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epicyon/pyjsonld.py

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"""
Python implementation of JSON-LD processor
This implementation is ported from the JavaScript implementation of
JSON-LD.
.. module:: jsonld
:synopsis: Python implementation of JSON-LD
.. moduleauthor:: Dave Longley
.. moduleauthor:: Mike Johnson
.. moduleauthor:: Tim McNamara <tim.mcnamara@okfn.org>
"""
__copyright__ = 'Copyright (c) 2011-2014 Digital Bazaar, Inc.'
__license__ = 'New BSD license'
__version__ = '0.6.8'
__module_group__ = "Security"
__all__ = [
'compact', 'expand', 'flatten', 'frame', 'link', 'from_rdf', 'to_rdf',
'normalize', 'set_document_loader', 'get_document_loader',
'parse_link_header', 'load_document',
'register_rdf_parser', 'unregister_rdf_parser',
'JsonLdProcessor', 'JsonLdError', 'ActiveContextCache']
import copy
import hashlib
import json
import os
import posixpath
import re
import socket
import ssl
import string
import sys
import traceback
from collections import deque, namedtuple
from numbers import Integral, Real
from context import getApschemaV1_9
from context import getApschemaV1_10
from context import getApschemaV1_20
from context import getApschemaV1_21
from context import getLitepubV0_1
from context import get_litepub_social
from context import get_v1schema
from context import get_v1security_schema
from context import get_activitystreams_schema
from context import get_webfinger_schema
from context import get_did_v1_schema
from context import get_multikey_v1_schema
from context import get_data_integrity_v1_schema
try:
from functools import cmp_to_key
except ImportError:
def cmp_to_key(mycmp):
"""
Convert a cmp= function into a key= function
Source: http://hg.python.org/cpython/file/default/Lib/functools.py
"""
class K(object):
__slots__ = ['obj']
def __init__(self, obj):
self.obj = obj
def __lt__(self, other):
return mycmp(self.obj, other.obj) < 0
def __gt__(self, other):
return mycmp(self.obj, other.obj) > 0
def __eq__(self, other):
return mycmp(self.obj, other.obj) == 0
def __le__(self, other):
return mycmp(self.obj, other.obj) <= 0
def __ge__(self, other):
return mycmp(self.obj, other.obj) >= 0
def __ne__(self, other):
return mycmp(self.obj, other.obj) != 0
__hash__ = None
return K
# support python 2
if sys.version_info[0] >= 3:
from urllib.request import HTTPSHandler
import urllib.parse as urllib_parse
from http.client import HTTPSConnection
basestring = str
def cmp(a, b):
return (a > b) - (a < b)
else:
from urllib2 import HTTPSHandler
import urlparse as urllib_parse
from httplib import HTTPSConnection
# XSD constants
XSD_BOOLEAN = 'http://www.w3.org/2001/XMLSchema#boolean'
XSD_DOUBLE = 'http://www.w3.org/2001/XMLSchema#double'
XSD_INTEGER = 'http://www.w3.org/2001/XMLSchema#integer'
XSD_STRING = 'http://www.w3.org/2001/XMLSchema#string'
# RDF constants
RDF = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#'
RDF_LIST = RDF + 'List'
RDF_FIRST = RDF + 'first'
RDF_REST = RDF + 'rest'
RDF_NIL = RDF + 'nil'
RDF_TYPE = RDF + 'type'
RDF_LANGSTRING = RDF + 'lang_string'
# JSON-LD keywords
KEYWORDS = [
'@base',
'@context',
'@container',
'@default',
'@embed',
'@explicit',
'@graph',
'@id',
'@index',
'@language',
'@list',
'@omitDefault',
'@preserve',
'@requireAll',
'@reverse',
'@set',
'@type',
'@value',
'@vocab']
# JSON-LD link header rel
LINK_HEADER_REL = 'http://www.w3.org/ns/json-ld#context'
# Restraints
MAX_CONTEXT_URLS = 10
def compact(input_, ctx, options=None):
"""
Performs JSON-LD compaction.
:param input_: the JSON-LD input to compact.
:param ctx: the JSON-LD context to compact with.
:param [options]: the options to use.
[base] the base IRI to use.
[compactArrays] True to compact arrays to single values when
appropriate, False not to (default: True).
[graph] True to always output a top-level graph (default: False).
[expandContext] a context to expand with.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the compacted JSON-LD output.
"""
return JsonLdProcessor().compact(input_, ctx, options)
def expand(input_, options=None):
"""
Performs JSON-LD expansion.
:param input_: the JSON-LD input to expand.
:param [options]: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the expanded JSON-LD output.
"""
return JsonLdProcessor().expand(input_, options)
def flatten(input_, ctx=None, options=None):
"""
Performs JSON-LD flattening.
:param input_: the JSON-LD input to flatten.
:param ctx: the JSON-LD context to compact with (default: None).
:param [options]: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the flattened JSON-LD output.
"""
return JsonLdProcessor().flatten(input_, ctx, options)
def frame(input_, frame, options=None):
"""
Performs JSON-LD framing.
:param input_: the JSON-LD input to frame.
:param frame: the JSON-LD frame to use.
:param [options]: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[embed] default @embed flag (default: True).
[explicit] default @explicit flag (default: False).
[requireAll] default @requireAll flag (default: True).
[omitDefault] default @omitDefault flag (default: False).
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the framed JSON-LD output.
"""
return JsonLdProcessor().frame(input_, frame, options)
def link(input_, ctx, options=None):
"""
**Experimental**
Links a JSON-LD document's nodes in memory.
:param input_: the JSON-LD document to link.
:param ctx: the JSON-LD context to apply or None.
:param [options]: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the linked JSON-LD output.
"""
# API matches running frame with a wildcard frame and embed: '@link'
# get arguments
frame = {'@embed': '@link'}
if ctx:
frame['@context'] = ctx
frame['@embed'] = '@link'
return frame(input, frame, options)
def normalize(input_: {}, options=None):
"""
Performs JSON-LD normalization.
:param input_: the JSON-LD input to normalize.
:param [options]: the options to use.
[base] the base IRI to use.
[format] the format if output is a string:
'application/nquads' for N-Quads.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the normalized JSON-LD output.
"""
return JsonLdProcessor().normalize(input_, options)
def from_rdf(input_, options=None):
"""
Converts an RDF dataset to JSON-LD.
:param input_: a serialized string of RDF in a format specified
by the format option or an RDF dataset to convert.
:param [options]: the options to use:
[format] the format if input is a string:
'application/nquads' for N-Quads (default: 'application/nquads').
[useRdfType] True to use rdf:type, False to use @type (default: False).
[useNativeTypes] True to convert XSD types into native types
(boolean, integer, double), False not to (default: True).
:return: the JSON-LD output.
"""
return JsonLdProcessor().from_rdf(input_, options)
def to_rdf(input_, options=None):
"""
Outputs the RDF dataset found in the given JSON-LD object.
:param input_: the JSON-LD input.
:param [options]: the options to use.
[base] the base IRI to use.
[format] the format to use to output a string:
'application/nquads' for N-Quads.
[produceGeneralizedRdf] true to output generalized RDF, false
to produce only standard RDF (default: false).
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the resulting RDF dataset (or a serialization of it).
"""
return JsonLdProcessor().to_rdf(input_, options)
def set_document_loader(load_document):
"""
Sets the default JSON-LD document loader.
:param load_document(url): the document loader to use.
"""
global _default_document_loader
_default_document_loader = load_document
def get_document_loader():
"""
Gets the default JSON-LD document loader.
:return: the default document loader.
"""
return _default_document_loader
def parse_link_header(header):
"""
Parses a link header. The results will be key'd by the value of "rel".
Link: <http://json-ld.org/contexts/person.jsonld>; \
rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"
Parses as: {
'http://www.w3.org/ns/json-ld#context': {
target: http://json-ld.org/contexts/person.jsonld,
type: 'application/ld+json'
}
}
If there is more than one "rel" with the same IRI, then entries in the
resulting map for that "rel" will be lists.
:param header: the link header to parse.
:return: the parsed result.
"""
rval = {}
# split on unbracketed/unquoted commas
entries = re.findall(r'(?:<[^>]*?>|"[^"]*?"|[^,])+', header)
if not entries:
return rval
r_link_header = r'\s*<([^>]*?)>\s*(?:;\s*(.*))?'
for entry in entries:
ldmatch = re.search(r_link_header, entry)
if not ldmatch:
continue
ldmatch = ldmatch.groups()
result = {'target': ldmatch[0]}
params = ldmatch[1]
r_params = r'(.*?)=(?:(?:"([^"]*?)")|([^"]*?))\s*(?:(?:;\s*)|$)'
matches = re.findall(r_params, params)
for ldmatch in matches:
result[ldmatch[0]] = \
ldmatch[2] if ldmatch[1] is None else ldmatch[1]
rel = result.get('rel', '')
if isinstance(rval.get(rel), list):
rval[rel].append(result)
elif rel in rval:
rval[rel] = [rval[rel], result]
else:
rval[rel] = result
return rval
def load_document(url):
"""
Retrieves JSON-LD at the given URL.
:param url: the URL to retrieve.
:return: the RemoteDocument.
"""
try:
# validate URL
pieces = urllib_parse.urlparse(url)
if (not all([pieces.scheme, pieces.netloc]) or
pieces.scheme not in ['http', 'https', 'hyper', 'ipfs', 'ipns'] or
set(pieces.netloc) > set(
string.ascii_letters + string.digits + '-.:')):
raise JsonLdError(
'URL could not be dereferenced; only http/https/dat '
'URLs are supported.',
'jsonld.InvalidUrl', {'url': url},
code='loading document failed')
if url == 'https://w3id.org/identity/v1':
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_v1schema()
}
return doc
if url == 'https://w3id.org/security/v1':
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_v1security_schema()
}
return doc
elif url == 'https://www.w3.org/ns/activitystreams':
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_activitystreams_schema()
}
return doc
elif url.endswith('/apschema/v1.9'):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': getApschemaV1_9()
}
return doc
elif url.endswith('/apschema/v1.10'):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': getApschemaV1_10()
}
return doc
elif url.endswith('/apschema/v1.20'):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': getApschemaV1_20()
}
return doc
elif url.endswith('/apschema/v1.21'):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': getApschemaV1_21()
}
return doc
elif url.endswith('/litepub-0.1.jsonld'):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': getLitepubV0_1()
}
return doc
elif (url.endswith('/socialweb/webfinger') or
url.endswith('/socialweb/webfinger.jsonld')):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_webfinger_schema()
}
return doc
elif (url == "https://w3id.org/security/multikey/v1" or
url.endswith("/vc-data-integrity/contexts/multikey/v1.jsonld")):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_multikey_v1_schema()
}
return doc
elif (url == "https://w3id.org/security/data-integrity/v1" or
url.endswith("/contexts/data-integrity/v1.jsonld")):
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_data_integrity_v1_schema()
}
return doc
elif url == 'https://litepub.social/litepub/context.jsonld':
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_litepub_social()
}
return doc
elif url == 'https://www.w3.org/ns/did/v1':
doc = {
'contextUrl': None,
'documentUrl': url,
'document': get_did_v1_schema()
}
return doc
return None
except JsonLdError as ex:
raise ex
except BaseException as cause:
raise JsonLdError(
'Could not retrieve a JSON-LD document from the URL.',
'jsonld.LoadDocumentError', code='loading document failed',
cause=cause)
def register_rdf_parser(content_type, parser):
"""
Registers a global RDF parser by content-type, for use with
from_rdf. Global parsers will be used by JsonLdProcessors that
do not register their own parsers.
:param content_type: the content-type for the parser.
:param parser(input): the parser function (takes a string as
a parameter and returns an RDF dataset).
"""
global _rdf_parsers
_rdf_parsers[content_type] = parser
def unregister_rdf_parser(content_type):
"""
Unregisters a global RDF parser by content-type.
:param content_type: the content-type for the parser.
"""
global _rdf_parsers
if content_type in _rdf_parsers:
del _rdf_parsers[content_type]
def prepend_base(base, iri):
"""
Prepends a base IRI to the given relative IRI.
:param base: the base IRI.
:param iri: the relative IRI.
:return: the absolute IRI.
"""
# skip IRI processing
if base is None:
return iri
# already an absolute iri
if _is_absolute_iri(iri):
return iri
# parse IRIs
base = parse_url(base)
rel = parse_url(iri)
# per RFC3986 5.2.2
transform = {
'scheme': base.scheme
}
if rel.authority is not None:
transform['authority'] = rel.authority
transform['path'] = rel.path
transform['query'] = rel.query
else:
transform['authority'] = base.authority
if rel.path == '':
transform['path'] = base.path
if rel.query is not None:
transform['query'] = rel.query
else:
transform['query'] = base.query
else:
if rel.path.startswith('/'):
# IRI represents an absolute path
transform['path'] = rel.path
else:
# merge paths
path = base.path
# append relative path to the end of the last
# directory from base
if rel.path != '':
path = path[0:path.rfind('/') + 1]
if len(path) > 0 and not path.endswith('/'):
path += '/'
path += rel.path
transform['path'] = path
transform['query'] = rel.query
# normalize path
path = transform['path']
add_slash = path.endswith('/')
path = posixpath.normpath(path)
if not path.endswith('/') and add_slash:
path += '/'
# do not include '.' path
if path == '.':
path = ''
transform['path'] = path
transform['fragment'] = rel.fragment
# construct URL
rval = unparse_url(transform)
# handle empty base case
if rval == '':
rval = './'
return rval
def remove_base(base, iri):
"""
Removes a base IRI from the given absolute IRI.
:param base: the base IRI.
:param iri: the absolute IRI.
:return: the relative IRI if relative to base, otherwise the absolute IRI.
"""
# skip IRI processing
if base is None:
return iri
base = parse_url(base)
rel = parse_url(iri)
# schemes and network locations (authorities) don't match, don't alter IRI
if not (base.scheme == rel.scheme and base.authority == rel.authority):
return iri
path = posixpath.relpath(rel.path, base.path) if rel.path else ''
path = posixpath.normpath(path)
# workaround a relpath bug in Python 2.6 (http://bugs.python.org/issue5117)
if base.path == '/' and path.startswith('../'):
path = path[3:]
if path == '.' and not rel.path.endswith('/') and not (
rel.query or rel.fragment):
path = posixpath.basename(rel.path)
if rel.path.endswith('/') and not path.endswith('/'):
path += '/'
# adjustments for base that is not a directory
if not base.path.endswith('/'):
if path.startswith('../'):
path = path[3:]
elif path.startswith('./'):
path = path[2:]
elif path.startswith('.'):
path = path[1:]
return unparse_url((None, None, path, rel.query, rel.fragment)) or './'
ParsedUrl = namedtuple(
'ParsedUrl', ['scheme', 'authority', 'path', 'query', 'fragment'])
def parse_url(url):
# regex from RFC 3986
p = r'^(?:([^:/?#]+):)?(?://([^/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?'
m = re.match(p, url)
return ParsedUrl(*m.groups())
def unparse_url(parsed):
if isinstance(parsed, dict):
parsed = ParsedUrl(**parsed)
elif isinstance(parsed, list) or isinstance(parsed, tuple):
parsed = ParsedUrl(*parsed)
rval = ''
if parsed.scheme:
rval += parsed.scheme + ':'
if parsed.authority is not None:
rval += '//' + parsed.authority
rval += parsed.path
if parsed.query is not None:
rval += '?' + parsed.query
if parsed.fragment is not None:
rval += '#' + parsed.fragment
return rval
# The default JSON-LD document loader.
_default_document_loader = load_document
# Registered global RDF parsers hashed by content-type.
_rdf_parsers = {}
class JsonLdProcessor(object):
"""
A JSON-LD processor.
"""
def __init__(self):
"""
Initialize the JSON-LD processor.
"""
# processor-specific RDF parsers
self.rdf_parsers = None
def compact(self, input_, ctx, options):
"""
Performs JSON-LD compaction.
:param input_: the JSON-LD input to compact.
:param ctx: the context to compact with.
:param options: the options to use.
[base] the base IRI to use.
[compactArrays] True to compact arrays to single values when
appropriate, False not to (default: True).
