Source code for rdflib.parser
"""
Parser plugin interface.
This module defines the parser plugin interface and contains other
related parser support code.
The module is mainly useful for those wanting to write a parser that
can plugin to rdflib. If you are wanting to invoke a parser you likely
want to do so through the Graph class parse method.
"""
import codecs
import os
import pathlib
import sys
from io import BufferedIOBase, BytesIO, RawIOBase, StringIO, TextIOBase, TextIOWrapper
from typing import (
IO,
TYPE_CHECKING,
Any,
BinaryIO,
List,
Optional,
TextIO,
Tuple,
Union,
)
from urllib.error import HTTPError
from urllib.parse import urljoin
from urllib.request import Request, url2pathname, urlopen
from xml.sax import xmlreader
import rdflib.util
from rdflib import __version__
from rdflib.namespace import Namespace
from rdflib.term import URIRef
if TYPE_CHECKING:
from http.client import HTTPMessage, HTTPResponse
from rdflib import Graph
__all__ = [
"Parser",
"InputSource",
"StringInputSource",
"URLInputSource",
"FileInputSource",
"PythonInputSource",
]
class BytesIOWrapper(BufferedIOBase):
__slots__ = ("wrapped", "encoded", "encoding")
def __init__(self, wrapped: str, encoding="utf-8"):
super(BytesIOWrapper, self).__init__()
self.wrapped = wrapped
self.encoding = encoding
self.encoded = None
def read(self, *args, **kwargs):
if self.encoded is None:
b, blen = codecs.getencoder(self.encoding)(self.wrapped)
self.encoded = BytesIO(b)
return self.encoded.read(*args, **kwargs)
def read1(self, *args, **kwargs):
if self.encoded is None:
b = codecs.getencoder(self.encoding)(self.wrapped)
self.encoded = BytesIO(b)
return self.encoded.read1(*args, **kwargs)
def readinto(self, *args, **kwargs):
raise NotImplementedError()
def readinto1(self, *args, **kwargs):
raise NotImplementedError()
def write(self, *args, **kwargs):
raise NotImplementedError()
[docs]class InputSource(xmlreader.InputSource, object):
"""
TODO:
"""
[docs] def __init__(self, system_id: Optional[str] = None):
xmlreader.InputSource.__init__(self, system_id=system_id)
self.content_type: Optional[str] = None
self.auto_close = False # see Graph.parse(), true if opened by us
[docs] def close(self):
c = self.getCharacterStream()
if c and hasattr(c, "close"):
try:
c.close()
except Exception:
pass
f = self.getByteStream()
if f and hasattr(f, "close"):
try:
f.close()
except Exception:
pass
[docs]class PythonInputSource(InputSource):
"""
Constructs an RDFLib Parser InputSource from a Python data structure,
for example, loaded from JSON with json.load or json.loads:
>>> import json
>>> as_string = \"\"\"{
... "@context" : {"ex" : "http://example.com/ns#"},
... "@graph": [{"@type": "ex:item", "@id": "#example"}]
... }\"\"\"
>>> as_python = json.loads(as_string)
>>> source = create_input_source(data=as_python)
>>> isinstance(source, PythonInputSource)
True
"""
[docs] def __init__(self, data, system_id=None):
self.content_type = None
self.auto_close = False # see Graph.parse(), true if opened by us
self.public_id = None
self.system_id = system_id
self.data = data
[docs]class StringInputSource(InputSource):
"""
Constructs an RDFLib Parser InputSource from a Python String or Bytes
"""
[docs] def __init__(
self,
value: Union[str, bytes],
encoding: str = "utf-8",
system_id: Optional[str] = None,
):
super(StringInputSource, self).__init__(system_id)
stream: Union[BinaryIO, TextIO]
if isinstance(value, str):
stream = StringIO(value)
self.setCharacterStream(stream)
self.setEncoding(encoding)
b_stream = BytesIOWrapper(value, encoding)
self.setByteStream(b_stream)
else:
stream = BytesIO(value)
self.setByteStream(stream)
c_stream = TextIOWrapper(stream, encoding)
self.setCharacterStream(c_stream)
self.setEncoding(c_stream.encoding)
headers = {
"User-agent": "rdflib-%s (https://rdflib.github.io/; eikeon@eikeon.com)"
% __version__
}
[docs]class URLInputSource(InputSource):
"""
Constructs an RDFLib Parser InputSource from a URL to read it from the Web.
