lua 5.1+ compatible encoding of unicode characters as escaped decimal bytes

Author: smarek

shared/src/main/scala/io/kaitai/struct/translators/LuaTranslator.scala

@@ -1,5 +1,7 @@
 package io.kaitai.struct.translators
 
+import java.nio.charset.StandardCharsets
+
 import io.kaitai.struct.ImportList
 import io.kaitai.struct.datatype.DataType
 import io.kaitai.struct.datatype.DataType._
@@ -22,8 +24,11 @@ class LuaTranslator(provider: TypeProvider, importList: ImportList) extends Base
     '\33' -> "\\027"
   )
 
-  override def strLiteralUnicode(code: Char): String =
-    "\\u{%04x}".format(code.toInt)
+  override def strLiteralUnicode(code: Char): String = {
+    // compatible unicode encoding UTF8 bytes as \ddd where d = number 0-255
+    // handles both 1 and 2 bytes Chars/codes
+    String.valueOf(code).getBytes(StandardCharsets.UTF_8).map("\\%d" format _ & 0xff).mkString
+  }
 
   override def numericBinOp(left: Ast.expr, op: Ast.operator, right: Ast.expr) = {
     (detectType(left), detectType(right), op) match {