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diff --git a/venv/lib/python3.11/site-packages/sqlalchemy/sql/visitors.py b/venv/lib/python3.11/site-packages/sqlalchemy/sql/visitors.py new file mode 100644 index 0000000..d1cd7a9 --- /dev/null +++ b/venv/lib/python3.11/site-packages/sqlalchemy/sql/visitors.py @@ -0,0 +1,1165 @@ +# sql/visitors.py +# Copyright (C) 2005-2024 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Visitor/traversal interface and library functions. + + +""" + +from __future__ import annotations + +from collections import deque +from enum import Enum +import itertools +import operator +import typing +from typing import Any +from typing import Callable +from typing import cast +from typing import ClassVar +from typing import Dict +from typing import Iterable +from typing import Iterator +from typing import List +from typing import Mapping +from typing import Optional +from typing import overload +from typing import Tuple +from typing import Type +from typing import TYPE_CHECKING +from typing import TypeVar +from typing import Union + +from .. import exc +from .. import util +from ..util import langhelpers +from ..util._has_cy import HAS_CYEXTENSION +from ..util.typing import Literal +from ..util.typing import Protocol +from ..util.typing import Self + +if TYPE_CHECKING: + from .annotation import _AnnotationDict + from .elements import ColumnElement + +if typing.TYPE_CHECKING or not HAS_CYEXTENSION: + from ._py_util import prefix_anon_map as prefix_anon_map + from ._py_util import cache_anon_map as anon_map +else: + from sqlalchemy.cyextension.util import ( # noqa: F401,E501 + prefix_anon_map as prefix_anon_map, + ) + from sqlalchemy.cyextension.util import ( # noqa: F401,E501 + cache_anon_map as anon_map, + ) + + +__all__ = [ + "iterate", + "traverse_using", + "traverse", + "cloned_traverse", + "replacement_traverse", + "Visitable", + "ExternalTraversal", + "InternalTraversal", + "anon_map", +] + + +class _CompilerDispatchType(Protocol): + def __call__(_self, self: Visitable, visitor: Any, **kw: Any) -> Any: ... + + +class Visitable: + """Base class for visitable objects. + + :class:`.Visitable` is used to implement the SQL compiler dispatch + functions. Other forms of traversal such as for cache key generation + are implemented separately using the :class:`.HasTraverseInternals` + interface. + + .. versionchanged:: 2.0 The :class:`.Visitable` class was named + :class:`.Traversible` in the 1.4 series; the name is changed back + to :class:`.Visitable` in 2.0 which is what it was prior to 1.4. + + Both names remain importable in both 1.4 and 2.0 versions. + + """ + + __slots__ = () + + __visit_name__: str + + _original_compiler_dispatch: _CompilerDispatchType + + if typing.TYPE_CHECKING: + + def _compiler_dispatch(self, visitor: Any, **kw: Any) -> str: ... + + def __init_subclass__(cls) -> None: + if "__visit_name__" in cls.__dict__: + cls._generate_compiler_dispatch() + super().__init_subclass__() + + @classmethod + def _generate_compiler_dispatch(cls) -> None: + visit_name = cls.__visit_name__ + + if "_compiler_dispatch" in cls.__dict__: + # class has a fixed _compiler_dispatch() method. + # copy it to "original" so that we can get it back if + # sqlalchemy.ext.compiles overrides it. + cls._original_compiler_dispatch = cls._compiler_dispatch + return + + if not isinstance(visit_name, str): + raise exc.InvalidRequestError( + f"__visit_name__ on class {cls.__name__} must be a string " + "at the class level" + ) + + name = "visit_%s" % visit_name + getter = operator.attrgetter(name) + + def _compiler_dispatch( + self: Visitable, visitor: Any, **kw: Any + ) -> str: + """Look for an attribute named "visit_<visit_name>" on the + visitor, and call it with the same kw params. + + """ + try: + meth = getter(visitor) + except AttributeError as err: + return visitor.visit_unsupported_compilation(self, err, **kw) # type: ignore # noqa: E501 + else: + return meth(self, **kw) # type: ignore # noqa: E501 + + cls._compiler_dispatch = ( # type: ignore + cls._original_compiler_dispatch + ) = _compiler_dispatch + + def __class_getitem__(cls, key: Any) -> Any: + # allow generic classes in py3.9+ + return cls + + +class InternalTraversal(Enum): + r"""Defines visitor symbols used for internal traversal. + + The :class:`.InternalTraversal` class is used in two ways. One is that + it can serve as the superclass for an object that implements the + various visit methods of the class. The other is that the symbols + themselves of :class:`.InternalTraversal` are used within + the ``_traverse_internals`` collection. Such as, the :class:`.Case` + object defines ``_traverse_internals`` as :: + + class Case(ColumnElement[_T]): + _traverse_internals = [ + ("value", InternalTraversal.dp_clauseelement), + ("whens", InternalTraversal.dp_clauseelement_tuples), + ("else_", InternalTraversal.dp_clauseelement), + ] + + Above, the :class:`.Case` class indicates its internal state as the + attributes named ``value``, ``whens``, and ``else_``. They each + link to an :class:`.InternalTraversal` method which indicates the type + of datastructure to which each attribute refers. + + Using the ``_traverse_internals`` structure, objects of type + :class:`.InternalTraversible` will have the following methods automatically + implemented: + + * :meth:`.HasTraverseInternals.get_children` + + * :meth:`.HasTraverseInternals._copy_internals` + + * :meth:`.HasCacheKey._gen_cache_key` + + Subclasses can also implement these methods directly, particularly for the + :meth:`.HasTraverseInternals._copy_internals` method, when special steps + are needed. + + .. versionadded:: 1.4 + + """ + + dp_has_cache_key = "HC" + """Visit a :class:`.HasCacheKey` object.""" + + dp_has_cache_key_list = "HL" + """Visit a list of :class:`.HasCacheKey` objects.""" + + dp_clauseelement = "CE" + """Visit a :class:`_expression.ClauseElement` object.""" + + dp_fromclause_canonical_column_collection = "FC" + """Visit a :class:`_expression.FromClause` object in the context of the + ``columns`` attribute. + + The column collection is "canonical", meaning it is the originally + defined location of the :class:`.ColumnClause` objects. Right now + this means that the object being visited is a + :class:`_expression.TableClause` + or :class:`_schema.Table` object only. + + """ + + dp_clauseelement_tuples = "CTS" + """Visit a list of tuples which contain :class:`_expression.ClauseElement` + objects. + + """ + + dp_clauseelement_list = "CL" + """Visit a list of :class:`_expression.ClauseElement` objects. + + """ + + dp_clauseelement_tuple = "CT" + """Visit a tuple of :class:`_expression.ClauseElement` objects. + + """ + + dp_executable_options = "EO" + + dp_with_context_options = "WC" + + dp_fromclause_ordered_set = "CO" + """Visit an ordered set of :class:`_expression.FromClause` objects. """ + + dp_string = "S" + """Visit a plain string value. + + Examples include table and column names, bound parameter keys, special + keywords such as "UNION", "UNION ALL". + + The string value is considered to be significant for cache key + generation. + + """ + + dp_string_list = "SL" + """Visit a list of strings.""" + + dp_anon_name = "AN" + """Visit a potentially "anonymized" string value. + + The string value is considered to be significant for cache key + generation. + + """ + + dp_boolean = "B" + """Visit a boolean value. + + The boolean value is considered to be significant for cache key + generation. + + """ + + dp_operator = "O" + """Visit an operator. + + The operator is a function from the :mod:`sqlalchemy.sql.operators` + module. + + The operator value is considered to be significant for cache key + generation. + + """ + + dp_type = "T" + """Visit a :class:`.TypeEngine` object + + The type object is considered to be significant for cache key + generation. + + """ + + dp_plain_dict = "PD" + """Visit a dictionary with string keys. + + The keys of the dictionary should be strings, the values should + be immutable and hashable. The dictionary is considered to be + significant for cache key generation. + + """ + + dp_dialect_options = "DO" + """Visit a dialect options structure.""" + + dp_string_clauseelement_dict = "CD" + """Visit a dictionary of string keys to :class:`_expression.ClauseElement` + objects. + + """ + + dp_string_multi_dict = "MD" + """Visit a dictionary of string keys to values which may either be + plain immutable/hashable or :class:`.HasCacheKey` objects. + + """ + + dp_annotations_key = "AK" + """Visit the _annotations_cache_key element. + + This is a dictionary of additional information about a ClauseElement + that modifies its role. It should be included when comparing or caching + objects, however generating this key is relatively expensive. Visitors + should check the "_annotations" dict for non-None first before creating + this key. + + """ + + dp_plain_obj = "PO" + """Visit a plain python object. + + The value should be immutable and hashable, such as an integer. + The value is considered to be significant for cache key generation. + + """ + + dp_named_ddl_element = "DD" + """Visit a simple named DDL element. + + The current object used by this method is the :class:`.Sequence`. + + The object is only considered to be important for cache key generation + as far as its name, but not any other aspects of it. + + """ + + dp_prefix_sequence = "PS" + """Visit the sequence represented by :class:`_expression.HasPrefixes` + or :class:`_expression.HasSuffixes`. + + """ + + dp_table_hint_list = "TH" + """Visit the ``_hints`` collection of a :class:`_expression.Select` + object. + + """ + + dp_setup_join_tuple = "SJ" + + dp_memoized_select_entities = "ME" + + dp_statement_hint_list = "SH" + """Visit the ``_statement_hints`` collection of a + :class:`_expression.Select` + object. + + """ + + dp_unknown_structure = "UK" + """Visit an unknown structure. + + """ + + dp_dml_ordered_values = "DML_OV" + """Visit the values() ordered tuple list of an + :class:`_expression.Update` object.""" + + dp_dml_values = "DML_V" + """Visit the values() dictionary of a :class:`.ValuesBase` + (e.g. Insert or Update) object. + + """ + + dp_dml_multi_values = "DML_MV" + """Visit the values() multi-valued list of dictionaries of an + :class:`_expression.Insert` object. + + """ + + dp_propagate_attrs = "PA" + """Visit the propagate attrs dict. This hardcodes to the particular + elements we care about right now.""" + + """Symbols that follow are additional symbols that are useful in + caching applications. + + Traversals for :class:`_expression.ClauseElement` objects only need to use + those symbols present in :class:`.InternalTraversal`. However, for + additional caching use cases within the ORM, symbols dealing with the + :class:`.HasCacheKey` class are added here. + + """ + + dp_ignore = "IG" + """Specify an object that should be ignored entirely. + + This currently applies function call argument caching where some + arguments should not be considered to be part of a cache key. + + """ + + dp_inspectable = "IS" + """Visit an inspectable object where the return value is a + :class:`.HasCacheKey` object.""" + + dp_multi = "M" + """Visit an object that may be a :class:`.HasCacheKey` or may be a + plain hashable object.""" + + dp_multi_list = "MT" + """Visit a tuple containing elements that may be :class:`.HasCacheKey` or + may be a plain hashable object.""" + + dp_has_cache_key_tuples = "HT" + """Visit a list of tuples which contain :class:`.HasCacheKey` + objects. + + """ + + dp_inspectable_list = "IL" + """Visit a list of inspectable objects which upon inspection are + HasCacheKey objects.""" + + +_TraverseInternalsType = List[Tuple[str, InternalTraversal]] +"""a structure that defines how a HasTraverseInternals should be +traversed. + +This structure consists of a list of (attributename, internaltraversal) +tuples, where the "attributename" refers to the name of an attribute on an +instance of the HasTraverseInternals object, and "internaltraversal" refers +to an :class:`.InternalTraversal` enumeration symbol defining what kind +of data this attribute stores, which indicates to the traverser how it should +be handled. + +""" + + +class HasTraverseInternals: + """base for classes that have a "traverse internals" element, + which defines all kinds of ways of traversing the elements of an object. + + Compared to :class:`.Visitable`, which relies upon an external visitor to + define how the object