# Copyright 2018 The dm_control Authors.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# ============================================================================

"""Helper object for keeping track of new elements created when copying MJCF."""

from dm_control.mjcf import constants

class Copier:

"""Helper for keeping track of new elements created when copying MJCF."""

def __init__(self, source):

if source._attachments: # pylint: disable=protected-access

raise NotImplementedError('Cannot copy from elements with attachments')

self._source = source

def copy_into(self, destination, override_attributes=False):

"""Copies this copier's element into a destination MJCF element."""

newly_created_elements = {}

destination._check_valid_attachment(self._source) # pylint: disable=protected-access

if override_attributes:

destination.set_attributes(**self._source.get_attributes())

else:

destination._sync_attributes(self._source, copying=True) # pylint: disable=protected-access

for source_child in self._source.all_children():

dest_child = None

# First, if source_child has an identifier, we look for an existing child

# element of self with the same identifier to override.

if source_child.spec.identifier and override_attributes:

identifier_attr = source_child.spec.identifier

if identifier_attr == constants.CLASS:

identifier_attr = constants.DCLASS

identifier = getattr(source_child, identifier_attr)

if identifier:

dest_child = destination.find(source_child.spec.namespace, identifier)

if dest_child is not None and dest_child.parent is not destination:

raise ValueError(

'<{}> with identifier {!r} is already a child of another element'

.format(source_child.spec.namespace, identifier))

# Next, we cover the case where either the child is not a repeated element

# or if source_child has an identifier attribute but it isn't set.

if not source_child.spec.repeated and dest_child is None:

dest_child = destination.get_children(source_child.tag)

# Add a new element if dest_child doesn't exist, either because it is

# supposed to be a repeated child, or because it's an uncreated on-demand.

if dest_child is None:

dest_child = destination.add(

source_child.tag, **source_child.get_attributes())

newly_created_elements[source_child] = dest_child

override_child_attributes = True

else:

override_child_attributes = override_attributes

# Finally, copy attributes into dest_child.

child_copier = Copier(source_child)

newly_created_elements.update(

child_copier.copy_into(dest_child, override_child_attributes))

return newly_created_elements