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.venv2/Lib/site-packages/alembic/ddl/_autogen.py

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+# mypy: allow-untyped-defs, allow-incomplete-defs, allow-untyped-calls
+# mypy: no-warn-return-any, allow-any-generics
+
+from __future__ import annotations
+
+from typing import Any
+from typing import ClassVar
+from typing import Dict
+from typing import Generic
+from typing import NamedTuple
+from typing import Optional
+from typing import Sequence
+from typing import Tuple
+from typing import Type
+from typing import TYPE_CHECKING
+from typing import TypeVar
+from typing import Union
+
+from sqlalchemy.sql.schema import Constraint
+from sqlalchemy.sql.schema import ForeignKeyConstraint
+from sqlalchemy.sql.schema import Index
+from sqlalchemy.sql.schema import UniqueConstraint
+from typing_extensions import TypeGuard
+
+from .. import util
+from ..util import sqla_compat
+
+if TYPE_CHECKING:
+    from typing import Literal
+
+    from alembic.autogenerate.api import AutogenContext
+    from alembic.ddl.impl import DefaultImpl
+
+CompareConstraintType = Union[Constraint, Index]
+
+_C = TypeVar("_C", bound=CompareConstraintType)
+
+_clsreg: Dict[str, Type[_constraint_sig]] = {}
+
+
+class ComparisonResult(NamedTuple):
+    status: Literal["equal", "different", "skip"]
+    message: str
+
+    @property
+    def is_equal(self) -> bool:
+        return self.status == "equal"
+
+    @property
+    def is_different(self) -> bool:
+        return self.status == "different"
+
+    @property
+    def is_skip(self) -> bool:
+        return self.status == "skip"
+
+    @classmethod
+    def Equal(cls) -> ComparisonResult:
+        """the constraints are equal."""
+        return cls("equal", "The two constraints are equal")
+
+    @classmethod
+    def Different(cls, reason: Union[str, Sequence[str]]) -> ComparisonResult:
+        """the constraints are different for the provided reason(s)."""
+        return cls("different", ", ".join(util.to_list(reason)))
+
+    @classmethod
+    def Skip(cls, reason: Union[str, Sequence[str]]) -> ComparisonResult:
+        """the constraint cannot be compared for the provided reason(s).
+
+        The message is logged, but the constraints will be otherwise
+        considered equal, meaning that no migration command will be
+        generated.
+        """
+        return cls("skip", ", ".join(util.to_list(reason)))
+
+
+class _constraint_sig(Generic[_C]):
+    const: _C
+
+    _sig: Tuple[Any, ...]
+    name: Optional[sqla_compat._ConstraintNameDefined]
+
+    impl: DefaultImpl
+
+    _is_index: ClassVar[bool] = False
+    _is_fk: ClassVar[bool] = False
+    _is_uq: ClassVar[bool] = False
+
+    _is_metadata: bool
+
+    def __init_subclass__(cls) -> None:
+        cls._register()
+
+    @classmethod
+    def _register(cls):
+        raise NotImplementedError()
+
+    def __init__(
+        self, is_metadata: bool, impl: DefaultImpl, const: _C
+    ) -> None:
+        raise NotImplementedError()
+
+    def compare_to_reflected(
+        self, other: _constraint_sig[Any]
+    ) -> ComparisonResult:
+        assert self.impl is other.impl
+        assert self._is_metadata
+        assert not other._is_metadata
+
+        return self._compare_to_reflected(other)
+
+    def _compare_to_reflected(
+        self, other: _constraint_sig[_C]
+    ) -> ComparisonResult:
+        raise NotImplementedError()
+
+    @classmethod
+    def from_constraint(
+        cls, is_metadata: bool, impl: DefaultImpl, constraint: _C
+    ) -> _constraint_sig[_C]:
+        # these could be cached by constraint/impl, however, if the
+        # constraint is modified in place, then the sig is wrong.  the mysql
+        # impl currently does this, and if we fixed that we can't be sure
+        # someone else might do it too, so play it safe.
