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

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

@@ -0,0 +1,57 @@
+package objects
+
+import "github.com/d5/tengo/compiler/token"
+
+// BytesIterator represents an iterator for a string.
+type BytesIterator struct {
+	v []byte
+	i int
+	l int
+}
+
+// TypeName returns the name of the type.
+func (i *BytesIterator) TypeName() string {
+	return "bytes-iterator"
+}
+
+func (i *BytesIterator) String() string {
+	return "<bytes-iterator>"
+}
+
+// BinaryOp returns another object that is the result of
+// a given binary operator and a right-hand side object.
+func (i *BytesIterator) BinaryOp(op token.Token, rhs Object) (Object, error) {
+	return nil, ErrInvalidOperator
+}
+
+// IsFalsy returns true if the value of the type is falsy.
+func (i *BytesIterator) IsFalsy() bool {
+	return true
+}
+
+// Equals returns true if the value of the type
+// is equal to the value of another object.
+func (i *BytesIterator) Equals(Object) bool {
+	return false
+}
+
+// Copy returns a copy of the type.
+func (i *BytesIterator) Copy() Object {
+	return &BytesIterator{v: i.v, i: i.i, l: i.l}
+}
+
+// Next returns true if there are more elements to iterate.
+func (i *BytesIterator) Next() bool {
+	i.i++
+	return i.i <= i.l
+}
+
+// Key returns the key or index value of the current element.
+func (i *BytesIterator) Key() Object {
+	return &Int{Value: int64(i.i - 1)}
+}
+
+// Value returns the value of the current element.
+func (i *BytesIterator) Value() Object {
+	return &Int{Value: int64(i.v[i.i-1])}
+}