# Source code for rdflib.plugins.sparql.results.xmlresults

    import logging
    from typing import IO, Optional

    from xml.sax.saxutils import XMLGenerator
    from xml.dom import XML_NAMESPACE
    from xml.sax.xmlreader import AttributesNSImpl

    from rdflib.compat import etree

    from rdflib import Literal, URIRef, BNode, Variable
    from rdflib.query import Result, ResultParser, ResultSerializer, ResultException

    SPARQL_XML_NAMESPACE = "http://www.w3.org/2005/sparql-results#"
    RESULTS_NS_ET = "{%s}" % SPARQL_XML_NAMESPACE

    log = logging.getLogger(__name__)

    """A Parser for SPARQL results in XML:

    http://www.w3.org/TR/rdf-sparql-XMLres/

    Bits and pieces borrowed from:
    http://projects.bigasterisk.com/sparqlhttp/

    Authors: Drew Perttula, Gunnar Aastrand Grimnes
    """

    class XMLResultParser(ResultParser):
        # TODO FIXME: content_type should be a keyword only arg.
        def parse(self, source, content_type: Optional[str] = None):  # type: ignore[override]
            return XMLResult(source)

    class XMLResult(Result):
        def __init__(self, source, content_type: Optional[str] = None):

            try:
                # try use as if etree is from lxml, and if not use it as normal.
                parser = etree.XMLParser(huge_tree=True)  # type: ignore[call-arg]
                tree = etree.parse(source, parser)
            except TypeError:
                tree = etree.parse(source)

            boolean = tree.find(RESULTS_NS_ET + "boolean")
            results = tree.find(RESULTS_NS_ET + "results")

            if boolean is not None:
                type_ = "ASK"
            elif results is not None:
                type_ = "SELECT"
            else:
                raise ResultException("No RDF result-bindings or boolean answer found!")

            Result.__init__(self, type_)

            if type_ == "SELECT":
                self.bindings = []
                for result in results:  # type: ignore[union-attr]
                    r = {}
                    for binding in result:
                        r[Variable(binding.get("name"))] = parseTerm(binding[0])
                    self.bindings.append(r)

                self.vars = [
                    Variable(x.get("name"))
                    for x in tree.findall(
                        "./%shead/%svariable" % (RESULTS_NS_ET, RESULTS_NS_ET)
                    )
                ]

            else:
                self.askAnswer = boolean.text.lower().strip() == "true"  # type: ignore[union-attr]

    def parseTerm(element):
        """rdflib object (Literal, URIRef, BNode) for the given
        elementtree element"""
        tag, text = element.tag, element.text
        if tag == RESULTS_NS_ET + "literal":
            if text is None:
                text = ""
            datatype = None
            lang = None
            if element.get("datatype", None):
                datatype = URIRef(element.get("datatype"))
            elif element.get("{%s}lang" % XML_NAMESPACE, None):
                lang = element.get("{%s}lang" % XML_NAMESPACE)

            ret = Literal(text, datatype=datatype, lang=lang)

            return ret
        elif tag == RESULTS_NS_ET + "uri":
            return URIRef(text)
        elif tag == RESULTS_NS_ET + "bnode":
            return BNode(text)
        else:
            raise TypeError("unknown binding type %r" % element)

    class XMLResultSerializer(ResultSerializer):
        def __init__(self, result):
            ResultSerializer.__init__(self, result)

        def serialize(self, stream: IO, encoding: str = "utf-8", **kwargs):

            writer = SPARQLXMLWriter(stream, encoding)
            if self.result.type == "ASK":
                writer.write_header([])
                writer.write_ask(self.result.askAnswer)
            else:
                writer.write_header(self.result.vars)
                writer.write_results_header()
                for b in self.result.bindings:
                    writer.write_start_result()
                    for key, val in b.items():
                        writer.write_binding(key, val)

                    writer.write_end_result()

            writer.close()

