;;;;;;;;;;;;;;;;;;; -*- Mode: Lisp; Package: Macsyma -*- ;;;;;;;;;;;;;;;;;;;
;;;     (c) Copyright 1980 Massachusetts Institute of Technology         ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(macsyma-module suspen)

;;; For ASB so that he can suspend macsyma at the point of
;;; a BUG. 12:53am  Wednesday, 4 February 1981 -gjc

;;; I've changed this so that SUSPEND should be able to be
;;; used in the middle of a BATCH/WRITEFILE and save the correct
;;; state for a re-start. 4:35pm  Sunday, 15 March 1981

;;; This still needs a lot of work in the way of systemic design if
;;; it is going to really win. (Reseting of terminal types etc).

(defmvar $suspend nil
	"If not FALSE then this is the name of the file to which the
	macsyma in question was last SUSPEND'ed. SUSPEND(); will
	then suspend the macsyma back into that file again.")

(defmfun $suspend (&optional
		   (filename (or $suspend
				 (merror "No filename given to suspend to."))))
	 (or (symbolp filename)
	     (merror "filename must be string~%~M" filename))
	 (setq filename (namestring
			 (mergef (stripdollar filename)
				 `((DSK ,(STATUS UDIR)) TS ,(STATUS UNAME)))))
	 (setq $suspend (concat '|&| filename))
	 (let ((file-object-state (close-files))
	       (TTY-RETURN NIL))
	      (print file-object-state t)
	      (terpri t)
	      (suspend (concat '|: Suspended to "|
			     filename
			     '|" î:KILLî|)
		       filename)
	      (open-files file-object-state)
	      $suspend))

(eval-when (eval compile)
	   (defstruct (filestate conc-name list default-pointer)
		      object
		      mode
		      operations
		      alist))

(defun close-files ()
       ;; "files" should include all state connected with the
       ;; outside world. When we re-open the TTY stream for example
       ;; it would be nice if all the state-variables associated with
       ;; it got reset. Fat chance though without restructuring all
       ;; macsyma I/O.
       (do ((gcmkl (munkam (examine (getddtsym 'GCMKL)))
		   ;; a list kept by the garbage collector.
		   ;; we really want a list kept by the macsyma system.
		   (cddr gcmkl))
	    (dedsar (getddtsym 'DEDSAR))
	    (filestates))
	   ((null gcmkl) filestates)
	   (if (and (not (eq (car gcmkl) dedsar))            ; not dead.
		    (memq (car (arraydims (car gcmkl)))
			  '(file sfa))                       ; is a file.
		    (status filemode (car gcmkl)))           ; is open.
	       (let ((filestate
		      (make-filestate
		       mode (car (status filemode (car gcmkl)))
		       operations (cdr (status filemode (car gcmkl)))
		       object (car gcmkl))))
		    (if (memq 'filepos (filestate-operations))
			(push `(filepos . ,(filepos (filestate-object)))
			      (filestate-alist)))
		    (close (filestate-object))
		    (push filestate filestates)))))

(defun open-files (l &aux
		     (io-lossage
		      #'(lambda (args)
				(declare (special args))
				(mformat-open
				 t
				 "~%Error in trying to ~A the object ~A.~
				 ~%~A. Cannot restore state without help.~%"
				 (car args) (cadr args)
				 (caaddr (errframe nil)))
				(*break t 'io-lossage))))
       (mapc #'(lambda (filestate)
		       (cond ((memq 'out (filestate-mode))
			      (open (filestate-object) 'append))
			     ((memq 'in (filestate-mode))
			      (open (filestate-object))
			      (if (memq 'filepos (filestate-operations))
				  (filepos (filestate-object)
					   (cdr (assq 'filepos
						      (filestate-alist))))))
			     (t
			      (open (filestate-object)))))
	     l))