🐍 Fix compatibility with Python 3.8 and 3.9

CHANGELOG.rst

@@ -10,6 +10,10 @@ Changelog
   all lines now rendered with the same leading.
   This is more consistent and allows for faster layouting.
 
+**Fixed**
+
+- 🐍 Fix compatibility with Python 3.8 and 3.9
+
 0.5.0 (2023-05-07)
 ------------------
 

src/pdfje/atoms.py

@@ -1,4 +1,6 @@
 """Low-level PDF objects and operations"""
+from __future__ import annotations
+
 import abc
 import re
 from binascii import hexlify
@@ -7,7 +9,7 @@
 from itertools import accumulate, chain, repeat, starmap
 from math import isfinite
 from secrets import token_bytes
-from typing import Collection, Iterable, Iterator, Sequence
+from typing import Collection, Iterable, Iterator, Sequence, Tuple
 from zlib import compress
 
 from .common import add_slots, setattr_frozen
@@ -32,7 +34,7 @@ def write(self) -> Iterable[bytes]:
         raise NotImplementedError()
 
 
-Object = tuple[ObjectID, Atom]
+Object = Tuple[ObjectID, Atom]
 
 
 @add_slots

src/pdfje/common.py

@@ -15,7 +15,9 @@
     Mapping,
     Protocol,
     Sequence,
+    Tuple,
     TypeVar,
+    Union,
     final,
     no_type_check,
     overload,
@@ -267,9 +269,9 @@ def parse(v: SidesLike, /) -> Sides:
             raise TypeError(f"Cannot parse {v} as sides")
 
 
-SidesLike = (
-    Sides | tuple[Pt, Pt, Pt, Pt] | tuple[Pt, Pt, Pt] | tuple[Pt, Pt] | Pt
-)
+SidesLike = Union[
+    Sides, Tuple[Pt, Pt, Pt, Pt], Tuple[Pt, Pt, Pt], Tuple[Pt, Pt], Pt
+]
 
 
 @final

src/pdfje/compat.py

@@ -0,0 +1,15 @@
+"Compatibility layer for various Python versions"
+from __future__ import annotations
+
+from itertools import tee
+from typing import Iterable, Iterator, TypeVar
+
+try:
+    from itertools import pairwise
+except ImportError:
+    T = TypeVar("T")
+
+    def pairwise(i: Iterable[T]) -> Iterator[tuple[T, T]]:
+        a, b = tee(i)
+        next(b, None)
+        return zip(a, b)

src/pdfje/fonts/common.py

@@ -2,13 +2,14 @@
 
 import abc
 from dataclasses import dataclass, field
-from itertools import chain, count, pairwise
+from itertools import chain, count
 from pathlib import Path
-from typing import TYPE_CHECKING, Iterable, final
+from typing import TYPE_CHECKING, Iterable, Tuple, Union, final
 
 from .. import atoms
 from ..atoms import ASCII
 from ..common import Char, Func, Pos, Pt, add_slots, setattr_frozen
+from ..compat import pairwise
 
 FontID = bytes  # unique, internal identifier assigned to a font within a PDF
 GlyphPt = float  # length unit in glyph space
@@ -158,7 +159,7 @@ def font(self, bold: bool, italic: bool) -> BuiltinFont:
             return self.italic if italic else self.regular
 
 
-Typeface = BuiltinTypeface | TrueType
+Typeface = Union[BuiltinTypeface, TrueType]
 
 
 @final
@@ -199,8 +200,8 @@ def to_resource(self) -> atoms.Dictionary:
         )
 
 
-KerningTable = Func[tuple[Char, Char], GlyphPt]
-Kern = tuple[Pos, GlyphPt]
+KerningTable = Func[Tuple[Char, Char], GlyphPt]
+Kern = Tuple[Pos, GlyphPt]
 
 
 def kern(

src/pdfje/fonts/registry.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from dataclasses import dataclass, field
 from itertools import chain, count
 from typing import Iterable, Iterator

src/pdfje/style.py

@@ -8,8 +8,8 @@
     Generator,
     Iterator,
     Sequence,
-    TypeGuard,
     TypeVar,
+    Union,
     final,
 )
 
@@ -203,7 +203,7 @@ def setdefault(self) -> StyleFull:
     EMPTY: ClassVar[Style]
 
 
-StyleLike = Style | RGB | Typeface | HexColor
+StyleLike = Union[Style, RGB, Typeface, HexColor]
 Style.EMPTY = Style()
 
 bold = Style(bold=True)
@@ -280,8 +280,16 @@ def _fallback(a: _T | None, b: _T) -> _T:
     return b if a is None else a
 
