| # Copyright 2021 The Bazel Authors. All rights reserved. |
| # |
| # 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. |
| |
| """Defines rule utilities""" |
| |
| def merge_attrs(*attribute_dicts, override_attrs = {}, remove_attrs = []): |
| """Merges attributes together. |
| |
| Attributes are first merged, then overridden and removed. |
| |
| If there are duplicate definitions of an attribute, the last one is used. |
| (Current API doesn't let us compare) |
| |
| Overridden and removed attributes need to be present. |
| |
| Args: |
| *attribute_dicts: (*dict[str,Attribute]) A list of attribute dictionaries |
| to merge together. |
| override_attrs: (dict[str,Attribute]) A dictionary of attributes to override |
| remove_attrs: (list[str]) A list of attributes to remove. |
| Returns: |
| (dict[str,Attribute]) The merged attributes dictionary. |
| """ |
| all_attributes = {} |
| for attribute_dict in attribute_dicts: |
| for key, attr in attribute_dict.items(): |
| all_attributes.setdefault(key, attr) |
| for key, attr in override_attrs.items(): |
| if all_attributes.get(key) == None: |
| fail("Trying to override attribute %s where there is none." % key) |
| all_attributes[key] = attr |
| for key in remove_attrs: |
| if key in override_attrs: |
| fail("Trying to remove overridden attribute %s." % key) |
| if key not in all_attributes: |
| fail("Trying to remove non-existent attribute %s." % key) |
| all_attributes.pop(key) |
| return all_attributes |
