sparqlstore.py 文件源码

def __len__(self, context=None):
        if not self.sparql11:
            raise NotImplementedError(
                "For performance reasons, this is not" +
                "supported for sparql1.0 endpoints")
        else:
            self.resetQuery()
            q = "SELECT (count(*) as ?c) WHERE {?s ?p ?o .}"
            if self._is_contextual(context):
                self.addParameter("default-graph-uri", context.identifier)
            self.setQuery(q)
            doc = ElementTree.parse(SPARQLWrapper.query(self).response)
            rt, vars = iter(
                _traverse_sparql_result_dom(
                    doc,
                    as_dictionary=True,
                    node_from_result=self.node_from_result
                )
            ).next()
            return int(rt.get(Variable("c")))