core: adjust System.Enumerator.Create interop

Part of #1201.

It should be able to create enumerator from primitive byte-array-like
stack items too.

pkg/core/interop/enumerator/interop.go

@@ -10,7 +10,7 @@ func Concat(_ *interop.Context, v *vm.VM) error {
 	return vm.EnumeratorConcat(v)
 }
 
-// Create creates an enumerator from an array-like stack item.
+// Create creates an enumerator from an array-like or bytearray-like stack item.
 func Create(_ *interop.Context, v *vm.VM) error {
 	return vm.EnumeratorCreate(v)
 }

pkg/interop/enumerator/enumerator.go

@@ -9,11 +9,11 @@ package enumerator
 // or structures that have values with no explicit keys.
 type Enumerator struct{}
 
-// Create creates a new enumerator from the given items (slice or structure).
-// New enumerator points at index -1 of its items, so the user of it has to
-// advance it first with Next. This function uses `System.Enumerator.Create`
-// syscall.
-func Create(items []interface{}) Enumerator {
+// Create creates a new enumerator from the given items (slice, structure, byte
+// array and integer or boolean converted to byte array). New enumerator points
+// at index -1 of its items, so the user of it has to advance it first with Next.
+// This function uses `System.Enumerator.Create` syscall.
+func Create(items interface{}) Enumerator {
 	return Enumerator{}
 }
 

pkg/vm/interop.go

@@ -126,12 +126,25 @@ func init() {
 
 // EnumeratorCreate handles syscall System.Enumerator.Create.
 func EnumeratorCreate(v *VM) error {
-	data := v.Estack().Pop().Array()
-	v.Estack().Push(&Element{
-		value: stackitem.NewInterop(&arrayWrapper{
+	var interop interface{}
+	switch t := v.Estack().Pop().value.(type) {
+	case *stackitem.Array, *stackitem.Struct:
+		interop = &arrayWrapper{
+			index: -1,
+			value: t.Value().([]stackitem.Item),
+		}
+	default:
+		data, err := t.TryBytes()
+		if err != nil {
+			return fmt.Errorf("can not create enumerator from type %s: %v", t.Type(), err)
+		}
+		interop = &byteArrayWrapper{
 			index: -1,
 			value: data,
-		}),
+		}
+	}
+	v.Estack().Push(&Element{
+		value: stackitem.NewInterop(interop),
 	})
 
 	return nil

pkg/vm/interop_iterators.go

@@ -1,6 +1,8 @@
 package vm
 
 import (
+	"math/big"
+
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
 
@@ -15,6 +17,11 @@ type (
 		value []stackitem.Item
 	}
 
+	byteArrayWrapper struct {
+		index int
+		value []byte
+	}
+
 	concatEnum struct {
 		current enumerator
 		second  enumerator
@@ -63,6 +70,23 @@ func (a *arrayWrapper) Key() stackitem.Item {
 	return stackitem.Make(a.index)
 }
 
+func (a *byteArrayWrapper) Next() bool {
+	if next := a.index + 1; next < len(a.value) {
+		a.index = next
+		return true
+	}
+
+	return false
+}
+
+func (a *byteArrayWrapper) Value() stackitem.Item {
+	return stackitem.NewBigInteger(big.NewInt(int64(a.value[a.index])))
+}
+
+func (a *byteArrayWrapper) Key() stackitem.Item {
+	return stackitem.Make(a.index)
+}
+
 func (c *concatEnum) Next() bool {
 	if c.current.Next() {
 		return true