Java/Apex 中的动态逻辑表达式解析器/求值

Question

End-user can define condition selections/logical expressions in String like below:

• String expression = "((1 OR 2) AND 6 AND (3 OR 4)) AND 5";
• or String expression = "(1 AND 2 AND 3 AND 4) OR (5 AND 6)";
• or etc...

and the values of 1, 2, 3, ... are pre-calculated stored in a map like {1: true, 2: false, 3: true, ...}

The requirement is to evaluate the above expression with the values stored in the map and get the final output in true/false.

For eg.:

String expression = "(1 AND 2) OR 3";
Map<Integer, Boolean> values = new Map<Integer, Boolean>{1=> true, 2=> false, 3=> true};
System.debug(evaluate(expression, values)); // This should print true

In the above example "(1 AND 2) OR 3" should evaluates to "(true AND false) OR true", which result in final true answer.

I need help in writing the evaluate method.

Answer 1

I covered such problems by embedding Apache Jexl . Otherwise if you want to create your own parser go for Antlr - it likely has a ready to use example for you.