Dynamic logical expression parsing/evaluation in PHP?

Question

I have a need to evaluate user-defined logical expressions of arbitrary complexity on some PHP pages. Assuming that form fields are the primary variables, it would need to:

Answer 1

You can try adapting my Evaluator class (https://github.com/djfm/Evaluator), it does arithmetic expressions (for now) and you can use variables too. All the major PHP operators are implemented.