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author kent <kent@cr.ie.u-ryukyu.ac.jp>
date Fri, 17 Jul 2009 14:47:48 +0900
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1 /* obstack.h - object stack macros
2 Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2008
4 Free Software Foundation, Inc.
5
6
7 NOTE: The canonical source of this file is maintained with the GNU C Library.
8 Bugs can be reported to bug-glibc@gnu.org.
9
10 This program is free software; you can redistribute it and/or modify it
11 under the terms of the GNU General Public License as published by the
12 Free Software Foundation; either version 2, or (at your option) any
13 later version.
14
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
19
20 You should have received a copy of the GNU General Public License
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,
23 USA. */
24
25 /* Summary:
26
27 All the apparent functions defined here are macros. The idea
28 is that you would use these pre-tested macros to solve a
29 very specific set of problems, and they would run fast.
30 Caution: no side-effects in arguments please!! They may be
31 evaluated MANY times!!
32
33 These macros operate a stack of objects. Each object starts life
34 small, and may grow to maturity. (Consider building a word syllable
35 by syllable.) An object can move while it is growing. Once it has
36 been "finished" it never changes address again. So the "top of the
37 stack" is typically an immature growing object, while the rest of the
38 stack is of mature, fixed size and fixed address objects.
39
40 These routines grab large chunks of memory, using a function you
41 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
42 by calling `obstack_chunk_free'. You must define them and declare
43 them before using any obstack macros.
44
45 Each independent stack is represented by a `struct obstack'.
46 Each of the obstack macros expects a pointer to such a structure
47 as the first argument.
48
49 One motivation for this package is the problem of growing char strings
50 in symbol tables. Unless you are "fascist pig with a read-only mind"
51 --Gosper's immortal quote from HAKMEM item 154, out of context--you
52 would not like to put any arbitrary upper limit on the length of your
53 symbols.
54
55 In practice this often means you will build many short symbols and a
56 few long symbols. At the time you are reading a symbol you don't know
57 how long it is. One traditional method is to read a symbol into a
58 buffer, realloc()ating the buffer every time you try to read a symbol
59 that is longer than the buffer. This is beaut, but you still will
60 want to copy the symbol from the buffer to a more permanent
61 symbol-table entry say about half the time.
62
63 With obstacks, you can work differently. Use one obstack for all symbol
64 names. As you read a symbol, grow the name in the obstack gradually.
65 When the name is complete, finalize it. Then, if the symbol exists already,
66 free the newly read name.
67
68 The way we do this is to take a large chunk, allocating memory from
69 low addresses. When you want to build a symbol in the chunk you just
70 add chars above the current "high water mark" in the chunk. When you
71 have finished adding chars, because you got to the end of the symbol,
72 you know how long the chars are, and you can create a new object.
73 Mostly the chars will not burst over the highest address of the chunk,
74 because you would typically expect a chunk to be (say) 100 times as
75 long as an average object.
76
77 In case that isn't clear, when we have enough chars to make up
78 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
79 so we just point to it where it lies. No moving of chars is
80 needed and this is the second win: potentially long strings need
81 never be explicitly shuffled. Once an object is formed, it does not
82 change its address during its lifetime.
83
84 When the chars burst over a chunk boundary, we allocate a larger
85 chunk, and then copy the partly formed object from the end of the old
86 chunk to the beginning of the new larger chunk. We then carry on
87 accreting characters to the end of the object as we normally would.
88
89 A special macro is provided to add a single char at a time to a
90 growing object. This allows the use of register variables, which
91 break the ordinary 'growth' macro.
92
93 Summary:
94 We allocate large chunks.
95 We carve out one object at a time from the current chunk.
96 Once carved, an object never moves.
97 We are free to append data of any size to the currently
98 growing object.
99 Exactly one object is growing in an obstack at any one time.
100 You can run one obstack per control block.
101 You may have as many control blocks as you dare.
102 Because of the way we do it, you can `unwind' an obstack
103 back to a previous state. (You may remove objects much
104 as you would with a stack.)
