duplicate_exponent now supports n-ary multiplication.

src/rules/powers.py

@@ -85,7 +85,7 @@ def match_duplicate_exponent(node):
     left, right = node
 
     if left.is_op(OP_MUL):
-        return [P(node, duplicate_exponent, tuple(left) + (right,))]
+        return [P(node, duplicate_exponent, (left.get_scope(), right))]
 
     return []
 
@@ -157,11 +157,16 @@ def multiply_exponents(root, args):
 
 def duplicate_exponent(root, args):
     """
-    (ab)^p  ->  a^p * b^p
+    (ab)^p   ->  a^p * b^p
+    (abc)^p  ->  a^p * b^p * c^p
     """
-    a, b, p = args
+    ab, p = args
+    result = ab[0] ** p
+
+    for b in ab[1:]:
+        result *= b ** p
 
-    return a ** p * b ** p
+    return result
 
 
 def remove_negative_exponent(root, args):

tests/test_rules_powers.py

@@ -77,7 +77,7 @@ class TestRulesPowers(RulesTestCase):
 
         possibilities = match_duplicate_exponent(root)
         self.assertEqualPos(possibilities,
-                [P(root, duplicate_exponent, (a, b, p))])
+                [P(root, duplicate_exponent, ([a, b], p))])
 
     def test_match_remove_negative_exponent(self):
         a, p = tree('a,p')
@@ -121,12 +121,16 @@ class TestRulesPowers(RulesTestCase):
                               a ** (p * q))
 
     def test_duplicate_exponent(self):
-        a, b, p = tree('a,b,p')
-        root = (a * b) ** p
+        a, b, c, p = tree('a,b,c,p')
 
-        self.assertEqualNodes(duplicate_exponent(root, (a, b, p)),
+        root = (a * b) ** p
+        self.assertEqualNodes(duplicate_exponent(root, ([a, b], p)),
                               a ** p * b ** p)
 
+        root = (a * b * c) ** p
+        self.assertEqualNodes(duplicate_exponent(root, ([a, b, c], p)),
+                              a ** p * b ** p * c ** p)
+
     def test_remove_negative_exponent(self):
         a, p, l1 = tree('a,p,1')
         root = a ** -p