Commit | Line | Data |
---|---|---|
1f1d88f5 MW |
1 | /* -*-c-*- |
2 | * | |
3 | * Sensible Object Design header file | |
4 | * | |
5 | * (c) 2009 Straylight/Edgeware | |
6 | */ | |
7 | ||
8 | /*----- Licensing notice --------------------------------------------------* | |
9 | * | |
e0808c47 | 10 | * This file is part of the Sensible Object Design, an object system for C. |
1f1d88f5 | 11 | * |
7d21069e MW |
12 | * The SOD Runtime Library is free software; you can redistribute it and/or |
13 | * modify it under the terms of the GNU Library General Public License as | |
14 | * published by the Free Software Foundation; either version 2 of the | |
15 | * License, or (at your option) any later version. | |
1f1d88f5 | 16 | * |
7d21069e | 17 | * The SOD Runtime is distributed in the hope that it will be useful, |
1f1d88f5 MW |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
7d21069e | 20 | * GNU Library General Public License for more details. |
1f1d88f5 | 21 | * |
7d21069e MW |
22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with SOD; if not, write to the Free | |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, | |
25 | * MA 02111-1307, USA. | |
1f1d88f5 MW |
26 | */ |
27 | ||
28 | #ifndef SOD_H | |
29 | #define SOD_H | |
30 | ||
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
68a4f8c9 MW |
35 | /*----- Preliminary utilities ---------------------------------------------*/ |
36 | ||
e674612e MW |
37 | /* --- @SOD__HAVE_VARARGS_MACROS@ --- * |
38 | * | |
39 | * Use: Defined if the compiler supports C99-style variadic macros. | |
40 | * | |
41 | * This is more complicated than just checking the value of | |
42 | * @__STDC_VERSION__@ because GCC has traditionally claimed C89 | |
43 | * by default, but provides the functionality anyway unless it's | |
44 | * been explicitly turned off. | |
45 | */ | |
46 | ||
47 | #if __STDC_VERSION__ >= 199901 | |
48 | /* The feature exists. All is well with the world. */ | |
49 | ||
50 | # define SOD__HAVE_VARARGS_MACROS | |
51 | ||
52 | #elif __GNUC__ >= 3 | |
53 | /* We're using GCC, which is trying to deny it but we don't believe it. | |
54 | * Unfortunately there's a fly in the ointment: if `-pedantic' -- or, | |
55 | * worse, `-pedantic-errors' -- is set, then GCC will warn about these | |
56 | * macros being defined, and there isn't a way to detect pedantry from the | |
57 | * preprocessor. | |
58 | * | |
59 | * We must deploy bodges. There doesn't seem to be a good way to suppress | |
60 | * particular warnings from the preprocessor: in particular, messing about | |
61 | * with `pragma GCC diagnostic' doesn't help. So we're left with this | |
62 | * hack: just declare all Sod-generated header files which try to do | |
63 | * varargs macro things to be `system headers', which means that GCC's | |
64 | * preprocessor will let them get away with all manner of nefarious stuff. | |
65 | */ | |
66 | ||
67 | # define SOD__HAVE_VARARGS_MACROS | |
68 | # define SOD__VARARGS_MACROS_PREAMBLE _Pragma("GCC system_header") | |
69 | ||
70 | #endif | |
71 | ||
72 | /* Make sure this gratuitous hack is understood, at least vacuously. */ | |
73 | #ifndef SOD__VARARGS_MACROS_PREAMBLE | |
74 | # define SOD__VARARGS_MACROS_PREAMBLE | |
75 | #endif | |
76 | ||
77 | /* We're going to want to make use of this ourselves. */ | |
78 | SOD__VARARGS_MACROS_PREAMBLE | |
79 | ||
68a4f8c9 MW |
80 | /* --- @SOD__CAR@ --- * |
81 | * | |
82 | * Arguments: @...@ = a nonempty list of arguments | |
83 | * | |
84 | * Returns: The first argument only. | |
85 | */ | |
86 | ||
e674612e | 87 | #ifdef SOD__HAVE_VARARGS_MACROS |
68a4f8c9 MW |
88 | # define SOD__CAR(...) SOD__CARx(__VA_LIST__, _) |
89 | # define SOD__CARx(a, ...) a | |
90 | #endif | |
91 | ||
1f1d88f5 MW |
92 | /*----- Header files ------------------------------------------------------*/ |
93 | ||
94 | #include <stdarg.h> | |
95 | #include <stddef.h> | |
96 | ||
9e91c8e7 | 97 | #include "keyword.h" |
ddee4bb1 | 98 | #include "sod-base.h" |
1f1d88f5 MW |
99 | |
100 | /*----- Data structures ---------------------------------------------------*/ | |
101 | ||
102 | /* A skeletal vtable structure. At the beginning of every ichain is a | |
