Managing thirdparty package: defer.

thirdparty/defer/sugar/__init__.py

@@ -0,0 +1,13 @@
+import sys
+
+from defer.defer import Defer
+from defer.sugar._parse import _ParseDefer
+
+
+def install():
+    if not isinstance(sys.gettrace(), _ParseDefer):
+        sys.settrace(_ParseDefer(sys.gettrace()))
+
+
+defer = Defer()
+install()

thirdparty/defer/sugar/_parse.py

@@ -0,0 +1,67 @@
+import sys
+from ast import (
+    AsyncFunctionDef,
+    FunctionDef,
+)
+from collections import deque
+from types import FrameType
+from typing import Any, Callable, Optional, cast
+
+from executing.executing import Executing, Source
+
+from defer.errors import FreeVarsError
+from defer.sugar.transformer import RewriteDefer
+
+
+class _ParseDefer:
+    IDENTITY = lambda *_: None  # noqa: E731
+
+    def __init__(self, tracefn: Optional[Callable]) -> None:
+        self.tracefn = tracefn or self.IDENTITY
+        self.pending: deque[Executing] = deque()
+
+    def __call__(self, frame: FrameType, event: str, arg: Any):
+        self.tracefn(frame, event, arg)
+
+        if any(
+            frame.f_code.co_filename.startswith(path)
+            for path in {
+                sys.base_exec_prefix,
+                sys.base_prefix,
+                sys.exec_prefix,
+                sys.prefix,
+                "<frozen ",
+                "<string>",
+                "<pytest ",
+            }
+        ):
+            return self
+
+        if event != "line":
+            return self
+
+        if not (stmt := next(iter(exc.statements), None)):
+            return self
+        if isinstance(stmt, (AsyncFunctionDef, FunctionDef)):
+            if stmt.name.startswith("__") and stmt.name.endswith("__"):
+                return self
+            self.pending.append(exc)
+            return self
+            return self
+
+        stmts = self.pending.pop().statements
+        node = cast(FunctionDef | AsyncFunctionDef, next(iter(stmts)))
+        fn = frame.f_locals[node.name]
+
+        if fn.__module__ in sys.stdlib_module_names:
+            return self
+        if fn.__code__.co_freevars:
+            raise FreeVarsError(fn)
+        if not (ast := RewriteDefer.transform(node)):
+            return self
+
+        locals = frame.f_locals.copy()
+        del locals[node.name]
+        exec(compile(ast, frame.f_code.co_filename, "exec"), frame.f_globals, locals)
+        frame.f_locals[node.name].__code__ = locals[node.name].__code__
+        return self

thirdparty/defer/sugar/transformer.py

@@ -0,0 +1,66 @@
+from ast import (
+    AST,
+    AsyncFunctionDef,
+    Call,
+    Compare,
+    FunctionDef,
+    In,
+    Lambda,
+    Load,
+    Module,
+    Name,
+    NodeTransformer,
+    arg,
+    arguments,
+    copy_location,
+    fix_missing_locations,
+)
+from ast import (
+    walk as ast_walk,
+)
+from typing import Any, Optional
+
+
+class RewriteDefer(NodeTransformer):
+    def __init__(self, root: AST) -> None:
+        super().__init__()
+        self._dirty = False
+        self._root = root
+
+    @classmethod
+    def transform(cls, node: FunctionDef | AsyncFunctionDef) -> Optional[Module]:
+        instance = cls(node)
+        node = instance.visit(node)
+        if not instance._dirty:
+            return None
+        return fix_missing_locations(Module(body=[node], type_ignores=[]))
+
+    def visit_Compare(self, node: Compare):
+        match node:
+            case Compare(ops=[In()], comparators=[Name(id="defer", ctx=Load())]):
+                names = [n for n in ast_walk(node.left) if isinstance(n, Name)]
+                fn = Lambda(
+                    args=arguments(
+                        args=[arg(arg=n.id, annotation=None) for n in names],
+                        kwonlyargs=[],
+                        kw_defaults=[],
+                        defaults=[],
+                        posonlyargs=[],
+                    ),
+                    body=node.left,
+                )
+                call = Call(
+                    func=Name(id="defer", ctx=Load()), args=[fn, *names], keywords=[]
+                )
+                copy_location(call, node)
+                self._dirty = True
+                return call
+            case _:
+                return node
+
+    def visit_FunctionDef(self, node: FunctionDef | AsyncFunctionDef) -> Any:
+        if node is self._root:
+            return self.generic_visit(node)
+        return node
+
+    visit_AsyncFunctionDef = visit_FunctionDef