;;; -*- mode: Lisp; Syntax: Common-Lisp; -*-
;;;
;;; Copyright (c) 2009 by the authors.
;;;
;;; See LICENCE for details.

(in-package :hu.dwim.excosy)

;;;;;;
;;; Nothing

(def class* nothing/ast (ast)
  ())

(def function read-nothing (machine ast input)
  (make-instance 'nothing))

(def function print-nothing (machine ast output)
  (values))

(def function interpret-nothing (machine ast)
  (values))

;;;;;;
;;; Boolean

;; TODO: kill?
(def class* boolean/ast (ast)
  ((reader-function 'read-boolean)
   (printer-function 'print-boolean)
   (interpreter-function 'interpret-abstraction)
   (memory-location-allocator-function 'allocate-boolean-memory-location)
   (value :type boolean)))

(def function read-boolean (machine ast input)
  ;; TODO:
  nil)

(def function print-boolean (machine ast output)
  (if (value-p ast)
      (format output "true")
      (format output "false")))

(def function allocate-boolean-memory-location (machine ast)
  (declare (ignore machine))
  (logior (ash (if (value-p ast) 0 1) 2) #b01))

;;;;;;
;;; Integer

(def class* integer/ast (ast)
  ((reader-function 'read-integer)
   (printer-function 'print-integer)
   (interpreter-function 'interpret-abstraction)
   (memory-location-allocator-function 'allocate-integer-memory-location)
   (value :type integer)))

(def function read-integer (machine ast input)
  (make-instance 'integer :value (parse-integer input)))

(def function print-integer (machine ast output)
  (format output "~A" (value-of ast)))

(def function allocate-integer-memory-location (machine ast)
  (declare (ignore machine))
  (logior (ash (value-of ast) 2) #b00))