pep-484: sqlalchemy.sql pass one

sqlalchemy.sql will require many passes to get all
modules even gradually typed.  Will have to pick and
choose what modules can be strictly typed vs. which
can be gradual.

in this patch, emphasis is on visitors.py, cache_key.py,
annotations.py for strict typing, compiler.py is on gradual
typing but has much more structure, in particular where it
connects with the outside world.

The work within compiler.py also reached back out to
engine/cursor.py , default.py quite a bit.

References: #6810
Change-Id: I6e8a29f6013fd216e43d45091bc193f8be0368fd

1 files changed, 11 insertions, 6 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index a94590da1..a408a010a 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -19,8 +19,10 @@ from itertools import zip_longest
 import operator
 import re
 import typing
+from typing import MutableMapping
 from typing import Optional
 from typing import Sequence
+from typing import Set
 from typing import TypeVar
 
 from . import roles
@@ -36,14 +38,9 @@ from .. import util
 from ..util import HasMemoized as HasMemoized
 from ..util import hybridmethod
 from ..util import typing as compat_typing
-from ..util._has_cy import HAS_CYEXTENSION
-
-if typing.TYPE_CHECKING or not HAS_CYEXTENSION:
-    from ._py_util import prefix_anon_map  # noqa
-else:
-    from sqlalchemy.cyextension.util import prefix_anon_map  # noqa
 
 if typing.TYPE_CHECKING:
+    from .elements import ColumnElement
     from ..engine import Connection
     from ..engine import Result
     from ..engine.interfaces import _CoreMultiExecuteParams
@@ -63,6 +60,8 @@ NO_ARG = util.symbol("NO_ARG")
 # symbols, mypy reports: "error: _Fn? not callable"
 _Fn = typing.TypeVar("_Fn", bound=typing.Callable)
 
+_AmbiguousTableNameMap = MutableMapping[str, str]
+
 
 class Immutable:
     """mark a ClauseElement as 'immutable' when expressions are cloned."""
@@ -87,6 +86,10 @@ class SingletonConstant(Immutable):
 
     _is_singleton_constant = True
 
+    _singleton: SingletonConstant
+
+    proxy_set: Set[ColumnElement]
+
     def __new__(cls, *arg, **kw):
         return cls._singleton
 
@@ -519,6 +522,8 @@ class CompileState:
 
     plugins = {}
 
+    _ambiguous_table_name_map: Optional[_AmbiguousTableNameMap]
+
     @classmethod
     def create_for_statement(cls, statement, compiler, **kw):
         # factory construction.