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# -*- coding: utf-8 -*-
import re
from uuid import uuid4
# Adapted from http://icodesnip.com/snippet/python/simple-universally-unique-id-uuid-or-guid
def bnode_uuid():
yield uuid4()
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'x') == True
>>> assert is_ncname(u'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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