libobjc/objc/objc.h

   1 /* Basic data types for Objective C.
   2    Copyright (C) 1993, 1995, 1996, 2004, 2009,
   3    2010 Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #ifndef __objc_INCLUDE_GNU
  27 #define __objc_INCLUDE_GNU
  28
  29 /* This file contains the definition of the basic types used by the
  30    Objective-C language.  It needs to be included to do almost
  31    anything with Objective-C.  */
  32
  33 #ifdef __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 #include <stddef.h>
  38
  39 /* objc-decls.h is included because deprecated/objc_msg_sendv.h needs
  40    it.  When that goes away, the include of objc-decls.h should be
  41    removed.  */
  42 #include "objc-decls.h"
  43
  44 /* The current version of the GNU Objective-C Runtime library in
  45    compressed ISO date format.  This should be updated any time a new
  46    version is released with changes to the public API (there is no
  47    need to update it if there were no API changes since the previous
  48    release).  This macro is only defined starting with the GNU
  49    Objective-C Runtime shipped with GCC 4.6.0.  If it is not defined,
  50    it is either an older version of the runtime, or another runtime.  */
  51 #define __GNU_LIBOBJC__ 20100911
  52
  53 /* Definition of the boolean type.
  54
  55    Compatibility note: the Apple/NeXT runtime defines a BOOL as a
  56    'signed char'.  The GNU runtime uses an 'unsigned char'.
  57
  58    Important: this could change and we could switch to 'typedef bool
  59    BOOL' in the future.  Do not depend on the type of BOOL.  */
  60 #undef BOOL
  61 typedef unsigned char  BOOL;
  62
  63 #define YES   (BOOL)1
  64 #define NO    (BOOL)0
  65
  66 /* The basic Objective-C types (SEL, Class, id) are defined as pointer
  67    to opaque structures.  The details of the structures are private to
  68    the runtime and may potentially change from one version to the
  69    other.  */
  70
  71 /* A SEL (selector) represents an abstract method (in the
  72    object-oriented sense) and includes all the details of how to
  73    invoke the method (which means its name, arguments and return
  74    types) but provides no implementation of its own.  You can check
  75    whether a class implements a selector or not, and if you have a
  76    selector and know that the class implements it, you can use it to
  77    call the method for an object in the class.  */
  78 typedef const struct objc_selector *SEL;
  79 #include "deprecated/struct_objc_selector.h"
  80
  81 /* A Class is a class (in the object-oriented sense).  In Objective-C
  82    there is the complication that each Class is an object itself, and
  83    so belongs to a class too.  This class that a class belongs to is
  84    called its 'meta class'.  */
  85 typedef struct objc_class *Class;
  86 #include "deprecated/MetaClass.h"
  87 #include "deprecated/struct_objc_class.h"
  88
  89 /* An 'id' is an object of an unknown class.  The way the object data
  90    is stored inside the object is private and what you see here is
  91    only the beginning of the actual struct.  The first field is always
  92    a pointer to the Class that the object belongs to.  */
  93 typedef struct objc_object
  94 {
  95   /* 'class_pointer' is the Class that the object belongs to.  In case
  96      of a Class object, this pointer points to the meta class.
  97
  98      Compatibility Note: The Apple/NeXT runtime calls this field
  99      'isa'.  To access this field, use object_getClass() from
 100      runtime.h, which is an inline function so does not add any
 101      overhead and is also portable to other runtimes.  */
 102   Class class_pointer;
 103 } *id;
 104
 105 /* 'IMP' is a C function that implements a method.  When retrieving
 106    the implementation of a method from the runtime, this is the type
 107    of the pointer returned.  The idea of the definition of IMP is to
 108    represent a 'pointer to a general function taking an id, a SEL,
 109    followed by other unspecified arguments'.  You must always cast an
 110    IMP to a pointer to a function taking the appropriate, specific
 111    types for that function, before calling it - to make sure the
 112    appropriate arguments are passed to it.  The code generated by the
 113    compiler to perform method calls automatically does this cast
 114    inside method calls.  */
 115 typedef id (*IMP)(id, SEL, ...);
 116
 117 /* 'nil' is the null object.  Messages to nil do nothing and always
 118    return 0.  */
 119 #define nil (id)0
 120
 121 /* 'Nil' is the null class.  Since classes are objects too, this is
 122    actually the same object as 'nil' (and behaves in the same way),
 123    but it has a type of Class, so it is good to use it instead of
 124    'nil' if you are comparing a Class object to nil as it enables the
 125    compiler to do some type-checking.  */
 126 #define Nil (Class)0
 127
 128 #include "deprecated/STR.h"
 129
 130 /* TODO: Move the 'Protocol' declaration into objc/runtime.h.  A
 131    Protocol is simply an object, not a basic Objective-C type.  The
 132    Apple runtime defines Protocol in objc/runtime.h too, so it's good
 133    to move it there for API compatibility.  */
 134
 135 /* A 'Protocol' is a formally defined list of selectors (normally
 136    created using the @protocol Objective-C syntax).  It is mostly used
 137    at compile-time to check that classes implement all the methods
 138    that they are supposed to.  Protocols are also available in the
 139    runtime system as Protocol objects.  */
 140 #ifndef __OBJC__
 141   /* Once we stop including the deprecated struct_objc_protocol.h
 142      there is no reason to even define a 'struct objc_protocol'.  As
 143      all the structure details will be hidden, a Protocol basically is
 144      simply an object (as it should be).  */
 145   /* typedef struct objc_object Protocol; */
 146   #include "deprecated/struct_objc_protocol.h"
 147 #else /* __OBJC__ */
 148   @class Protocol;
 149 #endif
 150
 151 /* Deprecated include - here temporarily, for backwards-compatibility
 152    as reval_t, apply_t, arglist_t and objc_msg_lookup() used to be
 153    defined here.  objc_msg_lookup() is now defined in message.h,
 154    included by objc-api.h or runtime.h.  */
 155 #include "deprecated/objc_msg_sendv.h"
 156
 157 /* Compatibility note: the Apple/NeXT runtime defines sel_getName(),
 158    sel_registerName(), object_getClassName(), object_getIndexedIvars()
 159    in this file while the GNU runtime defines them in runtime.h.
 160
 161    The reason the GNU runtime does not define them here is that they
 162    are not basic Objective-C types (defined in this file), but are
 163    part of the runtime API (defined in runtime.h).  */
 164
 165 #ifdef __cplusplus
 166 }
 167 #endif
 168
 169 #endif /* not __objc_INCLUDE_GNU */