metaprogramming - Creating meta language with Java

Question

guys! I need to create some sort of meta language which I could embed in XML and then parse with Java. For example:

<code>
    [if value1>value2 then "Hello, Bob!" else "Hello, Jack"]
</code>

or

 <code>
     [if value1+2>value2 return true]
 </code>

I need to implement conditional statements,arithmetics.

Any suggestions where should I start looking?

Answer 1

Java has a built-in JavaScript interpreter:

ScriptEngine jsEngine = new ScriptEngineManager().getEngineByName("JavaScript");
jsEngine.put("value1", 8);
jsEngine.put("value2", 9);
String script = "if(value1 + 2 > value2) {'Foo'} else {'Bar'}";
final Object result = jsEngine.eval(script);
System.out.println(result);  //yields "Foo" String

Of course you are free to both load the script from anywhere you need and to provide it with any context (value and value2 in this example) you want.

See also Scripting for the Java Platform article.