;;-*-Lisp-*-
(in-package goal)

;; name: glist-h.gc
;; name in dgo: glist-h
;; dgos: GAME, ENGINE


;; Very very weird linked list system.
;; TODO add examples because this is extremely confusing.

(when *debug-segment*

(deftype glst-node (structure)
  ((next glst-node  :offset-assert 0)
   (prev glst-node  :offset-assert 4)
   )
  :method-count-assert 9
  :size-assert         #x8
  :flag-assert         #x900000008
  )

(deftype glst-named-node (glst-node)
  ((privname string     :offset-assert 8)
   )
  :method-count-assert 9
  :size-assert         #xc
  :flag-assert         #x90000000c
  )

(deftype glst-list (structure)
  ((head     glst-node  :offset-assert 0)
   (tail     glst-node  :offset-assert 4)
   (tailpred glst-node  :offset-assert 8)
   (numelem  int32      :offset-assert 12)
   )
  :allow-misaligned
  :method-count-assert 9
  :size-assert         #x10
  :flag-assert         #x900000010
  )


;; FUN FACT! The "defun" macro only checks if the first item in the function body is a
;; string (the docstring), but because these functions were marked as inline (or debug)
;; BEFORE the docstring, they end up being considered part of the body and the compiled output!
;; This amusing mistake is reproduced here.

(defun-debug glst-next ((node glst-node))
  (declare (inline))
  "return the next node in the list"

  (-> node next)
  )

(defun-debug glst-prev ((node glst-node))
  (declare (inline))
  "return the previous node in the list"

  (-> node prev)
  )

(defun-debug glst-head ((list glst-list))
  (declare (inline))
  "return the start of the list"

  (-> list head)
  )

(defun-debug glst-tail ((list glst-list))
  (declare (inline))
  "return the tail of the list"

  (-> list tailpred)
  )

(defun-debug glst-end-of-list? ((node glst-node))
  (declare (inline))
  "is this node the end of the list. #t = end"

  (not (-> node next))
  )

(defun-debug glst-start-of-list? ((node glst-node))
  (declare (inline))
  "is this node the start of the list. #t = start"

  (not (-> node prev))
  )

(defun-debug glst-empty? ((list glst-list))
  (declare (inline))
  "is the list empty, #t = empty"

  (= (-> list tailpred) (&-> list head))
  )

(defun-debug glst-node-name ((node glst-named-node))
  "Return the name of the node"

  (-> node privname)
  )

(defun-debug glst-set-name! ((node glst-named-node) (name string))
  "Set the name of the node"
  (declare (inline))

  (set! (-> node privname) name)
  )

 )