Source code for rdflib.plugins.serializers.nt

"""
N-Triples RDF graph serializer for RDFLib.
See <http://www.w3.org/TR/rdf-testcases/#ntriples> for details about the
format.
"""
from rdflib.term import Literal
from rdflib.serializer import Serializer
from rdflib.py3compat import b
import warnings

__all__ = ['NTSerializer']


[docs]class NTSerializer(Serializer): """ Serializes RDF graphs to NTriples format. """
[docs] def serialize(self, stream, base=None, encoding=None, **args): if base is not None: warnings.warn("NTSerializer does not support base.") if encoding is not None: warnings.warn("NTSerializer does not use custom encoding.") encoding = self.encoding for triple in self.store: stream.write(_nt_row(triple).encode(encoding, "replace")) stream.write(b("\n"))
def _nt_row(triple): if isinstance(triple[2], Literal): return u"%s %s %s .\n" % ( triple[0].n3(), triple[1].n3(), _xmlcharref_encode(_quoteLiteral(triple[2]))) else: return u"%s %s %s .\n" % (triple[0].n3(), triple[1].n3(), _xmlcharref_encode(triple[2].n3())) def _quoteLiteral(l): ''' a simpler version of term.Literal.n3() ''' encoded = _quote_encode(l) if l.language: if l.datatype: raise Exception("Literal has datatype AND language!") return '%s@%s' % (encoded, l.language) elif l.datatype: return '%s^^<%s>' % (encoded, l.datatype) else: return '%s' % encoded def _quote_encode(l): return '"%s"' % l.replace('\\', '\\\\')\ .replace('\n', '\\n')\ .replace('"', '\\"')\ .replace('\r', '\\r') # from <http://code.activestate.com/recipes/303668/> def _xmlcharref_encode(unicode_data, encoding="ascii"): """Emulate Python 2.3's 'xmlcharrefreplace' encoding error handler.""" res = "" # Step through the unicode_data string one character at a time in # order to catch unencodable characters: for char in unicode_data: try: char.encode(encoding, 'strict') except UnicodeError: if ord(char) <= 0xFFFF: res += '\\u%04X' % ord(char) else: res += '\\U%08X' % ord(char) else: res += char return res