"""
links: List[str]
[docs] @classmethod
def getallmatchingheaders(cls, message: "HTTPMessage", name):
# This is reimplemented here, because the method
# getallmatchingheaders from HTTPMessage is broken since Python 3.0
name = name.lower()
return [val for key, val in message.items() if key.lower() == name]
[docs] @classmethod
def get_links(cls, response: "HTTPResponse"):
linkslines = cls.getallmatchingheaders(response.headers, "Link")
retarray = []
for linksline in linkslines:
links = [linkstr.strip() for linkstr in linksline.split(",")]
for link in links:
retarray.append(link)
return retarray
[docs] def get_alternates(self, type_: Optional[str] = None) -> List[str]:
typestr: Optional[str] = f'type="{type_}"' if type_ else None
relstr = 'rel="alternate"'
alts = []
for link in self.links:
parts = [p.strip() for p in link.split(";")]
if relstr not in parts:
continue
if typestr:
if typestr in parts:
alts.append(parts[0].strip("<>"))
else:
alts.append(parts[0].strip("<>"))
return alts
[docs] def __init__(self, system_id: Optional[str] = None, format: Optional[str] = None):
super(URLInputSource, self).__init__(system_id)
self.url = system_id
# copy headers to change
myheaders = dict(headers)
if format == "xml":
myheaders["Accept"] = "application/rdf+xml, */*;q=0.1"
elif format == "n3":
myheaders["Accept"] = "text/n3, */*;q=0.1"
elif format in ["turtle", "ttl"]:
myheaders["Accept"] = "text/turtle, application/x-turtle, */*;q=0.1"
elif format == "nt":
myheaders["Accept"] = "text/plain, */*;q=0.1"
elif format == "trig":
myheaders["Accept"] = "application/trig, */*;q=0.1"
elif format == "trix":
myheaders["Accept"] = "application/trix, */*;q=0.1"
elif format == "json-ld":
myheaders[
"Accept"
] = "application/ld+json, application/json;q=0.9, */*;q=0.1"
else:
# if format not given, create an Accept header from all registered
# parser Media Types
from rdflib.parser import Parser
from rdflib.plugin import plugins
acc = []
for p in plugins(kind=Parser): # only get parsers
if "/" in p.name: # all Media Types known have a / in them
acc.append(p.name)
myheaders["Accept"] = ", ".join(acc)
req = Request(system_id, None, myheaders) # type: ignore[arg-type]
def _urlopen(req: Request) -> Any:
try:
return urlopen(req)
except HTTPError as ex:
# 308 (Permanent Redirect) is not supported by current python version(s)
# See https://bugs.python.org/issue40321
# This custom error handling should be removed once all
# supported versions of python support 308.
if ex.code == 308:
req.full_url = ex.headers.get("Location")
return _urlopen(req)
else:
raise
response: HTTPResponse = _urlopen(req)
self.url = response.geturl() # in case redirections took place
self.links = self.get_links(response)
if format in ("json-ld", "application/ld+json"):
alts = self.get_alternates(type_="application/ld+json")
for link in alts:
full_link = urljoin(self.url, link)
if full_link != self.url and full_link != system_id:
response = _urlopen(Request(full_link))
self.url = response.geturl() # in case redirections took place
break
self.setPublicId(self.url)
content_types = self.getallmatchingheaders(response.headers, "content-type")
self.content_type = content_types[0] if content_types else None
if self.content_type is not None:
self.content_type = self.content_type.split(";", 1)[0]
self.setByteStream(response)
# TODO: self.setEncoding(encoding)
self.response_info = response.info() # a mimetools.Message instance
[docs]class FileInputSource(InputSource):
[docs] def __init__(
self, file: Union[BinaryIO, TextIO, TextIOBase, RawIOBase, BufferedIOBase]
):
base = pathlib.Path.cwd().as_uri()
system_id = URIRef(pathlib.Path(file.name).absolute().as_uri(), base=base) # type: ignore[union-attr]
super(FileInputSource, self).__init__(system_id)
self.file = file
if isinstance(file, TextIOBase): # Python3 unicode fp
self.setCharacterStream(file)
self.setEncoding(file.encoding)
try:
b = file.buffer # type: ignore[attr-defined]
self.setByteStream(b)
except (AttributeError, LookupError):
self.setByteStream(file)
else:
self.setByteStream(file)
