Objective-C to Lisp Binding with Transparent Layer

Dependencies:

(ql:quickload '(:alexandria :anaphora :closer-mop :cffi :cffi-libffi))

Packages:

OBJC

Main Package

OBJC-CLASS

For Class Definitions

OBJC-META

For Metaclass Definitions

OBJC-METHOD

For Obj-C -> Lisp Generic Function Methods

OBJC-PROP

Obj-C Properties -> Lisp Slot Names

The source code is separated using titles and #\Page, please use C-x [ and C-x ] to navigate throught subtitles.

Usage

To get a Obj-C class, either pass its string name or the Lisp name it should be translated to cls macro or ensure-objc-class function, or use string name for objc-lookup-class:

(objc:cls ns-object)
or
(objc:ensure-objc-class 'objc-class::ns-object)
(objc:ensure-objc-class "NSObject")
or
(objc:objc-lookup-class "NSObject")

;; => #<OBJC-META:NS-OBJECT OBJC-CLASS:NS-OBJECT>

(These are convenient functions, CLOS & MOP methods will be introduced below.)

The class object will be automatically created inside corresponding (OBJC-CLASS or OBJC-META) package, with all superclasses & metaclasses defined. By default, all methods under the class will also be registered in OBJC-METHOD package, and class properties will be registered as Lisp class slots named in OBJC-PROP package.

  #<OBJC-META:NS-OBJECT {7005C64A43}>
--------------------
Name: OBJC-CLASS:NS-OBJECT
Super classes: #<STANDARD-CLASS OBJC::OBJC-OBJECT>
Direct Slots: CLASS-DESCRIPTION, ATTRIBUTE-KEYS, TO-ONE-RELATIONSHIP-KEYS, TO-MANY-RELATIONSHIP-KEYS, OBSERVATION-INFO, CLASS-FOR-KEYED-ARCHIVER, AUTO-CONTENT-ACCESSING-PROXY, SCRIPTING-PROPERTIES, CLASS-CODE, CLASS-NAME, EXPOSED-BINDINGS, _NS_OBSERVATION-TRACKING-DICTIONARY, HASH, SUPERCLASS, DESCRIPTION, DEBUG-DESCRIPTION, HASH, SUPERCLASS, DESCRIPTION, DEBUG-DESCRIPTION, _AX-IS-WRAPPED-POINTER, ACCESSIBILITY-SWIFT-UI-DEFAULT-ACTION-STORED-BLOCK, ACCESSIBILITY-SWIFT-UI-STORED-LINK-ROTOR, SWIFTUI_ACCESSIBILITY-LABEL, KNOWN-REPRESENTED-ELEMENT, ROTOR-OWNER-ELEMENT, HASH, SUPERCLASS, DESCRIPTION, DEBUG-DESCRIPTION
Effective Slots: #<N/A (class not finalized)> [finalize]
Sub classes: NS-RULER-MARKER, NS-GRID-ROW, NS-GRID-COLUMN, NS-GRID-CELL, NS-CELL, NS-FILE-PROMISE-RECEIVER, NS-FILE-PROMISE-PROVIDER, NS-CONTROLLER, NS-DOCUMENT-CONTROLLER, NS-DOCUMENT, NS-PASTEBOARD-ITEM, NS-PASTEBOARD, NS-WORKSPACE, NS-RESPONDER, NS-DICTIONARY, NS-SET, NS-ARRAY, NS-STRING, NS-VALUE, PROTOCOL
Precedence List: #<N/A (class not finalized)>
Prototype: #<N/A (class not finalized)>
--------------------
 Group slots by inheritance [X]
 Sort slots alphabetically  [X]

CLASS:
[ ]  %DOCUMENTATION                     = NIL
[ ]  CLASS-EQ-SPECIALIZER               = #<SB-PCL::CLASS-EQ-SPECIALIZER #<OBJC-META:NS-OBJECT OBJC-CLASS:NS-OBJECT>>
[ ]  DIRECT-METHODS                     = (NIL)
[ ]  DIRECT-SUBCLASSES                  = (#<OBJC-META:NS-RULER-MARKER OBJC-CLASS:NS-RULER-MARKER> #<OBJC-META:NS-GRID-ROW OBJC-CLASS:NS-GRID-ROW> #<OBJC-META:NS-GRID-COLUMN OBJC-CLASS:NS-GRID-COLUMN> #<OBJC-META:NS-GRID-CELL OBJC-CLASS:NS-GRID-CELL> #<OBJC-META:NS-CELL OBJC-CLASS:NS-CELL> #<OBJC-META:NS-FILE-PROMISE-RECEIVER OBJC-CLASS:NS-FILE-PROMISE-RECEIVER> #<OBJC-META:NS-FILE-PROMISE-PROVIDER OBJC-CLASS:NS-FILE-PROMISE-PROVIDER> #<OBJC-META:NS-CONTROLLER OBJC-CLASS:NS-CONTROLLER> ..)
[ ]  DIRECT-SUPERCLASSES                = (#<STANDARD-CLASS OBJC::OBJC-OBJECT>)
[ ]  FINALIZED-P                        = NIL
[ ]  NAME                               = OBJC-CLASS:NS-OBJECT
[ ]  SAFE-P                             = NIL

DEFINITION-SOURCE-MIXIN:
[ ]  SOURCE                             = #S(SB-C:DEFINITION-SOURCE-LOCATION :NAMESTRING "/Users/april/common-lisp/objc/objc.lisp" :INDICES 4521988)