103 | * pointer to one of these. | |
104 | */ | |
105 | struct sod_vtable { | |
dea4d055 | 106 | const SodClass *_class; /* Pointer to class object */ |
1f1d88f5 MW |
107 | size_t _base; /* Offset to instance base */ |
108 | }; | |
109 | ||
110 | /* A skeletal instance structure. Every instance pointer points to one of | |
111 | * these. | |
112 | */ | |
113 | struct sod_instance { | |
d83a91c6 | 114 | const struct sod_vtable *_vt; /* Pointer to (chain's) vtable */ |
1f1d88f5 MW |
115 | }; |
116 | ||
117 | /* Information about a particular chain of superclasses. In each class, | |
118 | * there's a pointer to an array of these. If you search hard enough, you'll | |
119 | * be able to find out a fair amount of information about an instance and its | |
120 | * class. | |
121 | */ | |
122 | struct sod_chain { | |
123 | size_t n_classes; /* Number of classes in chain */ | |
124 | const SodClass *const *classes; /* Vector of classes, head first */ | |
125 | size_t off_ichain; /* Offset of ichain from base */ | |
126 | const struct sod_vtable *vt; /* Chain's vtable pointer */ | |
127 | size_t ichainsz; /* Size of the ichain structure */ | |
128 | }; | |
129 | ||
130 | /*----- Infrastructure macros ---------------------------------------------*/ | |
131 | ||
132 | /* --- @SOD_XCHAIN@ --- * | |
133 | * | |
134 | * Arguments: @chead@ = nickname of target chain's head | |
6a590fd0 | 135 | * @obj@ = pointer to an instance chain |
1f1d88f5 | 136 | * |
664b3951 | 137 | * Returns: Pointer to target chain, as a @void *@. |
1f1d88f5 MW |
138 | * |
139 | * Use: Utility for implementing cross-chain upcasts. It's probably | |
140 | * not that clever to use this macro directly; it's used to make | |
141 | * the automatically-generated upcast macros more palatable. | |
142 | */ | |
143 | ||
664b3951 MW |
144 | #define SOD_XCHAIN(chead, obj) \ |
145 | ((void *)((char *)(obj) + (obj)->_vt->_off_##chead)) | |
1f1d88f5 | 146 | |
a07d8d00 MW |
147 | /* --- @SOD_OFFSETDIFF@ --- * |
148 | * | |
149 | * Arguments: @type@ = a simple (i.e., declaratorless) type name | |
150 | * @mema, memb@ = members of @type@ | |
151 | * | |
152 | * Returns: The relative offset from @mema@ to @memb@, as a @ptrdiff_t@. | |
153 | * | |
154 | * Use: Computes a signed offset between structure members. | |
155 | */ | |
156 | ||
157 | #define SOD_OFFSETDIFF(type, mema, memb) \ | |
158 | ((ptrdiff_t)offsetof(type, memb) - (ptrdiff_t)offsetof(type, mema)) | |
159 | ||
1f1d88f5 MW |
160 | /* --- @SOD_ILAYOUT@ --- * |
161 | * | |
162 | * Arguments: @cls@ = name of a class | |
163 | * @chead@ = nickname of chain head of @cls@ | |
6a590fd0 MW |
164 | * @obj@ = pointer to the @chead@ ichain of an (exact) instance |
165 | * of @cls@ | |
1f1d88f5 MW |
166 | * |
167 | * Returns: A pointer to the instance's base, cast as a pointer to the | |
168 | * ilayout structure. | |
169 | * | |
170 | * Use: Finds an instance's base address given a pointer to one of | |
171 | * its ichains, if you know precisely the instance's class and | |
45c53484 MW |
172 | * which chain you're pointing to. If you don't, then (a) you |
173 | * want @SOD_INSTBASE@ below, and (b) you'll have the wrong | |
1f1d88f5 MW |
174 | * ilayout anyway. |
175 | * | |
176 | * This macro is not intended to be used directly outside of | |
177 | * automatically generated effective method and trampoline | |
178 | * functions, which have the kinds of specific knowledge | |
179 | * necessary to use it safely. | |
180 | */ | |
181 | ||
6a590fd0 | 182 | #define SOD_ILAYOUT(cls, chead, obj) \ |
1f1d88f5 | 183 | ((struct cls##__ilayout *) \ |
6a590fd0 MW |
184 | ((char *)(obj) - offsetof(struct cls##__ilayout, chead))) |
185 | ||
186 | /*----- Utility macros ----------------------------------------------------*/ | |
187 | ||
188 | /* --- @SOD_CLASSOF@ --- * | |
189 | * | |
190 | * Arguments: @p@ = pointer to an instance chain | |
191 | * | |
cb9f1e5e | 192 | * Returns: A pointer to the instance's class, as a @const SodClass *@. |
6a590fd0 MW |
193 | */ |
194 | ||
195 | #define SOD_CLASSOF(obj) ((const SodClass *)(obj)->_vt->_class) | |
1f1d88f5 | 196 | |
45c53484 MW |
197 | /* --- @SOD_INSTBASE@ --- * |
198 | * | |
