feat(ipsec): Use strings instead of enums in Robot

[csit.git] / resources / libraries / python / enum_util.py

diff --git a/resources/libraries/python/enum_util.py b/resources/libraries/python/enum_util.py
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+++ b/resources/libraries/python/enum_util.py
@@ -0,0 +1,67 @@
+# Copyright (c) 2024 Cisco and/or its affiliates.
+# 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.
+
+"""Utility functions for handling VPP API enum values from Robot."""
+
+
+from enum import Enum, IntEnum
+from typing import Type, Union
+
+
+# The return type is enum_class, but it is hard to explain that to pylint.
+def get_enum_instance(
+    enum_class: Type[Enum], value: Union[Enum, str, int, None]
+) -> Enum:
+    """Return an enum instance matching the string name.
+
+    In Robot, it is not convenient to construct Enum instances,
+    most values defined in Robot are strings.
+
+    This helper function can be used in Python L1 keywords
+    to convert string into the corresponding Enum instance.
+    Aliases are also recognized.
+
+    As an added benefit, support various Robot-like niceties,
+    like lower case, or dash or space instead of underscore.
+
+    As a common shortcut, value is returned it it already is an instance.
+
+    Another convenience: None or empty string is processed as "NONE".
+
+    If the class is a subclass of IntEnum, int values
+    and (string) values convertable to int are also accepted as input.
+
+    :param enum_class: Class object instance of which should be returned.
+    :param value: String or any other recognized form of an enum instance.
+    :type enum_class: Type[Enum]
+    :type value: Union[enum_class, str, int, None]
+    :returns: The matching instance, if found.
+    :rtype: enum_class
+    :raises: ValueError if no matching instance is found.
+    """
+    if issubclass(enum_class, IntEnum):
+        try:
+            int_value = int(value)
+            return enum_class(int_value)
+        except (TypeError, ValueError):
+            pass
+    if isinstance(value, enum_class):
+        return value
+    if not value:
+        value = "NONE"
+    normalized_name = str(value).upper().replace("-", "_").replace(" ", "_")
+    members = enum_class.__members__  # Includes aliases, useful for NONE.
+    if normalized_name not in members:
+        msg = f"Enum class {enum_class} does not have value {normalized_name!r}"
+        raise ValueError(msg)
+    return members[normalized_name]