NS-OBJECT:
[ ]  ACCESS-INSTANCE-VARIABLES-DIRECTLY = T

OBJC-CLASS:
[ ]  AUTO-BIND-PROPERTIES               = T
[ ]  AUTO-REGISTER-METHODS              = T
[ ]  OBJC-CLASS-NAME                    = "NSObject"

OBJC-OBJECT:
[ ]  OBJ                                = #.(SB-SYS:INT-SAP #X1F2689D70)

PCL-CLASS:
[ ]  %CLASS-PRECEDENCE-LIST             = #<unbound>
[ ]  CAN-PRECEDE-LIST                   = (#<SB-PCL:SYSTEM-CLASS COMMON-LISP:T> #<SB-PCL::SLOT-CLASS SB-PCL::SLOT-OBJECT> #<STANDARD-CLASS COMMON-LISP:STANDARD-OBJECT> #<STANDARD-CLASS OBJC::OBJC-OBJECT>)
[ ]  CPL-AVAILABLE-P                    = NIL
[ ]  INCOMPATIBLE-SUPERCLASS-LIST       = NIL
[ ]  PROTOTYPE                          = NIL
[ ]  WRAPPER                            = #<SB-KERNEL:LAYOUT for OBJC-CLASS:NS-OBJECT {7005241303}>

PLIST-MIXIN:
[ ]  PLIST                              = NIL

SLOT-CLASS:
[ ]  DIRECT-SLOTS                       = (#<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:CLASS-DESCRIPTION> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:ATTRIBUTE-KEYS> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:TO-ONE-RELATIONSHIP-KEYS> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:TO-MANY-RELATIONSHIP-KEYS> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:OBSERVATION-INFO> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:CLASS-FOR-KEYED-ARCHIVER> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:AUTO-CONTENT-ACCESSING-PROXY> #<OBJC::OBJC-PROPERTY-SLOT OBJC-PROP:SCRIPTING-PROPERTIES> ..)
[ ]  SLOTS                              = NIL

SPECIALIZER:
[ ]  %TYPE                              = (CLASS #<OBJC-META:NS-OBJECT OBJC-CLASS:NS-OBJECT>)

[set value]  [make unbound]

To control the behaviour, you can use the MOP function ensure-class, or even defclass directly.

(c2mop:ensure-class 'objc-class:ns-object
                    :metaclass 'objc:objc-class
                    :auto-bind-properties nil
                    :auto-register-methods nil)
or
(defclass objc-class:ns-object () ()
  (:metaclass objc-class))

FIXME: Currently we didn’t implemented change-class relative methods on objc-class, so all class can only be defined once. Execution of the form above will signal error because NSObject has been defined. It’s just demonstrating purpose.

To make an instance:

(make-instance (cls ns-object))

Note that this is using class_createInstance runtime function, you may need to do additional initialization for the object.

or if you has the object’s Obj-C pointer:

(make-instance (cls ns-object) :objc-object <pointer>)

To call a method:

(objc-method:new (objc:cls ns-object))
or
(funcall (objc:sel new) (objc:cls ns-object))

;; => #<OBJC-CLASS:NS-OBJECT {700964F153}>

Use slot-value to get the Obj-C property:

(slot-value (objc-method:new (objc::cls ns-object)) 'objc-prop:hash)
;; => 105553174675536 (47 bits, #x6000037B4050)

Source Explaination

The objc-raw.lisp are raw CFFI bindings for Obj-C runtime functions. All symbols are internal, and function argument are referenced by pointer. It’s for utility purpose.

---

The first page of objc.lisp is the Name Translator. It defines methods on cffi:translate-name-from-foreign and cffi:translate-name-to-foreign to makes it suitable for converting Obj-C names:

• Special words (“NS”, “UTF”, “URL”, etc.) are specially marked out;
• For Class and Metaclass names the translation should be initial-uppered;
• For selector, : will be converted to ., for Lisp compatibility.

These functions are specialized to OBJC* packages.

Example:

(cffi:translate-name-to-foreign name (find-package "OBJC-PROP"))

---

The second page is about Obj-C Type Encodings. We provide:

• parse-objc-type-encoding-to-lisp
• parse-objc-type-encoding-to-c
• parse-c-type-to-objc-encoding
• parse-lisp-type-to-c
• parse-lisp-type-to-objc-encoding

---

The third page is about objc-object and selector.

All Obj-C object pointer will be wrapped into an objc-object, which has a slot OBJC:OBJ for the wrapped pointer.

FIXME: Some Obj-C objects are not presented in pointer, like NSRange. For NSRange I’ve written a wrapper alone, but I’m not prepared to handle this problem systematically…

selector is an instance of funcallable-standard-class metaclass. it can be funcalled to invoke the method, just like regular Obj-C message sending.

selector is also a CFFI foreign type, which will automatically parse selector typed argument to the instance of selector.

---

The fourth page is about Obj-C property to Lisp class slot definition converter.

This page only contains slot definition metaobject definition, real converting method is two page after, as compute-effective-slot-definition method. That’s because the method must be defined after objc-class has been defined.

---

The fifth page is about Obj-C class foreign-type parser.

---

The sixth page contains the definition of obj-c class in Lisp: objc-class and objc-metaclass. It’s also contains method of compute-effective-slot-definition, slot-value-using-class, (setf slot-value-using-class)

---

The seventh page is Obj-C class => Lisp class converter, mainly ensure-class-using-class method. It will convert any class definition to Obj-C class (either regestering or defining), if it has objc-class as :metaobject