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#------------------------------------------------------------------------------
# Copyright (c) 2013-2025, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
#------------------------------------------------------------------------------
from .constrainable import ContentsConstrainable, ConstrainableMixin
from .constraint_helper import ConstraintHelper
BOUNDARY_ATTRS = (
'top',
'bottom',
'left',
'right',
)
CONTENT_BOUNDARY_ATTRS = (
'contents_top',
'contents_bottom',
'contents_left',
'contents_right',
)
class BoxHelper(ConstraintHelper, ConstrainableMixin):
""" A constraint helper for creating a box layouts.
Instances of BoxHelper are Constrainable and can be nested in other
box helpers to build up complex layouts. This is a base class which
should be subclassed to implement the desired functionality.
"""
def box_constraints(self, component):
""" Generate the boundary constraints for the box.
"""
cns = []
if component is not None:
a_attrs = b_attrs = BOUNDARY_ATTRS
if isinstance(component, ContentsConstrainable):
b_attrs = CONTENT_BOUNDARY_ATTRS
f = lambda a, b: getattr(self, a) == getattr(component, b)
cns.extend(f(a, b) for a, b in zip(a_attrs, b_attrs))
return cns
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