stackitem: allow to convert type from string

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

pkg/vm/stackitem/type.go

@@ -1,5 +1,7 @@
 package stackitem
 
+import "errors"
+
 // Type represents type of the stack item.
 type Type byte
 
@@ -54,3 +56,31 @@ func (t Type) IsValid() bool {
 		return false
 	}
 }
+
+// FromString returns stackitem type from string.
+func FromString(s string) (Type, error) {
+	switch s {
+	case "Any":
+		return AnyT, nil
+	case "Pointer":
+		return PointerT, nil
+	case "Boolean":
+		return BooleanT, nil
+	case "Integer":
+		return IntegerT, nil
+	case "ByteString":
+		return ByteArrayT, nil
+	case "Buffer":
+		return BufferT, nil
+	case "Array":
+		return ArrayT, nil
+	case "Struct":
+		return StructT, nil
+	case "Map":
+		return MapT, nil
+	case "Interop":
+		return InteropT, nil
+	default:
+		return 0xFF, errors.New("invalid type")
+	}
+}

pkg/vm/stackitem/type_test.go

@@ -0,0 +1,16 @@
+package stackitem
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFromString(t *testing.T) {
+	typs := []Type{AnyT, PointerT, BooleanT, IntegerT, ByteArrayT, BufferT, ArrayT, StructT, MapT, InteropT}
+	for _, typ := range typs {
+		actual, err := FromString(typ.String())
+		require.NoError(t, err)
+		require.Equal(t, typ, actual)
+	}
+}