Revert typing to Python 3.8 :(

.github/workflows/pytest-builds.yml

@@ -2,7 +2,7 @@ name: unit-tests
 
 on:
   push:
-    branches: [ master ]
+    branches: [ main ]
   pull_request:
 
 jobs:
@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
 
     steps:
     - uses: actions/checkout@v2

pylibjpeg/tools/jpegio.py

@@ -1,6 +1,7 @@
 import logging
 import os
-from typing import BinaryIO
+from pathlib import Path
+from typing import BinaryIO, Union, cast
 
 from .s10918 import parse, JPEG
 
@@ -33,16 +34,18 @@ def get_specification(fp: BinaryIO) -> str:
     )
 
 
-def jpgread(path: str | os.PathLike[str] | BinaryIO) -> JPEG:
+def jpgread(path: Union[str, os.PathLike[str], BinaryIO]) -> JPEG:
     """Return a represention of the JPEG file at `fpath`."""
     LOGGER.debug(f"Reading file: {path}")
-    if isinstance(path, str | os.PathLike[str]):
+    if not hasattr(path, "read"):
+        path = cast(str, path)
         with open(path, "rb") as fp:
             jpg_format = get_specification(fp)
             parser, jpg_class = PARSERS[jpg_format]
             meta = parser(fp)
             LOGGER.debug("File parsed successfully")
     else:
+        path = cast(BinaryIO, path)
         jpg_format = get_specification(path)
         parser, jpg_class = PARSERS[jpg_format]
         meta = parser(path)

pylibjpeg/tools/s10918/_markers.py

@@ -1,11 +1,11 @@
 """JPEG 10918 markers"""
 
-from typing import Callable
+from typing import Callable, Dict, Tuple, Union
 
 from ._parsers import APP, COM, DAC, DHT, DNL, DQT, DRI, EXP, SOF, SOS
 
 
-MARKERS: dict[int, tuple[str, str, None | Callable]] = {}
+MARKERS: Dict[int, Tuple[str, str, Union[None, Callable]]] = {}
 # JPEG reserved markers
 for _marker in range(0xFF02, 0xFFBF + 1):
     MARKERS[_marker] = ("RES", "Reserved", None)

pylibjpeg/tools/s10918/_parsers.py

@@ -51,12 +51,12 @@
 """
 
 from struct import unpack
-from typing import BinaryIO, Any, cast
+from typing import BinaryIO, Any, cast, Dict, Union, List, Tuple
 
 from pylibjpeg.tools.utils import split_byte
 
 
-def APP(fp: BinaryIO) -> dict[str, int | bytes]:
+def APP(fp: BinaryIO) -> Dict[str, Union[int, bytes]]:
     """Return a dict containing APP data.
 
     See ISO/IEC 10918-1 Section B.2.4.6.
@@ -83,7 +83,7 @@ def APP(fp: BinaryIO) -> dict[str, int | bytes]:
     return {"Lp": length, "Ap": fp.read(length - 2)}
 
 
-def COM(fp: BinaryIO) -> dict[str, int | str]:
+def COM(fp: BinaryIO) -> Dict[str, Union[int, str]]:
     """Return a dict containing COM data.
 
     See ISO/IEC 10918-1 Section B.2.4.5.
@@ -111,7 +111,7 @@ def COM(fp: BinaryIO) -> dict[str, int | str]:
     return {"Lc": length, "Cm": comment}
 
 
-def DAC(fp: BinaryIO) -> dict[str, int | list[int]]:
+def DAC(fp: BinaryIO) -> Dict[str, Union[int, List[int]]]:
     """Return a dict containing DAC segment data.
 
     See ISO/IEC 10918-1 Section B.2.4.3.
@@ -150,7 +150,7 @@ def DAC(fp: BinaryIO) -> dict[str, int | list[int]]:
     return {"La": length, "Tc": tc, "Tb": tb, "Cs": cs}
 
 
-def DHT(fp: BinaryIO) -> dict[str, int | list[int] | Any]:
+def DHT(fp: BinaryIO) -> Dict[str, Union[int, List[int], Any]]:
     """Return a dict containing DHT segment data.
 
     See ISO/IEC 10918-1 Section B.2.4.2.
@@ -182,7 +182,7 @@ def DHT(fp: BinaryIO) -> dict[str, int | list[int] | Any]:
     bytes_to_read = length - 2
 
     tc, th, li = [], [], []
-    vij: dict[tuple[int, int], dict[int, tuple[int]]] = {}
+    vij: Dict[Tuple[int, int], Dict[int, Tuple[int]]] = {}
     while bytes_to_read > 0:
         _tc, _th = split_byte(fp.read(1))
         tc.append(_tc)
@@ -209,7 +209,7 @@ def DHT(fp: BinaryIO) -> dict[str, int | list[int] | Any]:
     return {"Lh": length, "Tc": tc, "Th": th, "Li": li, "Vij": vij}
 
 
-def DNL(fp: BinaryIO) -> dict[str, int | list[int]]:
+def DNL(fp: BinaryIO) -> Dict[str, Union[int, List[int]]]:
     """Return a dict containing DNL segment data.
 