is travered (i.e. the :class:`.SQLCompiler`), the + :class:`.HasTraverseInternals` interface allows classes to define their own + traversal, that is, what attributes are accessed and in what order. + + """ + + __slots__ = () + + _traverse_internals: _TraverseInternalsType + + _is_immutable: bool = False + + @util.preload_module("sqlalchemy.sql.traversals") + def get_children( + self, *, omit_attrs: Tuple[str, ...] = (), **kw: Any + ) -> Iterable[HasTraverseInternals]: + r"""Return immediate child :class:`.visitors.HasTraverseInternals` + elements of this :class:`.visitors.HasTraverseInternals`. + + This is used for visit traversal. + + \**kw may contain flags that change the collection that is + returned, for example to return a subset of items in order to + cut down on larger traversals, or to return child items from a + different context (such as schema-level collections instead of + clause-level). + + """ + + traversals = util.preloaded.sql_traversals + + try: + traverse_internals = self._traverse_internals + except AttributeError: + # user-defined classes may not have a _traverse_internals + return [] + + dispatch = traversals._get_children.run_generated_dispatch + return itertools.chain.from_iterable( + meth(obj, **kw) + for attrname, obj, meth in dispatch( + self, traverse_internals, "_generated_get_children_traversal" + ) + if attrname not in omit_attrs and obj is not None + ) + + +class _InternalTraversalDispatchType(Protocol): + def __call__(s, self: object, visitor: HasTraversalDispatch) -> Any: ... + + +class HasTraversalDispatch: + r"""Define infrastructure for classes that perform internal traversals + + .. versionadded:: 2.0 + + """ + + __slots__ = () + + _dispatch_lookup: ClassVar[Dict[Union[InternalTraversal, str], str]] = {} + + def dispatch(self, visit_symbol: InternalTraversal) -> Callable[..., Any]: + """Given a method from :class:`.HasTraversalDispatch`, return the + corresponding method on a subclass. + + """ + name = _dispatch_lookup[visit_symbol] + return getattr(self, name, None) # type: ignore + + def run_generated_dispatch( + self, + target: object, + internal_dispatch: _TraverseInternalsType, + generate_dispatcher_name: str, + ) -> Any: + dispatcher: _InternalTraversalDispatchType + try: + dispatcher = target.__class__.__dict__[generate_dispatcher_name] + except KeyError: + # traversals.py -> _preconfigure_traversals() + # may be used to run these ahead of time, but + # is not enabled right now. + # this block will generate any remaining dispatchers. + dispatcher = self.generate_dispatch( + target.__class__, internal_dispatch, generate_dispatcher_name + ) + return dispatcher(target, self) + + def generate_dispatch( + self, + target_cls: Type[object], + internal_dispatch: _TraverseInternalsType, + generate_dispatcher_name: str, + ) -> _InternalTraversalDispatchType: + dispatcher = self._generate_dispatcher( + internal_dispatch, generate_dispatcher_name + ) + # assert isinstance(target_cls, type) + setattr(target_cls, generate_dispatcher_name, dispatcher) + return dispatcher + + def _generate_dispatcher( + self, internal_dispatch: _TraverseInternalsType, method_name: str + ) -> _InternalTraversalDispatchType: + names = [] + for attrname, visit_sym in internal_dispatch: + meth = self.dispatch(visit_sym) + if meth is not None: + visit_name = _dispatch_lookup[visit_sym] + names.append((attrname, visit_name)) + + code = ( + (" return [\n") + + ( + ", \n".join( + " (%r, self.%s, visitor.%s)" + % (attrname, attrname, visit_name) + for attrname, visit_name in names + ) + ) + + ("\n ]\n") + ) + meth_text = ("def %s(self, visitor):\n" % method_name) + code + "\n" + return cast( + _InternalTraversalDispatchType, + langhelpers._exec_code_in_env(meth_text, {}, method_name), + ) + + +ExtendedInternalTraversal = InternalTraversal + + +def _generate_traversal_dispatch() -> None: + lookup = _dispatch_lookup + + for sym in InternalTraversal: + key = sym.name + if key.startswith("dp_"): + visit_key = key.replace("dp_", "visit_") + sym_name = sym.value + assert sym_name not in lookup, sym_name + lookup[sym] = lookup[sym_name] = visit_key + + +_dispatch_lookup = HasTraversalDispatch._dispatch_lookup +_generate_traversal_dispatch() + + +class ExternallyTraversible(HasTraverseInternals, Visitable): + __slots__ = () + + _annotations: Mapping[Any, Any] = util.EMPTY_DICT + + if typing.TYPE_CHECKING: + + def _annotate(self, values: _AnnotationDict) -> Self: ... + + def get_children( + self, *, omit_attrs: Tuple[str, ...] = (), **kw: Any + ) -> Iterable[ExternallyTraversible]: ... + + def _clone(self, **kw: Any) -> Self: + """clone this element""" + raise NotImplementedError() + + def _copy_internals( + self, *, omit_attrs: Tuple[str, ...] = (), **kw: Any + ) -> None: + """Reassign internal elements to be clones of themselves. + + Called during a copy-and-traverse operation on newly + shallow-copied elements to create a deep copy. + + The given clone function should be used, which may be applying + additional transformations to the element (i.e. replacement + traversal, cloned traversal, annotations). + + """ + raise NotImplementedError() + + +_ET = TypeVar("_ET", bound=ExternallyTraversible) + +_CE = TypeVar("_CE", bound="ColumnElement[Any]") + +_TraverseCallableType = Callable[[_ET], None] + + +class _CloneCallableType(Protocol): + def __call__(self, element: _ET, **kw: Any) -> _ET: ... + + +class _TraverseTransformCallableType(Protocol[_ET]): + def __call__(self, element: _ET, **kw: Any) -> Optional[_ET]: ... + + +_ExtT = TypeVar("_ExtT", bound="ExternalTraversal") + + +class ExternalTraversal(util.MemoizedSlots): + """Base class for visitor objects which can traverse externally using + the :func:`.visitors.traverse` function. + + Direct usage of the :func:`.visitors.traverse` function is usually + preferred. + + """ + + __slots__ = ("_visitor_dict", "_next") + + __traverse_options__: Dict[str, Any] = {} + _next: Optional[ExternalTraversal] + + def traverse_single(self, obj: Visitable, **kw: Any) -> Any: + for v in self.visitor_iterator: + meth = getattr(v, "visit_%s" % obj.__visit_name__, None) + if meth: + return meth(obj, **kw) + + def iterate( + self, obj: Optional[ExternallyTraversible] + ) -> Iterator[ExternallyTraversible]: + """Traverse the given expression structure, returning an iterator + of all elements. + + """ + return iterate(obj, self.__traverse_options__) + + @overload + def traverse(self, obj: Literal[None]) -> None: ... + + @overload + def traverse( + self, obj: ExternallyTraversible + ) -> ExternallyTraversible: ... + + def traverse( + self, obj: Optional[ExternallyTraversible] + ) -> Optional[ExternallyTraversible]: + """Traverse and visit the given expression structure.""" + + return traverse(obj, self.__traverse_options__, self._visitor_dict) + + def _memoized_attr__visitor_dict( + self, + ) -> Dict[str, _TraverseCallableType[Any]]: + visitors = {} + + for name in dir(self): + if name.startswith("visit_"): + visitors[name[6:]] = getattr(self, name) + return visitors + + @property + def visitor_iterator(self) -> Iterator[ExternalTraversal]: + """Iterate through this visitor and each 'chained' visitor.""" + + v: Optional[ExternalTraversal] = self + while v: + yield v + v = getattr(v, "_next", None) + + def chain(self: _ExtT, visitor: ExternalTraversal) -> _ExtT: + """'Chain' an additional ExternalTraversal onto this ExternalTraversal + + The chained visitor will receive all visit events after this one. + + """ + tail = list(self.visitor_iterator)[-1] + tail._next = visitor + return self + + +class CloningExternalTraversal(ExternalTraversal): + """Base class for visitor objects which can traverse using + the :func:`.visitors.cloned_traverse` function. + + Direct usage of the :func:`.visitors.cloned_traverse` function is usually + preferred. + + + """ + + __slots__ = () + + def copy_and_process( + self, list_: List[ExternallyTraversible] + ) -> List[ExternallyTraversible]: + """Apply cloned traversal to the given list of elements, and return + the new list. + + """ + return [self.traverse(x) for x in list_] + + @overload + def traverse(self, obj: Literal[None]) -> None: ... + + @overload + def traverse( + self, obj: ExternallyTraversible + ) -> ExternallyTraversible: ... + + def traverse( + self, obj: Optional[ExternallyTraversible] + ) -> Optional[ExternallyTraversible]: + """Traverse and visit the given expression structure.""" + + return cloned_traverse( + obj, self.