text: import json
  from typing import IO, Any, Dict, Optional, TextIO, Union
  
  from rdflib.query import Result, ResultException, ResultSerializer, ResultParser
  from rdflib import Literal, URIRef, BNode, Variable
  
  
  """A Serializer for SPARQL results in JSON:
  
  http://www.w3.org/TR/rdf-sparql-json-res/
  
  Bits and pieces borrowed from:
  http://projects.bigasterisk.com/sparqlhttp/
  
  Authors: Drew Perttula, Gunnar Aastrand Grimnes
  
  """
  
  
  class JSONResultParser(ResultParser):
      def parse(self, source, content_type=None):
          inp = source.read()
          if isinstance(inp, bytes):
              inp = inp.decode("utf-8")
          return JSONResult(json.loads(inp))
  
  
  class JSONResultSerializer(ResultSerializer):
      def __init__(self, result):
          ResultSerializer.__init__(self, result)
  
      def serialize(self, stream: IO, encoding: str = None):  # type: ignore[override]
  
          res: Dict[str, Any] = {}
          if self.result.type == "ASK":
              res["head"] = {}
              res["boolean"] = self.result.askAnswer
          else:
              # select
              res["results"] = {}
              res["head"] = {}
              res["head"]["vars"] = self.result.vars
              res["results"]["bindings"] = [
                  self._bindingToJSON(x) for x in self.result.bindings
              ]
  
          r = json.dumps(res, allow_nan=False, ensure_ascii=False)
          if encoding is not None:
              stream.write(r.encode(encoding))
          else:
              stream.write(r)
  
      def _bindingToJSON(self, b):
          res = {}
          for var in b:
              j = termToJSON(self, b[var])
              if j is not None:
                  res[var] = termToJSON(self, b[var])
          return res
  
  
  class JSONResult(Result):
      def __init__(self, json):
          self.json = json
          if "boolean" in json:
              type_ = "ASK"
          elif "results" in json:
              type_ = "SELECT"
          else:
              raise ResultException("No boolean or results in json!")
  
          Result.__init__(self, type_)
  
          if type_ == "ASK":
              self.askAnswer = bool(json["boolean"])
          else:
              self.bindings = self._get_bindings()
              self.vars = [Variable(x) for x in json["head"]["vars"]]
  
      def _get_bindings(self):
          ret = []
          for row in self.json["results"]["bindings"]:
              outRow = {}
              for k, v in row.items():
                  outRow[Variable(k)] = parseJsonTerm(v)
              ret.append(outRow)
          return ret
  
  
  def parseJsonTerm(d):
      """rdflib object (Literal, URIRef, BNode) for the given json-format dict.
  
      input is like:
        { 'type': 'uri', 'value': 'http://famegame.com/2006/01/username' }
        { 'type': 'literal', 'value': 'drewp' }
      """
  
      t = d["type"]
      if t == "uri":
          return URIRef(d["value"])
      elif t == "literal":
          return Literal(d["value"], datatype=d.get("datatype"), lang=d.get("xml:lang"))
      elif t == "typed-literal":
          return Literal(d["value"], datatype=URIRef(d["datatype"]))
      elif t == "bnode":
          return BNode(d["value"])
      else:
          raise NotImplementedError("json term type %r" % t)
  
  
  def termToJSON(self, term):
      if isinstance(term, URIRef):
          return {"type": "uri", "value": str(term)}
      elif isinstance(term, Literal):
          r = {"type": "literal", "value": str(term)}
  
          if term.datatype is not None:
              r["datatype"] = str(term.datatype)
          if term.language is not None:
              r["xml:lang"] = term.language
          return r
  
      elif isinstance(term, BNode):
          return {"type": "bnode", "value": str(term)}
      elif term is None:
          return None
      else:
          raise ResultException("Unknown term type: %s (%s)" % (term, type(term)))
  