set: Implement __sub__ and __xor__ of set (#88)

* set: Implement __sub__ of set

* set: Implement __xor__ of set

Author: DoDaek

py/set.go

@@ -142,6 +142,43 @@ func (s *Set) M__or__(other Object) (Object, error) {
 	return ret, nil
 }
 
+func (s *Set) M__sub__(other Object) (Object, error) {
+	ret := NewSet()
+	b, ok := other.(*Set)
+	if !ok {
+		return nil, ExceptionNewf(TypeError, "unsupported operand type(s) for &: '%s' and '%s'", s.Type().Name, other.Type().Name)
+	}
+	for j := range s.items {
+		ret.items[j] = SetValue{}
+	}
+	for i := range b.items {
+		if _, ok := s.items[i]; ok {
+			delete(ret.items, i)
+		}
+	}
+	return ret, nil
+}
+
+func (s *Set) M__xor__(other Object) (Object, error) {
+	ret := NewSet()
+	b, ok := other.(*Set)
+	if !ok {
+		return nil, ExceptionNewf(TypeError, "unsupported operand type(s) for &: '%s' and '%s'", s.Type().Name, other.Type().Name)
+	}
+	for j := range s.items {
+		ret.items[j] = SetValue{}
+	}
+	for i := range b.items {
+		_, ok := s.items[i]
+		if ok {
+			delete(ret.items, i)
+		} else {
+			ret.items[i] = SetValue{}
+		}
+	}
+	return ret, nil
+}
+
 // Check interface is satisfied
 var _ I__len__ = (*Set)(nil)
 var _ I__bool__ = (*Set)(nil)

py/tests/set.py

@@ -30,4 +30,32 @@
 assert 4 in c
 assert 5 in c
 
+doc="__sub__"
+a = {1, 2, 3}
+b = {2, 3, 4, 5}
+c = a.__sub__(b)
+d = b.__sub__(a)
+assert 1 in c
+assert 4 in d
+assert 5 in d
+
+e = a - b
+f = b - a
+assert 1 in c
+assert 4 in d
+assert 5 in d
+
+doc="__xor__"
+a = {1, 2, 3}
+b = {2, 3, 4, 5}
+c = a.__xor__(b)
+assert 1 in c
+assert 4 in c
+assert 5 in c
+
+d = a ^ b
+assert 1 in c
+assert 4 in c
+assert 5 in c
+
 doc="finished"