[graph] True to always output a top-level graph (default: False).
[expandContext] a context to expand with.
[skipExpansion] True to assume the input is expanded and skip
expansion, False not to, (default: False).
[activeCtx] True to also return the active context used.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the compacted JSON-LD output.
"""
if ctx is None:
raise JsonLdError(
'The compaction context must not be null.',
'jsonld.CompactError', code='invalid local context')
# nothing to compact
if input_ is None:
return None
# set default options
options = options or {}
options.setdefault('base', input_ if _is_string(input_) else '')
options.setdefault('compactArrays', True)
options.setdefault('graph', False)
options.setdefault('skipExpansion', False)
options.setdefault('activeCtx', False)
options.setdefault('documentLoader', _default_document_loader)
options.setdefault('link', False)
if options['link']:
# force skip expansion when linking, "link" is not part of the
# public API, it should only be called from framing
options['skipExpansion'] = True
if options['skipExpansion']:
expanded = input_
else:
# expand input
try:
expanded = self.expand(input_, options)
except JsonLdError as cause:
raise JsonLdError(
'Could not expand input before compaction.',
'jsonld.CompactError', cause=cause)
# process context
active_ctx = self._get_initial_context(options)
try:
active_ctx = self.process_context(active_ctx, ctx, options)
except JsonLdError as cause:
raise JsonLdError(
'Could not process context before compaction.',
'jsonld.CompactError', cause=cause)
# do compaction
compacted = self._compact(active_ctx, None, expanded, options)
if (options['compactArrays'] and not options['graph'] and
_is_array(compacted)):
# simplify to a single item
if len(compacted) == 1:
compacted = compacted[0]
# simplify to an empty object
elif len(compacted) == 0:
compacted = {}
# always use an array if graph options is on
elif options['graph']:
compacted = JsonLdProcessor.arrayify(compacted)
# follow @context key
if _is_object(ctx) and '@context' in ctx:
ctx = ctx['@context']
# build output context
ctx = copy.deepcopy(ctx)
ctx = JsonLdProcessor.arrayify(ctx)
# remove empty contexts
tmp = ctx
ctx = []
for v in tmp:
if not _is_object(v) or len(v) > 0:
ctx.append(v)
# remove array if only one context
ctx_length = len(ctx)
has_context = (ctx_length > 0)
if ctx_length == 1:
ctx = ctx[0]
# add context and/or @graph
if _is_array(compacted):
# use '@graph' keyword
kwgraph = self._compact_iri(active_ctx, '@graph')
graph = compacted
compacted = {}
if has_context:
compacted['@context'] = ctx
compacted[kwgraph] = graph
elif _is_object(compacted) and has_context:
# reorder keys so @context is first
graph = compacted
compacted = {}
compacted['@context'] = ctx
for k, v in graph.items():
compacted[k] = v
if options['activeCtx']:
return {'compacted': compacted, 'activeCtx': active_ctx}
else:
return compacted
def expand(self, input_, options):
"""
Performs JSON-LD expansion.
:param input_: the JSON-LD input to expand.
:param options: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[keepFreeFloatingNodes] True to keep free-floating nodes,
False not to (default: False).
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the expanded JSON-LD output.
"""
# set default options
options = options or {}
options.setdefault('keepFreeFloatingNodes', False)
options.setdefault('documentLoader', _default_document_loader)
# if input is a string, attempt to dereference remote document
if _is_string(input_):
remote_doc = options['documentLoader'](input_)
else:
remote_doc = {
'contextUrl': None,
'documentUrl': None,
'document': input_
}
try:
if remote_doc['document'] is None:
raise JsonLdError(
'No remote document found at the given URL.',
'jsonld.NullRemoteDocument')
if _is_string(remote_doc['document']):
remote_doc['document'] = json.loads(remote_doc['document'])
except BaseException as cause:
raise JsonLdError(
'Could not retrieve a JSON-LD document from the URL.',
'jsonld.LoadDocumentError',
{'remoteDoc': remote_doc}, code='loading document failed',
cause=cause)
# set default base
options.setdefault('base', remote_doc['documentUrl'] or '')
# build meta-object and retrieve all @context urls
input_ = {
'document': copy.deepcopy(remote_doc['document']),
'remoteContext': {'@context': remote_doc['contextUrl']}
}
if 'expandContext' in options:
expand_context = copy.deepcopy(options['expandContext'])
if _is_object(expand_context) and '@context' in expand_context:
input_['expandContext'] = expand_context
else:
input_['expandContext'] = {'@context': expand_context}
try:
self._retrieve_context_urls(
input_, {}, options['documentLoader'], options['base'])
except BaseException as cause:
raise JsonLdError(
'Could not perform JSON-LD expansion.',
'jsonld.ExpandError', cause=cause)
active_ctx = self._get_initial_context(options)
document = input_['document']
remote_context = input_['remoteContext']['@context']
# process optional expandContext
if 'expandContext' in input_:
active_ctx = self.process_context(
active_ctx, input_['expandContext']['@context'], options)
# process remote context from HTTP Link Header
if remote_context is not None:
active_ctx = self.process_context(
active_ctx, remote_context, options)
# do expansion
expanded = self._expand(active_ctx, None, document, options, False)
# optimize away @graph with no other properties
if (_is_object(expanded) and '@graph' in expanded and
len(expanded) == 1):
expanded = expanded['@graph']
elif expanded is None:
expanded = []
# normalize to an array
return JsonLdProcessor.arrayify(expanded)
def flatten(self, input_, ctx, options):
"""
Performs JSON-LD flattening.
:param input_: the JSON-LD input to flatten.
:param ctx: the JSON-LD context to compact with (default: None).
:param options: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the flattened JSON-LD output.
"""
options = options or {}
options.setdefault('base', input_ if _is_string(input_) else '')
options.setdefault('documentLoader', _default_document_loader)
try:
# expand input
expanded = self.expand(input_, options)
except BaseException as cause:
raise JsonLdError(
'Could not expand input before flattening.',
'jsonld.FlattenError', cause=cause)
# do flattening
flattened = self._flatten(expanded)
if ctx is None:
return flattened
# compact result (force @graph option to true, skip expansion)
options['graph'] = True
options['skipExpansion'] = True
try:
compacted = self.compact(flattened, ctx, options)
except BaseException as cause:
raise JsonLdError(
'Could not compact flattened output.',
'jsonld.FlattenError', cause=cause)
return compacted
def frame(self, input_, frame, options):
"""
Performs JSON-LD framing.
:param input_: the JSON-LD object to frame.
:param frame: the JSON-LD frame to use.
:param options: the options to use.
[base] the base IRI to use.
[expandContext] a context to expand with.
[embed] default @embed flag: '@last', '@always', '@never', '@link'
(default: '@last').
[explicit] default @explicit flag (default: False).
[requireAll] default @requireAll flag (default: True).
[omitDefault] default @omitDefault flag (default: False).
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the framed JSON-LD output.
"""
# set default options
options = options or {}
options.setdefault('base', input_ if _is_string(input_) else '')
options.setdefault('compactArrays', True)
options.setdefault('embed', '@last')
options.setdefault('explicit', False)
options.setdefault('requireAll', True)
options.setdefault('omitDefault', False)
options.setdefault('documentLoader', _default_document_loader)
# if frame is a string, attempt to dereference remote document
if _is_string(frame):
remote_frame = options['documentLoader'](frame)
else:
remote_frame = {
'contextUrl': None,
'documentUrl': None,
'document': frame
}
try:
if remote_frame['document'] is None:
raise JsonLdError(
'No remote document found at the given URL.',
'jsonld.NullRemoteDocument')
if _is_string(remote_frame['document']):
remote_frame['document'] = json.loads(remote_frame['document'])
except BaseException as cause:
raise JsonLdError(
'Could not retrieve a JSON-LD document from the URL.',
'jsonld.LoadDocumentError',
{'remoteDoc': remote_frame}, code='loading document failed',
cause=cause)
# preserve frame context
frame = remote_frame['document']
if frame is not None:
ctx = frame.get('@context', {})
if remote_frame['contextUrl'] is not None:
if ctx is not None:
ctx = remote_frame['contextUrl']
else:
ctx = JsonLdProcessor.arrayify(ctx)
ctx.append(remote_frame['contextUrl'])
frame['@context'] = ctx
try:
# expand input
expanded = self.expand(input_, options)
except JsonLdError as cause:
raise JsonLdError(
'Could not expand input before framing.',
'jsonld.FrameError', cause=cause)
try:
# expand frame
opts = copy.deepcopy(options)
opts['keepFreeFloatingNodes'] = True
expanded_frame = self.expand(frame, opts)
except JsonLdError as cause:
raise JsonLdError(
'Could not expand frame before framing.',
'jsonld.FrameError', cause=cause)
# do framing
framed = self._frame(expanded, expanded_frame, options)
try:
# compact result (force @graph option to True, skip expansion,
# check for linked embeds)
options['graph'] = True
options['skipExpansion'] = True
options['link'] = {}
options['activeCtx'] = True
result = self.compact(framed, ctx, options)
except JsonLdError as cause:
raise JsonLdError(
'Could not compact framed output.',
'jsonld.FrameError', cause=cause)
compacted = result['compacted']
active_ctx = result['activeCtx']
# get graph alias
graph = self._compact_iri(active_ctx, '@graph')
# remove @preserve from results
compacted[graph] = self._remove_preserve(
active_ctx, compacted[graph], options)
return compacted
def normalize(self, input_, options):
"""
Performs RDF normalization on the given JSON-LD input.
:param input_: the JSON-LD input to normalize.
:param options: the options to use.
[base] the base IRI to use.
[format] the format if output is a string:
'application/nquads' for N-Quads.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the normalized output.
"""
# set default options
options = options or {}
options.setdefault('base', input_ if _is_string(input_) else '')
options.setdefault('documentLoader', _default_document_loader)
try:
# convert to RDF dataset then do normalization
opts = copy.deepcopy(options)
if 'format' in opts:
del opts['format']
opts['produceGeneralizedRdf'] = False
dataset = self.to_rdf(input_, opts)
except JsonLdError as cause:
raise JsonLdError(
'Could not convert input to RDF dataset before normalization.',
'jsonld.NormalizeError', cause=cause)
# do normalization
return self._normalize(dataset, options)
def from_rdf(self, dataset, options):
"""
Converts an RDF dataset to JSON-LD.
:param dataset: a serialized string of RDF in a format specified by
the format option or an RDF dataset to convert.
:param options: the options to use.
[format] the format if input is a string:
'application/nquads' for N-Quads (default: 'application/nquads').
[useRdfType] True to use rdf:type, False to use @type
(default: False).
[useNativeTypes] True to convert XSD types into native types
(boolean, integer, double), False not to (default: False).
:return: the JSON-LD output.
"""
global _rdf_parsers
# set default options
options = options or {}
options.setdefault('useRdfType', False)
options.setdefault('useNativeTypes', False)
if ('format' not in options) and _is_string(dataset):
options['format'] = 'application/nquads'
# handle special format
if 'format' in options:
# supported formats (processor-specific and global)
if ((self.rdf_parsers is not None and
not options['format'] in self.rdf_parsers) or
(self.rdf_parsers is None and
not options['format'] in _rdf_parsers)):
raise JsonLdError(
'Unknown input format.',
'jsonld.UnknownFormat', {'format': options['format']})
if self.rdf_parsers is not None:
parser = self.rdf_parsers[options['format']]
else:
parser = _rdf_parsers[options['format']]
dataset = parser(dataset)
# convert from RDF
return self._from_rdf(dataset, options)
def to_rdf(self, input_, options):
"""
Outputs the RDF dataset found in the given JSON-LD object.
:param input_: the JSON-LD input.
:param options: the options to use.
[base] the base IRI to use.
[format] the format if input is a string:
'application/nquads' for N-Quads.
[produceGeneralizedRdf] true to output generalized RDF, false
to produce only standard RDF (default: false).
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the resulting RDF dataset (or a serialization of it).
"""
# set default options
options = options or {}
options.setdefault('base', input_ if _is_string(input_) else '')
options.setdefault('produceGeneralizedRdf', False)
options.setdefault('documentLoader', _default_document_loader)
try:
# expand input
expanded = self.expand(input_, options)
except JsonLdError as cause:
raise JsonLdError(
'Could not expand input before serialization to '
'RDF.', 'jsonld.RdfError', cause=cause)
# create node map for default graph (and any named graphs)
namer = UniqueNamer('_:b')
node_map = {'@default': {}}
self._create_node_map(expanded, node_map, '@default', namer)
# output RDF dataset
dataset = {}
for graph_name, graph in sorted(node_map.items()):
# skip relative IRIs
if graph_name == '@default' or _is_absolute_iri(graph_name):
dataset[graph_name] = self._graph_to_rdf(graph, namer, options)
# convert to output format
if 'format' in options:
if options['format'] == 'application/nquads':
return self.to_nquads(dataset)
raise JsonLdError(
'Unknown output format.',
'jsonld.UnknownFormat', {'format': options['format']})
return dataset
def process_context(self, active_ctx, local_ctx, options):
"""
Processes a local context, retrieving any URLs as necessary, and
returns a new active context in its callback.
:param active_ctx: the current active context.
:param local_ctx: the local context to process.
:param options: the options to use.
[documentLoader(url)] the document loader
(default: _default_document_loader).
:return: the new active context.
"""
# return initial context early for None context
if local_ctx is None:
return self._get_initial_context(options)
# set default options
options = options or {}
options.setdefault('base', '')
options.setdefault('documentLoader', _default_document_loader)
# retrieve URLs in local_ctx
local_ctx = copy.deepcopy(local_ctx)
if (_is_string(local_ctx) or (
_is_object(local_ctx) and '@context' not in local_ctx)):
local_ctx = {'@context': local_ctx}
try:
self._retrieve_context_urls(
local_ctx, {}, options['documentLoader'], options['base'])
except BaseException as cause:
raise JsonLdError(
'Could not process JSON-LD context.',
'jsonld.ContextError', cause=cause)
# process context
return self._process_context(active_ctx, local_ctx, options)
def register_rdf_parser(self, content_type, parser):
"""
Registers a processor-specific RDF parser by content-type.
Global parsers will no longer be used by this processor.
:param content_type: the content-type for the parser.
:param parser(input): the parser function (takes a string as
a parameter and returns an RDF dataset).
"""
if self.rdf_parsers is None:
self.rdf_parsers = {}
self.rdf_parsers[content_type] = parser
def unregister_rdf_parser(self, content_type):
"""
Unregisters a process-specific RDF parser by content-type.
If there are no remaining processor-specific parsers, then the global
parsers will be re-enabled.
:param content_type: the content-type for the parser.
"""
if (self.rdf_parsers is not None and
content_type in self.rdf_parsers):
del self.rdf_parsers[content_type]
if len(self.rdf_parsers) == 0:
self.rdf_parsers = None
@staticmethod
def has_property(subject, property):
"""
Returns True if the given subject has the given property.
:param subject: the subject to check.
:param property: the property to look for.
:return: True if the subject has the given property, False if not.
"""
if property in subject:
value = subject[property]
return not _is_array(value) or len(value) > 0
return False
@staticmethod
def has_value(subject, property, value):
"""
Determines if the given value is a property of the given subject.
:param subject: the subject to check.
:param property: the property to check.
:param value: the value to check.
:return: True if the value exists, False if not.
"""
if JsonLdProcessor.has_property(subject, property):
val = subject[property]
is_list = _is_list(val)
if _is_array(val) or is_list:
if is_list:
val = val['@list']
for v in val:
if JsonLdProcessor.compare_values(value, v):
return True
# avoid matching the set of values with an array value parameter
elif not _is_array(value):
return JsonLdProcessor.compare_values(value, val)
return False
@staticmethod
def add_value(subject, property, value, options={}):
"""
Adds a value to a subject. If the value is an array, all values in the
array will be added.
:param subject: the subject to add the value to.
:param property: the property that relates the value to the subject.
:param value: the value to add.
:param [options]: the options to use:
[propertyIsArray] True if the property is always
an array, False if not (default: False).
