82 lines
2.3 KiB
Racket
82 lines
2.3 KiB
Racket
#lang racket/base
|
|
;; Trivial demonstration of an os-big-bang style virtual machine.
|
|
;; Engages in various I/O and timer operations.
|
|
|
|
(require racket/match)
|
|
(require racket/port)
|
|
(require "os-big-bang.rkt")
|
|
|
|
(define display-driver-handler
|
|
(message-handlers w
|
|
[`(display ,message)
|
|
(transition w (send-meta-message (lambda ()
|
|
(display message)
|
|
(flush-output))))]))
|
|
|
|
(define read-line-driver-handler
|
|
(message-handlers w
|
|
[`(request ,reply-addr read-line)
|
|
(transition w
|
|
(subscribe/fresh sid
|
|
(ground-message-handler w
|
|
[((list 'read-line reply-addr)
|
|
(read-line-evt (current-input-port) 'any)
|
|
=> l)
|
|
(transition w
|
|
(unsubscribe sid)
|
|
(send-message `(reply ,reply-addr ,l)))])))]))
|
|
|
|
;; This should be part of racket
|
|
(define (time-evt msecs)
|
|
(wrap-evt (alarm-evt msecs) (lambda (_) (current-inexact-milliseconds))))
|
|
|
|
(define (tick-driver self-sid interval)
|
|
(let loop ((last-tick-time 0) (counter 0))
|
|
(define next-time (+ last-tick-time interval))
|
|
(subscribe self-sid
|
|
(ground-message-handler w
|
|
[((list 'timer-alarm next-time)
|
|
(time-evt next-time)
|
|
=> now)
|
|
(transition w
|
|
(unsubscribe self-sid)
|
|
(send-message `(tick ,counter ,now))
|
|
(loop now (+ counter 1)))]))))
|
|
|
|
(define main
|
|
(os-big-bang 'none
|
|
(subscribe 'display-driver display-driver-handler)
|
|
(subscribe 'read-line-driver read-line-driver-handler)
|
|
(tick-driver 'ticker 1000)
|
|
(send-message `(display "Hello! "))
|
|
(send-message 'greet-loop)
|
|
(subscribe 'greet-loop-handler
|
|
(message-handlers w
|
|
['greet-loop
|
|
(transition w
|
|
(send-message `(display "Enter your name:\n"))
|
|
(send-message `(request read-name read-line)))]))
|
|
(subscribe 'ticker-handler
|
|
(message-handlers w
|
|
[`(tick ,counter ,_)
|
|
(transition w
|
|
(send-message
|
|
`(display ,(string-append "TICK "
|
|
(number->string counter)
|
|
"\n"))))]))
|
|
(subscribe 'read-line-result-handler
|
|
(message-handlers w
|
|
[`(reply read-name ,(== eof))
|
|
(transition w
|
|
(send-message `(display "Goodbye!\n")))]
|
|
[`(reply read-name ,name)
|
|
(transition w
|
|
(send-message `(display "Hello, "))
|
|
(send-message `(display ,name))
|
|
(send-message `(display "!\n"))
|
|
(unsubscribe 'ticker)
|
|
(send-message 'greet-loop)
|
|
)]))))
|
|
|
|
(ground-vm main)
|