Viewing file:  NamespaceManager.py (3.86 KB) -rw-r--r--
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from __future__ import generators
from rdflib import URIRef, Literal, RDFS, Variable
from rdflib.syntax.xml_names import split_uri
from urlparse import urljoin, urldefrag
from urllib import pathname2url, url2pathname
import os, sys, new
class NamespaceManager(object):
def __init__(self, graph):
self.graph = graph
self.__cache = {}
self.__log = None
self.bind("xml", u"http://www.w3.org/XML/1998/namespace")
self.bind("rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#")
self.bind("rdfs", "http://www.w3.org/2000/01/rdf-schema#")
def reset(self):
self.__cache = {}
def __get_store(self):
return self.graph.store
store = property(__get_store)
def qname(self, uri):
prefix, namespace, name = self.compute_qname(uri)
if prefix=="":
return name
else:
return ":".join((prefix, name))
def normalizeUri(self,rdfTerm):
"""
Takes an RDF Term and 'normalizes' it into a QName (using the registered prefix)
or (unlike compute_qname) the Notation 3 form for URIs: <...URI...>
"""
try:
namespace, name = split_uri(rdfTerm)
namespace = URIRef(namespace)
except:
if isinstance(rdfTerm,Variable):
return "?%s"%rdfTerm
else:
return "<%s>"%rdfTerm
prefix = self.store.prefix(namespace)
if prefix is None and isinstance(rdfTerm,Variable):
return "?%s"%rdfTerm
elif prefix is None:
return "<%s>"%rdfTerm
else:
qNameParts = self.compute_qname(rdfTerm)
return ':'.join([qNameParts[0],qNameParts[-1]])
def compute_qname(self, uri):
if not uri in self.__cache:
namespace, name = split_uri(uri)
namespace = URIRef(namespace)
prefix = self.store.prefix(namespace)
if prefix is None:
prefix = "_%s" % len(list(self.store.namespaces()))
self.bind(prefix, namespace)
self.__cache[uri] = (prefix, namespace, name)
return self.__cache[uri]
def bind(self, prefix, namespace, override=True):
namespace = URIRef(namespace)
# When documenting explain that override only applies in what cases
if prefix is None:
prefix = ''
bound_namespace = self.store.namespace(prefix)
if bound_namespace and bound_namespace!=namespace:
# prefix already in use for different namespace
#
# append number to end of prefix until we find one
# that's not in use.
if not prefix:
prefix = "default"
num = 1
while 1:
new_prefix = "%s%s" % (prefix, num)
if not self.store.namespace(new_prefix):
break
num +=1
self.store.bind(new_prefix, namespace)
else:
bound_prefix = self.store.prefix(namespace)
if bound_prefix is None:
self.store.bind(prefix, namespace)
elif bound_prefix == prefix:
pass # already bound
else:
if override or bound_prefix.startswith("_"): # or a generated prefix
self.store.bind(prefix, namespace)
def namespaces(self):
for prefix, namespace in self.store.namespaces():
namespace = URIRef(namespace)
yield prefix, namespace
def absolutize(self, uri, defrag=1):
base = urljoin("file:", pathname2url(os.getcwd()))
result = urljoin("%s/" % base, uri, allow_fragments=not defrag)
if defrag:
result = urldefrag(result)[0]
if not defrag:
if uri and uri[-1]=="#" and result[-1]!="#":
result = "%s#" % result
return URIRef(result)
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