105 */
106
107
108 /* Don't do the contents of this file more than once. */
109
110 #ifndef _OBSTACK_H
111 #define _OBSTACK_H 1
112
113 #ifdef __cplusplus
114 extern "C" {
115 #endif
116
117 /* We use subtraction of (char *) 0 instead of casting to int
118 because on word-addressable machines a simple cast to int
119 may ignore the byte-within-word field of the pointer. */
120
121 #ifndef __PTR_TO_INT
122 # define __PTR_TO_INT(P) ((P) - (char *) 0)
123 #endif
124
125 #ifndef __INT_TO_PTR
126 # define __INT_TO_PTR(P) ((P) + (char *) 0)
127 #endif
128
129 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
130 defined, as with GNU C, use that; that way we don't pollute the
131 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
132 available, include it and use ptrdiff_t. In traditional C, long is
133 the best that we can do. */
134
135 #ifdef __PTRDIFF_TYPE__
136 # define PTR_INT_TYPE __PTRDIFF_TYPE__
137 #else
138 # ifdef HAVE_STDDEF_H
139 # include <stddef.h>
140 # define PTR_INT_TYPE ptrdiff_t
141 # else
142 # define PTR_INT_TYPE long
143 # endif
144 #endif
145
146 #if defined _LIBC || defined HAVE_STRING_H
147 # include <string.h>
148 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
149 #else
150 # ifdef memcpy
151 # define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N))
152 # else
153 # define _obstack_memcpy(To, From, N) bcopy ((char *)(From), (To), (N))
154 # endif
155 #endif
156
157 struct _obstack_chunk /* Lives at front of each chunk. */
158 {
159 char *limit; /* 1 past end of this chunk */
160 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
161 char contents[4]; /* objects begin here */
162 };
163
164 struct obstack /* control current object in current chunk */
165 {
166 long chunk_size; /* preferred size to allocate chunks in */
167 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
168 char *object_base; /* address of object we are building */
169 char *next_free; /* where to add next char to current object */
170 char *chunk_limit; /* address of char after current chunk */
171 PTR_INT_TYPE temp; /* Temporary for some macros. */
172 int alignment_mask; /* Mask of alignment for each object. */
173 /* These prototypes vary based on `use_extra_arg', and we use
174 casts to the prototypeless function type in all assignments,
175 but having prototypes here quiets -Wstrict-prototypes. */
176 struct _obstack_chunk *(*chunkfun) (void *, long);
177 void (*freefun) (void *, struct _obstack_chunk *);
178 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
179 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
180 unsigned maybe_empty_object:1;/* There is a possibility that the current
181 chunk contains a zero-length object. This
182 prevents freeing the chunk if we allocate
183 a bigger chunk to replace it. */
184 unsigned alloc_failed:1; /* No longer used, as we now call the failed
185 handler on error, but retained for binary
186 compatibility. */
187 };
188
189 /* Declare the external functions we use; they are in obstack.c. */
190
191 extern void _obstack_newchunk (struct obstack *, int);
192 extern void _obstack_free (struct obstack *, void *);
193 extern int _obstack_begin (struct obstack *, int, int,
194 void *(*) (long), void (*) (void *));
195 extern int _obstack_begin_1 (struct obstack *, int, int,
196 void *(*) (void *, long),
197 void (*) (void *, void *), void *);
198 extern int _obstack_memory_used (struct obstack *);
199
200 /* Do the function-declarations after the structs
201 but before defining the macros. */
202
203 void obstack_init (struct obstack *obstack);
204
205 void * obstack_alloc (struct obstack *obstack, int size);
206
207 void * obstack_copy (struct obstack *obstack, void *address, int size);
208 void * obstack_copy0 (struct obstack *obstack, void *address, int size);
209
210 void obstack_free (struct obstack *obstack, void *block);
211
212 void obstack_blank (struct obstack *obstack, int size);
213
214 void obstack_grow (struct obstack *obstack, void *data, int size);
215 void obstack_grow0 (struct obstack *obstack, void *data, int size);
216
217 void obstack_1grow (struct obstack *obstack, int data_char);
218 void obstack_ptr_grow (struct obstack *obstack, void *data);
219 void obstack_int_grow (struct obstack *obstack, int data);
220
221 void * obstack_finish (struct obstack *obstack);
222
223 int obstack_object_size (struct obstack *obstack);
224
225 int obstack_room (struct obstack *obstack);
226 void obstack_make_room (struct obstack *obstack, int size);
227 void obstack_1grow_fast (struct obstack *obstack, int data_char);
228 void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
229 void obstack_int_grow_fast (struct obstack *obstack, int data);
230 void obstack_blank_fast (struct obstack *obstack, int size);
231
232 void * obstack_base (struct obstack *obstack);
233 void * obstack_next_free (struct obstack *obstack);
234 int obstack_alignment_mask (struct obstack *obstack);
235 int obstack_chunk_size (struct obstack *obstack);
236 int obstack_memory_used (struct obstack *obstack);
237
238 /* Error handler called when `obstack_chunk_alloc' failed to allocate
239 more memory. This can be set to a user defined function. The
240 default action is to print a message and abort. */
241 extern void (*obstack_alloc_failed_handler) (void);
242
243 /* Exit value used when `print_and_abort' is used. */
244 extern int obstack_exit_failure;
245
246 /* Pointer to beginning of object being allocated or to be allocated next.