# We cannot set characterStream here because
# we do not know the Raw Bytes File encoding.
def create_input_source(
source: Optional[
Union[IO[bytes], TextIO, InputSource, str, bytes, pathlib.PurePath]
] = None,
publicID: Optional[str] = None, # noqa: N803
location: Optional[str] = None,
file: Optional[Union[BinaryIO, TextIO]] = None,
data: Union[str, bytes, dict] = None,
format: str = None,
) -> InputSource:
"""
Return an appropriate InputSource instance for the given
parameters.
"""
# test that exactly one of source, location, file, and data is not None.
non_empty_arguments = list(
filter(
lambda v: v is not None,
[source, location, file, data],
)
)
if len(non_empty_arguments) != 1:
raise ValueError(
"exactly one of source, location, file or data must be given",
)
input_source = None
if source is not None:
if isinstance(source, InputSource):
input_source = source
else:
if isinstance(source, str):
location = source
elif isinstance(source, pathlib.PurePath):
location = str(source)
elif isinstance(source, bytes):
data = source
elif hasattr(source, "read") and not isinstance(source, Namespace): # type: ignore[unreachable]
f = source
input_source = InputSource()
if hasattr(source, "encoding"):
input_source.setCharacterStream(source)
input_source.setEncoding(source.encoding) # type: ignore[union-attr]
try:
b = file.buffer # type: ignore[union-attr]
input_source.setByteStream(b)
except (AttributeError, LookupError):
input_source.setByteStream(source)
else:
input_source.setByteStream(f)
if f is sys.stdin:
input_source.setSystemId("file:///dev/stdin")
elif hasattr(f, "name"):
input_source.setSystemId(f.name)
else:
raise Exception(
"Unexpected type '%s' for source '%s'" % (type(source), source)
)
absolute_location = None # Further to fix for issue 130
auto_close = False # make sure we close all file handles we open
if location is not None:
(
absolute_location,
auto_close,
file,
input_source,
) = _create_input_source_from_location(
file=file,
format=format,
input_source=input_source,
location=location,
)
if file is not None:
input_source = FileInputSource(file)
if data is not None:
if isinstance(data, dict):
input_source = PythonInputSource(data)
auto_close = True
elif isinstance(data, (str, bytes, bytearray)):
input_source = StringInputSource(data)
auto_close = True
else:
raise RuntimeError(f"parse data can only str, or bytes. not: {type(data)}")
if input_source is None:
raise Exception("could not create InputSource")
else:
input_source.auto_close |= auto_close
if publicID is not None: # Further to fix for issue 130
input_source.setPublicId(publicID)
# Further to fix for issue 130
elif input_source.getPublicId() is None:
input_source.setPublicId(absolute_location or "")
return input_source
def _create_input_source_from_location(
file: Optional[Union[BinaryIO, TextIO]],
format: Optional[str],
input_source: Optional[InputSource],
location: str,
) -> Tuple[URIRef, bool, Optional[Union[BinaryIO, TextIO]], Optional[InputSource]]:
# Fix for Windows problem https://github.com/RDFLib/rdflib/issues/145 and
# https://github.com/RDFLib/rdflib/issues/1430
# NOTE: using pathlib.Path.exists on a URL fails on windows as it is not a
# valid path. However os.path.exists() returns false for a URL on windows
# which is why it is being used instead.
if os.path.exists(location):
location = pathlib.Path(location).absolute().as_uri()
base = pathlib.Path.cwd().as_uri()
absolute_location = URIRef(rdflib.util._iri2uri(location), base=base)
if absolute_location.startswith("file:///"):
filename = url2pathname(absolute_location.replace("file:///", "/"))
file = open(filename, "rb")
else:
input_source = URLInputSource(absolute_location, format)
auto_close = True
# publicID = publicID or absolute_location # Further to fix
# for issue 130
return absolute_location, auto_close, file, input_source
