IPsec: add nth matching SPD entry outbound TCs

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

diff --git a/resources/libraries/python/IncrementUtil.py b/resources/libraries/python/IncrementUtil.py
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+# Copyright (c) 2021 PANTHEON.tech s.r.o.
+# 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.
+
+"""Increment utilities library."""
+
+
+class ObjIncrement(object):
+    """
+    An iterator class used to generate incremented values in each iteration
+    or when inc_fmt is called.
+
+    Subclasses should override:
+        _incr: when a simple '+' binary operation isn't sufficient.
+        _str_fmt: when a simple str representation of the incremented object
+            isn't the proper format.
+    """
+    def __init__(self, initial_value, increment):
+        """
+        :param initial_value: The first value to be returned.
+        :param increment: Each iteration/inc_fmt call will return the previous
+            value incremented by this.
+        :type initial_value: object supporting the '+' binary operation
+        :type increment: object supporting the '+' binary operation
+        """
+        self._value = initial_value
+        self._increment = increment
+
+    def _incr(self):
+        """
+        This function will be called in each iteration/inc_fmt call. Subclasses
+        should override this when their object is incremented differently.
+        The function must compute the next iterated value and store it in
+        self._value.
+        """
+        self._value += self._increment
+
+    def __next__(self):
+        """
+        Each iteration returns the current object and stores the incremented
+        object (which will be returned in the next iteration). The first
+        iteration returns the initial value.
+        """
+        return_value = self._value
+        self._incr()
+        return return_value
+
+    def __iter__(self):
+        return self
+
+    def _str_fmt(self):
+        """
+        The string representation is a standard string representation of the
+        incremented object. Subclasses may override this for a different
+        string representation.
+        """
+        return str(self._value)
+
+    def inc_fmt(self):
+        """
+        Return a string representation and increment the current value.
+        """
+        return_value = self._str_fmt()
+        self._incr()
+        return return_value