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# -*- coding: utf-8 -*-
import re
import sys
try:
from hashlib import md5
except ImportError:
from md5 import md5
from rdflib.py3compat import format_doctest_out
try:
from uuid import uuid4
except ImportError:
def uuid4():
"""
Generates a uuid on behalf of Python 2.4
"""
import random
import os
import time
import socket
try:
preseed = os.urandom(16)
except NotImplementedError:
preseed = ''
# Have doubts about this. random.seed will just hash the string
random.seed('%s%s%s' % (preseed, os.getpid(), time.time()))
del preseed
t = long( time.time() * 1000.0 )
r = long( random.random()*100000000000000000L )
try:
a = socket.gethostbyname( socket.gethostname() )
except:
# if we can't get a network address, just imagine one
a = random.random()*100000000000000000L
strdata = str(t)+' '+str(r)+' '+str(a)
data = md5(strdata.encode('ascii')).hexdigest()
yield data
# Adapted from http://icodesnip.com/snippet/python/simple-universally-unique-id-uuid-or-guid
def bnode_uuid():
yield uuid4()
@format_doctest_out
def is_ncname(value):
"""
BNode identifiers must be valid NCNames.
From the `W3C RDF Syntax doc <http://www.w3.org/TR/REC-rdf-syntax/#section-blank-nodeid-event>`_
"The value is a function of the value of the ``identifier`` accessor.
The string value begins with "_:" and the entire value MUST match
the `N-Triples nodeID <http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/#nodeID>`_ production".
The nodeID production is specified to be a `name <http://www.w3.org/TR/2004/REC-rdf-testcases-20040210/#name>`_
name ::= [A-Za-z][A-Za-z0-9]*
>>> assert is_ncname('') == False
>>> assert is_ncname('999') == False
>>> assert is_ncname('x') == True
>>> assert is_ncname(%(u)s'x') == True
>>> assert is_ncname(%(u)s'Michèle') == True
However, vanilla uuid4s are not necessarily NCNames:
>>> assert is_ncname('6fa459ea-ee8a-3ca4-894e-db77e160355e') == False
So this has to be finessed with an appropriate prefix ...
>>> assert is_ncname("urn:uuid:"+str(uuid4())) == True
>>> from rdflib import BNode
>>> assert is_ncname(BNode(_sn_gen=bnode_uuid, _prefix="urn:uuid:")) == True
"""
ncnameexp = re.compile('[A-Za-z][A-Za-z0-9]*')
if ncnameexp.match(value):
return True
else:
return False
if __name__ == '__main__':
import doctest
doctest.testmod()
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