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 /* The current version of the GNU Objective-C Runtime library in 40 compressed ISO date format. This should be updated any time a new 41 version is released with changes to the public API (there is no 42 need to update it if there were no API changes since the previous 43 release). This macro is only defined starting with the GNU 44 Objective-C Runtime shipped with GCC 4.6.0. If it is not defined, 45 it is either an older version of the runtime, or another runtime. */ 46 #define __GNU_LIBOBJC__ 20110608 47 48 /* Definition of the boolean type. 49 50 Compatibility note: the Apple/NeXT runtime defines a BOOL as a 51 'signed char'. The GNU runtime uses an 'unsigned char'. 52 53 Important: this could change and we could switch to 'typedef bool 54 BOOL' in the future. Do not depend on the type of BOOL. */ 55 #undef BOOL 56 typedef unsigned char BOOL; 57 58 #define YES (BOOL)1 59 #define NO (BOOL)0 60 61 /* The basic Objective-C types (SEL, Class, id) are defined as pointer 62 to opaque structures. The details of the structures are private to 63 the runtime and may potentially change from one version to the 64 other. */ 65 66 /* A SEL (selector) represents an abstract method (in the 67 object-oriented sense) and includes all the details of how to 68 invoke the method (which means its name, arguments and return 69 types) but provides no implementation of its own. You can check 70 whether a class implements a selector or not, and if you have a 71 selector and know that the class implements it, you can use it to 72 call the method for an object in the class. */ 73 typedef const struct objc_selector *SEL; 74 75 /* A Class is a class (in the object-oriented sense). In Objective-C 76 there is the complication that each Class is an object itself, and 77 so belongs to a class too. This class that a class belongs to is 78 called its 'meta class'. */ 79 typedef struct objc_class *Class; 80 81 /* An 'id' is an object of an unknown class. The way the object data 82 is stored inside the object is private and what you see here is 83 only the beginning of the actual struct. The first field is always 84 a pointer to the Class that the object belongs to. */ 85 typedef struct objc_object 86 { 87 /* 'class_pointer' is the Class that the object belongs to. In case 88 of a Class object, this pointer points to the meta class. 89 90 Compatibility Note: The Apple/NeXT runtime calls this field 91 'isa'. To access this field, use object_getClass() from 92 runtime.h, which is an inline function so does not add any 93 overhead and is also portable to other runtimes. */ 94 Class class_pointer; 95 } *id; 96 97 /* 'IMP' is a C function that implements a method. When retrieving 98 the implementation of a method from the runtime, this is the type 99 of the pointer returned. The idea of the definition of IMP is to 100 represent a 'pointer to a general function taking an id, a SEL, 101 followed by other unspecified arguments'. You must always cast an 102 IMP to a pointer to a function taking the appropriate, specific 103 types for that function, before calling it - to make sure the 104 appropriate arguments are passed to it. The code generated by the 105 compiler to perform method calls automatically does this cast 106 inside method calls. */ 107 typedef id (*IMP)(id, SEL, ...); 108 109 /* 'nil' is the null object. Messages to nil do nothing and always 110 return 0. */ 111 #define nil (id)0 112 113 /* 'Nil' is the null class. Since classes are objects too, this is 114 actually the same object as 'nil' (and behaves in the same way), 115 but it has a type of Class, so it is good to use it instead of 116 'nil' if you are comparing a Class object to nil as it enables the 117 compiler to do some type-checking. */ 118 #define Nil (Class)0 119 120 /* TODO: Move the 'Protocol' declaration into objc/runtime.h. A 121 Protocol is simply an object, not a basic Objective-C type. The 122 Apple runtime defines Protocol in objc/runtime.h too, so it's good 123 to move it there for API compatibility. */ 124 125 /* A 'Protocol' is a formally defined list of selectors (normally 126 created using the @protocol Objective-C syntax). It is mostly used 127 at compile-time to check that classes implement all the methods 128 that they are supposed to. Protocols are also available in the 129 runtime system as Protocol objects. */ 130 #ifndef __OBJC__ 131 /* Once we stop including the deprecated struct_objc_protocol.h 132 there is no reason to even define a 'struct objc_protocol'. As 133 all the structure details will be hidden, a Protocol basically is 134 simply an object (as it should be). */ 135 typedef struct objc_object Protocol; 136 #else /* __OBJC__ */ 137 @class Protocol; 138 #endif 139 140 /* Compatibility note: the Apple/NeXT runtime defines sel_getName(), 141 sel_registerName(), object_getClassName(), object_getIndexedIvars() 142 in this file while the GNU runtime defines them in runtime.h. 143 144 The reason the GNU runtime does not define them here is that they 145 are not basic Objective-C types (defined in this file), but are 146 part of the runtime API (defined in runtime.h). */ 147 148 #ifdef __cplusplus 149 } 150 #endif 151 152 #endif /* not __objc_INCLUDE_GNU */ 153