# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1330381353 -3600
# Node ID a898fc7c3998d11ef31f5b685a924c5584794624
# Parent  43d594f9c4367c107ee5cabe6493fdfe662364ee
Changed the combination of object set lists to discard empty lists. This should
mean that where no attribute usage is defined for a name, the resulting combined
object set does not retain the "null usage", thus preventing "bubbles" of absent
usage from forming and being incorporated into attribute usage deductions.

diff -r 43d594f9c436 -r a898fc7c3998 internal_tests/objectset.py
--- a/internal_tests/objectset.py	Mon Feb 27 23:17:50 2012 +0100
+++ b/internal_tests/objectset.py	Mon Feb 27 23:22:33 2012 +0100
@@ -2,12 +2,16 @@
 
 from micropython.common import ObjectSet, combine_mapping_dicts
 
+# Test storage.
+
 o1 = ObjectSet()
 o1.add("a")
 o1.add("b")
 o1.add("c")
 print "o1 =", o1
 
+# Test storage with associated data.
+
 o2 = ObjectSet()
 o2.add("b")
 o2["c"] = ["x"]
@@ -15,9 +19,11 @@
 o2["d"] += ["p", "q"]
 print "o2 =", o2
 
-assert o1 != o2
 print "o1 == o2", o1 == o2
 print "o1 != o2", o1 != o2
+assert o1 != o2
+
+# Test merging.
 
 o12 = o1.merge(o2)
 print "o1 =", o1
@@ -26,37 +32,47 @@
 
 o12_keys = o12.keys()
 o12_keys.sort()
+print "o12_keys =", o12_keys
 assert o12_keys == ["a", "b", "c", "d"]
-print "o12_keys =", o12_keys
+
+# Test copying.
 
 o1_copy = ObjectSet(o1)
-assert o1 == o1_copy
 print "o1 =", o1
 print "o1_copy =", o1_copy
 print "o1 == o1_copy", o1 == o1_copy
+assert o1 == o1_copy
+
+# Test updating.
 
 o1_copy.update(o2)
-assert o1 != o1_copy
-assert o12 == o1_copy
 print "o1_copy =", o1_copy
 print "o1 != o1_copy", o1 != o1_copy
 print "o12 == o1_copy", o12 == o1_copy
+assert o1 != o1_copy
+assert o12 == o1_copy
 
 o3 = ObjectSet()
 o3.add("c")
 o3["c"].append("y")
 print "o3 =", o3
 
+# Test combining.
+
 d1 = {'a' : [ObjectSet(['f', 'g']), ObjectSet(['f', 'h'])]}
 d2 = {'a' : [ObjectSet(['f']), ObjectSet(['e', 'f', 'g'])]}
 d3 = combine_mapping_dicts(d1, d2)
 print "d1 =", d1
 print "d2 =", d2
 print "d3 =", d3
+assert d3["a"] == [ObjectSet(['f', 'g']), ObjectSet(['f', 'h']), ObjectSet(['e', 'f', 'g']), ObjectSet(['e', 'f', 'g', 'h'])]
+
+# Test combining with empty sets.
 
 d4 = {'a' : None}
 d5 = combine_mapping_dicts(d1, d4)
 print "d4 =", d4
 print "d5 =", d5
+assert d5 == d1
 
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r 43d594f9c436 -r a898fc7c3998 micropython/common.py
--- a/micropython/common.py	Mon Feb 27 23:17:50 2012 +0100
+++ b/micropython/common.py	Mon Feb 27 23:22:33 2012 +0100
@@ -3,7 +3,7 @@
 """
 Common classes.
 
-Copyright (C) 2007, 2008, 2009, 2010, 2011 Paul Boddie <paul@boddie.org.uk>
+Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012 Paul Boddie <paul@boddie.org.uk>
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -76,7 +76,10 @@
         return hash(tuple(self.keys()))
 
     def __eq__(self, other):
-        return self.objects == other.objects
+        if hasattr(other, "objects"):
+            return self.objects == other.objects
+        else:
+            return set(self.objects.keys()) == set(other)
 
     # Set methods.
 
@@ -228,13 +231,16 @@
     members.
     """
 
+    # If either list is undefined (indicated by None), return the defined list,
+    # or return None if neither is defined.
+
     if l1 is None:
         if l2 is None:
             return None
         else:
-            return l2 + [None]
+            return l2 + []
     elif l2 is None:
-        return l1 + [None]
+        return l1 + []
 
     combined = ObjectSet()
     for i1 in l1:
diff -r 43d594f9c436 -r a898fc7c3998 tests/attributes_instance_assignment.py
--- a/tests/attributes_instance_assignment.py	Mon Feb 27 23:17:50 2012 +0100
+++ b/tests/attributes_instance_assignment.py	Mon Feb 27 23:22:33 2012 +0100
@@ -15,9 +15,17 @@
         pass
     a.x = 3
 
+def g(a):   # {{z}, {x, z}}
+    if a.z:
+        a.x # {x, z}
+            # {z} (else)
+    a.z = 4
+
 c = C(1)
-d = D(2)
+d = D(0)
 f(c)
+g(d)
 result_3 = c.x
+result_4 = d.z
 
 # vim: tabstop=4 expandtab shiftwidth=4
diff -r 43d594f9c436 -r a898fc7c3998 tests/attributes_instance_assignment_on_self.py
--- a/tests/attributes_instance_assignment_on_self.py	Mon Feb 27 23:17:50 2012 +0100
+++ b/tests/attributes_instance_assignment_on_self.py	Mon Feb 27 23:22:33 2012 +0100
@@ -15,9 +15,16 @@
         self.y = y
         self.z = None
 
+    def g(self, a):
+        if self.z:
+            self.x
+        self.z = a
+
 c = C(1)
 d = D(2)
 c.f(3)
+d.g(4)
 result_3 = c.x
+result_4 = d.z
 
 # vim: tabstop=4 expandtab shiftwidth=4