+        sig = _clsreg[constraint.__visit_name__](is_metadata, impl, constraint)
+        return sig
+
+    def md_name_to_sql_name(self, context: AutogenContext) -> Optional[str]:
+        return sqla_compat._get_constraint_final_name(
+            self.const, context.dialect
+        )
+
+    @util.memoized_property
+    def is_named(self):
+        return sqla_compat._constraint_is_named(self.const, self.impl.dialect)
+
+    @util.memoized_property
+    def unnamed(self) -> Tuple[Any, ...]:
+        return self._sig
+
+    @util.memoized_property
+    def unnamed_no_options(self) -> Tuple[Any, ...]:
+        raise NotImplementedError()
+
+    @util.memoized_property
+    def _full_sig(self) -> Tuple[Any, ...]:
+        return (self.name,) + self.unnamed
+
+    def __eq__(self, other) -> bool:
+        return self._full_sig == other._full_sig
+
+    def __ne__(self, other) -> bool:
+        return self._full_sig != other._full_sig
+
+    def __hash__(self) -> int:
+        return hash(self._full_sig)
+
+
+class _uq_constraint_sig(_constraint_sig[UniqueConstraint]):
+    _is_uq = True
+
+    @classmethod
+    def _register(cls) -> None:
+        _clsreg["unique_constraint"] = cls
+
+    is_unique = True
+
+    def __init__(
+        self,
+        is_metadata: bool,
+        impl: DefaultImpl,
+        const: UniqueConstraint,
+    ) -> None:
+        self.impl = impl
+        self.const = const
+        self.name = sqla_compat.constraint_name_or_none(const.name)
+        self._sig = tuple(sorted([col.name for col in const.columns]))
+        self._is_metadata = is_metadata
+
+    @property
+    def column_names(self) -> Tuple[str, ...]:
+        return tuple([col.name for col in self.const.columns])
+
+    def _compare_to_reflected(
+        self, other: _constraint_sig[_C]
+    ) -> ComparisonResult:
+        assert self._is_metadata
+        metadata_obj = self
+        conn_obj = other
+
+        assert is_uq_sig(conn_obj)
+        return self.impl.compare_unique_constraint(
+            metadata_obj.const, conn_obj.const
+        )
+
+
+class _ix_constraint_sig(_constraint_sig[Index]):
+    _is_index = True
+
+    name: sqla_compat._ConstraintName
+
+    @classmethod
+    def _register(cls) -> None:
+        _clsreg["index"] = cls
+
+    def __init__(
+        self, is_metadata: bool, impl: DefaultImpl, const: Index
+    ) -> None:
+        self.impl = impl
+        self.const = const
+        self.name = const.name
+        self.is_unique = bool(const.unique)
+        self._is_metadata = is_metadata
+
+    def _compare_to_reflected(
+        self, other: _constraint_sig[_C]
+    ) -> ComparisonResult:
+        assert self._is_metadata
+        metadata_obj = self
+        conn_obj = other
+
+        assert is_index_sig(conn_obj)
+        return self.impl.compare_indexes(metadata_obj.const, conn_obj.const)
+
+    @util.memoized_property
+    def has_expressions(self):
+        return sqla_compat.is_expression_index(self.const)
+
+    @util.memoized_property
+    def column_names(self) -> Tuple[str, ...]:
+        return tuple([col.name for col in self.const.columns])
+
+    @util.memoized_property
+    def column_names_optional(self) -> Tuple[Optional[str], ...]:
+        return tuple(
+            [getattr(col, "name", None) for col in self.const.expressions]
+        )
+
+    @util.memoized_property
+    def is_named(self):
+        return True
+
+    @util.memoized_property
+    def unnamed(self):
+        return (self.is_unique,) + self.column_names_optional
+
+
+class _fk_constraint_sig(_constraint_sig[ForeignKeyConstraint]):
+    _is_fk = True
+
+    @classmethod
+    def _register(cls) -> None:
+        _clsreg["foreign_key_constraint"] = cls
+
+    def __init__(
+        self,
+        is_metadata: bool,
+        impl: DefaultImpl,
+        const: ForeignKeyConstraint,
+    ) -> None:
+        self._is_metadata = is_metadata
+
+        self.impl = impl
+        self.const = const
+
+        self.name = sqla_compat.constraint_name_or_none(const.name)
+
+        (
+            self.source_schema,
+            self.source_table,
+            self.source_columns,
+            self.target_schema,
+            self.target_table,
+            self.target_columns,
+            onupdate,
+            ondelete,
+            deferrable,
+            initially,
+        ) = sqla_compat._fk_spec(const)
+
+        self._sig: Tuple[Any, ...] = (
+            self.source_schema,
+            self.source_table,
+            tuple(self.source_columns),
+            self.target_schema,
+            self.target_table,
+            tuple(self.target_columns),
+        ) + (
+            (None if onupdate.lower() == "no action" else onupdate.lower())
+            if onupdate
+            else None,
+            (None if ondelete.lower() == "no action" else ondelete.lower())
+            if ondelete
+            else None,
+            # convert initially + deferrable into one three-state value
+            "initially_deferrable"
+            if initially and initially.lower() == "deferred"
+            else "deferrable"
+            if deferrable
+            else "not deferrable",
+        )
+
+    @util.memoized_property
+    def unnamed_no_options(self):
+        return (
+            self.source_schema,
+            self.source_table,
+            tuple(self.source_columns),
+            self.target_schema,
+            self.target_table,
+            tuple(self.target_columns),
+        )
+
+
+def is_index_sig(sig: _constraint_sig) -> TypeGuard[_ix_constraint_sig]:
+    return sig._is_index
+
+
+def is_uq_sig(sig: _constraint_sig) -> TypeGuard[_uq_constraint_sig]:
+    return sig._is_uq
+
+
+def is_fk_sig(sig: _constraint_sig) -> TypeGuard[_fk_constraint_sig]:
+    return sig._is_fk