codeclone_detection: Add CountVector class

This class will be used later to count occurrences of variables under
certain conditions.

bears/codeclone_detection/CountVector.py

@@ -0,0 +1,37 @@
+class CountVector:
+    def __init__(self, name, conditions=None, weightings=None):
+        """
+        Creates a new count vector.
+
+        :param name:       The name of the variable in the original code.
+        :param conditions: The counting conditions as list of function objects,
+                           each shall return true when getting data indicating
+                           that this occurrence should be counted.
+        :param weightings: Optional factors to weight counting conditions.
+                           Defaults to 1 for all conditions.
+        """
+        self.name = name
+        self.conditions = conditions if conditions is not None else []
+        self.count_vector = [0 for elem in self.conditions]
+        self.weightings = weightings
+        if self.weightings is None:
+            self.weightings = [1 for elem in self.conditions]
+
+        assert len(self.count_vector) is len(self.weightings)
+
+    def count_reference(self, *args, **kwargs):
+        """
+        Counts the reference to the variable under the conditions held in this
+        object.
+
+        Any arguments or kwarguments will be passed to all conditions.
+        """
+        for i in range(len(self.conditions)):
+            if self.conditions[i](*args, **kwargs):
+                self.count_vector[i] += self.weightings[i]
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        return str(self.count_vector)

bears/tests/codeclone_detection/CountVectorTest.py

@@ -0,0 +1,48 @@
+import sys
+
+sys.path.insert(0, ".")
+import unittest
+from bears.codeclone_detection.CountVector import CountVector
+
+
+class CountVectorTest(unittest.TestCase):
+    def test_simple_creation(self):
+        uut = CountVector("varname")
+        self.assertEqual(uut.count_vector, [])
+        uut = CountVector("varname", [])
+        self.assertEqual(uut.count_vector, [])
+        self.assertRaises(AssertionError,
+                          CountVector,
+                          "varname",
+                          [],
+                          [2])
+
+    def test_counting(self):
+        uut = CountVector("varname", [lambda cursor, stack: cursor and stack])
+        self.assertEqual(uut.count_vector, [0])
+        uut.count_reference(True, True)
+        self.assertEqual(uut.count_vector, [1])
+        uut.count_reference(True, False)
+        self.assertEqual(uut.count_vector, [1])
+
+    def test_weighting(self):
+        uut = CountVector("varname",
+                          [lambda cursor, stack: cursor and stack,
+                           lambda cursor, stack: cursor],
+                          [2, 1])
+        uut.count_reference(True, True)
+        self.assertEqual(uut.count_vector, [2, 1])
+        uut.count_reference(True, False)
+        self.assertEqual(uut.count_vector, [2, 2])
+
+    def test_conversion(self):
+        uut = CountVector("varname",
+                          [lambda cursor, stack: cursor and stack],
+                          [2])
+        uut.count_reference(True, True)
+        self.assertEqual(repr(uut), str(uut))
+        self.assertEqual(repr(uut), "[2]")
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)