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(in-package #:mulk.objective-cl)
(defvar *id-objects* (make-weak-value-hash-table))
(defvar *class-objects* (make-weak-value-hash-table))
(defvar *exception-objects* (make-weak-value-hash-table))
;; We call the `retain' method on every object that we receive from a
;; method call or otherwise except non-convenience constructor methods
;; (i.e. those whose name starts with `alloc' or `new'). Upon
;; Lisp-side finalization of an object, wie `release' it.
(eval-when (:load-toplevel)
(dolist (type '(id objc-class exception))
(funcall
(compile
nil
`(lambda ()
(defmethod make-instance ((class (eql ',type)) &rest initargs &key)
(let* ((hash-table ,(ecase type
((id) '*id-objects*)
((objc-class) '*class-objects*)
((exception) '*exception-objects*)))
(hash-key (pointer-address (getf initargs :pointer)))
(obj (weak-gethash hash-key hash-table nil)))
(typecase obj
(keyword (assert (eq :incomplete obj))
(call-next-method))
(null (setf (weak-gethash hash-key hash-table)
:incomplete)
(let ((new-obj (call-next-method)))
(unless *skip-retaining*
(unsafe-primitive-invoke new-obj "retain" id))
(unless *skip-finalization*
;; We only put the new object into the hash
;; table if it is a regular wrapper object
;; rather than a temporary one, else the object
;; pointed to might be released prematurely
;; because of the lack of memory management.
(setf (weak-gethash hash-key hash-table) new-obj)
(assert (not (null (pointer-to new-obj))))
(let ((saved-pointer (pointer-to new-obj))
(saved-type (type-of new-obj)))
(flet ((finalizer ()
;; In order to send the `release'
;; message to the newly GC'd object,
;; we have to create a temporary
;; container object for the final
;; message delivery. Note that this
;; can cause an infinite recursion
;; or even memory corruption if we
;; don't take measure to skip both
;; finalization and retaining of the
;; temporary object.
(let ((temp (let ((*skip-finalization* t)
(*skip-retaining* t))
(make-instance saved-type
:pointer saved-pointer))))
(unsafe-primitive-invoke temp "release" id))))
(trivial-garbage:finalize new-obj #'finalizer))))
new-obj))
(t obj))))
(defmethod initialize-instance ((obj ,type) &key)
(call-next-method)))))))
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