[allowDuplicate] True to allow duplicates, False not to (uses
a simple shallow comparison of subject ID or value)
(default: True).
"""
options.setdefault('propertyIsArray', False)
options.setdefault('allowDuplicate', True)
if _is_array(value):
if (len(value) == 0 and options['propertyIsArray'] and
property not in subject):
subject[property] = []
for v in value:
JsonLdProcessor.add_value(subject, property, v, options)
elif property in subject:
# check if subject already has value if duplicates not allowed
has_value = \
(not options['allowDuplicate'] and
JsonLdProcessor.has_value(subject, property, value))
# make property an array if value not present or always an array
if (not _is_array(subject[property]) and
(not has_value or options['propertyIsArray'])):
subject[property] = [subject[property]]
# add new value
if not has_value:
subject[property].append(value)
else:
# add new value as set or single value
subject[property] = (
[value] if options['propertyIsArray'] else value)
@staticmethod
def get_values(subject, property):
"""
Gets all of the values for a subject's property as an array.
:param subject: the subject.
:param property: the property.
:return: all of the values for a subject's property as an array.
"""
return JsonLdProcessor.arrayify(subject.get(property) or [])
@staticmethod
def remove_property(subject, property):
"""
Removes a property from a subject.
:param subject: the subject.
:param property: the property.
"""
del subject[property]
@staticmethod
def remove_value(subject, property, value, options={}):
"""
Removes a value from a subject.
:param subject: the subject.
:param property: the property that relates the value to the subject.
:param value: the value to remove.
:param [options]: the options to use:
[propertyIsArray]: True if the property is always an array,
False if not (default: False).
"""
options.setdefault('propertyIsArray', False)
# filter out value
def filter_value(e):
return not JsonLdProcessor.compare_values(e, value)
values = JsonLdProcessor.get_values(subject, property)
values = list(filter(filter_value, values))
if len(values) == 0:
JsonLdProcessor.remove_property(subject, property)
elif len(values) == 1 and not options['propertyIsArray']:
subject[property] = values[0]
else:
subject[property] = values
@staticmethod
def compare_values(v1, v2):
"""
Compares two JSON-LD values for equality. Two JSON-LD values will be
considered equal if:
1. They are both primitives of the same type and value.
2. They are both @values with the same @value, @type, @language,
and @index, OR
3. They both have @ids that are the same.
:param v1: the first value.
:param v2: the second value.
:return: True if v1 and v2 are considered equal, False if not.
"""
# 1. equal primitives
if not _is_object(v1) and not _is_object(v2) and v1 == v2:
type1 = type(v1)
type2 = type(v2)
if type1 == bool or type2 == bool:
return type1 == type2
return True
# 2. equal @values
if (_is_value(v1) and _is_value(v2) and
v1['@value'] == v2['@value'] and
v1.get('@type') == v2.get('@type') and
v1.get('@language') == v2.get('@language') and
v1.get('@index') == v2.get('@index')):
type1 = type(v1['@value'])
type2 = type(v2['@value'])
if type1 == bool or type2 == bool:
return type1 == type2
return True
# 3. equal @ids
if (_is_object(v1) and '@id' in v1 and
_is_object(v2) and '@id' in v2):
return v1['@id'] == v2['@id']
return False
@staticmethod
def get_context_value(ctx, key, type_):
"""
Gets the value for the given active context key and type, None if none
is set.
:param ctx: the active context.
:param key: the context key.
:param [type_]: the type of value to get (eg: '@id', '@type'), if not
specified gets the entire entry for a key, None if not found.
:return: mixed the value.
"""
rval = None
# return None for invalid key
if key is None:
return rval
# get default language
if type_ == '@language' and type_ in ctx:
rval = ctx[type_]
# get specific entry information
if key in ctx['mappings']:
entry = ctx['mappings'][key]
if entry is None:
return None
# return whole entry
if type_ is None:
rval = entry
# return entry value for type
elif type_ in entry:
rval = entry[type_]
return rval
@staticmethod
def parse_nquads(input_):
"""
Parses RDF in the form of N-Quads.
:param input_: the N-Quads input to parse.
:return: an RDF dataset.
"""
# define partial regexes
iri = '(?:<([^:]+:[^>]*)>)'
bnode = '(_:(?:[A-Za-z][A-Za-z0-9]*))'
plain = '"([^"\\\\]*(?:\\\\.[^"\\\\]*)*)"'
datatype = '(?:\\^\\^' + iri + ')'
language = '(?:@([a-z]+(?:-[a-z0-9]+)*))'
literal = '(?:' + plain + '(?:' + datatype + '|' + language + ')?)'
ws = '[ \\t]+'
wso = '[ \\t]*'
eoln = r'(?:\r\n)|(?:\n)|(?:\r)'
empty = r'^' + wso + '$'
# define quad part regexes
subject = '(?:' + iri + '|' + bnode + ')' + ws
property = iri + ws
object = '(?:' + iri + '|' + bnode + '|' + literal + ')' + wso
graph = '(?:\\.|(?:(?:' + iri + '|' + bnode + ')' + wso + '\\.))'
# Note: Notice that the graph position does not include literals
# even though they are specified as a possible value in the
# N-Quads note (http://sw.deri.org/2008/07/n-quads/). This is
# intentional, as literals in that position are not supported by the
# RDF data model or the JSON-LD data model.
# See: https://github.com/digitalbazaar/pyld/pull/19
# full quad regex
quad = r'^' + wso + subject + property + object + graph + wso + '$'
# build RDF dataset
dataset = {}
# split N-Quad input into lines
lines = re.split(eoln, input_)
line_number = 0
for line in lines:
line_number += 1
# skip empty lines
if re.search(empty, line) is not None:
continue
# parse quad
ldmatch = re.search(quad, line)
if ldmatch is None:
raise JsonLdError(
'Error while parsing N-Quads invalid quad.',
'jsonld.ParseError', {'line': line_number})
ldmatch = ldmatch.groups()
# create RDF triple
triple = {'subject': {}, 'predicate': {}, 'object': {}}
# get subject
if ldmatch[0] is not None:
triple['subject'] = {'type': 'IRI', 'value': ldmatch[0]}
else:
triple['subject'] = {'type': 'blank node', 'value': ldmatch[1]}
# get predicate
triple['predicate'] = {'type': 'IRI', 'value': ldmatch[2]}
# get object
if ldmatch[3] is not None:
triple['object'] = {'type': 'IRI', 'value': ldmatch[3]}
elif ldmatch[4] is not None:
triple['object'] = {'type': 'blank node', 'value': ldmatch[4]}
else:
triple['object'] = {'type': 'literal'}
replacements = {
'\\"': '\"',
'\\t': '\t',
'\\n': '\n',
'\\r': '\r',
'\\\\': '\\'
}
unescaped = ldmatch[5]
for ldmatch, repl in replacements.items():
unescaped = unescaped.replace(ldmatch, repl)
if ldmatch[6] is not None:
triple['object']['datatype'] = ldmatch[6]
elif ldmatch[7] is not None:
triple['object']['datatype'] = RDF_LANGSTRING
triple['object']['language'] = ldmatch[7]
else:
triple['object']['datatype'] = XSD_STRING
triple['object']['value'] = unescaped
# get graph name ('@default' is used for the default graph)
name = '@default'
if ldmatch[8] is not None:
name = ldmatch[8]
elif ldmatch[9] is not None:
name = ldmatch[9]
# initialize graph in dataset
if name not in dataset:
dataset[name] = [triple]
# add triple if unique to its graph
else:
unique = True
triples = dataset[name]
for t in dataset[name]:
if JsonLdProcessor._compare_rdf_triples(t, triple):
unique = False
break
if unique:
triples.append(triple)
return dataset
@staticmethod
def to_nquads(dataset):
"""
Converts an RDF dataset to N-Quads.
:param dataset: the RDF dataset to convert.
:return: the N-Quads string.
"""
quads = []
for graph_name, triples in dataset.items():
for triple in triples:
if graph_name == '@default':
graph_name = None
quads.append(JsonLdProcessor.to_nquad(triple, graph_name))
quads.sort()
return ''.join(quads)
@staticmethod
def to_nquad(triple, graph_name, bnode=None):
"""
Converts an RDF triple and graph name to an N-Quad string (a single
quad).
:param triple: the RDF triple to convert.
:param graph_name: the name of the graph containing the triple, None
for the default graph.
:param bnode: the bnode the quad is mapped to (optional, for
use during normalization only).
:return: the N-Quad string.
"""
s = triple['subject']
p = triple['predicate']
o = triple['object']
g = graph_name
quad = ''
# subject is an IRI
if s['type'] == 'IRI':
quad += '<' + s['value'] + '>'
# bnode normalization mode
elif bnode is not None:
quad += '_:a' if s['value'] == bnode else '_:z'
# bnode normal mode
else:
quad += s['value']
quad += ' '
# property is an IRI
if p['type'] == 'IRI':
quad += '<' + p['value'] + '>'
# FIXME: TBD what to do with bnode predicates during normalization
# bnode normalization mode
elif bnode is not None:
quad += '_:p'
# bnode normal mode
else:
quad += p['value']
quad += ' '
# object is IRI, bnode, or literal
if o['type'] == 'IRI':
quad += '<' + o['value'] + '>'
elif (o['type'] == 'blank node'):
# normalization mode
if bnode is not None:
quad += '_:a' if o['value'] == bnode else '_:z'
# normal mode
else:
quad += o['value']
else:
replacements = {
'\\': '\\\\',
'\t': '\\t',
'\n': '\\n',
'\r': '\\r',
'\"': '\\"'
}
escaped = o['value']
for ldmatch, repl in replacements.items():
escaped = escaped.replace(ldmatch, repl)
quad += '"' + escaped + '"'
if o['datatype'] == RDF_LANGSTRING:
if o['language']:
quad += '@' + o['language']
elif o['datatype'] != XSD_STRING:
quad += '^^<' + o['datatype'] + '>'
# graph
if g is not None:
if not g.startswith('_:'):
quad += ' <' + g + '>'
elif bnode is not None:
quad += ' _:g'
else:
quad += ' ' + g
quad += ' .\n'
return quad
@staticmethod
def arrayify(value):
"""
If value is an array, returns value, otherwise returns an array
containing value as the only element.
:param value: the value.
:return: an array.
"""
return value if _is_array(value) else [value]
@staticmethod
def _compare_rdf_triples(t1, t2):
"""
Compares two RDF triples for equality.
:param t1: the first triple.
:param t2: the second triple.
:return: True if the triples are the same, False if not.
"""
for attr in ['subject', 'predicate', 'object']:
if t1[attr]['type'] != t2[attr]['type'] or \
t1[attr]['value'] != t2[attr]['value']:
return False
if t1['object'].get('language') != t2['object'].get('language'):
return False
if t1['object'].get('datatype') != t2['object'].get('datatype'):
return False
return True
def _compact(self, active_ctx, active_property, element, options):
"""
Recursively compacts an element using the given active context. All
values must be in expanded form before this method is called.
:param active_ctx: the active context to use.
:param active_property: the compacted property with the element to
compact, None for none.
:param element: the element to compact.
:param options: the compaction options.
:return: the compacted value.
"""
# recursively compact array
if _is_array(element):
rval = []
for e in element:
# compact, dropping any None values
e = self._compact(active_ctx, active_property, e, options)
if e is not None:
rval.append(e)
if options['compactArrays'] and len(rval) == 1:
# use single element if no container is specified
container = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@container')
if container is None:
rval = rval[0]
return rval
# recursively compact object
if _is_object(element):
if options['link'] and '@id' in element and \
element['@id'] in options['link']:
# check for a linked element to reuse
linked = options['link'][element['@id']]
for link in linked:
if link['expanded'] == element:
return link['compacted']
# do value compaction on @values and subject references
if _is_value(element) or _is_subject_reference(element):
rval = self._compact_value(
active_ctx, active_property, element)
if options['link'] and _is_subject_reference(element):
# store linked element
options['link'].setdefault(element['@id'], []).append(
{'expanded': element, 'compacted': rval})
return rval
# FIXME: avoid misuse of active property as an expanded property?
inside_reverse = (active_property == '@reverse')
rval = {}
if options['link'] and '@id' in element:
# store linked element
options['link'].setdefault(element['@id'], []).append(
{'expanded': element, 'compacted': rval})
# recursively process element keys in order
for expanded_property, expanded_value in sorted(element.items()):
# compact @id and @type(s)
if expanded_property == '@id' or expanded_property == '@type':
# compact single @id
if _is_string(expanded_value):
compacted_value = self._compact_iri(
active_ctx, expanded_value,
vocab=(expanded_property == '@type'))
# expanded value must be a @type array
else:
compacted_value = []
for ev in expanded_value:
compacted_value.append(self._compact_iri(
active_ctx, ev, vocab=True))
# use keyword alias and add value
alias = self._compact_iri(active_ctx, expanded_property)
is_array = (_is_array(compacted_value) and
len(compacted_value) == 0)
JsonLdProcessor.add_value(
rval, alias, compacted_value,
{'propertyIsArray': is_array})
continue
# handle @reverse
if expanded_property == '@reverse':
# recursively compact expanded value
compacted_value = self._compact(
active_ctx, '@reverse', expanded_value, options)
# handle double-reversed properties
for compacted_property, value in \
list(compacted_value.items()):
mapping = active_ctx['mappings'].get(
compacted_property)
if mapping and mapping['reverse']:
container = JsonLdProcessor.get_context_value(
active_ctx, compacted_property, '@container')
use_array = (container == '@set' or
not options['compactArrays'])
JsonLdProcessor.add_value(
rval, compacted_property, value,
{'propertyIsArray': use_array})
del compacted_value[compacted_property]
if len(compacted_value.keys()) > 0:
# use keyword alias and add value
alias = self._compact_iri(
active_ctx, expanded_property)
JsonLdProcessor.add_value(rval, alias, compacted_value)
continue
# handle @index
if expanded_property == '@index':
# drop @index if inside an @index container
container = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@container')
if container == '@index':
continue
# use keyword alias and add value
alias = self._compact_iri(active_ctx, expanded_property)
JsonLdProcessor.add_value(rval, alias, expanded_value)
continue
# skip array processing for keywords that aren't
# @graph or @list
if expanded_property != '@graph' and \
expanded_property != '@list' and \
_is_keyword(expanded_property):
# use keyword alias and add value as is
alias = self._compact_iri(active_ctx, expanded_property)
JsonLdProcessor.add_value(rval, alias, expanded_value)
continue
# Note: expanded value must be an array due to expansion
# algorithm.
# preserve empty arrays
if len(expanded_value) == 0:
item_active_property = self._compact_iri(
active_ctx, expanded_property, expanded_value,
vocab=True, reverse=inside_reverse)
JsonLdProcessor.add_value(
rval, item_active_property, [],
{'propertyIsArray': True})
# recusively process array values
for expanded_item in expanded_value:
# compact property and get container type
item_active_property = self._compact_iri(
active_ctx, expanded_property, expanded_item,
vocab=True, reverse=inside_reverse)
container = JsonLdProcessor.get_context_value(
active_ctx, item_active_property, '@container')
# get @list value if appropriate
is_list = _is_list(expanded_item)
list_ = None
if is_list:
list_ = expanded_item['@list']
# recursively compact expanded item
compacted_item = self._compact(
active_ctx, item_active_property,
list_ if is_list else expanded_item, options)
# handle @list
if is_list:
# ensure @list is an array
compacted_item = JsonLdProcessor.arrayify(
compacted_item)
if container != '@list':
# wrap using @list alias
wrapper = {}
wrapper[self._compact_iri(
active_ctx, '@list')] = compacted_item
compacted_item = wrapper
# include @index from expanded @list, if any
if '@index' in expanded_item:
alias = self._compact_iri(active_ctx, '@index')
compacted_item[alias] = (
expanded_item['@index'])
# can't use @list container for more than 1 list
elif item_active_property in rval:
raise JsonLdError(
'JSON-LD compact error; property has a '
'"@list" @container rule but there is more '
'than a single @list that matches the '
'compacted term in the document. Compaction '
'might mix unwanted items into the list.',
'jsonld.SyntaxError',
code='compaction to list of lists')
# handle language and index maps
if container == '@language' or container == '@index':
# get or create the map object
map_object = rval.setdefault(item_active_property, {})
# if container is a language map, simplify compacted
# value to a simple string
if (container == '@language' and
_is_value(compacted_item)):
compacted_item = compacted_item['@value']
# add compact value to map object using key from
# expanded value based on the container type
JsonLdProcessor.add_value(
map_object, expanded_item[container],
compacted_item)
else:
# use an array if compactArrays flag is false,
# @container is @set or @list, value is an empty
# array, or key is @graph
is_array = (not options['compactArrays'] or
container == '@set' or
container == '@list' or
(_is_array(compacted_item) and
len(compacted_item) == 0) or
expanded_property == '@list' or
expanded_property == '@graph')
# add compact value
JsonLdProcessor.add_value(
rval, item_active_property, compacted_item,
{'propertyIsArray': is_array})
return rval
# only primitives remain which are already compact
return element
def _expand(
self, active_ctx, active_property, element, options, inside_list):
"""
Recursively expands an element using the given context. Any context in
the element will be removed. All context URLs must have been retrieved
before calling this method.
