Add Python 3.11 support to Strata Python bindings

.github/workflows/ci.yml

@@ -142,7 +142,7 @@ jobs:
       contents: read
     strategy:
       matrix:
-        python_version: [3.12, 3.13, 3.14]
+        python_version: [3.11, 3.12, 3.13, 3.14]
     steps:
     - uses: actions/checkout@v4
     - uses: actions/setup-python@v5

Tools/Python/pyproject.toml

@@ -2,7 +2,7 @@
 name = "strata"
 version = "0.0.1"
 description = 'Python support for Strata.'
-requires-python = ">= 3.12"
+requires-python = ">= 3.11"
 dependencies = [
     "amazon.ion"
 ]

Tools/Python/scripts/run_cpython_tests.sh

@@ -52,6 +52,11 @@ elif [ "$VER" == "3.12" ]; then
   expected_failures="$expected_failures;/test_lib2to3/data/bom.py"
   expected_failures="$expected_failures;/test_lib2to3/data/py2_test_grammar.py"
   expected_failures="$expected_failures;/test_lib2to3/data/crlf.py"
+elif [ "$VER" == "3.11" ]; then
+  expected_failures="/tokenizedata/bad_coding.py"
+  expected_failures="$expected_failures;/tokenizedata/bad_coding2.py"
+  expected_failures="$expected_failures;/tokenizedata/badsyntax_3131.py"
+  expected_failures="$expected_failures;/tokenizedata/badsyntax_pep3120.py"
 else
   expected_failures=""
 fi

Tools/Python/strata/base.py

@@ -10,7 +10,7 @@
 from decimal import Decimal
 import sys
 import typing
-from typing import Any, Callable, Iterable, cast
+from typing import Any, Callable, Iterable, TypeVar, Generic, Union
 
 import amazon.ion.simpleion as ion
 
@@ -113,7 +113,8 @@ def __init__(self, name: QualifiedIdent, args: tuple['SyntaxCat', ...] | None =
         self.args = () if args is None else args
 
     def strPrec(self, prec: int) -> str:
-        s = f'{str(self.name)}{"".join(' ' + a.strPrec(10) for a in self.args)}'
+        args = ''.join(' ' + a.strPrec(10) for a in self.args)
+        s = f'{str(self.name)}{args}'
         return f'({s})' if prec > 0 else s
 
     def __str__(self) -> str:
@@ -353,12 +354,14 @@ def __init__(self, value: str, *, ann = None):
     def __str__(self):
         return f'StrLit({repr(self.value)})'
 
+T = TypeVar('T', bound='Arg')
+
 @dataclass
-class OptionArg[T : 'Arg']:
-    value: T|None
+class OptionArg(Generic[T]):
+    value: Union[T, None]
     ann : Any
 
-    def __init__(self, value: T|None, *, ann = None):
+    def __init__(self, value: Union[T, None], *, ann = None):
         self.value = value
         self.ann = ann
 
@@ -372,7 +375,7 @@ def __str__(self):
             return f'Some({self.value})'
 
 @dataclass
-class Seq[T : 'Arg']:
+class Seq(Generic[T]):
     values: tuple[T, ...]
     ann : Any
 
@@ -400,8 +403,7 @@ def __init__(self, values: list['Arg'], *, ann = None):
         self.values = values
         self.ann = ann
 
-type Arg = SyntaxCat | Operation | TypeExpr | Expr | Ident \
-    | BytesLit | NumLit | DecimalLit | StrLit | OptionArg['Arg'] | Seq['Arg'] | CommaSepBy
+Arg = Union[SyntaxCat, Operation, TypeExpr, Expr, Ident, BytesLit, NumLit, DecimalLit, StrLit, OptionArg['Arg'], Seq['Arg'], CommaSepBy]
 
 strlitSym = ion_symbol("strlit")
 numSym = ion_symbol("num")
@@ -493,7 +495,7 @@ class MetadataAttr:
     def to_ion(self):
         return ion_sexp(self.ident.to_ion(), *(metadata_arg_to_ion(a) for a in self.args))
 
