TOSCA: Create new utils module with memory units

Create new functions to handle memory units. These functions are created as
common utils for general use. Because of new module dependency unit tests are
created in a following patch.

Change-Id: I93af33c5a98b7f5afd66d32f167cfad0f7d3d1fe

TOSCA: Create new utils module with memory units

Create new functions to handle memory units. These functions are created as
common utils for general use. Because of new module dependency unit tests are
created in a following patch.

Change-Id: I93af33c5a98b7f5afd66d32f167cfad0f7d3d1fe

translator/common/utils.py

@@ -0,0 +1,70 @@
+#    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 math
+import numbers
+import re
+from translator.toscalib.utils.gettextutils import _
+
+
+class MemoryUnit(object):
+
+    UNIT_SIZE_DEFAULT = 'B'
+    UNIT_SIZE_DICT = {'B': 1, 'KB': 1000, 'KIB': 1024, 'MB': 1000000,
+                      'MIB': 1048576, 'GB': 1000000000,
+                      'GIB': 1073741824, 'TB': 1000000000000,
+                      'TIB': 1099511627776}
+
+    @staticmethod
+    def convert_unit_size_to_num(size, unit=None):
+        """Convert given size to a number representing given unit.
+        If unit is None, convert to a number representing UNIT_SIZE_DEFAULT
+
+        :param size: unit size e.g. 1 TB
+        :param unit: unit to be converted to e.g GB
+        :return: converted number e.g. 1000 for 1 TB size and unit GB
+        """
+
+        if unit:
+            MemoryUnit.validate_unit(unit)
+        else:
+            unit = MemoryUnit.UNIT_SIZE_DEFAULT
+
+        regex = re.compile('(\d*)\s*(\w*)')
+        result = regex.match(str(size)).groups()
+        if result[1]:
+            MemoryUnit.validate_unit(result[1])
+            converted = int(str_to_num(result[0])
+                            * MemoryUnit.UNIT_SIZE_DICT[result[1].upper()]
+                            * math.pow(MemoryUnit.UNIT_SIZE_DICT
+                                       [unit.upper()], -1))
+        else:
+            converted = (str_to_num(result[0]))
+        return converted
+
+    @staticmethod
+    def validate_unit(unit):
+        if unit.upper() not in MemoryUnit.UNIT_SIZE_DICT.keys():
+            msg = _('Provided unit "{0}" is not valid. The valid units are '
+                    '{1}').format(unit, MemoryUnit.UNIT_SIZE_DICT.keys())
+            raise ValueError(msg)
+
+
+def str_to_num(value):
+    '''Convert a string representation of a number into a numeric type.'''
+    if isinstance(value, numbers.Number):
+        return value
+    try:
+        return int(value)
+    except ValueError:
+        return float(value)