Implement __getitem__ & __setitem__ for List and __getitem__ for Tuple

ncw · ncw · commit 89966c1fbd7c · 2013-11-27T23:51:02.000Z
diff --git a/py/internal.go b/py/internal.go
@@ -67,6 +67,21 @@ func IndexInt(a Object) int {
 	return intI
 }
 
+// As IndexInt but if index is -ve addresses it from the end
+//
+// If index is out of range throws IndexError
+func IndexIntCheck(a Object, max int) int {
+	i := IndexInt(a)
+	if i < 0 {
+		i += max
+	}
+	if i < 0 || i >= max {
+		// FIXME IndexError
+		panic("IndexError: list index out of range")
+	}
+	return i
+}
+
 // Return the result of not a
 func Not(a Object) Object {
 	switch MakeBool(a) {
diff --git a/py/list.go b/py/list.go
@@ -35,9 +35,22 @@ func (t List) M__iter__() Object {
 	return NewIterator(t)
 }
 
+func (t List) M__getitem__(key Object) Object {
+	i := IndexIntCheck(key, len(t))
+	return t[i]
+}
+
+func (t List) M__setitem__(key, value Object) Object {
+	i := IndexIntCheck(key, len(t))
+	t[i] = value
+	return None
+}
+
 // Check interface is satisfied
 var _ I__len__ = List(nil)
 var _ I__bool__ = List(nil)
 var _ I__iter__ = List(nil)
+var _ I__getitem__ = List(nil)
+var _ I__setitem__ = List(nil)
 
 // var _ richComparison = List(nil)
diff --git a/py/tuple.go b/py/tuple.go
@@ -34,9 +34,15 @@ func (t Tuple) M__iter__() Object {
 	return NewIterator(t)
 }
 
+func (t Tuple) M__getitem__(key Object) Object {
+	i := IndexIntCheck(key, len(t))
+	return t[i]
+}
+
 // Check interface is satisfied
 var _ I__len__ = Tuple(nil)
 var _ I__bool__ = Tuple(nil)
 var _ I__iter__ = Tuple(nil)
+var _ I__getitem__ = Tuple(nil)
 
 // var _ richComparison = Tuple(nil)
