(in-package #:monparser)

(defun parse (parser data)
  (if (typep data 'string)
    (funcall parser
             (make-instance 'text :data data)
             (make-instance 'text :data data))
    (error "Only string parsing is allowed.")))

(defun append-on-failure (p message)
  (lambda (start input)
    (let ((result (funcall p start input)))
      (if (failure-p result)
        (make-failure :place (failure-place result)
                      :message (concatenate 'string message (failure-message result))
                      :priority (failure-priority result))
        result))))

(defmacro defparser (name args parser)
  (let ((message (format nil "In ~a:~&" name)))
    (cond ((equal args :const)
           `(defparameter ,name (append-on-failure ,parser ,message)))
          ((listp args)
           `(defun ,name ,args (append-on-failure ,parser ,message)))
          (t (error
               (format nil "Cannot define ~a: ~a is not :const or a list." name args))))))