notation3.py: don't normalize float representation

fix behavior of the n3 parser family to avoid normalizing raw float
string representation which makes it impossible to roundtrip the exact
original string representation of e.g. 1e10

Author: tgbugs

rdflib/plugins/parsers/notation3.py

@@ -380,6 +380,10 @@ def unicodeExpand(m: Match) -> str:
 langcode = re.compile(r"[a-zA-Z0-9]+(-[a-zA-Z0-9]+)*")
 
 
+class sfloat(str):
+    """ don't normalize raw XSD.double string representation """
+
+
 class SinkParser:
     def __init__(
         self,
@@ -1528,7 +1532,7 @@ def nodeOrLiteral(self, argstr: str, i: int, res: MutableSequence[Any]) -> int:
                 m = exponent_syntax.match(argstr, i)
                 if m:
                     j = m.end()
-                    res.append(float(argstr[i:j]))
+                    res.append(sfloat(argstr[i:j]))
                     return j
 
                 m = decimal_syntax.match(argstr, i)
@@ -1911,7 +1915,7 @@ def makeStatement(
     def normalise(
         self,
         f: Optional[Formula],
-        n: Union[Tuple[int, str], bool, int, Decimal, float, _AnyT],
+        n: Union[Tuple[int, str], bool, int, Decimal, sfloat, _AnyT],
     ) -> Union[URIRef, Literal, BNode, _AnyT]:
         if isinstance(n, tuple):
             return URIRef(str(n[1]))
@@ -1931,7 +1935,7 @@ def normalise(
             s = Literal(value, datatype=DECIMAL_DATATYPE)
             return s
 
-        if isinstance(n, float):
+        if isinstance(n, sfloat):
             s = Literal(str(n), datatype=DOUBLE_DATATYPE)
             return s