Add bit mask enumeration utilities

This changes adds several utilities for working with bit mask
enumerations, including functions to compute bit masks from lists
of enumeration values and vice versa. Unit tests have been added
to cover these new utilities.

kmip/core/enums.py

@@ -18,6 +18,7 @@
 
 import copy
 import enum
+import functools
 import six
 
 
@@ -1814,14 +1815,86 @@ def convert_attribute_tag_to_name(value):
     raise ValueError("Unrecognized attribute tag: {}".format(value))
 
 
+def get_bit_mask_from_enumerations(enumerations):
+    """
+    A utility function that computes a bit mask from a collection of
+    enumeration values.
 
-def is_enum_value(enum_class, potential_value):
+    Args:
+        enumerations (list): A list of enumeration values to be combined in a
+            composite bit mask.
+
+    Returns:
+        int: The composite bit mask.
+    """
+    return functools.reduce(
+        lambda x, y: x | y, [z.value for z in enumerations]
+    )
+
+
+def get_enumerations_from_bit_mask(enumeration, mask):
+    """
+    A utility function that creates a list of enumeration values from a bit
+    mask for a specific mask enumeration class.
+
+    Args:
+        enumeration (class): The enumeration class from which to draw
+            enumeration values.
+        mask (int): The bit mask from which to identify enumeration values.
+
+    Returns:
+        list: A list of enumeration values corresponding to the bit mask.
+    """
+    return [x for x in enumeration if (x.value & mask) == x.value]
+
+
+def is_bit_mask(enumeration, potential_mask):
+    """
+    A utility function that checks if the provided value is a composite bit
+    mask of enumeration values in the specified enumeration class.
+
+    Args:
+        enumeration (class): One of the mask enumeration classes found in this
+            file. These include:
+                * Cryptographic Usage Mask
+                * Protection Storage Mask
+                * Storage Status Mask
+        potential_mask (int): A potential bit mask composed of enumeration
+            values belonging to the enumeration class.
+
+    Returns:
+        True: if the potential mask is a valid bit mask of the mask enumeration
+        False: otherwise
+    """
+    if not isinstance(potential_mask, six.integer_types):
+        return False
+
+    mask_enumerations = (
+        CryptographicUsageMask,
+        ProtectionStorageMask,
+        StorageStatusMask
+    )
+    if enumeration not in mask_enumerations:
+        return False
+
+    mask = 0
+    for value in [e.value for e in enumeration]:
+        if (value & potential_mask) == value:
+            mask |= value
+
+    if mask != potential_mask:
+        return False
+
+    return True
+
+
+def is_enum_value(enumeration, potential_value):
     """
     A utility function that checks if the enumeration class contains the
     provided value.
 
     Args:
-        enum_class (class): One of the enumeration classes found in this file.
+        enumeration (class): One of the enumeration classes found in this file.
         potential_value (int, string): A potential value of the enumeration
             class.
 
@@ -1830,7 +1903,7 @@ def is_enum_value(enum_class, potential_value):
         False: otherwise
     """
     try:
-        enum_class(potential_value)
+        enumeration(potential_value)
     except ValueError:
         return False
 

kmip/tests/unit/core/test_enums.py

@@ -87,6 +87,63 @@ class TestEnumUtilityFunctions(testtools.TestCase):
     def tearDown(self):
         super(TestEnumUtilityFunctions, self).tearDown()
 
+    def test_get_bit_mask_from_enumerations(self):
+        self.assertEqual(
+            7,
+            enums.get_bit_mask_from_enumerations(
+                [
+                    enums.StorageStatusMask.ARCHIVAL_STORAGE,
+                    enums.StorageStatusMask.DESTROYED_STORAGE,
+                    enums.StorageStatusMask.ONLINE_STORAGE
+                ]
+            )
+        )
+
+    def test_get_enumerations_from_bit_mask(self):
+        expected = [
+                enums.StorageStatusMask.ARCHIVAL_STORAGE,
+                enums.StorageStatusMask.DESTROYED_STORAGE,
+                enums.StorageStatusMask.ONLINE_STORAGE
+        ]
+        observed = enums.get_enumerations_from_bit_mask(
+            enums.StorageStatusMask,
+            7
+        )
+
+        self.assertEqual(len(expected), len(observed))
+        for x in expected:
+            self.assertIn(x, observed)
+
+    def test_is_bit_mask(self):
+        self.assertTrue(
+            enums.is_bit_mask(
+                enums.StorageStatusMask,
+                enums.StorageStatusMask.ARCHIVAL_STORAGE.value |
+                enums.StorageStatusMask.ONLINE_STORAGE.value
+            )
+        )
+
+        self.assertFalse(
+            enums.is_bit_mask(
+                enums.StorageStatusMask,
+                enums.StorageStatusMask.DESTROYED_STORAGE
+            )
+        )
+
+        self.assertFalse(
+            enums.is_bit_mask(
+                enums.WrappingMethod,
+                enums.WrappingMethod.ENCRYPT.value
+            )
+        )
+
+        self.assertFalse(
+            enums.is_bit_mask(
+                enums.ProtectionStorageMask,
+                0x80000000
+            )
+        )
+
     def test_is_enum_value(self):
         result = enums.is_enum_value(
             enums.CryptographicAlgorithm,