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- # Copyright 2016 OpenMarket Ltd
- #
- # 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.
- import logging
- from typing import Dict
- from twisted.web.resource import Resource
- from synapse.http.server import UnrecognizedRequestResource
- logger = logging.getLogger(__name__)
- def create_resource_tree(
- desired_tree: Dict[str, Resource], root_resource: Resource
- ) -> Resource:
- """Create the resource tree for this homeserver.
- This in unduly complicated because Twisted does not support putting
- child resources more than 1 level deep at a time.
- Args:
- desired_tree: Dict from desired paths to desired resources.
- root_resource: The root resource to add the tree to.
- Returns:
- The ``root_resource`` with a tree of child resources added to it.
- """
- # ideally we'd just use getChild and putChild but getChild doesn't work
- # unless you give it a Request object IN ADDITION to the name :/ So
- # instead, we'll store a copy of this mapping so we can actually add
- # extra resources to existing nodes. See self._resource_id for the key.
- resource_mappings: Dict[str, Resource] = {}
- for full_path_str, res in desired_tree.items():
- # twisted requires all resources to be bytes
- full_path = full_path_str.encode("utf-8")
- logger.info("Attaching %s to path %s", res, full_path)
- last_resource = root_resource
- for path_seg in full_path.split(b"/")[1:-1]:
- if path_seg not in last_resource.listNames():
- # resource doesn't exist, so make a "dummy resource"
- child_resource: Resource = UnrecognizedRequestResource()
- last_resource.putChild(path_seg, child_resource)
- res_id = _resource_id(last_resource, path_seg)
- resource_mappings[res_id] = child_resource
- last_resource = child_resource
- else:
- # we have an existing Resource, use that instead.
- res_id = _resource_id(last_resource, path_seg)
- last_resource = resource_mappings[res_id]
- # ===========================
- # now attach the actual desired resource
- last_path_seg = full_path.split(b"/")[-1]
- # if there is already a resource here, thieve its children and
- # replace it
- res_id = _resource_id(last_resource, last_path_seg)
- if res_id in resource_mappings:
- # there is a dummy resource at this path already, which needs
- # to be replaced with the desired resource.
- existing_dummy_resource = resource_mappings[res_id]
- for child_name in existing_dummy_resource.listNames():
- child_res_id = _resource_id(existing_dummy_resource, child_name)
- child_resource = resource_mappings[child_res_id]
- # steal the children
- res.putChild(child_name, child_resource)
- # finally, insert the desired resource in the right place
- last_resource.putChild(last_path_seg, res)
- res_id = _resource_id(last_resource, last_path_seg)
- resource_mappings[res_id] = res
- return root_resource
- def _resource_id(resource: Resource, path_seg: bytes) -> str:
- """Construct an arbitrary resource ID so you can retrieve the mapping
- later.
- If you want to represent resource A putChild resource B with path C,
- the mapping should looks like _resource_id(A,C) = B.
- Args:
- resource: The *parent* Resourceb
- path_seg: The name of the child Resource to be attached.
- Returns:
- A unique string which can be a key to the child Resource.
- """
- return "%s-%r" % (resource, path_seg)
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