__traverse_options__, self._visitor_dict + ) + + +class ReplacingExternalTraversal(CloningExternalTraversal): + """Base class for visitor objects which can traverse using + the :func:`.visitors.replacement_traverse` function. + + Direct usage of the :func:`.visitors.replacement_traverse` function is + usually preferred. + + """ + + __slots__ = () + + def replace( + self, elem: ExternallyTraversible + ) -> Optional[ExternallyTraversible]: + """Receive pre-copied elements during a cloning traversal. + + If the method returns a new element, the element is used + instead of creating a simple copy of the element. Traversal + will halt on the newly returned element if it is re-encountered. + """ + return None + + @overload + def traverse(self, obj: Literal[None]) -> None: ... + + @overload + def traverse( + self, obj: ExternallyTraversible + ) -> ExternallyTraversible: ... + + def traverse( + self, obj: Optional[ExternallyTraversible] + ) -> Optional[ExternallyTraversible]: + """Traverse and visit the given expression structure.""" + + def replace( + element: ExternallyTraversible, + **kw: Any, + ) -> Optional[ExternallyTraversible]: + for v in self.visitor_iterator: + e = cast(ReplacingExternalTraversal, v).replace(element) + if e is not None: + return e + + return None + + return replacement_traverse(obj, self.__traverse_options__, replace) + + +# backwards compatibility +Traversible = Visitable + +ClauseVisitor = ExternalTraversal +CloningVisitor = CloningExternalTraversal +ReplacingCloningVisitor = ReplacingExternalTraversal + + +def iterate( + obj: Optional[ExternallyTraversible], + opts: Mapping[str, Any] = util.EMPTY_DICT, +) -> Iterator[ExternallyTraversible]: + r"""Traverse the given expression structure, returning an iterator. + + Traversal is configured to be breadth-first. + + The central API feature used by the :func:`.visitors.iterate` + function is the + :meth:`_expression.ClauseElement.get_children` method of + :class:`_expression.ClauseElement` objects. This method should return all + the :class:`_expression.ClauseElement` objects which are associated with a + particular :class:`_expression.ClauseElement` object. For example, a + :class:`.Case` structure will refer to a series of + :class:`_expression.ColumnElement` objects within its "whens" and "else\_" + member variables. + + :param obj: :class:`_expression.ClauseElement` structure to be traversed + + :param opts: dictionary of iteration options. This dictionary is usually + empty in modern usage. + + """ + if obj is None: + return + + yield obj + children = obj.get_children(**opts) + + if not children: + return + + stack = deque([children]) + while stack: + t_iterator = stack.popleft() + for t in t_iterator: + yield t + stack.append(t.get_children(**opts)) + + +@overload +def traverse_using( + iterator: Iterable[ExternallyTraversible], + obj: Literal[None], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> None: ... + + +@overload +def traverse_using( + iterator: Iterable[ExternallyTraversible], + obj: ExternallyTraversible, + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> ExternallyTraversible: ... + + +def traverse_using( + iterator: Iterable[ExternallyTraversible], + obj: Optional[ExternallyTraversible], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> Optional[ExternallyTraversible]: + """Visit the given expression structure using the given iterator of + objects. + + :func:`.visitors.traverse_using` is usually called internally as the result + of the :func:`.visitors.traverse` function. + + :param iterator: an iterable or sequence which will yield + :class:`_expression.ClauseElement` + structures; the iterator is assumed to be the + product of the :func:`.visitors.iterate` function. + + :param obj: the :class:`_expression.ClauseElement` + that was used as the target of the + :func:`.iterate` function. + + :param visitors: dictionary of visit functions. See :func:`.traverse` + for details on this dictionary. + + .. seealso:: + + :func:`.traverse` + + + """ + for target in iterator: + meth = visitors.get(target.