notation3.py: don't normalize float representation (#3020)

* added n3 test to check for internal float normalization

made as a separate commit to illustrate the old broken behavior priro to
the fix in the next commit

* 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

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* style: add noqa to sfloat class

* chore: remove unused mypy type ignore

* test: refactor test_float_no_norm to use pytest parametrization

---------

Co-authored-by: Nicholas Car <[email protected]>
Co-authored-by: Edmond Chuc <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Edmond Chuc <[email protected]>

Author: 4 people

rdflib/plugins/parsers/notation3.py

@@ -384,6 +384,10 @@ def unicodeExpand(m: Match) -> str:
 langcode = re.compile(r"[a-zA-Z0-9]+(-[a-zA-Z0-9]+)*")
 
 
+class sfloat(str):  # noqa: N801
+    """don't normalize raw XSD.double string representation"""
+
+
 class SinkParser:
     def __init__(
         self,
@@ -1530,7 +1534,7 @@ 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)
@@ -1921,15 +1925,15 @@ def normalise(self, f: Formula | Graph | None, n: int) -> Literal: ...
     def normalise(self, f: Formula | Graph | None, n: Decimal) -> Literal: ...
 
     @overload
-    def normalise(self, f: Formula | Graph | None, n: float) -> Literal: ...
+    def normalise(self, f: Formula | Graph | None, n: sfloat) -> Literal: ...
 
     @overload
     def normalise(self, f: Formula | Graph | None, n: Node) -> Node: ...
 
     def normalise(
         self,
         f: Formula | Graph | None,
-        n: Union[tuple[int, str], bool, int, Decimal, float, Node, _AnyT],
+        n: Union[tuple[int, str], bool, int, Decimal, sfloat, Node, _AnyT],
     ) -> Union[URIRef, Literal, BNode, Node, _AnyT]:
         if isinstance(n, tuple):
             return URIRef(str(n[1]))
@@ -1949,7 +1953,7 @@ 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
 
@@ -1965,7 +1969,7 @@ def normalise(
         #    f.universals[n] = f.newBlankNode()
         #    return f.universals[n]
         # type error: Incompatible return value type (got "Union[int, _AnyT]", expected "Union[URIRef, Literal, BNode, _AnyT]")  [return-value]
-        return n  # type: ignore[return-value]
+        return n
 
     def intern(self, something: _AnyT) -> _AnyT:
         return something

test/test_n3.py

@@ -251,6 +251,23 @@ def test_empty_prefix(self):
             g2
         ), "Document with declared empty prefix must match default #"
 
+    @pytest.mark.parametrize(
+        "do_normalize_literal, expected_result",
+        [(True, {"1.0", "10000000000.0"}), (False, {"1e10", "1e0"})],
+    )
+    def test_float_no_norm(self, do_normalize_literal, expected_result):
+        import rdflib
+
+        original_normalize_literal = rdflib.NORMALIZE_LITERALS
+        try:
+            rdflib.NORMALIZE_LITERALS = do_normalize_literal
+            g1 = Graph()
+            g1.parse(data=":a :b 1e10, 1e0 .", format="n3")
+            values = set(str(o) for o in g1.objects())
+            assert values == expected_result
+        finally:
+            rdflib.NORMALIZE_LITERALS = original_normalize_literal
+
 
 class TestRegularExpressions:
     def test_exponents(self):