Python 3.8+ (#7)

* workflows/tests: python 3.8+

Signed-off-by: William Woodruff <[email protected]>

* rfc8785: Python 3.8 accommodations

Signed-off-by: William Woodruff <[email protected]>

* conftest: deferred annotations

Signed-off-by: William Woodruff <[email protected]>

* _impl: Union

Signed-off-by: William Woodruff <[email protected]>

* _impl: more accommodations

Signed-off-by: William Woodruff <[email protected]>

* _impl: more accommodations

Signed-off-by: William Woodruff <[email protected]>

---------

Signed-off-by: William Woodruff <[email protected]>

.github/workflows/tests.yml

@@ -11,6 +11,8 @@ jobs:
     strategy:
       matrix:
         python:
+          - "3.8"
+          - "3.9"
           - "3.10"
           - "3.11"
           - "3.12"

pyproject.toml

@@ -17,7 +17,7 @@ classifiers = [
     "Topic :: Security :: Cryptography",
 ]
 dependencies = []
-requires-python = ">=3.10"
+requires-python = ">=3.8"
 
 [project.optional-dependencies]
 doc = ["pdoc"]

src/rfc8785/_impl.py

@@ -8,10 +8,19 @@
 
 import math
 import re
+import typing
 from io import BytesIO
-from typing import IO
 
-_Value = bool | int | str | float | None | list["_Value"] | tuple["_Value"] | dict[str, "_Value"]
+_Value = typing.Union[
+    bool,
+    int,
+    str,
+    float,
+    None,
+    typing.List["_Value"],
+    typing.Tuple["_Value"],
+    typing.Dict[str, "_Value"],
+]
 
 _INT_MAX = 2**53 - 1
 _INT_MIN = -(2**53) + 1
@@ -69,7 +78,7 @@ def __init__(self, f: float) -> None:
         super().__init__(f"{f} is not representable in JCS")
 
 
-def _serialize_str(s: str, sink: IO[bytes]) -> None:
+def _serialize_str(s: str, sink: typing.IO[bytes]) -> None:
     """
     Serialize a string as a JSON string, per RFC 8785 3.2.2.2.
     """
@@ -87,7 +96,7 @@ def _replace(match: re.Match) -> str:
     sink.write(b'"')
 
 
-def _serialize_float(f: float, sink: IO[bytes]) -> None:
+def _serialize_float(f: float, sink: typing.IO[bytes]) -> None:
     """
     Serialize a floating point number to a stable string format, as
     defined in ECMA 262 7.1.12.1 and amended by RFC 8785 3.2.2.3.
@@ -178,63 +187,63 @@ def dumps(obj: _Value) -> bytes:
     return sink.getvalue()
 
 
-def dump(obj: _Value, sink: IO[bytes]) -> None:
+def dump(obj: _Value, sink: typing.IO[bytes]) -> None:
     """
     Perform JCS serialization of `obj` into `sink`.
     """
-    match obj:
-        case bool():
-            if obj is True:
-                sink.write(b"true")
-            else:
-                sink.write(b"false")
-        case int():
-            # Annoyance: int can be subclassed by types like IntEnum,
-            # which then break or change `int.__str__`. Rather than plugging
-            # these individually, we coerce back to `int`.
-            obj = int(obj)
-
-            if obj < _INT_MIN or obj > _INT_MAX:
-                raise IntegerDomainError(obj)
-            sink.write(str(obj).encode("utf-8"))
-        case str():
-            _serialize_str(obj, sink)
-        case float():
-            _serialize_float(obj, sink)
-        case None:
-            sink.write(b"null")
-        case list() | tuple():
-            if not obj:
-                # Optimization for empty lists.
-                sink.write(b"[]")
-                return
-
-            sink.write(b"[")
-            for idx, elem in enumerate(obj):
-                if idx > 0:
-                    sink.write(b",")
-                dump(elem, sink)
-            sink.write(b"]")
-        case dict():
-            if not obj:
-                # Optimization for empty dicts.
-                sink.write(b"{}")
-                return
-
-            # RFC 8785 3.2.3: Objects are sorted by key; keys are ordered
-            # by their UTF-16 encoding. The spec isn't clear about which endianness,
-            # but the examples imply that the big endian encoding is used.
-            obj_sorted = sorted(obj.items(), key=lambda kv: kv[0].encode("utf-16be"))
-
-            sink.write(b"{")
-            for idx, (key, value) in enumerate(obj_sorted):
-                if idx > 0:
-                    sink.write(b",")
-
-                _serialize_str(key, sink)
-                sink.write(b":")
-                dump(value, sink)
-
-            sink.write(b"}")
-        case _:
-            raise CanonicalizationError(f"unsupported type: {type(obj)}")
+
+    if obj is None:
+        sink.write(b"null")
+    elif isinstance(obj, bool):
+        if obj is True:
+            sink.write(b"true")
+        else:
+            sink.write(b"false")
+    elif isinstance(obj, int):
+        # Annoyance: int can be subclassed by types like IntEnum,
+        # which then break or change `int.__str__`. Rather than plugging
+        # these individually, we coerce back to `int`.
+        obj = int(obj)
+
+        if obj < _INT_MIN or obj > _INT_MAX:
+            raise IntegerDomainError(obj)
+        sink.write(str(obj).encode("utf-8"))
+    elif isinstance(obj, str):
+        _serialize_str(obj, sink)
+    elif isinstance(obj, float):
+        _serialize_float(obj, sink)
+    elif isinstance(obj, (list, tuple)):
+        if not obj:
+            # Optimization for empty lists.
+            sink.write(b"[]")
+            return
+
+        sink.write(b"[")
+        for idx, elem in enumerate(obj):
+            if idx > 0:
+                sink.write(b",")
+            dump(elem, sink)
+        sink.write(b"]")
+    elif isinstance(obj, dict):
+        if not obj:
+            # Optimization for empty dicts.
+            sink.write(b"{}")
+            return
+
+        # RFC 8785 3.2.3: Objects are sorted by key; keys are ordered
+        # by their UTF-16 encoding. The spec isn't clear about which endianness,
+        # but the examples imply that the big endian encoding is used.
+        obj_sorted = sorted(obj.items(), key=lambda kv: kv[0].encode("utf-16be"))
+
+        sink.write(b"{")
+        for idx, (key, value) in enumerate(obj_sorted):
+            if idx > 0:
+                sink.write(b",")
+
+            _serialize_str(key, sink)
+            sink.write(b":")
+            dump(value, sink)
+
+        sink.write(b"}")
+    else:
+        raise CanonicalizationError(f"unsupported type: {type(obj)}")

test/conftest.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from collections.abc import Callable
 from pathlib import Path