:param active_ctx: the context to use.
:param active_property: the property for the element, None for none.
:param element: the element to expand.
:param options: the expansion options.
:param inside_list: True if the property is a list, False if not.
:return: the expanded value.
"""
# nothing to expand
if element is None:
return element
# recursively expand array
if _is_array(element):
rval = []
container = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@container')
inside_list = inside_list or container == '@list'
for e in element:
# expand element
e = self._expand(
active_ctx, active_property, e, options, inside_list)
if inside_list and (_is_array(e) or _is_list(e)):
# lists of lists are illegal
raise JsonLdError(
'Invalid JSON-LD syntax; lists of lists are not '
'permitted.', 'jsonld.SyntaxError',
code='list of lists')
# drop None values
if e is not None:
if _is_array(e):
rval.extend(e)
else:
rval.append(e)
return rval
# handle scalars
if not _is_object(element):
# drop free-floating scalars that are not in lists
if (not inside_list and (active_property is None or
self._expand_iri(
active_ctx, active_property, vocab=True) == '@graph')):
return None
# expand element according to value expansion rules
return self._expand_value(active_ctx, active_property, element)
# recursively expand object
# if element has a context, process it
if '@context' in element:
active_ctx = self._process_context(
active_ctx, element['@context'], options)
# expand the active property
expanded_active_property = self._expand_iri(
active_ctx, active_property, vocab=True)
rval = {}
for key, value in sorted(element.items()):
if key == '@context':
continue
# expand key to IRI
expanded_property = self._expand_iri(
active_ctx, key, vocab=True)
# drop non-absolute IRI keys that aren't keywords
if (expanded_property is None or not
(_is_absolute_iri(expanded_property) or
_is_keyword(expanded_property))):
continue
if _is_keyword(expanded_property):
if expanded_active_property == '@reverse':
raise JsonLdError(
'Invalid JSON-LD syntax; a keyword cannot be used as '
'a @reverse property.',
'jsonld.SyntaxError', {'value': value},
code='invalid reverse property map')
if expanded_property in rval:
raise JsonLdError(
'Invalid JSON-LD syntax; colliding keywords detected.',
'jsonld.SyntaxError', {'keyword': expanded_property},
code='colliding keywords')
# syntax error if @id is not a string
if expanded_property == '@id' and not _is_string(value):
if not options.get('isFrame'):
raise JsonLdError(
'Invalid JSON-LD syntax; "@id" value must a string.',
'jsonld.SyntaxError', {'value': value},
code='invalid @id value')
if not _is_object(value):
raise JsonLdError(
'Invalid JSON-LD syntax; "@id" value must be a '
'string or an object.', 'jsonld.SyntaxError',
{'value': value}, code='invalid @id value')
if expanded_property == '@type':
_validate_type_value(value)
# @graph must be an array or an object
if (expanded_property == '@graph' and
not (_is_object(value) or _is_array(value))):
raise JsonLdError(
'Invalid JSON-LD syntax; "@graph" must not be an '
'object or an array.', 'jsonld.SyntaxError',
{'value': value}, code='invalid @graph value')
# @value must not be an object or an array
if (expanded_property == '@value' and
(_is_object(value) or _is_array(value))):
raise JsonLdError(
'Invalid JSON-LD syntax; "@value" value must not be an '
'object or an array.', 'jsonld.SyntaxError',
{'value': value}, code='invalid value object value')
# @language must be a string
if expanded_property == '@language':
if value is None:
# drop null @language values, they expand as if they
# didn't exist
continue
if not _is_string(value):
raise JsonLdError(
'Invalid JSON-LD syntax; "@language" value must be '
'a string.', 'jsonld.SyntaxError', {'value': value},
code='invalid language-tagged string')
# ensure language value is lowercase
value = value.lower()
# @index must be a string
if expanded_property == '@index' and not _is_string(value):
raise JsonLdError(
'Invalid JSON-LD syntax; "@index" value must be '
'a string.', 'jsonld.SyntaxError', {'value': value},
code='invalid @index value')
# reverse must be an object
if expanded_property == '@reverse':
if not _is_object(value):
raise JsonLdError(
'Invalid JSON-LD syntax; "@reverse" value must be '
'an object.', 'jsonld.SyntaxError', {'value': value},
code='invalid @reverse value')
expanded_value = self._expand(
active_ctx, '@reverse', value, options, inside_list)
# properties double-reversed
if '@reverse' in expanded_value:
for rprop, rvalue in expanded_value['@reverse'].items():
JsonLdProcessor.add_value(
rval, rprop, rvalue,
{'propertyIsArray': True})
# merge in all reversed properties
reverse_map = rval.get('@reverse')
for property, items in expanded_value.items():
if property == '@reverse':
continue
if reverse_map is None:
reverse_map = rval['@reverse'] = {}
JsonLdProcessor.add_value(
reverse_map, property, [],
{'propertyIsArray': True})
for item in items:
if _is_value(item) or _is_list(item):
raise JsonLdError(
'Invalid JSON-LD syntax; "@reverse" '
'value must not be an @value or an @list',
'jsonld.SyntaxError',
{'value': expanded_value},
code='invalid reverse property value')
JsonLdProcessor.add_value(
reverse_map, property, item,
{'propertyIsArray': True})
continue
container = JsonLdProcessor.get_context_value(
active_ctx, key, '@container')
# handle language map container (skip if value is not an object)
if container == '@language' and _is_object(value):
expanded_value = self._expand_language_map(value)
# handle index container (skip if value is not an object)
elif container == '@index' and _is_object(value):
def expand_index_map(active_property):
rval = []
for k, v in sorted(value.items()):
v = self._expand(
active_ctx, active_property,
JsonLdProcessor.arrayify(v),
options, inside_list=False)
for item in v:
item.setdefault('@index', k)
rval.append(item)
return rval
expanded_value = expand_index_map(key)
else:
# recurse into @list or @set
is_list = (expanded_property == '@list')
if is_list or expanded_property == '@set':
next_active_property = active_property
if is_list and expanded_active_property == '@graph':
next_active_property = None
expanded_value = self._expand(
active_ctx, next_active_property, value, options,
is_list)
if is_list and _is_list(expanded_value):
raise JsonLdError(
'Invalid JSON-LD syntax; lists of lists are '
'not permitted.', 'jsonld.SyntaxError',
code='list of lists')
else:
# recursively expand value w/key as new active property
expanded_value = self._expand(
active_ctx, key, value, options, inside_list=False)
# drop None values if property is not @value (dropped below)
if expanded_value is None and expanded_property != '@value':
continue
# convert expanded value to @list if container specifies it
if (expanded_property != '@list' and not _is_list(expanded_value)
and container == '@list'):
# ensure expanded value is an array
expanded_value = {
'@list': JsonLdProcessor.arrayify(expanded_value)
}
# merge in reverse properties
mapping = active_ctx['mappings'].get(key)
if mapping and mapping['reverse']:
reverse_map = rval.setdefault('@reverse', {})
expanded_value = JsonLdProcessor.arrayify(expanded_value)
for item in expanded_value:
if _is_value(item) or _is_list(item):
raise JsonLdError(
'Invalid JSON-LD syntax; "@reverse" value must '
'not be an @value or an @list.',
'jsonld.SyntaxError', {'value': expanded_value},
code='invalid reverse property value')
JsonLdProcessor.add_value(
reverse_map, expanded_property, item,
{'propertyIsArray': True})
continue
# add value for property, use an array exception for certain
# key words
use_array = (expanded_property not in ['@index', '@id', '@type',
'@value', '@language'])
JsonLdProcessor.add_value(
rval, expanded_property, expanded_value,
{'propertyIsArray': use_array})
# get property count on expanded output
count = len(rval)
if '@value' in rval:
# @value must only have @language or @type
if '@type' in rval and '@language' in rval:
raise JsonLdError(
'Invalid JSON-LD syntax; an element containing '
'"@value" may not contain both "@type" and "@language".',
'jsonld.SyntaxError', {'element': rval},
code='invalid value object')
valid_count = count - 1
if '@type' in rval:
valid_count -= 1
if '@index' in rval:
valid_count -= 1
if '@language' in rval:
valid_count -= 1
if valid_count != 0:
raise JsonLdError(
'Invalid JSON-LD syntax; an element containing "@value" '
'may only have an "@index" property and at most one other '
'property which can be "@type" or "@language".',
'jsonld.SyntaxError', {'element': rval},
code='invalid value object')
# drop None @values
if rval['@value'] is None:
rval = None
# if @language is present, @value must be a string
elif '@language' in rval and not _is_string(rval['@value']):
raise JsonLdError(
'Invalid JSON-LD syntax; only strings may be '
'language-tagged.', 'jsonld.SyntaxError',
{'element': rval}, code='invalid language-tagged value')
elif ('@type' in rval and (not _is_absolute_iri(rval['@type']) or
rval['@type'].startswith('_:'))):
raise JsonLdError(
'Invalid JSON-LD syntax; an element containing "@value" '
'and "@type" must have an absolute IRI for the value '
'of "@type".', 'jsonld.SyntaxError', {'element': rval},
code='invalid typed value')
# convert @type to an array
elif '@type' in rval and not _is_array(rval['@type']):
rval['@type'] = [rval['@type']]
# handle @set and @list
elif '@set' in rval or '@list' in rval:
if count > 1 and not (count == 2 and '@index' in rval):
raise JsonLdError(
'Invalid JSON-LD syntax; if an element has the '
'property "@set" or "@list", then it can have at most '
'one other property, which is "@index".',
'jsonld.SyntaxError', {'element': rval},
code='invalid set or list object')
# optimize away @set
if '@set' in rval:
rval = rval['@set']
count = len(rval)
# drop objects with only @language
elif count == 1 and '@language' in rval:
rval = None
# drop certain top-level objects that do not occur in lists
if (_is_object(rval) and not options.get('keepFreeFloatingNodes') and
not inside_list and (active_property is None or
expanded_active_property == '@graph')):
# drop empty object or top-level @value/@list,
# or object with only @id
if (count == 0 or '@value' in rval or '@list' in rval or
(count == 1 and '@id' in rval)):
rval = None
return rval
def _flatten(self, input):
"""
Performs JSON-LD flattening.
:param input_: the expanded JSON-LD to flatten.
:return: the flattened JSON-LD output.
"""
# produce a map of all subjects and name each bnode
namer = UniqueNamer('_:b')
graphs = {'@default': {}}
self._create_node_map(input, graphs, '@default', namer)
# add all non-default graphs to default graph
default_graph = graphs['@default']
for graph_name, node_map in graphs.items():
if graph_name == '@default':
continue
graph_subject = default_graph.setdefault(
graph_name, {'@id': graph_name, '@graph': []})
graph_subject.setdefault('@graph', []).extend(
[v for k, v in sorted(node_map.items())
if not _is_subject_reference(v)])
# produce flattened output
return [value for key, value in sorted(default_graph.items())
if not _is_subject_reference(value)]
def _frame(self, input_, frame, options):
"""
Performs JSON-LD framing.
:param input_: the expanded JSON-LD to frame.
:param frame: the expanded JSON-LD frame to use.
:param options: the framing options.
:return: the framed output.
"""
# create framing state
state = {
'options': options,
'graphs': {'@default': {}, '@merged': {}},
'subjectStack': [],
'link': {}
}
# produce a map of all graphs and name each bnode
# FIXME: currently uses subjects from @merged graph only
namer = UniqueNamer('_:b')
self._create_node_map(input_, state['graphs'], '@merged', namer)
state['subjects'] = state['graphs']['@merged']
# frame the subjects
framed = []
self._match_frame(
state, sorted(state['subjects'].keys()), frame, framed, None)
return framed
def _normalize(self, dataset, options):
"""
Performs RDF normalization on the given RDF dataset.
:param dataset: the RDF dataset to normalize.
:param options: the normalization options.
:return: the normalized output.
"""
# create quads and map bnodes to their associated quads
quads = []
bnodes = {}
for graph_name, triples in dataset.items():
if graph_name == '@default':
graph_name = None
for triple in triples:
quad = triple
if graph_name is not None:
if graph_name.startswith('_:'):
quad['name'] = {'type': 'blank node'}
else:
quad['name'] = {'type': 'IRI'}
quad['name']['value'] = graph_name
quads.append(quad)
for attr in ['subject', 'object', 'name']:
if attr in quad and quad[attr]['type'] == 'blank node':
id_ = quad[attr]['value']
bnodes.setdefault(id_, {}).setdefault(
'quads', []).append(quad)
# mapping complete, start canonical naming
namer = UniqueNamer('_:c14n')
# continue to hash bnode quads while bnodes are assigned names
unnamed = None
next_unnamed = bnodes.keys()
duplicates = None
while True:
unnamed = next_unnamed
next_unnamed = []
duplicates = {}
unique = {}
for bnode in unnamed:
# hash quads for each unnamed bnode
hash = self._hash_quads(bnode, bnodes)
# store hash as unique or a duplicate
if hash in duplicates:
duplicates[hash].append(bnode)
next_unnamed.append(bnode)
elif hash in unique:
duplicates[hash] = [unique[hash], bnode]
next_unnamed.append(unique[hash])
next_unnamed.append(bnode)
del unique[hash]
else:
unique[hash] = bnode
# name unique bnodes in sorted hash order
for hash, bnode in sorted(unique.items()):
namer.get_name(bnode)
# done when no more bnodes named
if len(unnamed) == len(next_unnamed):
break
# enumerate duplicate hash groups in sorted order
for hash, group in sorted(duplicates.items()):
# process group
results = []
for bnode in group:
# skip already-named bnodes
if namer.is_named(bnode):
continue
# hash bnode paths
path_namer = UniqueNamer('_:b')
path_namer.get_name(bnode)
bnode_path = None
try:
bnode_path = self._hash_paths(
bnode, bnodes, namer, path_namer)
except BaseException:
print('WARN: jsonld bnode_path failed')
if bnode_path:
results.append(bnode_path)
# name bnodes in hash order
cmp_hashes = cmp_to_key(lambda x, y: cmp(x['hash'], y['hash']))
for result in sorted(results, key=cmp_hashes):
# name all bnodes in path namer in key-entry order
for bnode in result['pathNamer'].order:
namer.get_name(bnode)
# create normalized array
normalized = []
# Note: At this point all bnodes in the set of RDF quads have been
# assigned canonical names, which have been stored in the 'namer'
# object. Here each quad is updated by assigning each of its bnodes its
# new name via the 'namer' object.
# update bnode names in each quad and serialize
for quad in quads:
for attr in ['subject', 'object', 'name']:
if (attr in quad and
quad[attr]['type'] == 'blank node' and
not quad[attr]['value'].startswith('_:c14n')):
quad[attr]['value'] = namer.get_name(quad[attr]['value'])
normalized.append(JsonLdProcessor.to_nquad(
quad, quad['name']['value'] if 'name' in quad else None))
# sort normalized output
normalized.sort()
# handle output format
if 'format' in options:
if options['format'] == 'application/nquads':
return ''.join(normalized)
raise JsonLdError(
'Unknown output format.',
'jsonld.UnknownFormat', {'format': options['format']})
# return parsed RDF dataset
return JsonLdProcessor.parse_nquads(''.join(normalized))
def _from_rdf(self, dataset, options):
"""
Converts an RDF dataset to JSON-LD.
