Source code for rdflib.plugins.parsers.hext

"""
This is a rdflib plugin for parsing Hextuple files, which are Newline-Delimited JSON
(ndjson) files, into Conjunctive. The store that backs the graph *must* be able to
handle contexts, i.e. multiple graphs.
"""
import json

from typing import List, Union
from rdflib.parser import Parser
from rdflib import ConjunctiveGraph, URIRef, Literal, BNode
import warnings


__all__ = ["HextuplesParser"]


[docs]class HextuplesParser(Parser): """ An RDFLib parser for Hextuples """
[docs] def __init__(self): pass
def _load_json_line(self, line: str): return [x if x != "" else None for x in json.loads(line)] def _parse_hextuple(self, cg: ConjunctiveGraph, tup: List[Union[str, None]]): # all values check # subject, predicate, value, datatype cannot be None # language and graph may be None if tup[0] is None or tup[1] is None or tup[2] is None or tup[3] is None: raise ValueError("subject, predicate, value, datatype cannot be None") # 1 - subject s: Union[URIRef, BNode] if tup[0].startswith("_"): s = BNode(value=tup[0].replace("_:", "")) else: s = URIRef(tup[0]) # 2 - predicate p = URIRef(tup[1]) # 3 - value o: Union[URIRef, BNode, Literal] if tup[3] == "globalId": o = URIRef(tup[2]) elif tup[3] == "localId": o = BNode(value=tup[2].replace("_:", "")) else: # literal if tup[4] is None: o = Literal(tup[2], datatype=URIRef(tup[3])) else: o = Literal(tup[2], lang=tup[4]) # 6 - context if tup[5] is not None: c = URIRef(tup[5]) cg.add((s, p, o, c)) else: cg.add((s, p, o))
[docs] def parse(self, source, graph, **kwargs): if kwargs.get("encoding") not in [None, "utf-8"]: warnings.warn( f"Hextuples files are always utf-8 encoded, " f"I was passed: {kwargs.get('encoding')}, " "but I'm still going to use utf-8" ) assert ( graph.store.context_aware ), "Hextuples Parser needs a context-aware store!" cg = ConjunctiveGraph(store=graph.store, identifier=graph.identifier) cg.default_context = graph # handle different source types - only file and string (data) for now if hasattr(source, "file"): with open(source.file.name) as fp: for l in fp: self._parse_hextuple(cg, self._load_json_line(l)) elif hasattr(source, "_InputSource__bytefile"): if hasattr(source._InputSource__bytefile, "wrapped"): for l in source._InputSource__bytefile.wrapped.strip().splitlines(): self._parse_hextuple(cg, self._load_json_line(l))