Class.h File Reference

Classes describe the state and behavior of an Objectively type. More...

#include <Objectively/Types.h>
#include <Objectively/Once.h>

Go to the source code of this file.

Data Structures
struct	Class
	The runtime representation of a Class. More...
struct	ClassDef
	ClassDefs are passed to _initialize via an archetype to initialize a Class. More...

Macros
#define	alloc(type)    ((type *) _alloc(_##type()))
	Allocate and initialize and instance of type.
#define	cast(type, obj)    ((type *) _cast(_##type(), (const ident) obj))
	Safely cast obj to type.
#define	classnameof(obj)    classof(obj)->def.name
	Resolve the Class name of the given Object instance.
#define	classof(obj)    ((Object *) obj)->clazz
	Resolve the Class of an Object instance.
#define	instanceof(type, obj)    (isobject(obj) && $((Object *) obj, isKindOfClass, _##type()))
	Test if the given pointer is an instance of the specified type.
#define	interfaceof(type, clazz)    ((type##Interface *) (clazz)->interface)
	Resolve the typed interface of a Class.
#define	isobject(obj)    (obj && *((unsigned int *) obj) == OBJECTIVELY_MAGIC)
	Test if the given pointer is an Object.
#define	obj
#define	OBJECTIVELY_MAGIC   0xdeadbeef
	The header value identifying Objectively types.
#define	super(type, obj, method, ...)    interfaceof(type, _Class()->def.superclass)->method(cast(type, obj), ## __VA_ARGS__)
#define	type

Functions
OBJECTIVELY_EXPORT ident	_alloc (Class *clazz)
	Instantiate a type through the given Class.
OBJECTIVELY_EXPORT ident	_cast (const Class *clazz, const ident obj)
	Perform a type-checking cast.
OBJECTIVELY_EXPORT Class *	_initialize (const ClassDef *clazz)
	Initializes the given Class.
OBJECTIVELY_EXPORT Class *	classForName (const char *name)
OBJECTIVELY_EXPORT ident	release (ident obj)
	Atomically decrement the given Object's reference count. If the resulting reference count is 0, the Object is deallocated.
OBJECTIVELY_EXPORT ident	retain (ident obj)
	Atomically increment the given Object's reference count.

Variables
OBJECTIVELY_EXPORT size_t	_pageSize
	The page size, in bytes, of the target host.

Detailed Description

Classes describe the state and behavior of an Objectively type.

Definition in file Class.h.

Macro Definition Documentation

alloc

#define alloc

(

type

)

((type *) _alloc(_##type()))

Allocate and initialize and instance of type.

Definition at line 176 of file Class.h.

   { \
    typeof(obj) _obj = obj; \
    _obj->interface->method(_obj, ## __VA_ARGS__); \
  })
 
#define $$(type, method, ...) \
  ({ \
    interfaceof(type, _##type())->method(__VA_ARGS__); \
  })
 
#define super(type, obj, method, ...) \
  interfaceof(type, _Class()->def.superclass)->method(cast(type, obj), ## __VA_ARGS__)

cast

#define cast	(		type,
			obj
	)		((type *) _cast(_##type(), (const ident) obj))

Safely cast obj to type.

Definition at line 182 of file Class.h.

classnameof

#define classnameof

(

obj

)

classof(obj)->def.name

Resolve the Class name of the given Object instance.

Definition at line 194 of file Class.h.

classof

#define classof

(

obj

)

((Object *) obj)->clazz

Resolve the Class of an Object instance.

Definition at line 188 of file Class.h.

instanceof

#define instanceof	(		type,
			obj
	)		(isobject(obj) && $((Object *) obj, isKindOfClass, _##type()))

Test if the given pointer is an instance of the specified type.

Definition at line 170 of file Class.h.

interfaceof

#define interfaceof	(		type,
			clazz
	)		((type##Interface *) (clazz)->interface)

Resolve the typed interface of a Class.

Definition at line 200 of file Class.h.

isobject

#define isobject

(

obj

)

(obj && *((unsigned int *) obj) == OBJECTIVELY_MAGIC)

Test if the given pointer is an Object.

Definition at line 164 of file Class.h.

obj

#define obj

Value:

  , method, ...) \
  ({ \
    typeof(obj) _obj = obj; \
    _obj->interface->method(_obj, ## __VA_ARGS__); \
  })

OBJECTIVELY_MAGIC

#define OBJECTIVELY_MAGIC   0xdeadbeef

The header value identifying Objectively types.