:param dataset: the RDF dataset.
:param options: the RDF serialization options.
:return: the JSON-LD output.
"""
default_graph = {}
graph_map = {'@default': default_graph}
referenced_once = {}
for name, graph in dataset.items():
graph_map.setdefault(name, {})
if name != '@default' and name not in default_graph:
default_graph[name] = {'@id': name}
node_map = graph_map[name]
for triple in graph:
# get subject, predicate, object
s = triple['subject']['value']
p = triple['predicate']['value']
o = triple['object']
node = node_map.setdefault(s, {'@id': s})
object_is_id = (o['type'] == 'IRI' or
o['type'] == 'blank node')
if object_is_id and o['value'] not in node_map:
node_map[o['value']] = {'@id': o['value']}
if (p == RDF_TYPE and not options.get('useRdfType', False) and
object_is_id):
JsonLdProcessor.add_value(
node, '@type', o['value'], {'propertyIsArray': True})
continue
value = self._rdf_to_object(o, options['useNativeTypes'])
JsonLdProcessor.add_value(
node, p, value, {'propertyIsArray': True})
# object may be an RDF list/partial list node but we
# can't know easily until all triples are read
if object_is_id:
# track rdf:nil uniquely per graph
if o['value'] == RDF_NIL:
object = node_map[o['value']]
if 'usages' not in object:
object['usages'] = []
object['usages'].append({
'node': node,
'property': p,
'value': value
})
# object referenced more than once
elif o['value'] in referenced_once:
referenced_once[o['value']] = False
# track single reference
else:
referenced_once[o['value']] = {
'node': node,
'property': p,
'value': value
}
# convert linked lists to @list arrays
for name, graph_object in graph_map.items():
# no @lists to be converted, continue
if RDF_NIL not in graph_object:
continue
# iterate backwards through each RDF list
nil = graph_object[RDF_NIL]
for usage in nil['usages']:
node = usage['node']
property = usage['property']
head = usage['value']
list_ = []
list_nodes = []
# ensure node is a well-formed list node; it must:
# 1. Be referenced only once.
# 2. Have an array for rdf:first that has 1 item.
# 3. Have an array for rdf:rest that has 1 item
# 4. Have no keys other than: @id, rdf:first, rdf:rest
# and, optionally, @type where the value is rdf:List.
node_key_count = len(node.keys())
while (property == RDF_REST and
_is_object(referenced_once.get(node['@id'])) and
_is_array(node[RDF_FIRST]) and
len(node[RDF_FIRST]) == 1 and
_is_array(node[RDF_REST]) and
len(node[RDF_REST]) == 1 and
(node_key_count == 3 or
(node_key_count == 4 and
_is_array(node.get('@type')) and
len(node['@type']) == 1 and
node['@type'][0] == RDF_LIST))):
list_.append(node[RDF_FIRST][0])
list_nodes.append(node['@id'])
# get next node, moving backwards through list
usage = referenced_once[node['@id']]
node = usage['node']
property = usage['property']
head = usage['value']
node_key_count = len(node.keys())
# if node is not a blank node, then list head found
if not node['@id'].startswith('_:'):
break
# the list is nested in another list
if property == RDF_FIRST:
# empty list
if node['@id'] == RDF_NIL:
# can't convert rdf:nil to a @list object because it
# would result in a list of lists which isn't supported
continue
# preserve list head
head = graph_object[head['@id']][RDF_REST][0]
list_.pop()
list_nodes.pop()
# transform list into @list object
del head['@id']
list_.reverse()
head['@list'] = list_
for node in list_nodes:
graph_object.pop(node, None)
nil.pop('usages', None)
result = []
for subject, node in sorted(default_graph.items()):
if subject in graph_map:
graph = node['@graph'] = []
for s, n in sorted(graph_map[subject].items()):
# only add full subjects to top-level
if not _is_subject_reference(n):
graph.append(n)
# only add full subjects to top-level
if not _is_subject_reference(node):
result.append(node)
return result
def _process_context(self, active_ctx, local_ctx, options):
"""
Processes a local context and returns a new active context.
:param active_ctx: the current active context.
:param local_ctx: the local context to process.
:param options: the context processing options.
:return: the new active context.
"""
global _cache
# normalize local context to an array
if _is_object(local_ctx) and _is_array(local_ctx.get('@context')):
local_ctx = local_ctx['@context']
ctxs = JsonLdProcessor.arrayify(local_ctx)
# no contexts in array, clone existing context
if len(ctxs) == 0:
return self._clone_active_context(active_ctx)
# process each context in order, update active context on each
# iteration to ensure proper caching
rval = active_ctx
for ctx in ctxs:
# reset to initial context
if ctx is None:
rval = active_ctx = self._get_initial_context(options)
continue
# dereference @context key if present
if _is_object(ctx) and '@context' in ctx:
ctx = ctx['@context']
# context must be an object now, all URLs retrieved prior to call
if not _is_object(ctx):
raise JsonLdError(
'Invalid JSON-LD syntax; @context must be an object.',
'jsonld.SyntaxError', {'context': ctx},
code='invalid local context')
# get context from cache if available
if _cache.get('activeCtx') is not None:
cached = _cache['activeCtx'].get(active_ctx, ctx)
if cached:
rval = active_ctx = cached
continue
# update active context and clone new one before updating
active_ctx = rval
rval = self._clone_active_context(active_ctx)
# define context mappings for keys in local context
defined = {}
# handle @base
if '@base' in ctx:
base = ctx['@base']
if base is None:
base = None
elif not _is_string(base):
raise JsonLdError(
'Invalid JSON-LD syntax; the value of "@base" in a '
'@context must be a string or null.',
'jsonld.SyntaxError', {'context': ctx},
code='invalid base IRI')
elif base != '' and not _is_absolute_iri(base):
raise JsonLdError(
'Invalid JSON-LD syntax; the value of "@base" in a '
'@context must be an absolute IRI or the empty '
'string.', 'jsonld.SyntaxError', {'context': ctx},
code='invalid base IRI')
rval['@base'] = base
defined['@base'] = True
# handle @vocab
if '@vocab' in ctx:
value = ctx['@vocab']
if value is None:
del rval['@vocab']
elif not _is_string(value):
raise JsonLdError(
'Invalid JSON-LD syntax; the value of "@vocab" in a '
'@context must be a string or null.',
'jsonld.SyntaxError', {'context': ctx},
code='invalid vocab mapping')
elif not _is_absolute_iri(value):
raise JsonLdError(
'Invalid JSON-LD syntax; the value of "@vocab" in a '
'@context must be an absolute IRI.',
'jsonld.SyntaxError', {'context': ctx},
code='invalid vocab mapping')
else:
rval['@vocab'] = value
defined['@vocab'] = True
# handle @language
if '@language' in ctx:
value = ctx['@language']
if value is None:
del rval['@language']
elif not _is_string(value):
raise JsonLdError(
'Invalid JSON-LD syntax; the value of "@language" in '
'a @context must be a string or null.',
'jsonld.SyntaxError', {'context': ctx},
code='invalid default language')
else:
rval['@language'] = value.lower()
defined['@language'] = True
# process all other keys
for k, v in ctx.items():
self._create_term_definition(rval, ctx, k, defined)
# cache result
if _cache.get('activeCtx') is not None:
_cache.get('activeCtx').set(active_ctx, ctx, rval)
return rval
def _expand_language_map(self, language_map):
"""
Expands a language map.
:param language_map: the language map to expand.
:return: the expanded language map.
"""
rval = []
for key, values in sorted(language_map.items()):
values = JsonLdProcessor.arrayify(values)
for item in values:
if not _is_string(item):
raise JsonLdError(
'Invalid JSON-LD syntax; language map values must be '
'strings.', 'jsonld.SyntaxError',
{'languageMap': language_map},
code='invalid language map value')
rval.append({'@value': item, '@language': key.lower()})
return rval
def _expand_value(self, active_ctx, active_property, value):
"""
Expands the given value by using the coercion and keyword rules in the
given context.
:param active_ctx: the active context to use.
:param active_property: the property the value is associated with.
:param value: the value to expand.
:return: the expanded value.
"""
# nothing to expand
if value is None:
return None
# special-case expand @id and @type (skips '@id' expansion)
expanded_property = self._expand_iri(
active_ctx, active_property, vocab=True)
if expanded_property == '@id':
return self._expand_iri(active_ctx, value, base=True)
elif expanded_property == '@type':
return self._expand_iri(active_ctx, value, vocab=True, base=True)
# get type definition from context
type_ = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@type')
# do @id expansion (automatic for @graph)
if (type_ == '@id' or (expanded_property == '@graph'
and _is_string(value))):
return {'@id': self._expand_iri(active_ctx, value, base=True)}
# do @id expansion w/vocab
if type_ == '@vocab':
return {'@id': self._expand_iri(
active_ctx, value, vocab=True, base=True)}
# do not expand keyword values
if _is_keyword(expanded_property):
return value
rval = {}
# other type
if type_ is not None:
rval['@type'] = type_
# check for language tagging
elif _is_string(value):
language = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@language')
if language is not None:
rval['@language'] = language
rval['@value'] = value
return rval
def _graph_to_rdf(self, graph, namer, options):
"""
Creates an array of RDF triples for the given graph.
:param graph: the graph to create RDF triples for.
:param namer: the UniqueNamer for assigning blank node names.
:param options: the RDF serialization options.
:return: the array of RDF triples for the given graph.
"""
rval = []
for id_, node in sorted(graph.items()):
for property, items in sorted(node.items()):
if property == '@type':
property = RDF_TYPE
elif _is_keyword(property):
continue
for item in items:
# skip relative IRI subjects and predicates
if not (_is_absolute_iri(id_) and
_is_absolute_iri(property)):
continue
# RDF subject
subject = {}
if id_.startswith('_:'):
subject['type'] = 'blank node'
else:
subject['type'] = 'IRI'
subject['value'] = id_
# RDF predicate
predicate = {}
if property.startswith('_:'):
# skip bnode predicates unless producing
# generalized RDF
if not options['produceGeneralizedRdf']:
continue
predicate['type'] = 'blank node'
else:
predicate['type'] = 'IRI'
predicate['value'] = property
# convert @list to triples
if _is_list(item):
self._list_to_rdf(
item['@list'], namer, subject, predicate, rval)
# convert value or node object to triple
else:
object = self._object_to_rdf(item)
# skip None objects (they are relative IRIs)
if object is not None:
rval.append({
'subject': subject,
'predicate': predicate,
'object': object
})
return rval
def _list_to_rdf(self, list, namer, subject, predicate, triples):
"""
Converts a @list value into a linked list of blank node RDF triples
(and RDF collection).
:param list: the @list value.
:param namer: the UniqueNamer for assigning blank node names.
:param subject: the subject for the head of the list.
:param predicate: the predicate for the head of the list.
:param triples: the array of triples to append to.
"""
first = {'type': 'IRI', 'value': RDF_FIRST}
rest = {'type': 'IRI', 'value': RDF_REST}
nil = {'type': 'IRI', 'value': RDF_NIL}
for item in list:
blank_node = {'type': 'blank node', 'value': namer.get_name()}
triples.append({
'subject': subject,
'predicate': predicate,
'object': blank_node
})
subject = blank_node
predicate = first
object = self._object_to_rdf(item)
# skip None objects (they are relative IRIs)
if object is not None:
triples.append({
'subject': subject,
'predicate': predicate,
'object': object
})
predicate = rest
triples.append({
'subject': subject,
'predicate': predicate,
'object': nil
})
def _object_to_rdf(self, item):
"""
Converts a JSON-LD value object to an RDF literal or a JSON-LD string
or node object to an RDF resource.
:param item: the JSON-LD value or node object.
:return: the RDF literal or RDF resource.
"""
object = {}
if _is_value(item):
object['type'] = 'literal'
value = item['@value']
datatype = item.get('@type')
# convert to XSD datatypes as appropriate
if _is_bool(value):
object['value'] = 'true' if value else 'false'
object['datatype'] = datatype or XSD_BOOLEAN
elif _is_double(value) or datatype == XSD_DOUBLE:
# canonical double representation
object['value'] = re.sub(r'(\d)0*E\+?0*(\d)', r'\1E\2',
('%1.15E' % value))
object['datatype'] = datatype or XSD_DOUBLE
elif _is_integer(value):
object['value'] = str(value)
object['datatype'] = datatype or XSD_INTEGER
elif '@language' in item:
object['value'] = value
object['datatype'] = datatype or RDF_LANGSTRING
object['language'] = item['@language']
else:
object['value'] = value
object['datatype'] = datatype or XSD_STRING
# convert string/node object to RDF
else:
id_ = item['@id'] if _is_object(item) else item
if id_.startswith('_:'):
object['type'] = 'blank node'
else:
object['type'] = 'IRI'
object['value'] = id_
# skip relative IRIs
if object['type'] == 'IRI' and not _is_absolute_iri(object['value']):
return None
return object
def _rdf_to_object(self, o, use_native_types):
"""
Converts an RDF triple object to a JSON-LD object.
:param o: the RDF triple object to convert.
:param use_native_types: True to output native types, False not to.
:return: the JSON-LD object.
"""
# convert IRI/BlankNode object to JSON-LD
if o['type'] == 'IRI' or o['type'] == 'blank node':
return {'@id': o['value']}
# convert literal object to JSON-LD
rval = {'@value': o['value']}
# add language
if 'language' in o:
rval['@language'] = o['language']
# add datatype
else:
type_ = o['datatype']
# use native types for certain xsd types
if use_native_types:
if type_ == XSD_BOOLEAN:
if rval['@value'] == 'true':
rval['@value'] = True
elif rval['@value'] == 'false':
rval['@value'] = False
elif _is_numeric(rval['@value']):
if type_ == XSD_INTEGER:
if rval['@value'].isdigit():
rval['@value'] = int(rval['@value'])
elif type_ == XSD_DOUBLE:
rval['@value'] = float(rval['@value'])
# do not add native type
if type_ not in [XSD_BOOLEAN, XSD_INTEGER, XSD_DOUBLE,
XSD_STRING]:
rval['@type'] = type_
elif type_ != XSD_STRING:
rval['@type'] = type_
return rval
def _create_node_map(
self, input_, graphs, graph, namer, name=None, list_=None):
"""
Recursively flattens the subjects in the given JSON-LD expanded
input into a node map.
:param input_: the JSON-LD expanded input.
:param graphs: a map of graph name to subject map.
:param graph: the name of the current graph.
:param namer: the UniqueNamer for assigning blank node names.
:param name: the name assigned to the current input if it is a bnode.
:param list_: the list to append to, None for none.
