chatikbot/utils.lisp

(in-package #:chatikbot)

(defvar *backoff-start* 1 "Initial back-off")
(defvar *backoff-max* 64 "Maximum back-off delay")

(defun loop-with-error-backoff (func)
  (let ((backoff *backoff-start*))
    (loop
       do
         (handler-case
             (progn
               (funcall func)
               (setf backoff *backoff-start*))
           (error (e)
             (log:error e)
             (log:info "Backing off for" backoff)
             (sleep backoff)
             (setf backoff (min *backoff-max*
                                (* 2 backoff))))
	   (bordeaux-threads:timeout (e)
             (log:error e)
             (log:info "Backing off for" backoff)
             (sleep backoff)
             (setf backoff (min *backoff-max*
                                (* 2 backoff))))))))

(defun replace-all (string part replacement &key (test #'char=))
  "Returns a new string in which all the occurences of the part
is replaced with replacement."
  (with-output-to-string (out)
    (loop with part-length = (length part)
       for old-pos = 0 then (+ pos part-length)
       for pos = (search part string
                         :start2 old-pos
                         :test test)
       do (write-string string out
                        :start old-pos
                        :end (or pos (length string)))
       when pos do (write-string replacement out)
       while pos)))

(defmacro aget (key alist)
  `(cdr (assoc ,key ,alist :test #'equal)))

(defun mappend (fn &rest lists)
  "Apply fn to each element of lists and append the results."
  (apply #'append (apply #'mapcar fn lists)))

(defun random-elt (choices)
  "Choose an element from a list at random."
  (elt choices (random (length choices))))

(defun flatten (the-list)
  "Append together elements (or lists) in the list."
  (mappend #'(lambda (x) (if (listp x) (flatten x) (list x))) the-list))

(defun make-circular (items)
  "Make items list circular"
  (setf (cdr (last items)) items))

(defmacro push-circular (obj circ)
  "Move circ list and set head to obj"
  `(progn
     (pop ,circ)
     (setf (car ,circ) ,obj)))

(defmacro peek-circular (circ)
  "Get head of circular list"
  `(car ,circ))

(defmacro pop-circular (circ)
  "Get head of circular list"
  `(pop ,circ))

(defun flat-circular (circ)
  "Flattens circular list"
  (do ((cur (cdr circ) (cdr cur))
       (head circ)
       result)
      ((eq head cur)
       (nreverse (push (car cur) result)))
    (push (car cur) result)))