Evolutionary Goo

Since my JEval open source project was released on February 21, 2007, it has been downloaded 464 times. Far from staggering numbers. I doubt I will writing a book on it anytime soon. However, shortly after the release I got some positive feedback, which was cool and its still nice to see downloads every week.

What does JEval do you ask? Its a simple, lightweight functional expression parser and evaluator. And It has NO dependencies to any other libraries.

A few quick code examples:

Evaluator evaluator = new Evaluator();
String result = null;

// A mathematical expression.
result = evaluator.evaluate(”4 + (3 * 1) - (3 + 1) + 1″);
System.out.println(result);
// A built-in mathematical function.
result = evaluator.evaluate(”1 + abs(-1)”) ;
System.out.println(result);

// A string expression.
result = evaluator.evaluate(”‘A’ + ‘C’”);
System.out.println(result);

// A built-in string function.
result = evaluator.evaluate(”trim(’abc ‘) + ‘d’”);
System.out.println(result);

// A boolean expression.
result = evaluator.evaluate(”((2 < 3) || (1 == 1)) && (3 < 3)”) ;
System.out.println(result);

// A variable.
evaluator.putVariable(”a”, “‘Hello’”);
evaluator.putVariable(”b”, “‘World’”);
evaluator.evaluate(”#{a} + ‘ ‘ + #{b} + ‘!’”);
System.out.println(result);

// A nested function using a built-in mathematical function.
result = evaluator.evaluate(”atan2(atan2(1, 1), 1)”);
System.out.println(result);

// A custom function.
evaluator.putFunction(new StringReverseFunction());
result = evaluator.evaluate(”stringReverse(’Hello World!’)”);
System.out.println(result);

Download here.

Craig McClanahan, the creator of Struts and Java Server Faces, is singing the praises of Ruby on Rails. This is awesome PR for Rails, that’s for sure.