"""
# recurse through array
if _is_array(input_):
for e in input_:
self._create_node_map(e, graphs, graph, namer, None, list_)
return
# add non-object to list
if not _is_object(input_):
if list_ is not None:
list_.append(input_)
return
# add values to list
if _is_value(input_):
if '@type' in input_:
type_ = input_['@type']
# rename @type blank node
if type_.startswith('_:'):
type_ = input_['@type'] = namer.get_name(type_)
if list_ is not None:
list_.append(input_)
return
# Note: At this point, input must be a subject.
# spec requires @type to be named first, so assign names early
if '@type' in input_:
for type_ in input_['@type']:
if type_.startswith('_:'):
namer.get_name(type_)
# get name for subject
if name is None:
name = input_.get('@id')
if _is_bnode(input_):
name = namer.get_name(name)
# add subject reference to list
if list_ is not None:
list_.append({'@id': name})
# create new subject or merge into existing one
subject = graphs.setdefault(graph, {}).setdefault(name, {'@id': name})
for property, objects in sorted(input_.items()):
# skip @id
if property == '@id':
continue
# handle reverse properties
if property == '@reverse':
referenced_node = {'@id': name}
reverse_map = input_['@reverse']
for reverse_property, items in reverse_map.items():
for item in items:
item_name = item.get('@id')
if _is_bnode(item):
item_name = namer.get_name(item_name)
self._create_node_map(
item, graphs, graph, namer, item_name)
JsonLdProcessor.add_value(
graphs[graph][item_name], reverse_property,
referenced_node,
{'propertyIsArray': True, 'allowDuplicate': False})
continue
# recurse into graph
if property == '@graph':
# add graph subjects map entry
graphs.setdefault(name, {})
g = graph if graph == '@merged' else name
self._create_node_map(objects, graphs, g, namer)
continue
# copy non-@type keywords
if property != '@type' and _is_keyword(property):
if property == '@index' and '@index' in subject \
and (input_['@index'] != subject['@index'] or
input_['@index']['@id'] != subject['@index']['@id']):
raise JsonLdError(
'Invalid JSON-LD syntax; conflicting @index property '
' detected.', 'jsonld.SyntaxError',
{'subject': subject}, code='conflicting indexes')
subject[property] = input_[property]
continue
# if property is a bnode, assign it a new id
if property.startswith('_:'):
property = namer.get_name(property)
# ensure property is added for empty arrays
if len(objects) == 0:
JsonLdProcessor.add_value(
subject, property, [], {'propertyIsArray': True})
continue
for o in objects:
if property == '@type':
# rename @type blank nodes
o = namer.get_name(o) if o.startswith('_:') else o
# handle embedded subject or subject reference
if _is_subject(o) or _is_subject_reference(o):
# rename blank node @id
id_ = o.get('@id')
if _is_bnode(o):
id_ = namer.get_name(id_)
# add reference and recurse
JsonLdProcessor.add_value(
subject, property, {'@id': id_},
{'propertyIsArray': True, 'allowDuplicate': False})
self._create_node_map(o, graphs, graph, namer, id_)
# handle @list
elif _is_list(o):
olist = []
self._create_node_map(
o['@list'], graphs, graph, namer, name, olist)
o = {'@list': olist}
JsonLdProcessor.add_value(
subject, property, o,
{'propertyIsArray': True, 'allowDuplicate': False})
# handle @value
else:
self._create_node_map(o, graphs, graph, namer, name)
JsonLdProcessor.add_value(
subject, property, o,
{'propertyIsArray': True, 'allowDuplicate': False})
def _match_frame(self, state, subjects, frame, parent, property):
"""
Frames subjects according to the given frame.
:param state: the current framing state.
:param subjects: the subjects to filter.
:param frame: the frame.
:param parent: the parent subject or top-level array.
:param property: the parent property, initialized to None.
"""
# validate the frame
self._validate_frame(frame)
frame = frame[0]
# get flags for current frame
options = state['options']
flags = {
'embed': self._get_frame_flag(frame, options, 'embed'),
'explicit': self._get_frame_flag(frame, options, 'explicit'),
'requireAll': self._get_frame_flag(frame, options, 'requireAll')
}
# filter out subjects that match the frame
matches = self._filter_subjects(state, subjects, frame, flags)
# add matches to output
for id_, subject in sorted(matches.items()):
if flags['embed'] == '@link' and id_ in state['link']:
# TODO: may want to also match an existing linked subject
# against the current frame ... so different frames could
# produce different subjects that are only shared in-memory
# when the frames are the same
# add existing linked subject
self._add_frame_output(parent, property, state['link'][id_])
continue
# Note: In order to treat each top-level match as a
# compartmentalized result, clear the unique embedded subjects map
# when the property is None, which only occurs at the top-level.
if property is None:
state['uniqueEmbeds'] = {}
# start output for subject
output = {'@id': id_}
state['link'][id_] = output
# if embed is @never or if a circular reference would be created
# by an embed, the subject cannot be embedded, just add the
# reference; note that a circular reference won't occur when the
# embed flag is `@link` as the above check will short-circuit
# before reaching this point
if (flags['embed'] == '@never' or self._creates_circular_reference(
subject, state['subjectStack'])):
self._add_frame_output(parent, property, output)
continue
# if only the last match should be embedded
if flags['embed'] == '@last':
# remove any existing embed
if id_ in state['uniqueEmbeds']:
self._remove_embed(state, id_)
state['uniqueEmbeds'][id_] = {
'parent': parent,
'property': property
}
# push matching subject onto stack to enable circular embed checks
state['subjectStack'].append(subject)
# iterate over subject properties in order
for prop, objects in sorted(subject.items()):
# copy keywords to output
if _is_keyword(prop):
output[prop] = copy.deepcopy(subject[prop])
continue
# explicit is on and property isn't in frame, skip processing
if flags['explicit'] and prop not in frame:
continue
# add objects
objects = subject[prop]
for o in objects:
# recurse into list
if _is_list(o):
# add empty list
list_ = {'@list': []}
self._add_frame_output(output, prop, list_)
# add list objects
src = o['@list']
for o in src:
if _is_subject_reference(o):
# recurse into subject reference
if prop in frame:
subframe = frame[prop][0]['@list']
else:
subframe = self._create_implicit_frame(
flags)
self._match_frame(
state, [o['@id']],
subframe, list_, '@list')
else:
# include other values automatically
self._add_frame_output(
list_, '@list', copy.deepcopy(o))
continue
if _is_subject_reference(o):
# recurse into subject reference
if prop in frame:
subframe = frame[prop]
else:
subframe = self._create_implicit_frame(flags)
self._match_frame(
state, [o['@id']], subframe, output, prop)
else:
# include other values automatically
self._add_frame_output(output, prop, copy.deepcopy(o))
# handle defaults in order
for prop in sorted(frame.keys()):
# skip keywords
if _is_keyword(prop):
continue
# if omit default is off, then include default values for
# properties that appear in the next frame but are not in
# the matching subject
next = frame[prop][0]
omit_default_on = self._get_frame_flag(
next, options, 'omitDefault')
if not omit_default_on and prop not in output:
preserve = '@null'
if '@default' in next:
preserve = copy.deepcopy(next['@default'])
preserve = JsonLdProcessor.arrayify(preserve)
output[prop] = [{'@preserve': preserve}]
# add output to parent
self._add_frame_output(parent, property, output)
# pop matching subject from circular ref-checking stack
state['subjectStack'].pop()
def _create_implicit_frame(self, flags):
"""
Creates an implicit frame when recursing through subject matches. If
a frame doesn't have an explicit frame for a particular property, then
a wildcard child frame will be created that uses the same flags that
the parent frame used.
:param flags: the current framing flags.
:return: the implicit frame.
"""
frame = {}
for key in flags:
frame['@' + key] = [flags[key]]
return [frame]
def _creates_circular_reference(self, subject_to_embed, subject_stack):
"""
Checks the current subject stack to see if embedding the given subject
would cause a circular reference.
:param subject_to_embed: the subject to embed.
:param subject_stack: the current stack of subjects.
:return: true if a circular reference would be created, false if not.
"""
for subject in reversed(subject_stack[:-1]):
if subject['@id'] == subject_to_embed['@id']:
return True
return False
def _get_frame_flag(self, frame, options, name):
"""
Gets the frame flag value for the given flag name.
:param frame: the frame.
:param options: the framing options.
:param name: the flag name.
:return: the flag value.
"""
rval = frame.get('@' + name, [options[name]])[0]
if name == 'embed':
# default is "@last"
# backwards-compatibility support for "embed" maps:
# true => "@last"
# false => "@never"
if rval is True:
rval = '@last'
elif rval is False:
rval = '@never'
elif rval != '@always' and rval != '@never' and rval != '@link':
rval = '@last'
return rval
def _validate_frame(self, frame):
"""
Validates a JSON-LD frame, throwing an exception if the frame is
invalid.
:param frame: the frame to validate.
"""
if (not _is_array(frame) or len(frame) != 1 or
not _is_object(frame[0])):
raise JsonLdError(
'Invalid JSON-LD syntax; a JSON-LD frame must be a single '
'object.', 'jsonld.SyntaxError', {'frame': frame})
def _filter_subjects(self, state, subjects, frame, flags):
"""
Returns a map of all of the subjects that match a parsed frame.
:param state: the current framing state.
:param subjects: the set of subjects to filter.
:param frame: the parsed frame.
:param flags: the frame flags.
:return: all of the matched subjects.
"""
rval = {}
for id_ in subjects:
subject = state['subjects'][id_]
if self._filter_subject(subject, frame, flags):
rval[id_] = subject
return rval
def _filter_subject(self, subject, frame, flags):
"""
Returns True if the given subject matches the given frame.
:param subject: the subject to check.
:param frame: the frame to check.
:param flags: the frame flags.
:return: True if the subject matches, False if not.
"""
# check @type (object value means 'any' type, fall through to
# ducktyping)
if ('@type' in frame and
not (len(frame['@type']) == 1 and
_is_object(frame['@type'][0]))):
types = frame['@type']
for t in types:
# any matching @type is a match
if JsonLdProcessor.has_value(subject, '@type', t):
return True
return False
# check ducktype
wildcard = True
matches_some = False
for k, v in frame.items():
if _is_keyword(k):
# skip non-@id and non-@type
if k != '@id' and k != '@type':
continue
wildcard = True
# check @id for a specific @id value
if k == '@id' and _is_string(v):
if subject.get(k) != v:
return False
matches_some = True
continue
wildcard = False
if k in subject:
# v == [] means do not match if property is present
if _is_array(v) and len(v) == 0:
return False
matches_some = True
continue
# all properties must match to be a duck unless a @default is
# specified
has_default = (_is_array(v) and len(v) == 1 and
_is_object(v[0]) and '@default' in v[0])
if flags['requireAll'] and not has_default:
return False
# return true if wildcard or subject matches some properties
return wildcard or matches_some
def _remove_embed(self, state, id_):
"""
Removes an existing embed.
:param state: the current framing state.
:param id_: the @id of the embed to remove.
"""
# get existing embed
embeds = state['uniqueEmbeds']
embed = embeds[id_]
property = embed['property']
# create reference to replace embed
subject = {'@id': id_}
# remove existing embed
if _is_array(embed['parent']):
# replace subject with reference
for i, parent in enumerate(embed['parent']):
if JsonLdProcessor.compare_values(parent, subject):
embed['parent'][i] = subject
break
else:
# replace subject with reference
use_array = _is_array(embed['parent'][property])
JsonLdProcessor.remove_value(
embed['parent'], property, subject,
{'propertyIsArray': use_array})
JsonLdProcessor.add_value(
embed['parent'], property, subject,
{'propertyIsArray': use_array})
# recursively remove dependent dangling embeds
def remove_dependents(id_):
# get embed keys as a separate array to enable deleting keys
# in map
try:
ids = list(embeds.iterkeys())
except AttributeError:
ids = list(embeds.keys())
for next in ids:
if (next in embeds and
_is_object(embeds[next]['parent']) and
embeds[next]['parent']['@id'] == id_):
del embeds[next]
remove_dependents(next)
remove_dependents(id_)
def _add_frame_output(self, parent, property, output):
"""
Adds framing output to the given parent.
:param parent: the parent to add to.
:param property: the parent property.
:param output: the output to add.
"""
if _is_object(parent):
JsonLdProcessor.add_value(
parent, property, output, {'propertyIsArray': True})
else:
parent.append(output)
def _remove_preserve(self, ctx, input_, options):
"""
Removes the @preserve keywords as the last step of the framing
algorithm.
:param ctx: the active context used to compact the input.
:param input_: the framed, compacted output.
:param options: the compaction options used.
:return: the resulting output.
"""
# recurse through arrays
if _is_array(input_):
output = []
for e in input_:
result = self._remove_preserve(ctx, e, options)
# drop Nones from arrays
if result is not None:
output.append(result)
return output
elif _is_object(input_):
# remove @preserve
if '@preserve' in input_:
if input_['@preserve'] == '@null':
return None
return input_['@preserve']
# skip @values
if _is_value(input_):
return input_
# recurse through @lists
if _is_list(input_):
input_['@list'] = self._remove_preserve(
ctx, input_['@list'], options)
return input_
# handle in-memory linked nodes
id_alias = self._compact_iri(ctx, '@id')
if id_alias in input_:
id_ = input_[id_alias]
if id_ in options['link']:
try:
idx = options['link'][id_].index(input_)
# already visited
return options['link'][id_][idx]
except BaseException:
# prevent circular visitation
options['link'][id_].append(input_)
else:
# prevent circular visitation
options['link'][id_] = [input_]
# recurse through properties
for prop, v in input_.items():
result = self._remove_preserve(ctx, v, options)
container = JsonLdProcessor.get_context_value(
ctx, prop, '@container')
if (options['compactArrays'] and
_is_array(result) and len(result) == 1 and
container != '@set' and container != '@list'):
result = result[0]
input_[prop] = result
return input_
def _hash_quads(self, id_, bnodes):
"""
Hashes all of the quads about a blank node.
:param id_: the ID of the bnode to hash quads for.
:param bnodes: the mapping of bnodes to quads.
:param namer: the canonical bnode namer.
:return: the new hash.
"""
# return cached hash
if 'hash' in bnodes[id_]:
return bnodes[id_]['hash']
# serialize all of bnode's quads
quads = bnodes[id_]['quads']
nquads = []
for quad in quads:
nquads.append(JsonLdProcessor.to_nquad(
quad, quad['name']['value'] if 'name' in quad else None, id_))
# sort serialized quads
nquads.sort()
# cache and return hashed quads
md = hashlib.sha1()
md.update(''.join(nquads).encode('utf-8'))
hash = bnodes[id_]['hash'] = md.hexdigest()
return hash
def _hash_paths(self, id_, bnodes, namer, path_namer):
"""
Produces a hash for the paths of adjacent bnodes for a bnode,
incorporating all information about its subgraph of bnodes. This
method will recursively pick adjacent bnode permutations that produce
the lexicographically-least 'path' serializations.
:param id_: the ID of the bnode to hash paths for.
:param bnodes: the map of bnode quads.
:param namer: the canonical bnode namer.
:param path_namer: the namer used to assign names to adjacent bnodes.
:return: the hash and path namer used.
"""
# create SHA-1 digest
md = hashlib.sha1()
# group adjacent bnodes by hash, keep properties & references separate
groups = {}
quads = bnodes[id_]['quads']
for quad in quads:
# get adjacent bnode
bnode = self._get_adjacent_bnode_name(quad['subject'], id_)
if bnode is not None:
# normal property
direction = 'p'
else:
bnode = self._get_adjacent_bnode_name(quad['object'], id_)
if bnode is None:
continue
# reference property
direction = 'r'
# get bnode name (try canonical, path, then hash)
if namer.is_named(bnode):
name = namer.get_name(bnode)
elif path_namer.is_named(bnode):
name = path_namer.get_name(bnode)
else:
name = self._hash_quads(bnode, bnodes)
# hash direction, property, and bnode name/hash
group_md = hashlib.sha1()
group_md.update(direction.encode('utf-8'))
group_md.update(quad['predicate']['value'].encode('utf-8'))
group_md.update(name.encode('utf-8'))
group_hash = group_md.hexdigest()
# add bnode to hash group
groups.setdefault(group_hash, []).append(bnode)
# iterate over groups in sorted hash order
for group_hash, group in sorted(groups.items()):
# digest group hash
md.update(group_hash.encode('utf8'))
# choose a path and namer from the permutations
chosen_path = None
chosen_namer = None
for permutation in permutations(group):
path_namer_copy = copy.deepcopy(path_namer)
# build adjacent path
path = ''
skipped = False
recurse = []
for bnode in permutation:
# use canonical name if available
if namer.is_named(bnode):
path += namer.get_name(bnode)
else:
# recurse if bnode isn't named in the path yet
if not path_namer_copy.is_named(bnode):
recurse.append(bnode)
path += path_namer_copy.get_name(bnode)
# skip permutation if path is already >= chosen path
if (chosen_path is not None and
len(path) >= len(chosen_path) and
path > chosen_path):
skipped = True
break
# recurse
if not skipped:
for bnode in recurse:
result = self._hash_paths(
bnode, bnodes, namer, path_namer_copy)
path += path_namer_copy.get_name(bnode)
path += '<%s>' % result['hash']
path_namer_copy = result['pathNamer']
# skip permutation if path is already >= chosen path
if (chosen_path is not None and
len(path) >= len(chosen_path) and
path > chosen_path):
skipped = True
break
if (not skipped and
(chosen_path is None or path < chosen_path)):
chosen_path = path
chosen_namer = path_namer_copy
# digest chosen path and update namer
md.update(chosen_path.encode('utf-8'))
path_namer = chosen_namer
# return SHA-1 hash and path namer
return {'hash': md.hexdigest(), 'pathNamer': path_namer}
def _get_adjacent_bnode_name(self, node, id_):
"""
A helper function that gets the blank node name from an RDF quad
node (subject or object). If the node is not a blank node or its
value does not match the given blank node ID, it will be returned.
