path: root/Lisp/method-invocation.lisp

(in-package #:mulk.objective-cl)


;;; (@* "Method invocation")
(defun invoke (receiver message-start &rest message-components)
  "Send a message to an Objective C instance.

## Arguments and Values:

*receiver* --- an Objective C wrapper object.

*message-start* --- a **symbol**.

*message-components* --- an alternating **list** of **object**s and
**symbol**s.

Returns: *result* --- the return value of the method invocation.


## Description:

All even-numbered *message components* are collected in order and the
resulting **list** used as if as additional **argument**s to
__invoke-by-name__.

All uneven-numbered *message components*, which must be **symbol**s, are
first split into parts separated by hyphens and each part converted into
a **string** according to the following rules:

1. The first part is fully converted to **lowercase**.

2. Any additional parts are also fully converted to **lowercase** except
   for their first letters, which are left intact.

3. If the symbol is a **keyword**, the resulting **string** is suffixed
   by a **colon** (`:').

After that, all parts are concatenated in order to form a
single *message name component*.  The *message name components* are in
turn concatenated in order to form the *message name* which is used as
if as the second **argument** to __invoke-by-name__.


## Examples:

    (invoke (find-objc-class 'ns-string)
            :string-with-c-string \"Mulk.\")
      ;=> #<GSCBufferString `Mulk.' {5B36087}>

    (invoke (find-objc-class 'ns-object)
            'self)                           
      ;=> #<NSObject `NSObject' {16ECF598}>

    (invoke (find-objc-class 'ns-object)
            'name)                           
      ;=> \"NSObject\"

    (invoke (find-objc-class 'ns-string)
            :string-with-c-string \"Mulk.\"
            :encoding 4)
      ;=> #<GSCBufferString `Mulk.' {5B36087}>


## See also:

  __invoke-by-name__"

  (check-type receiver (or id objc-class exception)
              "an Objective C instance (ID, OBJC-CLASS or EXCEPTION)")
  (do* ((components-left (cons message-start message-components)
                         (cddr components-left))
        (message-list    (list message-start)
                         (cons (first components-left) message-list))
        (arglist         (if (null (rest components-left))
                             nil
                             (list (second components-left)))
                         (if (null (rest components-left))
                             arglist
                             (cons (second components-left) arglist))))
       ((null (cddr components-left))
        (apply #'invoke-by-name
               receiver
               (symbol-list->message-name (nreverse message-list))
               (nreverse arglist)))))


(defun invoke-by-name (receiver method-name &rest args)
  "Send a message to an Objective C object by the name of the method.

## Arguments and Values:

*receiver* --- an Objective C wrapper object.

*method-name* --- a **string**.

*args* --- a list of **object**s.

Returns: *result* --- the return value of the method invocation.


## Examples:

    (invoke-by-name (find-objc-class 'ns-string)
                    \"stringWithCString:\" \"Mulk.\")
      ;=> #<GSCBufferString `Mulk.' {5B36087}>

    (invoke-by-name (find-objc-class 'ns-object)
                    \"self\")
      ;=> #<NSObject `NSObject' {16ECF598}>

    (invoke-by-name (find-objc-class 'ns-string)
                    \"stringWithCString:encoding:\"
                    \"Mulk.\"
                    4)
      ;=> #<GSCBufferString `Mulk.' {5B36087}>


## See also:

  __invoke__"

  (check-type receiver (or id objc-class exception)
              "an Objective C instance (ID, OBJC-CLASS or EXCEPTION)")
  (when *trace-method-calls*
    (format t "~&Invoking [~A].~%" method-name))
  (flet ((convert/signal (foreign-value)
           ;; Convert a foreign value into a Lisp value.  If the value
           ;; to be converted represents an exception, signal it instead
           ;; of returning it as a value.
           (let ((lisp-value (obj-data->lisp foreign-value)))
             (if (typep lisp-value 'condition)
                 (cerror "Return NIL from OBJCL-INVOKE-METHOD." lisp-value)
                 lisp-value))))
    (let ((objc-arglist (arglist->objc-arglist args))
          (selector (selector method-name)))
      (unwind-protect
           (with-foreign-conversion ((objc-receiver receiver))
             (with-foreign-objects ((return-value
                                     (apply-macro '%objcl-invoke-method
                                                  objc-receiver
                                                  (pointer-to selector)
                                                  (length args)
                                                  objc-arglist)))
               (let ((*skip-retaining* (or *skip-retaining*
                                           (constructor-name-p method-name))))
                 (convert/signal return-value))))
        (dealloc-objc-arglist objc-arglist)))))


