;;;
;;; gauche.mop.typed-slot - Slot type annotation
;;;
;;;   Copyright (c) 2023-2025  Shiro Kawai  <shiro@acm.org>
;;;
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;;;   are met:
;;;
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;;;      notice, this list of conditions and the following disclaimer.
;;;
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;; EXPERIMENTAL: This metaclass adds :type slot definition option.

(define-module gauche.mop.typed-slot
  (use util.match)
  (export <typed-slot-meta> <typed-slot-mixin>)
  )
(select-module gauche.mop.typed-slot)

(define-class <typed-slot-meta> (<class>) ())

(define-class <typed-slot-mixin> () () :metaclass <typed-slot-meta>)

(define-method compute-slot-accessor ((class <typed-slot-meta>) slotdef gns)
  (let1 accessor (next-method)
    (if-let1 type (slot-definition-option slotdef :type #f)
      (make-type-checked-accessor class slotdef accessor type)
      gns)))

(define (make-type-checked-accessor class slotdef accessor type)
  (define (check v)
    (unless (of-type? v type)
      (errorf "Slot ~a of ~a must be of type ~a, but got: ~s"
              (slot-definition-name slotdef)
              (class-name class) (~ type 'name) v)))
  ;; TODO: Probably we should have a built-in utility to create a
  ;; 'wrapper' accessor.
  (make <slot-accessor>
    :class class :name (slot-definition-name slotdef)
    :getter (^o (slot-ref-using-accessor o accessor))
    :setter (^[o v] (check v) (slot-set-using-accessor! o accessor v))
    :bound? (^o (slot-bound-using-accessor? o accessor))
    :initializable (~ accessor'initializable)
    :init-value (if (slot-bound? accessor 'init-value)
                  (~ accessor'init-value)
                  (undefined))
    :init-keyword (if (slot-bound? accessor 'init-keyword)
                    (~ accessor'init-keyword)
                    (undefined))
    :init-thunk (if (slot-bound? accessor 'init-thunk)
                  (~ accessor'init-thunk)
                  (undefined))
    :immutable (~ accessor'immutable)
    ))