:param node: the RDF quad node.
:param id_: the ID of the blank node to look next to.
:return: the adjacent blank node name or None if none was found.
"""
if node['type'] == 'blank node' and node['value'] != id_:
return node['value']
return None
def _select_term(
self, active_ctx, iri, value, containers,
type_or_language, type_or_language_value):
"""
Picks the preferred compaction term from the inverse context entry.
:param active_ctx: the active context.
:param iri: the IRI to pick the term for.
:param value: the value to pick the term for.
:param containers: the preferred containers.
:param type_or_language: either '@type' or '@language'.
:param type_or_language_value: the preferred value for '@type' or
'@language'
:return: the preferred term.
"""
if type_or_language_value is None:
type_or_language_value = '@null'
# preferred options for the value of @type or language
prefs = []
# determine prefs for @id based on whether value compacts to term
if ((type_or_language_value == '@id' or
type_or_language_value == '@reverse') and
_is_subject_reference(value)):
# prefer @reverse first
if type_or_language_value == '@reverse':
prefs.append('@reverse')
# try to compact value to a term
term = self._compact_iri(
active_ctx, value['@id'], None, vocab=True)
mapping = active_ctx['mappings'].get(term)
if term is not None and mapping and mapping['@id'] == value['@id']:
# prefer @vocab
prefs.extend(['@vocab', '@id'])
else:
# prefer @id
prefs.extend(['@id', '@vocab'])
else:
prefs.append(type_or_language_value)
prefs.append('@none')
container_map = active_ctx['inverse'][iri]
for container in containers:
# skip container if not in map
if container not in container_map:
continue
type_or_language_value_map = (
container_map[container][type_or_language])
for pref in prefs:
# skip type/language preference if not in map
if pref not in type_or_language_value_map:
continue
return type_or_language_value_map[pref]
return None
def _compact_iri(
self, active_ctx, iri, value=None, vocab=False, reverse=False):
"""
Compacts an IRI or keyword into a term or CURIE if it can be. If the
IRI has an associated value it may be passed.
:param active_ctx: the active context to use.
:param iri: the IRI to compact.
:param value: the value to check or None.
:param vocab: True to compact using @vocab if available, False not to.
:param reverse: True if a reverse property is being compacted, False if
not.
:return: the compacted term, prefix, keyword alias, or original IRI.
"""
# can't compact None
if iri is None:
return iri
# term is a keyword, force vocab to True
if _is_keyword(iri):
vocab = True
# use inverse context to pick a term if iri is relative to vocab
if vocab and iri in self._get_inverse_context(active_ctx):
default_language = active_ctx.get('@language', '@none')
# prefer @index if available in value
containers = []
if _is_object(value) and '@index' in value:
containers.append('@index')
# defaults for term selection based on type/language
type_or_language = '@language'
type_or_language_value = '@null'
if reverse:
type_or_language = '@type'
type_or_language_value = '@reverse'
containers.append('@set')
# choose most specific term that works for all elements in @list
elif _is_list(value):
# only select @list containers if @index is NOT in value
if '@index' not in value:
containers.append('@list')
list_ = value['@list']
common_language = default_language if len(list_) == 0 else None
common_type = None
for item in list_:
item_language = '@none'
item_type = '@none'
if _is_value(item):
if '@language' in item:
item_language = item['@language']
elif '@type' in item:
item_type = item['@type']
# plain literal
else:
item_language = '@null'
else:
item_type = '@id'
if common_language is None:
common_language = item_language
elif item_language != common_language and _is_value(item):
common_language = '@none'
if common_type is None:
common_type = item_type
elif item_type != common_type:
common_type = '@none'
# there are different languages and types in the list, so
# choose the most generic term, no need to keep iterating
if common_language == '@none' and common_type == '@none':
break
if common_language is None:
common_language = '@none'
if common_type is None:
common_type = '@none'
if common_type != '@none':
type_or_language = '@type'
type_or_language_value = common_type
else:
type_or_language_value = common_language
# non-@list
else:
if _is_value(value):
if '@language' in value and '@index' not in value:
containers.append('@language')
type_or_language_value = value['@language']
elif '@type' in value:
type_or_language = '@type'
type_or_language_value = value['@type']
else:
type_or_language = '@type'
type_or_language_value = '@id'
containers.append('@set')
# do term selection
containers.append('@none')
term = self._select_term(
active_ctx, iri, value, containers,
type_or_language, type_or_language_value)
if term is not None:
return term
# no term match, use @vocab if available
if vocab:
if '@vocab' in active_ctx:
vocab_ = active_ctx['@vocab']
if iri.startswith(vocab_) and iri != vocab_:
# use suffix as relative iri if it is not a term in the
# active context
suffix = iri[len(vocab_):]
if suffix not in active_ctx['mappings']:
return suffix
# no term or @vocab match, check for possible CURIEs
candidate = None
for term, definition in active_ctx['mappings'].items():
# skip terms with colons, they can't be prefixes
if ':' in term:
continue
# skip entries with @ids that are not partial matches
if (definition is None or definition['@id'] == iri or
not iri.startswith(definition['@id'])):
continue
# a CURIE is usable if:
# 1. it has no mapping, OR
# 2. value is None, which means we're not compacting an @value, AND
# the mapping matches the IRI
curie = term + ':' + iri[len(definition['@id']):]
is_usable_curie = (
curie not in active_ctx['mappings'] or
(value is None and
active_ctx['mappings'].get(curie, {}).get('@id') == iri))
# select curie if it is shorter or the same length but
# lexicographically less than the current choice
if (is_usable_curie and (candidate is None or
_compare_shortest_least(curie,
candidate) < 0)):
candidate = curie
# return curie candidate
if candidate is not None:
return candidate
# compact IRI relative to base
if not vocab:
return remove_base(active_ctx['@base'], iri)
# return IRI as is
return iri
def _compact_value(self, active_ctx, active_property, value):
"""
Performs value compaction on an object with @value or @id as the only
property.
:param active_ctx: the active context.
:param active_property: the active property that points to the value.
:param value: the value to compact.
"""
if _is_value(value):
# get context rules
type_ = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@type')
language = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@language')
container = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@container')
# whether or not the value has an @index that must be preserved
preserve_index = '@index' in value and container != '@index'
# if there's no @index to preserve
if not preserve_index:
# matching @type or @language specified in context, compact
if (('@type' in value and value['@type'] == type_) or
('@language' in value and
value['@language'] == language)):
return value['@value']
# return just the value of @value if all are true:
# 1. @value is the only key or @index isn't being preserved
# 2. there is no default language or @value is not a string or
# the key has a mapping with a null @language
key_count = len(value)
is_value_only_key = \
(key_count == 1 or (key_count == 2 and
'@index' in value and not preserve_index))
has_default_language = '@language' in active_ctx
is_value_string = _is_string(value['@value'])
has_null_mapping = (
active_ctx['mappings'].get(active_property) is not None and
'@language' in active_ctx['mappings'][active_property] and
active_ctx['mappings'][active_property]['@language'] is None)
if (is_value_only_key and (
not has_default_language or not is_value_string or
has_null_mapping)):
return value['@value']
rval = {}
# preserve @index
if preserve_index:
rval[self._compact_iri(active_ctx, '@index')] = value['@index']
# compact @type IRI
if '@type' in value:
rval[self._compact_iri(active_ctx, '@type')] = (
self._compact_iri(active_ctx, value['@type'], vocab=True))
# alias @language
elif '@language' in value:
rval[self._compact_iri(active_ctx, '@language')] = (
value['@language'])
# alias @value
rval[self._compact_iri(active_ctx, '@value')] = value['@value']
return rval
# value is a subject reference
expanded_property = self._expand_iri(
active_ctx, active_property, vocab=True)
type_ = JsonLdProcessor.get_context_value(
active_ctx, active_property, '@type')
compacted = self._compact_iri(
active_ctx, value['@id'], vocab=(type_ == '@vocab'))
# compact to scalar
if type_ in ['@id', '@vocab'] or expanded_property == '@graph':
return compacted
rval = {}
rval[self._compact_iri(active_ctx, '@id')] = compacted
return rval
def _create_term_definition(self, active_ctx, local_ctx, term, defined):
"""
Creates a term definition during context processing.
:param active_ctx: the current active context.
:param local_ctx: the local context being processed.
:param term: the key in the local context to define the mapping for.
:param defined: a map of defining/defined keys to detect cycles
and prevent double definitions.
"""
if term in defined:
# term already defined
if defined[term]:
return
# cycle detected
raise JsonLdError(
'Cyclical context definition detected.',
'jsonld.CyclicalContext', {
'context': local_ctx,
'term': term
}, code='cyclic IRI mapping')
# now defining term
defined[term] = False
if _is_keyword(term):
raise JsonLdError(
'Invalid JSON-LD syntax; keywords cannot be overridden.',
'jsonld.SyntaxError', {'context': local_ctx, 'term': term},
code='keyword redefinition')
if term == '':
raise JsonLdError(
'Invalid JSON-LD syntax; a term cannot be an empty string.',
'jsonld.SyntaxError', {'context': local_ctx},
code='invalid term definition')
# remove old mapping
if term in active_ctx['mappings']:
del active_ctx['mappings'][term]
# get context term value
value = local_ctx[term]
# clear context entry
if (value is None or (_is_object(value) and '@id' in value and
value['@id'] is None)):
active_ctx['mappings'][term] = None
defined[term] = True
return
# convert short-hand value to object w/@id
if _is_string(value):
value = {'@id': value}
if not _is_object(value):
raise JsonLdError(
'Invalid JSON-LD syntax; @context property values must be '
'strings or objects.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid term definition')
# create new mapping
mapping = active_ctx['mappings'][term] = {'reverse': False}
if '@reverse' in value:
if '@id' in value:
raise JsonLdError(
'Invalid JSON-LD syntax; an @reverse term definition must '
'not contain @id.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid reverse property')
reverse = value['@reverse']
if not _is_string(reverse):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @reverse value must be '
'a string.', 'jsonld.SyntaxError', {'context': local_ctx},
code='invalid IRI mapping')
# expand and add @id mapping
id_ = self._expand_iri(
active_ctx, reverse, vocab=True, base=False,
local_ctx=local_ctx, defined=defined)
if not _is_absolute_iri(id_):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @reverse value must be '
'an absolute IRI or a blank node identifier.',
'jsonld.SyntaxError', {'context': local_ctx},
code='invalid IRI mapping')
mapping['@id'] = id_
mapping['reverse'] = True
elif '@id' in value:
id_ = value['@id']
if not _is_string(id_):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @id value must be a '
'string.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid IRI mapping')
if id_ != term:
# add @id to mapping
id_ = self._expand_iri(
active_ctx, id_, vocab=True, base=False,
local_ctx=local_ctx, defined=defined)
if not _is_absolute_iri(id_) and not _is_keyword(id_):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @id value must be '
'an absolute IRI, a blank node identifier, or a '
'keyword.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid IRI mapping')
mapping['@id'] = id_
if '@id' not in mapping:
# see if the term has a prefix
colon = term.find(':')
if colon != -1:
prefix = term[0:colon]
if prefix in local_ctx:
# define parent prefix
self._create_term_definition(
active_ctx, local_ctx, prefix, defined)
# set @id based on prefix parent
if active_ctx['mappings'].get(prefix) is not None:
suffix = term[colon + 1:]
mapping['@id'] = (active_ctx['mappings'][prefix]['@id'] +
suffix)
# term is an absolute IRI
else:
mapping['@id'] = term
else:
# non-IRIs MUST define @ids if @vocab not available
if '@vocab' not in active_ctx:
raise JsonLdError(
'Invalid JSON-LD syntax; @context terms must define '
'an @id.', 'jsonld.SyntaxError', {
'context': local_ctx,
'term': term
}, code='invalid IRI mapping')
# prepend vocab to term
mapping['@id'] = active_ctx['@vocab'] + term
# IRI mapping now defined
defined[term] = True
if '@type' in value:
type_ = value['@type']
if not _is_string(type_):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @type value must be '
'a string.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid type mapping')
if type_ != '@id' and type_ != '@vocab':
# expand @type to full IRI
type_ = self._expand_iri(
active_ctx, type_, vocab=True,
local_ctx=local_ctx, defined=defined)
if not _is_absolute_iri(type_):
raise JsonLdError(
'Invalid JSON-LD syntax; an @context @type value must '
'be an absolute IRI.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid type mapping')
if type_.startswith('_:'):
raise JsonLdError(
'Invalid JSON-LD syntax; an @context @type values '
'must be an IRI, not a blank node identifier.',
'jsonld.SyntaxError', {'context': local_ctx},
code='invalid type mapping')
# add @type to mapping
mapping['@type'] = type_
if '@container' in value:
container = value['@container']
if container not in ['@list', '@set', '@index', '@language']:
raise JsonLdError(
'Invalid JSON-LD syntax; @context @container value '
'must be one of the following: @list, @set, @index, or '
'@language.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid container mapping')
if (mapping['reverse'] and container != '@index' and
container != '@set' and container is not None):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @container value for '
'an @reverse type definition must be @index or @set.',
'jsonld.SyntaxError', {'context': local_ctx},
code='invalid reverse property')
# add @container to mapping
mapping['@container'] = container
if '@language' in value and '@type' not in value:
language = value['@language']
if not (language is None or _is_string(language)):
raise JsonLdError(
'Invalid JSON-LD syntax; @context @language value must be '
'a string or null.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid language mapping')
# add @language to mapping
if language is not None:
language = language.lower()
mapping['@language'] = language
# disallow aliasing @context and @preserve
id_ = mapping['@id']
if id_ == '@context' or id_ == '@preserve':
raise JsonLdError(
'Invalid JSON-LD syntax; @context and @preserve '
'cannot be aliased.', 'jsonld.SyntaxError',
{'context': local_ctx}, code='invalid keyword alias')
def _expand_iri(
self, active_ctx, value, base=False, vocab=False,
local_ctx=None, defined=None):
"""
Expands a string value to a full IRI. The string may be a term, a
prefix, a relative IRI, or an absolute IRI. The associated absolute
IRI will be returned.
:param active_ctx: the current active context.
:param value: the string value to expand.
:param base: True to resolve IRIs against the base IRI, False not to.
:param vocab: True to concatenate after @vocab, False not to.
:param local_ctx: the local context being processed (only given if
called during context processing).
:param defined: a map for tracking cycles in context definitions (only
given if called during context processing).
:return: the expanded value.
"""
# already expanded
if value is None or _is_keyword(value):
return value
# define dependency not if defined
if (local_ctx and value in local_ctx and
defined.get(value) is not True):
self._create_term_definition(active_ctx, local_ctx, value, defined)
if vocab and value in active_ctx['mappings']:
mapping = active_ctx['mappings'].get(value)
# value is explicitly ignored with None mapping
if mapping is None:
return None
# value is a term
return mapping['@id']
# split value into prefix:suffix
if ':' in value:
prefix, suffix = value.split(':', 1)
# do not expand blank nodes (prefix of '_') or already-absolute
# IRIs (suffix of '//')
if prefix == '_' or suffix.startswith('//'):
return value
# prefix dependency not defined, define it
if local_ctx and prefix in local_ctx:
self._create_term_definition(
active_ctx, local_ctx, prefix, defined)
# use mapping if prefix is defined
mapping = active_ctx['mappings'].get(prefix)
if mapping:
return mapping['@id'] + suffix
# already absolute IRI
return value
# prepend vocab
if vocab and '@vocab' in active_ctx:
return active_ctx['@vocab'] + value
# resolve against base
rval = value
if base:
rval = prepend_base(active_ctx['@base'], rval)
return rval
def _find_context_urls(self, input_, urls, replace, base):
"""
Finds all @context URLs in the given JSON-LD input.
