Category : Miscellaneous Language Source Code
Archive   : XLISP21D.ZIP
Filename : TURTLES.LSP

(unless (fboundp 'defclass) (load 'classes))

; On an IBM PC, ANSI escape sequences probably won't work unless you use
; NNANSI.SYS because the buffered output used bypasses the BIOS.

; This is a sample XLISP program
; It implements a simple form of programmable turtle for VT100 compatible
; terminals.

; To run it:

; A>xlisp turtles

; This should cause the screen to be cleared and two turtles to appear.
; They should each execute their simple programs and then the prompt
; should return. Look at the code to see how all of this works.

; Get some more memory
(expand 1)

; delay a while
(if (fboundp 'get-internal-run-time)
(defun pause (time)
(let ((fintime (+ (* time internal-time-units-per-second)
(get-internal-run-time))))
(loop (when (> (get-internal-run-time) fintime)
(return-from pause)))))
(defun pause () (dotimes (x (* time 1000)))))

(defmacro delay () (pause 0.5))


; Clear the screen
(defun clear ()
(princ "\033[H\033[2J"))


; Move the cursor
(defun setpos (x y)
(princ "\033[") (princ y) (princ ";") (princ x) (princ "H"))

; Kill the remainder of the line
(defun kill ()
(princ "\033[K"))

; Move the cursor to the currently set bottom position and clear the line
; under it
(defun bottom ()
(setpos *bx* (+ *by* 1))
(kill)
(setpos *bx* *by*)
(kill))

; Clear the screen and go to the bottom
(defun cb ()
(clear)
(bottom))


; ::::::::::::
; :: Turtle ::
; ::::::::::::

; Define "Turtle" class
(defclass Turtle ((xpos (setq *newx* (+ *newx* 1))) (ypos 12) (char "*")))

; Message ":display" prints its char at its current position
(defmethod Turtle :display ()
(setpos xpos ypos)
(princ char)
(bottom)
self)

; When the character is set, we want to redisplay
(defmethod Turtle :set-char (c)
(setq char c)
(send self :display))

; Message ":char" sets char to its arg and displays it
(defmethod Turtle :set-char (c)
(setq char c)
(send self :display))

; Message ":goto" goes to a new place after clearing old one
(defmethod Turtle :goto (x y)
(setpos xpos ypos) (princ " ")
(setq xpos x)
(setq ypos y)
(send self :display))

; Message ":up" moves up if not at top
(defmethod Turtle :up ()
(if (> ypos 0)
(send self :goto xpos (- ypos 1))
(bottom)))

; Message ":down" moves down if not at bottom
(defmethod Turtle :down ()
(if (< ypos *by*)
(send self :goto xpos (+ ypos 1))
(bottom)))

; Message ":right" moves right if not at right
(defmethod Turtle :right ()
(if (< xpos 80)
(send self :goto (+ xpos 1) ypos)
(bottom)))

; Message ":left" moves left if not at left
(defmethod Turtle :left ()
(if (> xpos 0)
(send self :goto (- xpos 1) ypos)
(bottom)))

; :::::::::::::::::::
; :: Circular-List ::
; :::::::::::::::::::


; Define a class to represent a circular list
(defclass Circular-List (prog pc))

; Replace :isnew with something more appropriate
(defmethod Circular-List :isnew (&optional list)
(setf prog list pc list)
self) ; return self

; Method to get next item in list
(defmethod Circular-List :next ()
(when (null pc) (setq pc prog))
(prog1 (car pc) (setq pc (cdr pc))))


; :::::::::::::
; :: PTurtle ::
; :::::::::::::

; Define "PTurtle" programable turtle class
(defclass PTurtle (prog) () Turtle)

; Message ":program" stores a program
(defmethod PTurtle :program (p)
(setf prog (send Circular-List :new p))
self)

; Message ":step" executes a single program step
(defmethod PTurtle :step ()
(when prog (send self (send prog :next)))
(delay)
self)

; Message ":step#" steps each turtle program n times
(defmethod PTurtle :step# (n)
(dotimes (x n) (send self :step))
self)


; ::::::::::::::
; :: PTurtles ::
; ::::::::::::::

; Define "PTurtles" class
(defclass PTurtles (Turtles))

; Message ":make" makes a programable turtle and adds it to the collection
(defmethod PTurtles :make (x y &aux newturtle)
(setq newturtle (send PTurtle :new :xpos x :ypos y))
(setq Turtles (cons newturtle Turtles))
newturtle)

; Message ":step" steps each turtle program once
(defmethod PTurtles :step ()
(mapcar #'(lambda (Turtle) (send Turtle :step)) Turtles)
self)

; Message ":step#" steps each turtle program n times
(defmethod PTurtles :step# (n)
(dotimes (x n) (send self :step))
self)


; Initialize things and start up
(defvar *bx* 0)
(defvar *by* 20)
(defvar *newx* 0)

; Create some programmable turtles
(cb)
(definst PTurtles Turtles)
(setq t1 (send Turtles :make 40 10))
(setq t2 (send Turtles :make 41 10))
(send t1 :program '(:left :left :right :right :up :up :down :down))
(send t2 :program '(:right :right :down :down :left :left :up :up))
(send t1 :set-char "+")
(defun doit ()
(progn
(cb)
(send t1 :step# 8)
(send t2 :step# 8)
(send Turtles :step# 8)))
(doit)