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# sql/roles.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
from __future__ import annotations
from typing import Any
from typing import Generic
from typing import Optional
from typing import TYPE_CHECKING
from typing import TypeVar
from .. import util
from ..util.typing import Literal
if TYPE_CHECKING:
from ._typing import _PropagateAttrsType
from .elements import Label
from .selectable import _SelectIterable
from .selectable import FromClause
from .selectable import Subquery
_T = TypeVar("_T", bound=Any)
_T_co = TypeVar("_T_co", bound=Any, covariant=True)
class SQLRole:
"""Define a "role" within a SQL statement structure.
Classes within SQL Core participate within SQLRole hierarchies in order
to more accurately indicate where they may be used within SQL statements
of all types.
.. versionadded:: 1.4
"""
__slots__ = ()
allows_lambda = False
uses_inspection = False
class UsesInspection:
__slots__ = ()
_post_inspect: Literal[None] = None
uses_inspection = True
class AllowsLambdaRole:
__slots__ = ()
allows_lambda = True
class HasCacheKeyRole(SQLRole):
__slots__ = ()
_role_name = "Cacheable Core or ORM object"
class ExecutableOptionRole(SQLRole):
__slots__ = ()
_role_name = "ExecutionOption Core or ORM object"
class LiteralValueRole(SQLRole):
__slots__ = ()
_role_name = "Literal Python value"
class ColumnArgumentRole(SQLRole):
__slots__ = ()
_role_name = "Column expression"
class ColumnArgumentOrKeyRole(ColumnArgumentRole):
__slots__ = ()
_role_name = "Column expression or string key"
class StrAsPlainColumnRole(ColumnArgumentRole):
__slots__ = ()
_role_name = "Column expression or string key"
class ColumnListRole(SQLRole):
"""Elements suitable for forming comma separated lists of expressions."""
__slots__ = ()
class StringRole(SQLRole):
"""mixin indicating a role that results in strings"""
__slots__ = ()
class TruncatedLabelRole(StringRole, SQLRole):
__slots__ = ()
_role_name = "String SQL identifier"
class ColumnsClauseRole(AllowsLambdaRole, UsesInspection, ColumnListRole):
__slots__ = ()
_role_name = (
"Column expression, FROM clause, or other columns clause element"
)
@property
def _select_iterable(self) -> _SelectIterable:
raise NotImplementedError()
class TypedColumnsClauseRole(Generic[_T_co], SQLRole):
"""element-typed form of ColumnsClauseRole"""
__slots__ = ()
class LimitOffsetRole(SQLRole):
__slots__ = ()
_role_name = "LIMIT / OFFSET expression"
class ByOfRole(ColumnListRole):
__slots__ = ()
_role_name = "GROUP BY / OF / etc. expression"
class GroupByRole(AllowsLambdaRole, UsesInspection, ByOfRole):
__slots__ = ()
# note there's a special case right now where you can pass a whole
# ORM entity to group_by() and it splits out. we may not want to keep
# this around
_role_name = "GROUP BY expression"
class OrderByRole(AllowsLambdaRole, ByOfRole):
__slots__ = ()
_role_name = "ORDER BY expression"
class StructuralRole(SQLRole):
__slots__ = ()
class StatementOptionRole(StructuralRole):
__slots__ = ()
_role_name = "statement sub-expression element"
class OnClauseRole(AllowsLambdaRole, StructuralRole):
__slots__ = ()
_role_name = (
"ON clause, typically a SQL expression or "
"ORM relationship attribute"
)
class WhereHavingRole(OnClauseRole):
__slots__ = ()
_role_name = "SQL expression for WHERE/HAVING role"
class ExpressionElementRole(TypedColumnsClauseRole[_T_co]):
# note when using generics for ExpressionElementRole,
# the generic type needs to be in
# sqlalchemy.sql.coercions._impl_lookup mapping also.
# these are set up for basic types like int, bool, str, float
# right now
__slots__ = ()
_role_name = "SQL expression element"
def label(self, name: Optional[str]) -> Label[_T]:
raise NotImplementedError()
class ConstExprRole(ExpressionElementRole[_T]):
__slots__ = ()
_role_name = "Constant True/False/None expression"
class LabeledColumnExprRole(ExpressionElementRole[_T]):
__slots__ = ()
class BinaryElementRole(ExpressionElementRole[_T]):
__slots__ = ()
_role_name = "SQL expression element or literal value"
class InElementRole(SQLRole):
__slots__ = ()
_role_name = (
"IN expression list, SELECT construct, or bound parameter object"
)
class JoinTargetRole(AllowsLambdaRole, UsesInspection, StructuralRole):
__slots__ = ()
_role_name = (
"Join target, typically a FROM expression, or ORM "
"relationship attribute"
)
class FromClauseRole(ColumnsClauseRole, JoinTargetRole):
__slots__ = ()
_role_name = "FROM expression, such as a Table or alias() object"
_is_subquery = False
named_with_column: bool
class StrictFromClauseRole(FromClauseRole):
__slots__ = ()
# does not allow text() or select() objects
class AnonymizedFromClauseRole(StrictFromClauseRole):
__slots__ = ()
if TYPE_CHECKING:
def _anonymous_fromclause(
self, *, name: Optional[str] = None, flat: bool = False
) -> FromClause: ...
class ReturnsRowsRole(SQLRole):
__slots__ = ()
_role_name = (
"Row returning expression such as a SELECT, a FROM clause, or an "
"INSERT/UPDATE/DELETE with RETURNING"
)
class StatementRole(SQLRole):
__slots__ = ()
_role_name = "Executable SQL or text() construct"
if TYPE_CHECKING:
@util.memoized_property
def _propagate_attrs(self) -> _PropagateAttrsType: ...
else:
_propagate_attrs = util.EMPTY_DICT
class SelectStatementRole(StatementRole, ReturnsRowsRole):
__slots__ = ()
_role_name = "SELECT construct or equivalent text() construct"
def subquery(self) -> Subquery:
raise NotImplementedError(
"All SelectStatementRole objects should implement a "
".subquery() method."
)
class HasCTERole(ReturnsRowsRole):
__slots__ = ()
class IsCTERole(SQLRole):
__slots__ = ()
_role_name = "CTE object"
class CompoundElementRole(AllowsLambdaRole, SQLRole):
"""SELECT statements inside a CompoundSelect, e.g. UNION, EXTRACT, etc."""
__slots__ = ()
_role_name = (
"SELECT construct for inclusion in a UNION or other set construct"
)
# TODO: are we using this?
class DMLRole(StatementRole):
__slots__ = ()
class DMLTableRole(FromClauseRole):
__slots__ = ()
_role_name = "subject table for an INSERT, UPDATE or DELETE"
class DMLColumnRole(SQLRole):
__slots__ = ()
_role_name = "SET/VALUES column expression or string key"
class DMLSelectRole(SQLRole):
"""A SELECT statement embedded in DML, typically INSERT from SELECT"""
__slots__ = ()
_role_name = "SELECT statement or equivalent textual object"
class DDLRole(StatementRole):
__slots__ = ()
class DDLExpressionRole(StructuralRole):
__slots__ = ()
_role_name = "SQL expression element for DDL constraint"
class DDLConstraintColumnRole(SQLRole):
__slots__ = ()
_role_name = "String column name or column expression for DDL constraint"
class DDLReferredColumnRole(DDLConstraintColumnRole):
__slots__ = ()
_role_name = (
"String column name or Column object for DDL foreign key constraint"
)