6a590fd0 MW |
199 | * Arguments: @obj@ = pointer to an instance (i.e., the address of one of |
200 | * its instance chains) | |
45c53484 | 201 | * |
6a590fd0 | 202 | * Returns: The base address of @obj@'s instance layout, as a @void *@. |
45c53484 MW |
203 | * |
204 | * Use: Finds the base address of an instance. If you know the | |
205 | * dynamic class of the object then @SOD_ILAYOUT@ is faster. If | |
206 | * you don't, this is the right macro, but your options for | |
207 | * doing something sensible with the result are limited, mostly | |
208 | * to simple memory management operations such as freeing or | |
209 | * zeroizing the instance structure. | |
210 | */ | |
211 | ||
6a590fd0 | 212 | #define SOD_INSTBASE(obj) ((void *)((char *)(obj) - (obj)->_vt->_base)) |
77027cca | 213 | |
6a590fd0 | 214 | /* --- @SOD_CONVERT@ --- * |
77027cca | 215 | * |
6a590fd0 MW |
216 | * Arguments: @cls@ = a class type name |
217 | * @const void *obj@ = a pointer to an instance | |
77027cca | 218 | * |
6a590fd0 MW |
219 | * Returns: Pointer to appropriate instance ichain, or null if the |
220 | * instance isn't of the specified class. | |
221 | * | |
222 | * Use: This is a simple wrapper around the @sod_convert@, which | |
223 | * you should see for full details. It accepts a class type | |
224 | * name rather than a pointer to a class object, and arranges to | |
225 | * return a pointer of the correct type. | |
77027cca MW |
226 | */ |
227 | ||
6a590fd0 | 228 | #define SOD_CONVERT(cls, obj) ((cls *)sod_convert(cls##__class, (obj))) |
77027cca | 229 | |
267dd3e7 MW |
230 | /* --- @SOD_DECL@ --- * |
231 | * | |
232 | * Arguments: @cls_@ = a class type name | |
233 | * @var_@ = a variable name | |
234 | * | |
235 | * Use: Declare @var_@ as a pointer to an initialized instance of | |
236 | * @cls_@ with automatic lifetime. | |
237 | */ | |
238 | ||
239 | #define SOD_DECL(cls_, var_) \ | |
240 | struct cls_##__ilayout var_##__layout; \ | |
241 | cls_ *var_ = cls_##__class->cls.init(&var_##__layout) | |
242 | ||
1f1d88f5 MW |
243 | /*----- Functions provided ------------------------------------------------*/ |
244 | ||
77027cca MW |
245 | /* --- @sod_subclassp@ --- * |
246 | * | |
dea4d055 | 247 | * Arguments: @const SodClass *sub, *super@ = pointers to two classes |
77027cca MW |
248 | * |
249 | * Returns: Nonzero if @c@ is a subclass of @d@. | |
250 | */ | |
251 | ||
dea4d055 | 252 | extern int sod_subclassp(const SodClass */*sub*/, const SodClass */*super*/); |
77027cca | 253 | |
1f1d88f5 MW |
254 | /* --- @sod_convert@ --- * |
255 | * | |
256 | * Arguments: @const SodClass *cls@ = desired class object | |
257 | * @const void *obj@ = pointer to instance | |
258 | * | |
259 | * Returns: Pointer to appropriate ichain of object, or null if the | |
260 | * instance isn't of the specified class. | |
261 | * | |
262 | * Use: General down/cross-casting function. | |
263 | * | |
264 | * Upcasts can be performed efficiently using the automatically | |
dea4d055 | 265 | * generated macros. In particular, upcasts within a chain are |
1f1d88f5 MW |
266 | * trivial; cross-chain upcasts require information from vtables |
267 | * but are fairly fast. This function is rather slower, but is | |
268 | * much more general. | |
269 | * | |
270 | * Suppose we have an instance of a class C, referred to by a | |
dea4d055 | 271 | * pointer to an instance of one of C's superclasses S. If T |
1f1d88f5 | 272 | * is some other superclass of C then this function will return |
dea4d055 | 273 | * a pointer to C suitable for use as an instance of T. If T |
1f1d88f5 MW |
274 | * is not a superclass of C, then the function returns null. |
275 | * (If the pointer doesn't point to an instance of some class | |
276 | * then the behaviour is undefined.) Note that you don't need | |
dea4d055 | 277 | * to know what either C or S actually are. |
1f1d88f5 MW |
278 | */ |
279 | ||
6a590fd0 | 280 | extern void *sod_convert(const SodClass */*cls*/, const void */*obj*/); |
1f1d88f5 MW |
281 | |
282 | /*----- That's all, folks -------------------------------------------------*/ | |
283 | ||
284 | #ifdef __cplusplus | |
285 | } | |
286 | #endif | |
287 | ||
288 | #endif |