     See ISO/IEC 10918-1 Section B.2.5.
@@ -237,7 +237,7 @@ def DNL(fp: BinaryIO) -> dict[str, int | list[int]]:
     return {"Ld": length, "NL": nr_lines}
 
 
-def DQT(fp: BinaryIO) -> dict[str, int | list[int] | list[list[int]]]:
+def DQT(fp: BinaryIO) -> Dict[str, Union[int, List[int], List[List[int]]]]:
     """Return a dict containing DQT segment data.
 
     See ISO/IEC 10918-1 Section B.2.4.1.
@@ -290,7 +290,7 @@ def DQT(fp: BinaryIO) -> dict[str, int | list[int] | list[list[int]]]:
     return {"Lq": length, "Pq": pq, "Tq": tq, "Qk": qk}
 
 
-def DRI(fp: BinaryIO) -> dict[str, int]:
+def DRI(fp: BinaryIO) -> Dict[str, int]:
     """Return a dict containing DRI segment data.
 
     See ISO/IEC 10918-1 Section B.2.4.4.
@@ -315,7 +315,7 @@ def DRI(fp: BinaryIO) -> dict[str, int]:
     return {"Lr": unpack(">H", fp.read(2))[0], "Ri": unpack(">H", fp.read(2))[0]}
 
 
-def EXP(fp: BinaryIO) -> dict[str, int]:
+def EXP(fp: BinaryIO) -> Dict[str, int]:
     """Return a dict containing EXP segment data.
 
     See ISO/IEC 10918-1 Section B.3.3.
@@ -344,7 +344,7 @@ def EXP(fp: BinaryIO) -> dict[str, int]:
     return {"Le": length, "Eh": eh, "Ev": ev}
 
 
-def SOF(fp: BinaryIO) -> dict[str, int | dict[int, dict[str, int]]]:
+def SOF(fp: BinaryIO) -> Dict[str, Union[int, Dict[int, Dict[str, int]]]]:
     """Return a dict containing SOF header data.
 
     See ISO/IEC 10918-1 Section B.2.2.
@@ -405,7 +405,7 @@ def SOF(fp: BinaryIO) -> dict[str, int | dict[int, dict[str, int]]]:
     }
 
 
-def SOS(fp: BinaryIO) -> dict[str, int | list[int]]:
+def SOS(fp: BinaryIO) -> Dict[str, Union[int, List[int]]]:
     """Return a dict containing SOS header data.
 
     See ISO/IEC 10918-1 Section B.2.3.

pylibjpeg/tools/s10918/_printers.py

@@ -18,7 +18,7 @@
 """
 
 from struct import unpack
-from typing import Any, cast
+from typing import Any, cast, Tuple, Dict, Union
 
 
 ZIGZAG = [
@@ -99,7 +99,7 @@
 }
 
 
-def _print_app(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_app(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for an APP segment."""
     _, _, sub = info
 
@@ -160,7 +160,7 @@ def _print_app(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_com(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_com(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a COM segment."""
     _m, fill, sub = info
 
@@ -182,7 +182,7 @@ def _print_com(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dac(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dac(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DAC segment."""
     m_bytes, fill, sub = info
 
@@ -193,7 +193,7 @@ def _print_dac(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dhp(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dhp(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DHP segment."""
     m_bytes, fill, sub = info
 
@@ -219,7 +219,7 @@ def _print_dhp(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dht(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dht(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DHT segment."""
     m_bytes, fill, sub = info
 
@@ -248,7 +248,7 @@ def _print_dht(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dqt(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dqt(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DQT segment."""
     m_bytes, fill, sub = info
 
@@ -280,7 +280,7 @@ def _print_dqt(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dnl(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dnl(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DNL segment."""
     m_bytes, fill, sub = info
 
@@ -291,7 +291,7 @@ def _print_dnl(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_dri(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_dri(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a DRI segment."""
     m_bytes, fill, sub = info
 
@@ -302,7 +302,7 @@ def _print_dri(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_eoi(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_eoi(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for an EOI segment."""
     m_bytes, fill, sub = info
     header = f"{marker} marker at offset {offset}"
@@ -311,7 +311,7 @@ def _print_eoi(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_exp(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_exp(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for an EXP segment."""
     m_bytes, fill, sub = info
 