;;; (@* "Helper functions")
(defun arglist->objc-arglist (arglist)
  (arglist-intersperse-types (mapcar #'lisp->obj-data arglist)))


(defun dealloc-objc-arglist (objc-arglist)
  (do ((objc-arglist objc-arglist (cddr objc-arglist)))
      ((null objc-arglist))
    ;; (first objc-arglist) is a CFFI type name.
    (dealloc-obj-data (second objc-arglist))))


(defun arglist-intersperse-types (arglist)
  (mapcan #'(lambda (arg)
              (list :pointer arg))
          arglist))


(defun constructor-name-p (method-name)
  (flet ((method-name-starts-with (prefix)
           (and (>= (length method-name) (length prefix))
                (or (and (string= prefix
                                  (subseq method-name 0 (length prefix)))
                         (or (= (length method-name)
                                (length prefix))
                             (not (lower-case-p (char method-name (length prefix))))))))))
    (or (method-name-starts-with "alloc")
        (method-name-starts-with "new"))))


;;; (@* "High-level Data Conversion")
(defgeneric coerce-object (object type))

(defcoercion id ((x id))
  x)

(defcoercion id ((x class))
  (invoke x 'self))

(defcoercion id ((x exception))
  (invoke x 'self))

(defcoercion id ((x integer))
  (let ((id (invoke (find-class 'ns-number)
                    :number-with-long x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))

(defcoercion id ((x float))
  (let ((id (invoke (find-class 'ns-number)
                    :number-with-double x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))

(defcoercion id ((x string))
  (let ((id (invoke (find-class 'ns-string)
                    :string-with-c-string x)))
    (invoke id 'retain)
    (invoke id 'autorelease)
    id))


(defcoercion class ((x id))
  (invoke x 'class))

(defcoercion class ((x exception))
  (invoke x 'class))

(defcoercion class ((x class))
  x)

(defcoercion class ((x string))
  (find-objc-class x t))

(defcoercion class ((x symbol))
  (find-objc-class x t))


(defcoercion integer ((x id))
  (assert (objc-typep x 'ns-number))
  (invoke x 'long-value))

(defcoercion integer ((x number))
  (truncate x))

(defcoercion integer ((x null))
  0)

(defcoercion integer ((x symbol))
  (assert (eq 't x))
  1)


(defcoercion selector ((x selector))
  x)

(defcoercion selector ((x symbol))
  (selector x))

(defcoercion selector ((x string))
  (selector x))

(defcoercion selector ((x cons))
  (selector x))


(defcoercion exception ((x exception))
  x)


(defcoercion character ((x character))
  x)

(defcoercion character ((x integer))
  x)


(defcoercion float ((x number))
  (float x))


(defcoercion double ((x number))
  (float x))


(defcoercion bool ((x null))
  x)

(defcoercion bool ((x symbol))
  (assert (eq 't x))
  x)

(defcoercion bool ((x integer))
  x)


(defcoercion string ((x string))
  x)

(defcoercion string ((x foreign-pointer))
  (check-type x foreign-pointer)
  x)


(defcoercion pointer ((x foreign-pointer))
  (check-type x foreign-pointer)
  x)

(defcoercion pointer ((x exception))
  (pointer-to x))

(defcoercion pointer ((x c-pointer-wrapper))
  (pointer-to x))

(defcoercion pointer ((x number))
  (pointer-to (->id x)))