    # TODO: Rewrite with ElementTree?
    class SPARQLXMLWriter:
        """
        Python saxutils-based SPARQL XML Writer
        """

        def __init__(self, output, encoding="utf-8"):
            writer = XMLGenerator(output, encoding)
            writer.startDocument()
            writer.startPrefixMapping("", SPARQL_XML_NAMESPACE)
            writer.startPrefixMapping("xml", XML_NAMESPACE)
            writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "sparql"), "sparql", AttributesNSImpl({}, {})
            )
            self.writer = writer
            self._output = output
            self._encoding = encoding
            self._results = False

        def write_header(self, allvarsL):
            self.writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "head"), "head", AttributesNSImpl({}, {})
            )
            for i in range(0, len(allvarsL)):
                attr_vals = {
                    (None, "name"): str(allvarsL[i]),
                }
                attr_qnames = {
                    (None, "name"): "name",
                }
                self.writer.startElementNS(
                    (SPARQL_XML_NAMESPACE, "variable"),
                    "variable",
                    AttributesNSImpl(attr_vals, attr_qnames),
                )
                self.writer.endElementNS((SPARQL_XML_NAMESPACE, "variable"), "variable")
            self.writer.endElementNS((SPARQL_XML_NAMESPACE, "head"), "head")

        def write_ask(self, val):
            self.writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "boolean"), "boolean", AttributesNSImpl({}, {})
            )
            self.writer.characters(str(val).lower())
            self.writer.endElementNS((SPARQL_XML_NAMESPACE, "boolean"), "boolean")

        def write_results_header(self):
            self.writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "results"), "results", AttributesNSImpl({}, {})
            )
            self._results = True

        def write_start_result(self):
            self.writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "result"), "result", AttributesNSImpl({}, {})
            )
            self._resultStarted = True

        def write_end_result(self):
            assert self._resultStarted
            self.writer.endElementNS((SPARQL_XML_NAMESPACE, "result"), "result")
            self._resultStarted = False

        def write_binding(self, name, val):
            assert self._resultStarted

            attr_vals = {
                (None, "name"): str(name),
            }
            attr_qnames = {
                (None, "name"): "name",
            }
            self.writer.startElementNS(
                (SPARQL_XML_NAMESPACE, "binding"),
                "binding",
                AttributesNSImpl(attr_vals, attr_qnames),
            )

            if isinstance(val, URIRef):
                self.writer.startElementNS(
                    (SPARQL_XML_NAMESPACE, "uri"), "uri", AttributesNSImpl({}, {})
                )
                self.writer.characters(val)
                self.writer.endElementNS((SPARQL_XML_NAMESPACE, "uri"), "uri")
            elif isinstance(val, BNode):
                self.writer.startElementNS(
                    (SPARQL_XML_NAMESPACE, "bnode"), "bnode", AttributesNSImpl({}, {})
                )
                self.writer.characters(val)
                self.writer.endElementNS((SPARQL_XML_NAMESPACE, "bnode"), "bnode")
            elif isinstance(val, Literal):
                attr_vals = {}
                attr_qnames = {}
                if val.language:
                    attr_vals[(XML_NAMESPACE, "lang")] = val.language
                    attr_qnames[(XML_NAMESPACE, "lang")] = "xml:lang"
                elif val.datatype:
                    attr_vals[(None, "datatype")] = val.datatype
                    attr_qnames[(None, "datatype")] = "datatype"

                self.writer.startElementNS(
                    (SPARQL_XML_NAMESPACE, "literal"),
                    "literal",
                    AttributesNSImpl(attr_vals, attr_qnames),
                )
                self.writer.characters(val)
                self.writer.endElementNS((SPARQL_XML_NAMESPACE, "literal"), "literal")

            else:
                raise Exception("Unsupported RDF term: %s" % val)

            self.writer.endElementNS((SPARQL_XML_NAMESPACE, "binding"), "binding")

        def close(self):
            if self._results:
                self.writer.endElementNS((SPARQL_XML_NAMESPACE, "results"), "results")
            self.writer.endElementNS((SPARQL_XML_NAMESPACE, "sparql"), "sparql")
            self.writer.endDocument()