(defpackage :mfa-tool.store
   (:use :cl)

   (:export #:store #:execute #:dispatch
            #:next-store
            #:next-store-p

            #:propagate
            #:recording-store
            #:record))

 (in-package :mfa-tool.store)
 
 (defclass store ()

   ((%next-store :initarg :next-store :reader next-store)))
 (defun next-store-p (store)
   (slot-boundp store '%next-store))

 (fw.lu:defclass+ recording-store ()
   ((%record :reader record :accessor %record :initform ())))
 

 (defgeneric execute (store action)
   (:argument-precedence-order action store)
   (:method :around (store action)

     (call-next-method)
     store)

   (:method (store action)

     store))

 
 (defgeneric dispatch (store action)
   (:argument-precedence-order action store)
   (:method ((store store) action)

     (execute store action))
   (:method ((store symbol) action)
     (execute store action)))
 
 (defun propagate (store action)
   (when (next-store-p store)
     (dispatch (next-store store)
               action))
   store)

 
 (defmethod dispatch :before ((store recording-store) action)
   (push action
         (%record store)))