__visit_name__, None) + if meth: + meth(target) + return obj + + +@overload +def traverse( + obj: Literal[None], + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> None: ... + + +@overload +def traverse( + obj: ExternallyTraversible, + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> ExternallyTraversible: ... + + +def traverse( + obj: Optional[ExternallyTraversible], + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> Optional[ExternallyTraversible]: + """Traverse and visit the given expression structure using the default + iterator. + + e.g.:: + + from sqlalchemy.sql import visitors + + stmt = select(some_table).where(some_table.c.foo == 'bar') + + def visit_bindparam(bind_param): + print("found bound value: %s" % bind_param.value) + + visitors.traverse(stmt, {}, {"bindparam": visit_bindparam}) + + The iteration of objects uses the :func:`.visitors.iterate` function, + which does a breadth-first traversal using a stack. + + :param obj: :class:`_expression.ClauseElement` structure to be traversed + + :param opts: dictionary of iteration options. This dictionary is usually + empty in modern usage. + + :param visitors: dictionary of visit functions. The dictionary should + have strings as keys, each of which would correspond to the + ``__visit_name__`` of a particular kind of SQL expression object, and + callable functions as values, each of which represents a visitor function + for that kind of object. + + """ + return traverse_using(iterate(obj, opts), obj, visitors) + + +@overload +def cloned_traverse( + obj: Literal[None], + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> None: ... + + +# a bit of controversy here, as the clone of the lead element +# *could* in theory replace with an entirely different kind of element. +# however this is really not how cloned_traverse is ever used internally +# at least. +@overload +def cloned_traverse( + obj: _ET, + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> _ET: ... + + +def cloned_traverse( + obj: Optional[ExternallyTraversible], + opts: Mapping[str, Any], + visitors: Mapping[str, _TraverseCallableType[Any]], +) -> Optional[ExternallyTraversible]: + """Clone the given expression structure, allowing modifications by + visitors for mutable objects. + + Traversal usage is the same as that of :func:`.visitors.traverse`. + The visitor functions present in the ``visitors`` dictionary may also + modify the internals of the given structure as the traversal proceeds. + + The :func:`.cloned_traverse` function does **not** provide objects that are + part of the :class:`.Immutable` interface to the visit methods (this + primarily includes :class:`.ColumnClause`, :class:`.Column`, + :class:`.TableClause` and :class:`.Table` objects). As this traversal is + only intended to allow in-place mutation of objects, :class:`.Immutable` + objects are skipped. The :meth:`.Immutable._clone` method is still called + on each object to allow for objects to replace themselves with a different + object based on a clone of their sub-internals (e.g. a + :class:`.ColumnClause` that clones its subquery to return a new + :class:`.ColumnClause`). + + .. versionchanged:: 2.0 The :func:`.cloned_traverse` function omits + objects that are part of the :class:`.Immutable` interface. + + The central API feature used by the :func:`.visitors.cloned_traverse` + and :func:`.visitors.replacement_traverse` functions, in addition to the + :meth:`_expression.ClauseElement.get_children` + function that is used to achieve + the iteration, is the :meth:`_expression.ClauseElement._copy_internals` + method. + For a :class:`_expression.ClauseElement` + structure to support cloning and replacement + traversals correctly, it needs to be able to pass a cloning function into + its internal members in order to make copies of them. + + .. seealso:: + + :func:`.visitors.traverse` + + :func:`.visitors.replacement_traverse` + + """ + + cloned: Dict[int, ExternallyTraversible] = {} + stop_on = set(opts.get("stop_on", [])) + + def deferred_copy_internals( + obj: ExternallyTraversible, + ) -> ExternallyTraversible: + return cloned_traverse(obj, opts, visitors) + + def clone(elem: ExternallyTraversible, **kw: Any) -> ExternallyTraversible: + if elem in stop_on: + return elem + else: + if id(elem) not in cloned: + if "replace" in kw: + newelem = cast( + Optional[ExternallyTraversible], kw["replace"](elem) + ) + if newelem is not None: + cloned[id(elem)] = newelem + return newelem + + # the _clone method for immutable normally returns "self". + # however, the method is still allowed to return a + # different object altogether; ColumnClause._clone() will + # based on options clone the subquery to which it is associated + # and return the new corresponding column. + cloned[id(elem)] = newelem = elem._clone(clone=clone, **kw) + newelem._copy_internals(clone=clone, **kw) + + # however, visit methods which are tasked with in-place + # mutation of the object should not get access to the immutable + # object. + if not elem._is_immutable: + meth = visitors.get(newelem.__visit_name__, None) + if meth: + meth(newelem) + return cloned[id(elem)] + + if obj is not None: + obj = clone( + obj, deferred_copy_internals=deferred_copy_internals, **opts + ) + clone = None # type: ignore[assignment] # remove gc cycles + return obj + + +@overload +def replacement_traverse( + obj: Literal[None], + opts: Mapping[str, Any], + replace: _TraverseTransformCallableType[Any], +) -> None: ... + + +@overload +def replacement_traverse( + obj: _CE, + opts: Mapping[str, Any], + replace: _TraverseTransformCallableType[Any], +) -> _CE: ... + + +@overload +def replacement_traverse( + obj: ExternallyTraversible, + opts: Mapping[str, Any], + replace: _TraverseTransformCallableType[Any], +) -> ExternallyTraversible: ... + + +def replacement_traverse( + obj: Optional[ExternallyTraversible], + opts: Mapping[str, Any], + replace: _TraverseTransformCallableType[Any], +) -> Optional[ExternallyTraversible]: + """Clone the given expression structure, allowing element + replacement by a given replacement function. + + This function is very similar to the :func:`.visitors.cloned_traverse` + function, except instead of being passed a dictionary of visitors, all + elements are unconditionally passed into the given replace function. + The replace function then has the option to return an entirely new object + which will replace the one given. If it returns ``None``, then the object + is kept in place. + + The difference in usage between :func:`.visitors.cloned_traverse` and + :func:`.visitors.replacement_traverse` is that in the former case, an + already-cloned object is passed to the visitor function, and the visitor + function can then manipulate the internal state of the object. + In the case of the latter, the visitor function should only return an + entirely different object, or do nothing. + + The use case for :func:`.visitors.replacement_traverse` is that of + replacing a FROM clause inside of a SQL structure with a different one, + as is a common use case within the ORM. + + """ + + cloned = {} + stop_on = {id(x) for x in opts.get("stop_on", [])} + + def deferred_copy_internals( + obj: ExternallyTraversible, + ) -> ExternallyTraversible: + return replacement_traverse(obj, opts, replace) + + def clone(elem: ExternallyTraversible, **kw: Any) -> ExternallyTraversible: + if ( + id(elem) in stop_on + or "no_replacement_traverse" in elem._annotations + ): + return elem + else: + newelem = replace(elem) + if newelem is not None: + stop_on.add(id(newelem)) + return newelem # type: ignore + else: + # base "already seen" on id(), not hash, so that we don't + # replace an Annotated element with its non-annotated one, and + # vice versa + id_elem = id(elem) + if id_elem not in cloned: + if "replace" in kw: + newelem = kw["replace"](elem) + if newelem is not None: + cloned[id_elem] = newelem + return newelem # type: ignore + + cloned[id_elem] = newelem = elem._clone(**kw) + newelem._copy_internals(clone=clone, **kw) + return cloned[id_elem] # type: ignore + + if obj is not None: + obj = clone( + obj, deferred_copy_internals=deferred_copy_internals, **opts + ) + clone = None # type: ignore[assignment] # remove gc cycles + return obj |