-type Metadata = list[MetadataAttr]
+Metadata = list[MetadataAttr]
 
 def metadata_to_ion(values):
     return [ v.to_ion() for v in values ]
@@ -531,7 +533,7 @@ def __init__(self, indent: int, args: tuple['SyntaxDefAtom', ...]):
     def to_ion(self):
         return ion_sexp(ion_symbol("indent"), self.indent, *(syntaxdef_atom_to_ion(a) for a in self.args))
 
-type SyntaxDefAtom = SyntaxDefAtomBase | str
+SyntaxDefAtom = Union[SyntaxDefAtomBase, str]
 
 def syntaxdef_atom_to_ion(atom : SyntaxDefAtom) -> object:
     if isinstance(atom, str):
@@ -846,7 +848,9 @@ def read_string(reader) -> str:
     assert isinstance(scalar, str)
     return scalar
 
-def read_list[X](reader : object, f : Callable[[object, ion.IonEvent], X] ) -> tuple[X, ...]:
+X = TypeVar('X')
+
+def read_list(reader : object, f : Callable[[object, ion.IonEvent], X] ) -> tuple[X, ...]:
     res = []
     while True:
         event = read_event(reader)
@@ -855,7 +859,7 @@ def read_list[X](reader : object, f : Callable[[object, ion.IonEvent], X] ) -> t
         v = f(reader, event)
         res.append(v)
 
-def read_sexpr[X](reader : object, f : Callable[[object, ion.IonEvent], X] ) -> tuple[X, ...]:
+def read_sexpr(reader : object, f : Callable[[object, ion.IonEvent], X] ) -> tuple[X, ...]:
     res = []
     while True:
         event = read_event(reader)

Tools/Python/strata/pythonast.py

@@ -191,7 +191,13 @@ def populate_op(name : str, op : type) -> Op:
             arg = decl.args[idx]
             cat = arg.kind
             assert isinstance(cat, SyntaxCat)
-            missing = strata.OptionArg(None)
+            # Default value depends on the category type
+            if cat.name == Init.Option.ident:
+                missing = strata.OptionArg(None)
+            elif cat.name == Init.Seq.ident:
+                missing = strata.Seq(())
+            else:
+                raise ValueError(f"Unexpected category type for missing field: {cat.name}")
             op_args.append(OpArg(None, cat, missing=missing))
 
         return Op(decl, op_args)
@@ -214,13 +220,21 @@ def populate_op(name : str, op : type) -> Op:
 new_args : list[tuple[type, str]]
 if sys.version_info >= (3, 13):
     new_args = []
-else:
-    assert sys.version_info >= (3, 12)
+elif sys.version_info >= (3, 12):
     new_args = [
         (ast.TypeVar, "default_value"),
         (ast.ParamSpec, "default_value"),
         (ast.TypeVarTuple, "default_value"),
     ]
+else:
+    # Python 3.11 - missing type_params added in 3.12 and type parameter nodes
+    new_args = [
+        (ast.FunctionDef, "type_params"),
+        (ast.AsyncFunctionDef, "type_params"),
+        (ast.ClassDef, "type_params"),
+    ]
+    # TypeVar, ParamSpec, TypeVarTuple nodes don't exist in 3.11 but are in the 3.14 dialect
+    # We need to handle them separately since we can't reference non-existent AST nodes
 
 def check_op(d : strata.Dialect, name, op : type):
     opd = getattr(d, name)
@@ -238,7 +252,8 @@ def check_op(d : strata.Dialect, name, op : type):
         assert (op, arg.name) in new_args, f"Extra field name {arg.name} in {opd.name}"
         k = arg.kind
         assert isinstance(k, SyntaxCat)
-        assert k.name == Init.Option.ident, f"Bad type for {op} {arg.name}"
+        # Extra fields can be Option (defaults to None) or Seq (defaults to empty list)
+        assert k.name == Init.Option.ident or k.name == Init.Seq.ident, f"Bad type for {op} {arg.name}: {k.name}"
         l += 1
 
 def check_ast(d : strata.Dialect):