:param input_: the JSON-LD input.
:param urls: a map of URLs (url => False/@contexts).
:param replace: True to replace the URLs in the given input with
the @contexts from the urls map, False not to.
:param base: the base URL to resolve relative URLs against.
"""
if _is_array(input_):
for e in input_:
self._find_context_urls(e, urls, replace, base)
elif _is_object(input_):
for k, v in input_.items():
if k != '@context':
self._find_context_urls(v, urls, replace, base)
continue
# array @context
if _is_array(v):
length = len(v)
for i in range(length):
if _is_string(v[i]):
url = prepend_base(base, v[i])
# replace w/@context if requested
if replace:
ctx = urls[url]
if _is_array(ctx):
# add flattened context
v.pop(i)
for e in reversed(ctx):
v.insert(i, e)
i += len(ctx) - 1
length = len(v)
else:
v[i] = ctx
# @context URL found
elif url not in urls:
urls[url] = False
# string @context
elif _is_string(v):
v = prepend_base(base, v)
# replace w/@context if requested
if replace:
input_[k] = urls[v]
# @context URL found
elif v not in urls:
urls[v] = False
def _retrieve_context_urls(self, input_, cycles, load_document,
base: str = ''):
"""
Retrieves external @context URLs using the given document loader. Each
instance of @context in the input that refers to a URL will be
replaced with the JSON @context found at that URL.
:param input_: the JSON-LD input with possible contexts.
:param cycles: an object for tracking context cycles.
:param load_document(url): the document loader.
:param base: the base URL to resolve relative URLs against.
:return: the result.
"""
if len(cycles) > MAX_CONTEXT_URLS:
raise JsonLdError(
'Maximum number of @context URLs exceeded.',
'jsonld.ContextUrlError', {'max': MAX_CONTEXT_URLS},
code='loading remote context failed')
# for tracking URLs to retrieve
urls = {}
# find all URLs in the given input
self._find_context_urls(input_, urls, replace=False, base=base)
# queue all unretrieved URLs
queue = []
for url, ctx in urls.items():
if ctx is False:
queue.append(url)
# retrieve URLs in queue
for url in queue:
# check for context URL cycle
if url in cycles:
raise JsonLdError(
'Cyclical @context URLs detected.',
'jsonld.ContextUrlError', {'url': url},
code='recursive context inclusion')
cycles_ = copy.deepcopy(cycles)
cycles_[url] = True
# retrieve URL
try:
remote_doc = load_document(url)
ctx = remote_doc['document']
except BaseException as cause:
raise JsonLdError(
'Dereferencing a URL did not result in a valid JSON-LD '
'context.',
'jsonld.ContextUrlError', {'url': url},
code='loading remote context failed', cause=cause)
# parse string context as JSON
if _is_string(ctx):
try:
ctx = json.loads(ctx)
except BaseException as cause:
raise JsonLdError(
'Could not parse JSON from URL.',
'jsonld.ParseError', {'url': url},
code='loading remote context failed', cause=cause)
# ensure ctx is an object
if not _is_object(ctx):
raise JsonLdError(
'Dereferencing a URL did not result in a valid JSON-LD '
'object.',
'jsonld.InvalidUrl', {'url': url},
code='invalid remote context')
# use empty context if no @context key is present
if '@context' not in ctx:
ctx = {'@context': {}}
else:
ctx = {'@context': ctx['@context']}
# append context URL to context if given
if remote_doc['contextUrl'] is not None:
ctx['@context'] = JsonLdProcessor.arrayify(ctx['@context'])
ctx['@context'].append(remote_doc['contextUrl'])
# recurse
self._retrieve_context_urls(ctx, cycles_, load_document, url)
urls[url] = ctx['@context']
# replace all URLs in the input
self._find_context_urls(input_, urls, replace=True, base=base)
def _get_initial_context(self, options):
"""
Gets the initial context.
:param options: the options to use.
[base] the document base IRI.
:return: the initial context.
"""
return {
'@base': options['base'],
'mappings': {},
'inverse': None
}
def _get_inverse_context(self, active_ctx):
"""
Generates an inverse context for use in the compaction algorithm, if
not already generated for the given active context.
:param active_ctx: the active context to use.
:return: the inverse context.
"""
# inverse context already generated
if active_ctx['inverse']:
return active_ctx['inverse']
inverse = active_ctx['inverse'] = {}
# handle default language
default_language = active_ctx.get('@language', '@none')
# create term selections for each mapping in the context, ordered by
# shortest and then lexicographically least
for term, mapping in sorted(
active_ctx['mappings'].items(),
key=cmp_to_key(_compare_shortest_least)):
if mapping is None:
continue
# add term selection where it applies
container = mapping.get('@container', '@none')
# iterate over every IRI in the mapping
iris = JsonLdProcessor.arrayify(mapping['@id'])
for iri in iris:
container_map = inverse.setdefault(iri, {})
entry = container_map.setdefault(
container, {'@language': {}, '@type': {}})
# term is preferred for values using @reverse
if mapping['reverse']:
entry['@type'].setdefault('@reverse', term)
# term is preferred for values using specific type
elif '@type' in mapping:
entry['@type'].setdefault(mapping['@type'], term)
# term is preferred for values using specific language
elif '@language' in mapping:
language = mapping['@language']
if language is None:
language = '@null'
entry['@language'].setdefault(language, term)
# term is preferred for values w/default language or not type
# and no language
else:
# add an entry for the default language
entry['@language'].setdefault(default_language, term)
# add entries for no type and no language
entry['@type'].setdefault('@none', term)
entry['@language'].setdefault('@none', term)
return inverse
def _clone_active_context(self, active_ctx):
"""
Clones an active context, creating a child active context.
:param active_ctx: the active context to clone.
:return: a clone (child) of the active context.
"""
child = {
'@base': active_ctx['@base'],
'mappings': copy.deepcopy(active_ctx['mappings']),
'inverse': None
}
if '@language' in active_ctx:
child['@language'] = active_ctx['@language']
if '@vocab' in active_ctx:
child['@vocab'] = active_ctx['@vocab']
return child
# register the N-Quads RDF parser
register_rdf_parser('application/nquads', JsonLdProcessor.parse_nquads)
class JsonLdError(Exception):
"""
Base class for JSON-LD errors.
"""
def __init__(self, message, type_, details=None, code=None, cause=None):
Exception.__init__(self, message)
self.type = type_
self.details = details
self.code = code
self.cause = cause
self.causeTrace = traceback.extract_tb(*sys.exc_info()[2:])
def __str__(self):
if not hasattr(self, 'message'):
return 'Unknown exception'
rval = repr(self.message)
rval += '\nType: ' + self.type
if self.code:
rval += '\nCode: ' + self.code
if self.details:
rval += '\nDetails: ' + repr(self.details)
if self.cause:
rval += '\nCause: ' + str(self.cause)
rval += ''.join(traceback.format_list(self.causeTrace))
return rval
class UniqueNamer(object):
"""
A UniqueNamer issues unique names, keeping track of any previously issued
names.
"""
def __init__(self, prefix):
"""
Initializes a new UniqueNamer.
:param prefix: the prefix to use ('<prefix><counter>').
"""
self.prefix = prefix
self.counter = 0
self.existing = {}
self.order = []
"""
Gets the new name for the given old name, where if no old name is
given a new name will be generated.
:param [old_name]: the old name to get the new name for.
:return: the new name.
"""
def get_name(self, old_name=None):
# return existing old name
if old_name and old_name in self.existing:
return self.existing[old_name]
# get next name
name = self.prefix + str(self.counter)
self.counter += 1
# save mapping
if old_name is not None:
self.existing[old_name] = name
self.order.append(old_name)
return name
def is_named(self, old_name):
"""
Returns True if the given old name has already been assigned a new
name.
:param old_name: the old name to check.
:return: True if the old name has been assigned a new name, False if
not.
"""
return old_name in self.existing
def permutations(elements):
"""
Generates all of the possible permutations for the given list of elements.
:param elements: the list of elements to permutate.
"""
# begin with sorted elements
elements.sort()
# initialize directional info for permutation algorithm
left = {}
for v in elements:
left[v] = True
length = len(elements)
last = length - 1
while True:
yield elements
# Calculate the next permutation using the Steinhaus-Johnson-Trotter
# permutation algorithm.
# get largest mobile element k
# (mobile: element is greater than the one it is looking at)
k, pos = None, 0
for i in range(length):
e = elements[i]
is_left = left[e]
if ((k is None or e > k) and
((is_left and i > 0 and e > elements[i - 1]) or
(not is_left and i < last and e > elements[i + 1]))):
k, pos = e, i
# no more permutations
if k is None:
raise StopIteration
# swap k and the element it is looking at
swap = pos - 1 if left[k] else pos + 1
elements[pos], elements[swap] = elements[swap], k
# reverse the direction of all elements larger than k
for i in range(length):
if elements[i] > k:
left[elements[i]] = not left[elements[i]]
def _compare_shortest_least(a, b):
"""
Compares two strings first based on length and then lexicographically.
:param a: the first string.
:param b: the second string.
:return: -1 if a < b, 1 if a > b, 0 if a == b.
"""
rval = cmp(len(a), len(b))
if rval == 0:
rval = cmp(a, b)
return rval
def _is_keyword(v):
"""
Returns whether or not the given value is a keyword.
:param v: the value to check.
:return: True if the value is a keyword, False if not.
"""
if not _is_string(v):
return False
return v in KEYWORDS
def _is_object(v):
"""
Returns True if the given value is an Object.
:param v: the value to check.
:return: True if the value is an Object, False if not.
"""
return isinstance(v, dict)
def _is_empty_object(v):
"""
Returns True if the given value is an empty Object.
:param v: the value to check.
:return: True if the value is an empty Object, False if not.
"""
return _is_object(v) and len(v) == 0
def _is_array(v):
"""
Returns True if the given value is an Array.
:param v: the value to check.
:return: True if the value is an Array, False if not.
"""
return isinstance(v, list)
def _is_string(v):
"""
Returns True if the given value is a String.
:param v: the value to check.
:return: True if the value is a String, False if not.
"""
return isinstance(v, basestring)
def _validate_type_value(v):
"""
Raises an exception if the given value is not a valid @type value.
:param v: the value to check.
"""
# must be a string or empty object
if (_is_string(v) or _is_empty_object(v)):
return
# must be an array
is_valid = False
if _is_array(v):
# must contain only strings
is_valid = True
for e in v:
if not _is_string(e):
is_valid = False
break
if not is_valid:
raise JsonLdError(
'Invalid JSON-LD syntax; "@type" value must a string, an array of '
'strings, or an empty object.',
'jsonld.SyntaxError', {'value': v}, code='invalid type value')
def _is_bool(v):
"""
Returns True if the given value is a Boolean.
:param v: the value to check.
:return: True if the value is a Boolean, False if not.
"""
return isinstance(v, bool)
def _is_integer(v):
"""
Returns True if the given value is an Integer.
:param v: the value to check.
:return: True if the value is an Integer, False if not.
"""
return isinstance(v, Integral)
def _is_double(v):
"""
Returns True if the given value is a Double.
:param v: the value to check.
:return: True if the value is a Double, False if not.
"""
return not isinstance(v, Integral) and isinstance(v, Real)
def _is_numeric(v):
"""
Returns True if the given value is numeric.
:param v: the value to check.
:return: True if the value is numeric, False if not.
"""
try:
float(v)
return True
except ValueError:
return False
def _is_subject(v):
"""
Returns True if the given value is a subject with properties.
:param v: the value to check.
:return: True if the value is a subject with properties, False if not.
"""
# Note: A value is a subject if all of these hold True:
# 1. It is an Object.
# 2. It is not a @value, @set, or @list.
# 3. It has more than 1 key OR any existing key is not @id.
rval = False
if (_is_object(v) and
'@value' not in v and '@set' not in v and '@list' not in v):
rval = len(v) > 1 or '@id' not in v
return rval
def _is_subject_reference(v):
"""
Returns True if the given value is a subject reference.
:param v: the value to check.
:return: True if the value is a subject reference, False if not.
"""
# Note: A value is a subject reference if all of these hold True:
# 1. It is an Object.
# 2. It has a single key: @id.
return (_is_object(v) and len(v) == 1 and '@id' in v)
def _is_value(v):
"""
Returns True if the given value is a @value.
:param v: the value to check.
:return: True if the value is a @value, False if not.
"""
# Note: A value is a @value if all of these hold True:
# 1. It is an Object.
# 2. It has the @value property.
return _is_object(v) and '@value' in v
def _is_list(v):
"""
Returns True if the given value is a @list.
:param v: the value to check.
:return: True if the value is a @list, False if not.
"""
# Note: A value is a @list if all of these hold True:
# 1. It is an Object.
# 2. It has the @list property.
return _is_object(v) and '@list' in v
def _is_bnode(v):
"""
Returns True if the given value is a blank node.
:param v: the value to check.
:return: True if the value is a blank node, False if not.
"""
# Note: A value is a blank node if all of these hold True:
# 1. It is an Object.
# 2. If it has an @id key its value begins with '_:'.
# 3. It has no keys OR is not a @value, @set, or @list.
rval = False
if _is_object(v):
if '@id' in v:
rval = v['@id'].startswith('_:')
else:
rval = (len(v) == 0 or not
('@value' in v or '@set' in v or '@list' in v))
return rval
def _is_absolute_iri(v):
"""
Returns True if the given value is an absolute IRI, False if not.
:param v: the value to check.
:return: True if the value is an absolute IRI, False if not.
"""
return ':' in v
class ActiveContextCache(object):
"""
An ActiveContextCache caches active contexts so they can be reused without
the overhead of recomputing them.
"""
def __init__(self, size: int = 100):
self.order = deque()
self.cache = {}
self.size = size
def get(self, active_ctx, local_ctx):
key1 = json.dumps(active_ctx)
key2 = json.dumps(local_ctx)
return self.cache.get(key1, {}).get(key2)
def set(self, active_ctx, local_ctx, result):
if len(self.order) == self.size:
entry = self.order.popleft()
del self.cache[entry['activeCtx']][entry['localCtx']]
key1 = json.dumps(active_ctx)
key2 = json.dumps(local_ctx)
self.order.append({'activeCtx': key1, 'localCtx': key2})
self.cache.setdefault(key1, {})[key2] = json.loads(json.dumps(result))
class VerifiedHTTPSConnection(HTTPSConnection):
"""
Used to verify SSL certificates when resolving URLs.
Taken from: http://thejosephturner.com/blog/2011/03/19/https-\
certificate-verification-in-python-with-urllib2/
"""
def connect(self):
global _trust_root_certificates
# overrides the version in httplib to do certificate verification
sock = socket.create_connection((self.host, self.port), self.timeout)
if self._tunnel_host:
self.sock = sock
self._tunnel()
# wrap the socket using verification with trusted_root_certs
self.sock = ssl.wrap_socket(sock,
self.key_file,
self.cert_file,
cert_reqs=ssl.CERT_REQUIRED,
ca_certs=_trust_root_certificates)
class VerifiedHTTPSHandler(HTTPSHandler):
"""
Wraps urllib2 HTTPS connections enabling SSL certificate verification.
"""
def __init__(self, connection_class=VerifiedHTTPSConnection):
self.specialized_conn_class = connection_class
HTTPSHandler.__init__(self)
def https_open(self, req):
return self.do_open(self.specialized_conn_class, req)
# the path to the system's default trusted root SSL certificates
_trust_root_certificates = None
_possible_trust_root_certificates = [
'/etc/ssl/certs/ca-certificates.crt',
'~/Library/OpenSSL/certs/ca-certificates.crt',
'/System/Library/OpenSSL/certs/ca-certificates.crt',
]
for path in _possible_trust_root_certificates:
path = os.path.expanduser(path)
if os.path.exists(path):
_trust_root_certificates = path
break
# FIXME: warn if not found? MacOS X uses keychain vs file.
# Shared in-memory caches.
_cache = {
'activeCtx': ActiveContextCache()
}
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