Implement and of set (#82)

* set: implement __and__ of set

* set: add test code of set

* set: modify year of the copyright and return value of the function

Author: DoDaek

py/set.go

@@ -111,6 +111,20 @@ func (s *Set) M__iter__() (Object, error) {
 	return NewIterator(items), nil
 }
 
+func (s *Set) M__and__(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 i := range b.items {
+		if _, ok := s.items[i]; ok {
+			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

@@ -0,0 +1,16 @@
+# Copyright 2019 The go-python Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+doc="__and__"
+a = {1, 2, 3}
+b = {2, 3, 4, 5}
+c = a.__and__(b)
+assert 2 in c
+assert 3 in c
+
+d = a & b
+assert 2 in d
+assert 3 in d
+
+doc="finished"