university-final-iot-backend/env/lib/python3.6/site-packages/sqlalchemy/sql/naming.py

# sqlalchemy/naming.py
# Copyright (C) 2005-2018 the SQLAlchemy authors and contributors
# <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php

"""Establish constraint and index naming conventions.


"""

from .schema import Constraint, ForeignKeyConstraint, PrimaryKeyConstraint, \
    UniqueConstraint, CheckConstraint, Index, Table, Column
from .. import event, events
from .. import exc
from .elements import _truncated_label, _defer_name, _defer_none_name, conv
import re


class ConventionDict(object):

    def __init__(self, const, table, convention):
        self.const = const
        self._is_fk = isinstance(const, ForeignKeyConstraint)
        self.table = table
        self.convention = convention
        self._const_name = const.name

    def _key_table_name(self):
        return self.table.name

    def _column_X(self, idx):
        if self._is_fk:
            fk = self.const.elements[idx]
            return fk.parent
        else:
            return list(self.const.columns)[idx]

    def _key_constraint_name(self):
        if isinstance(self._const_name, (type(None), _defer_none_name)):
            raise exc.InvalidRequestError(
                "Naming convention including "
                "%(constraint_name)s token requires that "
                "constraint is explicitly named."
            )
        if not isinstance(self._const_name, conv):
            self.const.name = None
        return self._const_name

    def _key_column_X_name(self, idx):
        return self._column_X(idx).name

    def _key_column_X_label(self, idx):
        return self._column_X(idx)._label

    def _key_referred_table_name(self):
        fk = self.const.elements[0]
        refs = fk.target_fullname.split(".")
        if len(refs) == 3:
            refschema, reftable, refcol = refs
        else:
            reftable, refcol = refs
        return reftable

    def _key_referred_column_X_name(self, idx):
        fk = self.const.elements[idx]
        refs = fk.target_fullname.split(".")
        if len(refs) == 3:
            refschema, reftable, refcol = refs
        else:
            reftable, refcol = refs
        return refcol

    def __getitem__(self, key):
        if key in self.convention:
            return self.convention[key](self.const, self.table)
        elif hasattr(self, '_key_%s' % key):
            return getattr(self, '_key_%s' % key)()
        else:
            col_template = re.match(r".*_?column_(\d+)_.+", key)
            if col_template:
                idx = col_template.group(1)
                attr = "_key_" + key.replace(idx, "X")
                idx = int(idx)
                if hasattr(self, attr):
                    return getattr(self, attr)(idx)
        raise KeyError(key)

_prefix_dict = {
    Index: "ix",
    PrimaryKeyConstraint: "pk",
    CheckConstraint: "ck",
    UniqueConstraint: "uq",
    ForeignKeyConstraint: "fk"
}


def _get_convention(dict_, key):

    for super_ in key.__mro__:
        if super_ in _prefix_dict and _prefix_dict[super_] in dict_:
            return dict_[_prefix_dict[super_]]
        elif super_ in dict_:
            return dict_[super_]
    else:
        return None


def _constraint_name_for_table(const, table):
    metadata = table.metadata
    convention = _get_convention(metadata.naming_convention, type(const))

    if isinstance(const.name, conv):
        return const.name
    elif convention is not None and \
        not isinstance(const.name, conv) and \
            (
            const.name is None or
            "constraint_name" in convention or
            isinstance(const.name, _defer_name)):
        return conv(
            convention % ConventionDict(const, table,
                                        metadata.naming_convention)
        )
    elif isinstance(convention, _defer_none_name):
        return None


@event.listens_for(Constraint, "after_parent_attach")
@event.listens_for(Index, "after_parent_attach")
def _constraint_name(const, table):
    if isinstance(table, Column):
        # for column-attached constraint, set another event
        # to link the column attached to the table as this constraint
        # associated with the table.
        event.listen(table, "after_parent_attach",
                     lambda col, table: _constraint_name(const, table)
                     )
    elif isinstance(table, Table):
        if isinstance(const.name, (conv, _defer_name)):
            return

        newname = _constraint_name_for_table(const, table)
        if newname is not None:
            const.name = newname