Fix for issue1957 sparql parser percent encoded reserved chars (#1959)

Seems like [`_hexExpand`](https://github.com/RDFLib/rdflib/blob/6ed2ef48ed38679bcdafe7cae250a2ef4b315e7b/rdflib/plugins/sparql/parser.py#L230) internal SPARQL parser function inappropriately expands [percent-encoded reserved characters](https://en.wikipedia.org/wiki/Percent-encoding).

Removed it as this does not seem like it is needed.

Merged with only one review as this is fairly well tested and not a very complicated fix.

Co-authored-by: Iwan Aucamp <aucampia@gmail.com>

rdflib/plugins/sparql/parser.py

@@ -226,13 +226,6 @@ def expandCollection(terms):
 )
 
 
-def _hexExpand(match):
-    return chr(int(match.group(0)[1:], 16))
-
-
-PN_LOCAL.setParseAction(lambda x: re.sub("(%s)" % PERCENT_re, _hexExpand, x[0]))
-
-
 # [141] PNAME_LN ::= PNAME_NS PN_LOCAL
 PNAME_LN = PNAME_NS + Param("localname", PN_LOCAL.leaveWhitespace())
 

test/test_sparql/test_prefixed_name.py

@@ -0,0 +1,135 @@
+import itertools
+import logging
+from contextlib import ExitStack
+from typing import Type, Union
+
+import pyparsing
+import pytest
+from pyparsing import Optional
+
+import rdflib
+from rdflib import Graph
+from rdflib.namespace import Namespace
+from rdflib.term import URIRef
+
+RESERVED_PCHARS = [
+    "%20",
+    "%21",
+    "%23",
+    "%24",
+    "%25",
+    "%26",
+    "%27",
+    "%28",
+    "%29",
+    "%2A",
+    "%2B",
+    "%2C",
+    "%2F",
+    "%3A",
+    "%3B",
+    "%3D",
+    "%3F",
+    "%40",
+    "%5B",
+    "%5D",
+]
+
+
+@pytest.mark.parametrize(
+    "reserved_char_percent_encoded",
+    RESERVED_PCHARS,
+)
+def test_sparql_parse_reserved_char_percent_encoded(reserved_char_percent_encoded):
+    data = f"""@prefix : <https://www.example.co/reserved/language#> .
+
+<https://www.example.co/reserved/root> :_id "01G39WKRH76BGY5D3SKDHJP2SX" ;
+    :transcript{reserved_char_percent_encoded}data [ :_id "01G39WKRH7JYRX78X7FG4RCNYF" ;
+            :_key "transcript{reserved_char_percent_encoded}data" ;
+            :value "value" ;
+            :value_id "01G39WKRH7PVK1DXQHWT08DZA8" ] ."""
+
+    q = f"""PREFIX : <https://www.example.co/reserved/language#>
+    SELECT  ?o
+    WHERE {{ ?s :transcript{reserved_char_percent_encoded}data/:value ?o . }}"""
+
+    g = rdflib.Graph()
+    g.parse(data=data, format="ttl")
+    res = g.query(q)
+
+    assert list(res)[0][0] == rdflib.term.Literal("value")
+
+    assert reserved_char_percent_encoded in str(
+        rdflib.plugins.sparql.parser.parseQuery(q)
+    )
+
+
+PNAME_PREFIX = Namespace("https://example.com/test_pnames/")
+
+
+@pytest.fixture(scope="module")
+def blank_graph() -> Graph:
+    return Graph()
+
+
+@pytest.mark.parametrize(
+    ["pname_ns", "pname", "expected_result"],
+    itertools.chain(
+        [
+            ("eg", "invalid/PN_PREFIX", pyparsing.exceptions.ParseException),
+            ("", "eg:a", Exception),
+            ("", ":invalid PN_LOCAL", pyparsing.exceptions.ParseException),
+            ("", ":invalid/PN_LOCAL", pyparsing.exceptions.ParseException),
+            ("", ":a:b:c", PNAME_PREFIX["a:b:c"]),
+            ("", ":", URIRef(f"{PNAME_PREFIX}")),
+            ("", ":a", PNAME_PREFIX.a),
+            ("eg", " eg:obj ", PNAME_PREFIX.obj),
+            ("", "  :obj  ", PNAME_PREFIX.obj),
+            ("eg", " \t eg:obj \t ", PNAME_PREFIX.obj),
+            ("", " \n :obj \n ", PNAME_PREFIX.obj),
+            ("eg", "eg:", URIRef(f"{PNAME_PREFIX}")),
+            ("eg", "eg:a", PNAME_PREFIX.a),
+            ("", ":transcript%20data", PNAME_PREFIX["transcript%20data"]),
+        ],
+        (
+            ("", f":aaa{pchar}zzz", PNAME_PREFIX[f"aaa{pchar}zzz"])
+            for pchar in RESERVED_PCHARS
+        ),
+    ),
+)
+def test_pnames(
+    pname_ns: str,
+    pname: str,
+    expected_result: Union[URIRef, Type[Exception]],
+    blank_graph: Graph,
+) -> None:
+    """
+    The given pname produces the expected result.
+    """
+    catcher: Optional[pytest.ExceptionInfo[Exception]] = None
+
+    with ExitStack() as xstack:
+        if isinstance(expected_result, type) and issubclass(expected_result, Exception):
+            catcher = xstack.enter_context(pytest.raises(expected_result))
+        query_string = f"""\
+        PREFIX {pname_ns}: <{PNAME_PREFIX}>
+
+        CONSTRUCT {{
+            <example:_subject> <example:_predicate> {pname}.
+        }} WHERE {{}}
+        """
+        query_result = blank_graph.query(query_string)
+        assert query_result.type == "CONSTRUCT"
+        assert isinstance(query_result.graph, Graph)
+        triples = list(query_result.graph.triples((None, None, None)))
+        assert len(triples) == 1
+        triple = triples[0]
+        result = triple[2]
+        logging.debug("result = %s", result)
+
+    if catcher is not None:
+        assert isinstance(catcher, pytest.ExceptionInfo)
+        assert catcher.value is not None
+    else:
+        assert isinstance(expected_result, URIRef)
+        assert expected_result == result