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# (C) Copyright 2005-2023 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
""" A generic base-class for items in a tree data structure.
An example::
root = TreeItem(data='Root')
fruit = TreeItem(data='Fruit')
fruit.append(TreeItem(data='Apple', allows_children=False))
fruit.append(TreeItem(data='Orange', allows_children=False))
fruit.append(TreeItem(data='Pear', allows_children=False))
root.append(fruit)
veg = TreeItem(data='Veg')
veg.append(TreeItem(data='Carrot', allows_children=False))
veg.append(TreeItem(data='Cauliflower', allows_children=False))
veg.append(TreeItem(data='Sprout', allows_children=False))
root.append(veg)
"""
from traits.api import Any, Bool, HasTraits, Instance, List, Property
class TreeItem(HasTraits):
""" A generic base-class for items in a tree data structure. """
# 'TreeItem' interface -------------------------------------------------
# Does this item allow children?
allows_children = Bool(True)
# The item's children.
children = List(Instance("TreeItem"))
# Arbitrary data associated with the item.
data = Any()
# Does the item have any children?
has_children = Property(Bool)
# The item's parent.
parent = Instance("TreeItem")
# ------------------------------------------------------------------------
# 'object' interface.
# ------------------------------------------------------------------------
def __str__(self):
""" Returns the informal string representation of the object. """
if self.data is None:
s = ""
else:
s = str(self.data)
return s
# ------------------------------------------------------------------------
# 'TreeItem' interface.
# ------------------------------------------------------------------------
# Properties -----------------------------------------------------------
# has_children
def _get_has_children(self):
""" True iff the item has children. """
return len(self.children) != 0
# Methods -------------------------------------------------------------#
def append(self, child):
""" Appends a child to this item.
This removes the child from its current parent (if it has one).
"""
return self.insert(len(self.children), child)
def insert(self, index, child):
""" Inserts a child into this item at the specified index.
This removes the child from its current parent (if it has one).
"""
if child.parent is not None:
child.parent.remove(child)
child.parent = self
self.children.insert(index, child)
return child
def remove(self, child):
""" Removes a child from this item. """
child.parent = None
self.children.remove(child)
return child
def insert_before(self, before, child):
""" Inserts a child into this item before the specified item.
This removes the child from its current parent (if it has one).
"""
index = self.children.index(before)
self.insert(index, child)
return (index, child)
def insert_after(self, after, child):
""" Inserts a child into this item after the specified item.
This removes the child from its current parent (if it has one).
"""
index = self.children.index(after)
self.insert(index + 1, child)
return (index, child)
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