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"""
This is a rdflib plugin for parsing NQuad files into Conjunctive
graphs that can be used and queried. The store that backs the graph
*must* be able to handle contexts.
>>> from rdflib import ConjunctiveGraph, URIRef, Namespace
>>> g = ConjunctiveGraph()
>>> data = open("test/example.nquads", "rb")
>>> g.parse(data, format="nquads") # doctest:+ELLIPSIS
<Graph identifier=... (<class 'rdflib.graph.Graph'>)>
>>> assert len(g.store) == 449
>>> # There should be 16 separate contexts
>>> assert len([x for x in g.store.contexts()]) == 16
>>> # is the name of entity E10009 "Arco Publications"? (in graph http://bibliographica.org/entity/E10009)
>>> # Looking for:
>>> # <http://bibliographica.org/entity/E10009> <http://xmlns.com/foaf/0.1/name> "Arco Publications" <http://bibliographica.org/entity/E10009>
>>> s = URIRef("http://bibliographica.org/entity/E10009")
>>> FOAF = Namespace("http://xmlns.com/foaf/0.1/")
>>> assert(g.value(s, FOAF.name) == "Arco Publications")
"""
from rdflib.py3compat import b
# Build up from the NTriples parser:
from rdflib.plugins.parsers.ntriples import NTriplesParser
from rdflib.plugins.parsers.ntriples import ParseError
from rdflib.plugins.parsers.ntriples import r_tail
from rdflib.plugins.parsers.ntriples import r_wspace
from rdflib.plugins.parsers.ntriples import r_wspaces
__all__ = ['QuadSink', 'NQuadsParser']
class QuadSink(object):
def __init__(self):
class FakeStore(object):
def __init__(self, addn):
self.addN = addn
self.length = 0
self.__quads = []
self.__store = FakeStore(self.addN)
def addN(self, quads):
self.length += 1
self.__quads.append(quads)
def quads(self, (s,p,o)):
for s,p,o,ctx in self.__quads:
yield s,p,o,ctx
class NQuadsParser(NTriplesParser):
def __init__(self, sink=None):
if sink is not None:
assert sink.store.context_aware, ("NQuadsParser must be given"
" a context aware store.")
self.sink = sink
else: self.sink = QuadSink()
def parse(self, inputsource, sink, **kwargs):
"""Parse f as an N-Triples file."""
assert sink.store.context_aware, ("NQuadsParser must be given"
" a context aware store.")
self.sink = sink
source = inputsource.getByteStream()
if not hasattr(source, 'read'):
raise ParseError("Item to parse must be a file-like object.")
self.file = source
self.buffer = ''
while True:
self.line = self.readline()
if self.line is None: break
try: self.parseline()
except ParseError:
raise ParseError("Invalid line: %r" % self.line)
return self.sink
def context(self):
context = self.uriref()
if not context:
raise ParseError("Context must be a uriref")
return context
def parseline(self):
self.eat(r_wspace)
if (not self.line) or self.line.startswith(b('#')):
return # The line is empty or a comment
subject = self.subject()
self.eat(r_wspaces)
predicate = self.predicate()
self.eat(r_wspaces)
obj = self.object()
self.eat(r_wspaces)
context = self.context()
self.eat(r_tail)
if self.line:
raise ParseError("Trailing garbage")
# Must have a context aware store - add on a normal Graph
# discards anything where the ctx != graph.identifier
self.sink.store.add((subject, predicate, obj), context)
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