# sql/_py_util.py
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# Copyright (C) 2005-2023 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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from __future__ import annotations
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import typing
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from typing import Any
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from typing import Dict
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from typing import Tuple
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from typing import Union
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from ..util.typing import Literal
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if typing.TYPE_CHECKING:
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from .cache_key import CacheConst
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class prefix_anon_map(Dict[str, str]):
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"""A map that creates new keys for missing key access.
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Considers keys of the form "<ident> <name>" to produce
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new symbols "<name>_<index>", where "index" is an incrementing integer
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corresponding to <name>.
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Inlines the approach taken by :class:`sqlalchemy.util.PopulateDict` which
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is otherwise usually used for this type of operation.
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"""
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def __missing__(self, key: str) -> str:
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(ident, derived) = key.split(" ", 1)
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anonymous_counter = self.get(derived, 1)
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self[derived] = anonymous_counter + 1 # type: ignore
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value = f"{derived}_{anonymous_counter}"
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self[key] = value
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return value
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class cache_anon_map(
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Dict[Union[int, "Literal[CacheConst.NO_CACHE]"], Union[Literal[True], str]]
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):
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"""A map that creates new keys for missing key access.
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Produces an incrementing sequence given a series of unique keys.
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This is similar to the compiler prefix_anon_map class although simpler.
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Inlines the approach taken by :class:`sqlalchemy.util.PopulateDict` which
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is otherwise usually used for this type of operation.
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"""
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_index = 0
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def get_anon(self, object_: Any) -> Tuple[str, bool]:
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idself = id(object_)
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if idself in self:
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s_val = self[idself]
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assert s_val is not True
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return s_val, True
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else:
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# inline of __missing__
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self[idself] = id_ = str(self._index)
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self._index += 1
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return id_, False
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def __missing__(self, key: int) -> str:
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self[key] = val = str(self._index)
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self._index += 1
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return val
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