Definition at line 159 of file Class.h.

super

#define super	(		type,
			obj,
			method,
			...
	)		interfaceof(type, _Class()->def.superclass)->method(cast(type, obj), ## __VA_ARGS__)

type

#define type

Value:

  , method, ...) \
  ({ \
    interfaceof(type, _##type())->method(__VA_ARGS__); \
  })

Function Documentation

_alloc()

OBJECTIVELY_EXPORT ident _alloc

(

Class *

clazz

)

Instantiate a type through the given Class.

Definition at line 123 of file Class.c.

                           {
 
  ident obj = calloc(1, clazz->def.instanceSize);
  assert(obj);
 
  Object *object = (Object *) obj;
 
  object->magic = OBJECTIVELY_MAGIC;
  object->clazz = clazz;
  object->referenceCount = 1;
 
  ident interface = clazz->interface;
  do {
    *(ident *) (obj + clazz->def.interfaceOffset) = interface;
  } while ((clazz = clazz->def.superclass));
 
  return obj;
}

_cast()

OBJECTIVELY_EXPORT ident _cast	(	const Class *	clazz,
		const ident	obj
	)

Perform a type-checking cast.

Definition at line 142 of file Class.c.

                                                 {
 
  if (obj) {
    const Class *c = ((Object *) obj)->clazz;
    while (c) {
 
      // as a special case, we optimize for _Object
      if (c == clazz || clazz == _Object()) {
        break;
      }
 
      c = c->def.superclass;
    }
    assert(c);
  }
 
  return (ident) obj;
}

_initialize()

OBJECTIVELY_EXPORT Class * _initialize

(

const ClassDef *

clazz

)

Initializes the given Class.

Parameters

clazz

The Class descriptor.

Returns

The initialized Class.

Definition at line 86 of file Class.c.

                                        {
 
  static Once once;
  do_once(&once, setup());
 
  assert(def);
  assert(def->name);
  assert(def->instanceSize);
  assert(def->interfaceSize);
  assert(def->interfaceOffset);
 
  Class *clazz = calloc(1, sizeof(Class));
  assert(clazz);
 
  clazz->def = *def;
 
  clazz->interface = calloc(1, def->interfaceSize);
  assert(clazz->interface);
 
  Class *superclass = clazz->def.superclass;
  if (superclass) {
 
    assert(superclass->def.instanceSize <= def->instanceSize);
    assert(superclass->def.interfaceSize <= def->interfaceSize);
 
    memcpy(clazz->interface, superclass->interface, superclass->def.interfaceSize);
  }
 
  if (clazz->def.initialize) {
    clazz->def.initialize(clazz);
  }
 
  clazz->next = __sync_lock_test_and_set(&_classes, clazz);
 
  return clazz;
}

classForName()

OBJECTIVELY_EXPORT Class * classForName

(

const char *

name

)

Returns

The Class with the given name, or NULL if no such Class has been initialized.

Definition at line 161 of file Class.c.

                                      {
 
  if (name) {
    Class *c = _classes;
    while (c) {
      if (strcmp(name, c->def.name) == 0) {
        return c;
      }
      c = c->next;
    }
 
    char *s;
    if (asprintf(&s, "_%s", name) > 0) {
      Class *clazz = NULL;
#if defined(_WIN32)
      static Once once;
      static ident handle;
      do_once(&once, { handle = dlopen(NULL, RTLD_LAZY); });
      Class *(*archetype)(void) = handle ? dlsym(handle, s) : NULL;
#else
      Class *(*archetype)(void) = dlsym(RTLD_DEFAULT, s);
#endif
      if (archetype) {
        clazz = archetype();
      }
 
      free(s);
      return clazz;
    }
  }
 
  return NULL;
}

release()

OBJECTIVELY_EXPORT ident release

(

ident

obj

)

Atomically decrement the given Object's reference count. If the resulting reference count is 0, the Object is deallocated.

Returns

This function always returns NULL.

Definition at line 195 of file Class.c.

                         {
 
  if (obj) {
    Object *object = cast(Object, obj);
 
    assert(object);
 
    if (__sync_add_and_fetch(&object->referenceCount, -1) == 0) {
      $(object, dealloc);
    }
  }
 
  return NULL;
}

retain()

OBJECTIVELY_EXPORT ident retain

(

ident

obj

)

Atomically increment the given Object's reference count.

Returns

The Object.

Remarks

By calling this, the caller is expressing ownership of the Object, and preventing it from being released. Be sure to balance calls to retain with calls to release.

Definition at line 210 of file Class.c.

                        {
 
  Object *object = cast(Object, obj);
 
  assert(object);
 
  __sync_add_and_fetch(&object->referenceCount, 1);
 
  return obj;
}

Variable Documentation

_pageSize

OBJECTIVELY_EXPORT size_t _pageSize

The page size, in bytes, of the target host.

Definition at line 154 of file Class.h.