Update tengo vendor and load the stdlib. Fixes #789 (#792)

vendor/github.com/d5/tengo/objects/object_ptr.go

@@ -0,0 +1,41 @@
+package objects
+
+import (
+	"github.com/d5/tengo/compiler/token"
+)
+
+// ObjectPtr represents a free variable.
+type ObjectPtr struct {
+	Value *Object
+}
+
+func (o *ObjectPtr) String() string {
+	return "free-var"
+}
+
+// TypeName returns the name of the type.
+func (o *ObjectPtr) TypeName() string {
+	return "<free-var>"
+}
+
+// BinaryOp returns another object that is the result of
+// a given binary operator and a right-hand side object.
+func (o *ObjectPtr) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	return nil, ErrInvalidOperator
+}
+
+// Copy returns a copy of the type.
+func (o *ObjectPtr) Copy() Object {
+	return o
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (o *ObjectPtr) IsFalsy() bool {
+	return o.Value == nil
+}
+
+// Equals returns true if the value of the type
+// is equal to the value of another object.
+func (o *ObjectPtr) Equals(x Object) bool {
+	return o == x
+}