Implement Ellipsis type (#230)

runtime/builtin_types.go

@@ -27,6 +27,11 @@ var (
 	builtinStr = NewStr("__builtin__")
 	// ExceptionTypes contains all builtin exception types.
 	ExceptionTypes []*Type
+	// EllipsisType is the object representing the Python 'ellipsis' type
+	EllipsisType = newSimpleType("ellipsis", ObjectType)
+	// Ellipsis is the singleton ellipsis object representing the Python
+	// 'Ellipsis' object.
+	Ellipsis = &Object{typ: EllipsisType}
 	// NoneType is the object representing the Python 'NoneType' type.
 	NoneType = newSimpleType("NoneType", ObjectType)
 	// None is the singleton NoneType object representing the Python 'None'
@@ -44,10 +49,19 @@ var (
 	UnboundLocal = newObject(unboundLocalType)
 )
 
+func ellipsisRepr(*Frame, *Object) (*Object, *BaseException) {
+	return NewStr("Ellipsis").ToObject(), nil
+}
+
 func noneRepr(*Frame, *Object) (*Object, *BaseException) {
 	return NewStr("None").ToObject(), nil
 }
 
+func initEllipsisType(map[string]*Object) {
+	EllipsisType.flags &= ^(typeFlagInstantiable | typeFlagBasetype)
+	EllipsisType.slots.Repr = &unaryOpSlot{ellipsisRepr}
+}
+
 func initNoneType(map[string]*Object) {
 	NoneType.flags &= ^(typeFlagInstantiable | typeFlagBasetype)
 	NoneType.slots.Repr = &unaryOpSlot{noneRepr}
@@ -93,6 +107,7 @@ var builtinTypes = map[*Type]*builtinTypeInfo{
 	dictKeyIteratorType:           {init: initDictKeyIteratorType},
 	dictValueIteratorType:         {init: initDictValueIteratorType},
 	DictType:                      {init: initDictType, global: true},
+	EllipsisType:                  {init: initEllipsisType, global: true},
 	enumerateType:                 {init: initEnumerateType, global: true},
 	EnvironmentErrorType:          {global: true},
 	ExceptionType:                 {global: true},
@@ -628,6 +643,7 @@ func init() {
 		"cmp":            newBuiltinFunction("cmp", builtinCmp).ToObject(),
 		"delattr":        newBuiltinFunction("delattr", builtinDelAttr).ToObject(),
 		"dir":            newBuiltinFunction("dir", builtinDir).ToObject(),
+		"Ellipsis":       Ellipsis,
 		"False":          False.ToObject(),
 		"getattr":        newBuiltinFunction("getattr", builtinGetAttr).ToObject(),
 		"globals":        newBuiltinFunction("globals", builtinGlobals).ToObject(),

runtime/builtin_types_test.go

@@ -327,6 +327,13 @@ func TestBuiltinGlobals(t *testing.T) {
 	}
 }
 
+func TestEllipsisRepr(t *testing.T) {
+	cas := invokeTestCase{args: wrapArgs(Ellipsis), want: NewStr("Ellipsis").ToObject()}
+	if err := runInvokeMethodTestCase(EllipsisType, "__repr__", &cas); err != "" {
+		t.Error(err)
+	}
+}
+
 func TestNoneRepr(t *testing.T) {
 	cas := invokeTestCase{args: wrapArgs(None), want: NewStr("None").ToObject()}
 	if err := runInvokeMethodTestCase(NoneType, "__repr__", &cas); err != "" {

third_party/stdlib/types.py

@@ -72,7 +72,7 @@ except TypeError:
     del tb
 
 SliceType = slice
-#EllipsisType = type(Ellipsis)
+EllipsisType = type(Ellipsis)
 
 #DictProxyType = type(TypeType.__dict__)
 NotImplementedType = type(NotImplemented)