Merge pull request #13326 from Carreau/clean-ast-asyncify

Remove pre-3.8 code path

IPython/core/async_helpers.py

@@ -12,13 +12,10 b' Python semantics.'
 
 
 import ast
-import sys
 import inspect
-from textwrap import dedent, indent
 
 
 class _AsyncIORunner:
-
     def __call__(self, coro):
         """
         Handler for asyncio autoawait
@@ -28,7 +25,8 b' class _AsyncIORunner:'
         return asyncio.get_event_loop_policy().get_event_loop().run_until_complete(coro)
 
     def __str__(self):
-        return 'asyncio'
+        return "asyncio"
+
 
 _asyncio_runner = _AsyncIORunner()
 
@@ -74,69 +72,6 b' def _pseudo_sync_runner(coro):'
         )
 
 
-def _asyncify(code: str) -> str:
-    """wrap code in async def definition.
-
-    And setup a bit of context to run it later.
-    """
-    res = dedent(
-        """
-    async def __wrapper__():
-        try:
-    {usercode}
-        finally:
-            locals()
-    """
-    ).format(usercode=indent(code, " " * 8))
-    return res
-
-
-class _AsyncSyntaxErrorVisitor(ast.NodeVisitor):
-    """
-    Find syntax errors that would be an error in an async repl, but because
-    the implementation involves wrapping the repl in an async function, it
-    is erroneously allowed (e.g. yield or return at the top level)
-    """
-    def __init__(self):
-        if sys.version_info >= (3,8):
-            raise ValueError('DEPRECATED in Python 3.8+')
-        self.depth = 0
-        super().__init__()
-
-    def generic_visit(self, node):
-        func_types = (ast.FunctionDef, ast.AsyncFunctionDef)
-        invalid_types_by_depth = {
-            0: (ast.Return, ast.Yield, ast.YieldFrom),
-            1: (ast.Nonlocal,)
-        }
-
-        should_traverse = self.depth < max(invalid_types_by_depth.keys())
-        if isinstance(node, func_types) and should_traverse:
-            self.depth += 1
-            super().generic_visit(node)
-            self.depth -= 1
-        elif isinstance(node, invalid_types_by_depth[self.depth]):
-            raise SyntaxError()
-        else:
-            super().generic_visit(node)
-
-
-def _async_parse_cell(cell: str) -> ast.AST:
-    """
-    This is a compatibility shim for pre-3.7 when async outside of a function
-    is a syntax error at the parse stage.
-
-    It will return an abstract syntax tree parsed as if async and await outside
-    of a function were not a syntax error.
-    """
-    if sys.version_info < (3, 7):
-        # Prior to 3.7 you need to asyncify before parse
-        wrapped_parse_tree = ast.parse(_asyncify(cell))
-        return wrapped_parse_tree.body[0].body[0]
-    else:
-        return ast.parse(cell)
-
-
 def _should_be_async(cell: str) -> bool:
     """Detect if a block of code need to be wrapped in an `async def`
 
@@ -148,25 +83,10 b' def _should_be_async(cell: str) -> bool:'
     Not handled yet: If the block of code has a return statement as the top
     level, it will be seen as async. This is a know limitation.
     """
-    if sys.version_info > (3, 8):
-        try:
-            code = compile(cell, "<>", "exec", flags=getattr(ast,'PyCF_ALLOW_TOP_LEVEL_AWAIT', 0x0))
-            return inspect.CO_COROUTINE & code.co_flags == inspect.CO_COROUTINE
-        except (SyntaxError, MemoryError):
-            return False
     try:
-        # we can't limit ourself to ast.parse, as it __accepts__ to parse on
-        # 3.7+, but just does not _compile_
-        code = compile(cell, "<>", "exec")
+        code = compile(
+            cell, "<>", "exec", flags=getattr(ast, "PyCF_ALLOW_TOP_LEVEL_AWAIT", 0x0)
+        )
+        return inspect.CO_COROUTINE & code.co_flags == inspect.CO_COROUTINE
     except (SyntaxError, MemoryError):
-        try:
-            parse_tree = _async_parse_cell(cell)
-
-            # Raise a SyntaxError if there are top-level return or yields
-            v = _AsyncSyntaxErrorVisitor()
-            v.visit(parse_tree)
-
-        except (SyntaxError, MemoryError):
-            return False
-        return True
-    return False
+        return False