Looking for an expression evaluator

user_23428 0
Viewed 31200

I'm looking for an evaluator for simple condition expressions. Expressions should include variables (read only), strings, numbers and some basic operators.

E.g. expressions something like this:

${a} == "Peter" && ( ${b} == null || ${c} > 10 )

So far i implemented a rather "magical" parser that returns an AST that i can evaluate, but i can't believe that i'm the first one to solve that problem.

What existing code could i use instead?

java
7 Answers

Here is a little library I've worked on that supports expression evaluation (including variables, strings, boolean, etc...).

A little example :

String expression = "EXP(var)";
ExpressionEvaluator evaluator = new ExpressionEvaluator();
evaluator.putVariable(new Variable("var", VariableType.NUMBER, new BigDecimal(20)));

System.out.println("Value of exp(var) : " + evaluator.evaluate(expression).getValue());
user_36088310
Related