Add sort keyword argument to DualBase simplify()

This commit adds a "sort" keyword argument to the simplify() function of
the DualBase class. This allows simplification of boolean algebra
expressions to be completed correctly, but does not sort the final
expression. This is needed for various applications where maintaining order matters.

Signed-off-by: Steven Esser <[email protected]>

Author: steven-esser

boolean/boolean.py

@@ -1135,7 +1135,7 @@ def __contains__(self, expr):
         if isinstance(expr, self.__class__):
             return all(arg in self.args for arg in expr.args)
 
-    def simplify(self):
+    def simplify(self, sort=True):
         """
         Return a new simplified expression in canonical form from this
         expression.
@@ -1254,7 +1254,8 @@ def simplify(self):
             return args[0]
 
         # Commutativity: A & B = B & A, A | B = B | A
-        args.sort()
+        if sort:
+            args.sort()
 
         # Create new (now canonical) expression.
         expr = self.__class__(*args)

boolean/test_boolean.py

@@ -705,6 +705,17 @@ def test_simplify(self):
         # Elimination
         self.assertEqual(a, ((a & ~b) | (a & b)).simplify())
 
+        # Commutativity + Non-Commutativity 
+        sorted_expression = (b & b & a).simplify()
+        unsorted_expression = (b & b & a).simplify(sort=False)
+        self.assertEqual(sorted_expression, unsorted_expression)
+        self.assertNotEqual(sorted_expression.pretty(), unsorted_expression.pretty())
+
+        sorted_expression = (b | b | a).simplify()
+        unsorted_expression = (b | b | a).simplify(sort=False)
+        self.assertEqual(sorted_expression, unsorted_expression)
+        self.assertNotEqual(sorted_expression.pretty(), unsorted_expression.pretty())
+
         expected = algebra1.parse('(a&b)|(b&c)|(a&c)')
         result = algebra1.parse('(~a&b&c) | (a&~b&c) | (a&b&~c) | (a&b&c)', simplify=True)
         self.assertEqual(expected, result)