@@ -322,7 +322,7 @@ def _print_exp(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_sof(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_sof(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a SOF segment."""
     m_bytes, fill, sub = info
 
@@ -368,7 +368,7 @@ def _print_sof(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
     return "\n".join(ss)
 
 
-def _print_soi(marker: str, offset: int, info: tuple[int, int, dict[str, Any]]) -> str:
+def _print_soi(marker: str, offset: int, info: Tuple[int, int, Dict[str, Any]]) -> str:
     """String output for a SOI segment."""
     m_bytes, fill, sub = info
 
@@ -381,7 +381,7 @@ def _print_soi(marker: str, offset: int, info: tuple[int, int, dict[str, Any]])
 def _print_sos(
     marker: str,
     offset: int,
-    info: tuple[int, int, dict[str | tuple[str, int], Any]],
+    info: Tuple[int, int, Dict[Union[str, Tuple[str, int]], Any]],
 ) -> str:
     """String output for a SOS segment."""
     m_bytes, fill, sub = info
@@ -408,7 +408,7 @@ def _print_sos(
             ss.append(f"\n{' ENC marker at offset {key[1]}':.^63}")
             ss.append(f"\n{len(sub[key])} bytes of entropy-coded data")
         else:
-            (name, offset) = cast(tuple[str, int], key)
+            (name, offset) = cast(Tuple[str, int], key)
             ss.append(f"{offset:<7}{name}(FFD{name[-1]})")
 
     return "\n".join(ss)

pylibjpeg/tools/s10918/io.py

@@ -2,15 +2,15 @@
 
 import logging
 from struct import unpack
-from typing import BinaryIO, Any, Callable, cast
+from typing import BinaryIO, Any, Callable, cast, Dict, Tuple
 
 from ._markers import MARKERS
 
 
 LOGGER = logging.getLogger(__name__)
 
 
-def parse(fp: BinaryIO) -> dict[tuple[str, int], Any]:
+def parse(fp: BinaryIO) -> Dict[Tuple[str, int], Any]:
     """Return a JPEG but don't decode yet."""
     _fill_bytes = 0
     while fp.read(1) == b"\xff":
@@ -23,7 +23,7 @@ def parse(fp: BinaryIO) -> dict[tuple[str, int], Any]:
     if fp.read(2) != b"\xFF\xD8":
         raise ValueError("SOI marker not found")
 
-    info: dict[tuple[str, int], tuple[int, int, Any]] = {
+    info: Dict[Tuple[str, int], Tuple[int, int, Any]] = {
         ("SOI", fp.tell() - 2): (unpack(">H", b"\xFF\xD8")[0], _fill_bytes, {})
     }
 

pylibjpeg/tools/s10918/rep.py

@@ -1,4 +1,4 @@
-from typing import Any, cast
+from typing import Any, cast, Dict, Tuple, List
 
 from ._printers import PRINTERS
 
@@ -53,7 +53,7 @@ class JPEG:
 
     """
 
-    def __init__(self, meta: dict[tuple[str, int], Any]) -> None:
+    def __init__(self, meta: Dict[Tuple[str, int], Any]) -> None:
         """Initialise a new JPEG.
 
         Parameters
@@ -75,7 +75,7 @@ def columns(self) -> int:
             "marker was found"
         )
 
-    def get_keys(self, name: str) -> list[Any]:
+    def get_keys(self, name: str) -> List[Any]:
         """Return a list of keys with marker containing `name`."""
         return [mm for mm in self._keys if name in mm[0]]
 
@@ -161,12 +161,12 @@ def is_sequential(self) -> bool:
         return not self.is_hierarchical
 
     @property
-    def _keys(self) -> list[tuple[str, int]]:
+    def _keys(self) -> List[Tuple[str, int]]:
         """Return a list of the info keys, ordered by offset."""
         return sorted(self.info.keys(), key=lambda x: x[1])
 
     @property
-    def markers(self) -> list[str]:
+    def markers(self) -> List[str]:
         """Return a list of the found JPEG markers, ordered by offset."""
         return [mm[0] for mm in self._keys]
 

pylibjpeg/tools/utils.py

@@ -1,5 +1,7 @@
 """Utility functions."""
 
+from typing import Tuple
+
 
 def get_bit(byte: bytes, index: int) -> int:
     """Return the value of the bit at `index` of `byte`.
@@ -24,7 +26,7 @@ def get_bit(byte: bytes, index: int) -> int:
     return (value >> (7 - index)) & 1
 
 
-def split_byte(byte: bytes) -> tuple[int, int]:
+def split_byte(byte: bytes) -> Tuple[int, int]:
     """Return the 8-bit `byte` as two 4-bit unsigned integers.
 
     Parameters