How to evaluate variables that are themselves expressions

[cabintech]

I want to be able to evaluate an expression that contains variables. The value of those variables may themselves be expression strings, e.g. I want the following to output "10":

		Map<String,Object> m = new HashMap<>();
		m.put("X", "3");
		m.put("Y", "X+2");
		try {
			Expression expr = new Expression("Y+5");
			System.out.println(expr.withValues(m).evaluate().getStringValue()+"");
		}
		catch (Throwable t) {
			System.out.println("eval failed: "+t.getMessage());
		}

As written this outputs "X+25".

Is this possible?

[uklimaschewski]

See the discussion in #229. With EvalEx 3, you have the possibility of having sub-expressions with the EXPRESSION_NODE data type, e.g.:

Expression expression = new Expression("a*b");

ASTNode subExpression = expression.createExpressionNode("4+3");

EvaluationValue result = expression
    .with("a", 2)
    .and("b", subExpression)
    .evaluate();

System.out.println(result); // prints 14