// requires class _javax and ctex

static String execute(String src) ctex {
  Class<?> mainClass = execute_compileAndLoadMainClass(src);
  Method m = execute_findCalcMethod(mainClass);
  return String.valueOf(m.invoke(null));
}

// compile JavaX source and load main class
static Class<?> execute_compileAndLoadMainClass(String src) tex {
  File srcDir = _javax.TempDirMaker_make();
  File classesDir = _javax.TempDirMaker_make();
  _javax.saveTextFile(new File(srcDir, "main.java").getPath(), src);
  new List<File> libraries;
  _javax.safeTranslate = true;
  File transpiledDir = _javax.topLevelTranslate(srcDir, libraries);
  String javacOutput = _javax.compileJava(transpiledDir, libraries, classesDir);
  System.out.println(javacOutput);
  URL[] urls = {classesDir.toURI().toURL()};
  
  // make class loader
  URLClassLoader classLoader = new URLClassLoader(urls);

  // load main class
  Class<?> mainClass = classLoader.loadClass("main");
  return mainClass;
}
    
static Method execute_findCalcMethod(Class<?> theClass) {
  for (Method method : theClass.getMethods())
    if (method.getName().equals("calc"))
      return method;
  throw new RuntimeException("Method 'calc' not found in " + theClass.getName());
}