Make deepfreeze.py palatable to Python 3.7 and up

Author: gvanrossum

Tools/scripts/deepfreeze.py

@@ -7,7 +7,7 @@
 import re
 import time
 import types
-import typing
+from typing import Dict, FrozenSet, Tuple, TextIO
 
 import umarshal
 
@@ -42,13 +42,14 @@ def get_localsplus(code: types.CodeType):
 
 
 def get_localsplus_counts(code: types.CodeType,
-                          names: tuple[str, ...],
-                          kinds: bytes) -> tuple[int, int, int, int]:
+                          names: Tuple[str, ...],
+                          kinds: bytes) -> Tuple[int, int, int, int]:
     nlocals = 0
     nplaincellvars = 0
     ncellvars = 0
     nfreevars = 0
-    for name, kind in zip(names, kinds, strict=True):
+    assert len(names) == len(kinds)
+    for name, kind in zip(names, kinds):
         if kind & CO_FAST_LOCAL:
             nlocals += 1
             if kind & CO_FAST_CELL:
@@ -71,7 +72,7 @@ def get_localsplus_counts(code: types.CodeType,
 PyUnicode_4BYTE_KIND = 4
 
 
-def analyze_character_width(s: str) -> tuple[int, bool]:
+def analyze_character_width(s: str) -> Tuple[int, bool]:
     maxchar = ' '
     for c in s:
         maxchar = max(maxchar, c)
@@ -86,12 +87,17 @@ def analyze_character_width(s: str) -> tuple[int, bool]:
     return kind, ascii
 
 
+def removesuffix(base, suffix):
+    if base.endswith(suffix):
+        return base[:len(base) - len(suffix)]
+    return base
+
 class Printer:
 
-    def __init__(self, file: typing.TextIO):
+    def __init__(self, file: TextIO):
         self.level = 0
         self.file = file
-        self.cache: dict[tuple[type, object], str] = {}
+        self.cache: Dict[Tuple[type, object], str] = {}
         self.hits, self.misses = 0, 0
         self.patchups: list[str] = []
         self.write('#include "Python.h"')
@@ -231,7 +237,7 @@ def generate_code(self, name: str, code: types.CodeType) -> str:
             # otherwise MSVC doesn't like it.
             self.write(f".co_consts = {co_consts},")
             self.write(f".co_names = {co_names},")
-            self.write(f".co_firstinstr = (_Py_CODEUNIT *) {co_code.removesuffix('.ob_base.ob_base')}.ob_sval,")
+            self.write(f".co_firstinstr = (_Py_CODEUNIT *) {removesuffix(co_code, '.ob_base.ob_base')}.ob_sval,")
             self.write(f".co_exceptiontable = {co_exceptiontable},")
             self.field(code, "co_flags")
             self.write(".co_warmup = QUICKENING_INITIAL_WARMUP_VALUE,")
@@ -259,7 +265,7 @@ def generate_code(self, name: str, code: types.CodeType) -> str:
             self.write(f".co_freevars = {co_freevars},")
         return f"& {name}.ob_base"
 
-    def generate_tuple(self, name: str, t: tuple[object, ...]) -> str:
+    def generate_tuple(self, name: str, t: Tuple[object, ...]) -> str:
         items = [self.generate(f"{name}_{i}", it) for i, it in enumerate(t)]
         self.write("static")
         with self.indent():
@@ -323,7 +329,7 @@ def generate_complex(self, name: str, z: complex) -> str:
             self.write(f".cval = {{ {z.real}, {z.imag} }},")
         return f"&{name}.ob_base"
 
-    def generate_frozenset(self, name: str, fs: frozenset[object]) -> str:
+    def generate_frozenset(self, name: str, fs: FrozenSet[object]) -> str:
         ret = self.generate_tuple(name, tuple(sorted(fs)))
         self.write("// TODO: The above tuple should be a frozenset")
         return ret
@@ -336,34 +342,33 @@ def generate(self, name: str, obj: object) -> str:
             # print(f"Cache hit {key!r:.40}: {self.cache[key]!r:.40}")
             return self.cache[key]
         self.misses += 1
-        match obj:
-            case types.CodeType() | umarshal.Code() as code:
-                val = self.generate_code(name, code)
-            case tuple(t):
-                val = self.generate_tuple(name, t)
-            case str(s):
-                val = self.generate_unicode(name, s)
-            case bytes(b):
-                val = self.generate_bytes(name, b)
-            case True:
-                return "Py_True"
-            case False:
-                return "Py_False"
-            case int(i):
-                val = self.generate_int(name, i)
-            case float(x):
-                val = self.generate_float(name, x)
-            case complex() as z:
-                val = self.generate_complex(name, z)
-            case frozenset(fs):
-                val = self.generate_frozenset(name, fs)
-            case builtins.Ellipsis:
-                return "Py_Ellipsis"
-            case None:
-                return "Py_None"
-            case _:
-                raise TypeError(
-                    f"Cannot generate code for {type(obj).__name__} object")
+        if isinstance(obj, types.CodeType) or isinstance(obj, umarshal.Code):
+            val = self.generate_code(name, obj)
+        elif isinstance(obj, tuple):
+            val = self.generate_tuple(name, obj)
+        elif isinstance(obj, str):
+            val = self.generate_unicode(name, obj)
+        elif isinstance(obj, bytes):
+            val = self.generate_bytes(name, obj)
+        elif obj is True:
+            return "Py_True"
+        elif obj is False:
+            return "Py_False"
+        elif isinstance(obj, int):
+            val = self.generate_int(name, obj)
+        elif isinstance(obj, float):
+            val = self.generate_float(name, obj)
+        elif isinstance(obj, complex):
+            val = self.generate_complex(name, obj)
+        elif isinstance(obj, frozenset):
+            val = self.generate_frozenset(name, obj)
+        elif obj is builtins.Ellipsis:
+            return "Py_Ellipsis"
+        elif obj is None:
+            return "Py_None"
+        else:
+            raise TypeError(
+                f"Cannot generate code for {type(obj).__name__} object")
         # print(f"Cache store {key!r:.40}: {val!r:.40}")
         self.cache[key] = val
         return val
@@ -393,12 +398,12 @@ def decode_frozen_data(source: str) -> types.CodeType:
         del lines[0]
     while lines and re.match(FROZEN_DATA_LINE, lines[-1]) is None:
         del lines[-1]
-    values: tuple[int, ...] = ast.literal_eval("".join(lines))
+    values: Tuple[int, ...] = ast.literal_eval("".join(lines).strip())
     data = bytes(values)
     return umarshal.loads(data)
 
 
-def generate(source: str, filename: str, modname: str, file: typing.TextIO) -> None:
+def generate(source: str, filename: str, modname: str, file: TextIO) -> None:
     if is_frozen_header(source):
         code = decode_frozen_data(source)
     else:
@@ -439,7 +444,7 @@ def main() -> None:
     verbose = args.verbose
     with open(args.file, encoding="utf-8") as f:
         source = f.read()
-    modname = args.module or os.path.basename(args.file).removesuffix(".py")
+    modname = args.module or removesuffix(os.path.basename(args.file), ".py")
     output = args.output or modname + ".c"
     with open(output, "w", encoding="utf-8") as file:
         with report_time("generate"):