Merge pull request #8 from Sean-Der/implement-tuple2-decode

Implement the TUPLE2 Opcode

ogórek.go

@@ -205,6 +205,8 @@ func (d Decoder) Decode() (interface{}, error) {
 			err = d.loadSetItem()
 		case opTuple:
 			err = d.loadTuple()
+		case opTuple2:
+			err = d.loadTuple2()
 		case opEmptyTuple:
 			d.push([]interface{}{})
 		case opSetitems:
@@ -607,6 +609,13 @@ func (d *Decoder) loadTuple() error {
 	return nil
 }
 
+func (d *Decoder) loadTuple2() error {
+	k := len(d.stack) - 2
+	v := append([]interface{}{}, d.stack[k:]...)
+	d.stack = append(d.stack[:k], v)
+	return nil
+}
+
 func (d *Decoder) obj() error {
 	return errNotImplemented
 }

ogórek_test.go

@@ -41,6 +41,7 @@ func TestDecode(t *testing.T) {
 		{"tuple of two ints", "(I1\nI2\ntp0\n.", []interface{}{int64(1), int64(2)}},
 		{"nested tuples", "((I1\nI2\ntp0\n(I3\nI4\ntp1\ntp2\n.",
 			[]interface{}{[]interface{}{int64(1), int64(2)}, []interface{}{int64(3), int64(4)}}},
+		{"tuple with top 2 items from stack", "I0\nI1\n\x86.", []interface{}{int64(0), int64(1)}},
 		{"empty list", "(lp0\n.", []interface{}{}},
 		{"list of numbers", "(lp0\nI1\naI2\naI3\naI4\na.", []interface{}{int64(1), int64(2), int64(3), int64(4)}},
 		{"string", "S'abc'\np0\n.", string("abc")},