#!/usr/bin/env newlisp


;;; Only options that begin with two dashes may be set to a value.
;;;
;;; Option is the public class.  Members are:
;;;   * Switch: string token identifying the option in (main-args)
;;;   * Required: whether or not this option is required to exist in (main-args)
;;;     - affects validation
;;;   * Predicate: if this is set to a lambda, this will be used to validate
;;;     the value.


(catch
  (define (Class:Class)
    (cons (context) (args))))


(map (curry new Class) '(Option Switch Required Predicate))


(define (Option:get self , loc val)
  (set 'switch (last (assoc (self Switch))))
  (if (set 'loc (find switch (main-args)))
    (cond
      ((and (starts-with switch "--") (catch (nth (+ 1 loc) (main-args)) 'val))
        val)
      ((starts-with switch "--") true)
      ((starts-with switch "-") true)
      (true nil))
    nil))


(define (Option:valid? self , val req pred req? pred?)
  (set 'val (:get self))
  (set 'req? (assoc (self Required)))
  (set 'pred? (assoc (self Predicate)))
  (set 'req (if req? (true? val) true))
  (set 'pred (if pred? ((last pred?) val) true))
  (and req pred))