 
-def _differs(a: _T | None, b: _T) -> TypeGuard[_T]:
-    return a is not None and a != b
+if TYPE_CHECKING:  # pragma: no cover
+    from typing import TypeGuard
+
+    def _differs(a: _T | None, b: _T) -> TypeGuard[_T]:
+        return a is not None and a != b
+
+else:
+
+    def _differs(a: _T | None, b: _T) -> bool:
+        return a is not None and a != b
 
 
 class StyledMixin:

src/pdfje/typeset/hyphens.py

@@ -1,6 +1,8 @@
 from functools import partial
-from itertools import chain, pairwise, starmap
-from typing import TYPE_CHECKING, Callable, Iterable
+from itertools import chain, starmap
+from typing import TYPE_CHECKING, Callable, Iterable, Union
+
+from ..compat import pairwise
 
 Hyphenator = Callable[[str], Iterable[str]]
 " hyphenation -> hy phen ation "
@@ -31,10 +33,10 @@ def positions(self, txt: str) -> Iterable[int]:
         from pyphen import Pyphen
     except ImportError:  # pragma: no cover
         HAS_PYPHEN = False
-        HyphenatorLike = Hyphenator | None
+        HyphenatorLike = Union[Hyphenator, None]
     else:
         HAS_PYPHEN = True
-        HyphenatorLike = Hyphenator | Pyphen | None
+        HyphenatorLike = Union[Hyphenator, Pyphen, None]
 
 
 if HAS_PYPHEN:

src/pdfje/typeset/tex.py

@@ -7,12 +7,12 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from itertools import pairwise
 from math import sqrt
 from operator import attrgetter
 from typing import Callable, Iterable, Literal, Sequence
 
 from ..common import add_slots
+from ..compat import pairwise
 
 Pos = int  # position in the list of boxes
 LineNum = int  # zero-based line number

src/pdfje/typeset/words.py

@@ -8,7 +8,7 @@
 
 import re
 from dataclasses import dataclass
-from itertools import chain, pairwise
+from itertools import chain
 from typing import Generator, Iterable, Iterator, Sequence
 
 from pdfje.atoms import Array, LiteralStr, Real
@@ -22,6 +22,7 @@
     add_slots,
     prepend,
 )
+from ..compat import pairwise
 from ..fonts.common import TEXTSPACE_TO_GLYPHSPACE, GlyphPt
 from .common import NO_OP, Chain, Command, Slug, State, Stretch
 

src/pdfje/vendor/get_kerning_pairs.py

@@ -27,6 +27,7 @@
 # - OTFKernReader takes a TTFont object as input instead of a path
 # - added a `for_font` helper method
 # - formatted with black and isort
+from __future__ import annotations
 
 from typing import Mapping
 

tests/common.py

@@ -1,10 +1,13 @@
+from __future__ import annotations
+
 from dataclasses import dataclass, field
 from functools import partial
 from typing import (
     TYPE_CHECKING,
     ClassVar,
     Collection,
     Iterable,
+    List,
     Sequence,
     TypeVar,
 )
@@ -27,7 +30,7 @@
 T = TypeVar("T")
 
 
-class eq_iter(list[T]):
+class eq_iter(List[T]):
     """Test helper for comparing iterables."""
 
     def __eq__(self, other: object) -> bool:

tests/conftest.py

@@ -22,7 +22,7 @@ def outfile(tmpdir, request) -> Path:
     return (
         base
         / "-".join(
-            [func.__module__.removeprefix("tests."), func.__qualname__]
+            [func.__module__.strip("tests."), func.__qualname__]
         ).replace(".", "-")
     ).with_suffix(".pdf")
 

tests/test_common.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import pytest
 
 from pdfje.common import RGB, XY, BranchableIterator, Sides

tests/test_document.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from itertools import cycle, islice
 from pathlib import Path
 

tests/typeset/test_common.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from dataclasses import replace
 
 from pdfje.atoms import LiteralStr, Real

tests/typeset/test_lines.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from typing import Iterable
 
 from pdfje.common import BranchableIterator, Pt

tests/typeset/test_tex.py

@@ -1,5 +1,7 @@
+from __future__ import annotations
+
 import re
-from typing import Callable, Iterator, Sequence, cast
+from typing import Callable, Iterator, Sequence, Tuple, cast
 from unittest.mock import ANY
 
 import pytest
@@ -491,6 +493,6 @@ def _into_boxes(
 
 
 WORDS, BOXES = cast(
-    tuple[tuple[str, ...], tuple[Box, ...]],
+    Tuple[Tuple[str, ...], Tuple[Box, ...]],
     zip(*_into_boxes(EXAMPLE, times_roman.regular.width)),
 )

tests/typeset/test_words.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from dataclasses import replace
 from functools import partial
 from typing import Generator, TypeVar

tox.ini

@@ -11,6 +11,8 @@ commands_pre=
 extras=
     fonts
     hyphens
+commands=
+    pytest
 
 [testenv:py311]
 commands =