Make SSM library actually usable.

load/simple-state-machines.el

@@ -61,7 +61,31 @@
 ;; 'test-step' -- Calls the handler for the current state.
 ;; 'test-set-state' -- Tries to set the current state to the provided one, and
 ;; signals an error if the transition is invalid.
-
+;;
+;; Here is the recreation of the counter example from
+;; https://www.emacswiki.org/emacs/StateMachine
+;; 
+;; (ssm-defstate-machine counter
+;;   :states (start count end)
+;;   :transitions ((start . count)
+;;                 (count . end)
+;;                 (count . count))
+;;   :handlers ((start . (lambda (name)
+;;                         (princ "Starting...")
+;;                         (terpri)
+;;                         (ssm-update-state name 'count 0)))
+;;              (count . (lambda (name)
+;;                         (cond ((<= (ssm-get-state-data name) 10)
+;;                                (princ (ssm-get-state-data name))
+;;                                (ssm-update-state
+;;                                 name
+;;                                 'count
+;;                                 (1+ (ssm-get-state-data name))))
+;;                               (t (terpri) (ssm-update-state name 'end nil)))))))
+;; 
+;; (ssm-run-until-state 'counter 'end)
+;;
+;; As you can see, ssm-update-state definitely needs some love. It is unwieldy.
 ;;; Code:
 
 (require 'cl-lib)
@@ -142,7 +166,7 @@ Each entry of this alist has the form (FROM . TO)."))
                  (let ((,handler (alist-get ,current-state ,handlers-table))
                        (,prev-state ,current-state))
                    (cl-assert ,handler nil "There is no handler for the current state")
-                   (funcall ,handler ,machine-name)
+                   (funcall ,handler ',name)
                    (cl-assert
                     (cl-find
                      (cons ,prev-state ,current-state)
@@ -165,12 +189,31 @@ Each entry of this alist has the form (FROM . TO)."))
                  (setq ,current-state state
                        ,state-data new-data))))))))
 
-(defun ssm-update-state (machine new-state &optional new-data)
+(defun ssm-update-state (machine new-state new-data)
   "Updates the state of the state machine MACHINE. Signals an error if the
 state transition is invalid."
   (let ((state-fn
-         (intern-soft (concat machine "-set-state"))))
+         (intern-soft (concat (symbol-name machine) "-set-state"))))
     (funcall state-fn new-state new-data)))
 
+(defun ssm-get-state (machine)
+  "Returns the state of the specified machine."
+  (let ((state
+         (intern-soft (concat (symbol-name machine) "-current-state"))))
+    (symbol-value state)))
+
+(defun ssm-get-state-data (machine)
+  "Returns the state data of the specified machine."
+  (let ((state-data
+         (intern-soft (concat (symbol-name machine) "-state-data"))))
+    (symbol-value state-data)))
+
+(defun ssm-run-until-state (machine state)
+  "Steps the specified MACHINE until it enters state STATE."
+  (let ((step-fn
+         (intern-soft (concat (symbol-name machine) "-step"))))
+    (while (not (equal (ssm-get-state machine) state))
+      (funcall step-fn))))
+
 (provide 'simple-state-machines)
 ;;; simple-state-machines.el ends here