uri, iri2uri(uri))

        def test_iri(self):
            """ Test that the right type of escaping is done for each part of the URI."""
            self.assertEqual("http://xn--o3h.com/%E2%98%84", iri2uri(u"http://\N{COMET}.com/\N{COMET}"))
            self.assertEqual("http://bitworking.org/?fred=%E2%98%84", iri2uri(u"http://bitworking.org/?fred=\N{COMET}"))
            self.assertEqual("http://bitworking.org/#%E2%98%84", iri2uri(u"http://bitworking.org/#\N{COMET}"))
            self.assertEqual("#%E2%98%84", iri2uri(u"#\N{COMET}"))
            self.assertEqual("/fred?bar=%E2%98%9A#%E2%98%84", iri2uri(u"/fred?bar=\N{BLACK LEFT POINTING INDEX}#\N{COMET}"))
            self.assertEqual("/fred?bar=%E2%98%9A#%E2%98%84", iri2uri(iri2uri(u"/fred?bar=\N{BLACK LEFT POINTING INDEX}#\N{COMET}")))
            self.assertNotEqual("/fred?bar=%E2%98%9A#%E2%98%84", iri2uri(u"/fred?bar=\N{BLACK LEFT POINTING INDEX}#\N{COMET}".encode('utf-8')))

    unittest.main()