247 Note that this might not be the final address of the object
248 because a new chunk might be needed to hold the final size. */
249
250 #define obstack_base(h) ((h)->object_base)
251
252 /* Size for allocating ordinary chunks. */
253
254 #define obstack_chunk_size(h) ((h)->chunk_size)
255
256 /* Pointer to next byte not yet allocated in current chunk. */
257
258 #define obstack_next_free(h) ((h)->next_free)
259
260 /* Mask specifying low bits that should be clear in address of an object. */
261
262 #define obstack_alignment_mask(h) ((h)->alignment_mask)
263
264 /* To prevent prototype warnings provide complete argument list in
265 standard C version. */
266 # define obstack_init(h) \
267 _obstack_begin ((h), 0, 0, \
268 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
269
270 # define obstack_begin(h, size) \
271 _obstack_begin ((h), (size), 0, \
272 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
273
274 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
275 _obstack_begin ((h), (size), (alignment), \
276 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
277
278 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
279 _obstack_begin_1 ((h), (size), (alignment), \
280 (void *(*) (void *, long)) (chunkfun), \
281 (void (*) (void *, void *)) (freefun), (arg))
282
283 # define obstack_chunkfun(h, newchunkfun) \
284 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
285
286 # define obstack_freefun(h, newfreefun) \
287 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
288
289 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar))
290
291 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
292
293 #define obstack_memory_used(h) _obstack_memory_used (h)
294
295 #if defined __GNUC__ && defined __STDC__ && __STDC__
296 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
297 does not implement __extension__. But that compiler doesn't define
298 __GNUC_MINOR__. */
299 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
300 # define __extension__
301 # endif
302
303 /* For GNU C, if not -traditional,
304 we can define these macros to compute all args only once
305 without using a global variable.
306 Also, we can avoid using the `temp' slot, to make faster code. */
307
308 # define obstack_object_size(OBSTACK) \
309 __extension__ \
310 ({ struct obstack *__o = (OBSTACK); \
311 (unsigned) (__o->next_free - __o->object_base); })
312
313 # define obstack_room(OBSTACK) \
314 __extension__ \
315 ({ struct obstack *__o = (OBSTACK); \
316 (unsigned) (__o->chunk_limit - __o->next_free); })
317
318 # define obstack_make_room(OBSTACK,length) \
319 __extension__ \
320 ({ struct obstack *__o = (OBSTACK); \
321 int __len = (length); \
322 if (__o->chunk_limit - __o->next_free < __len) \
323 _obstack_newchunk (__o, __len); \
324 (void) 0; })
325
326 # define obstack_empty_p(OBSTACK) \
327 __extension__ \
328 ({ struct obstack *__o = (OBSTACK); \
329 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
330
331 # define obstack_grow(OBSTACK,where,length) \
332 __extension__ \
333 ({ struct obstack *__o = (OBSTACK); \
334 int __len = (length); \
335 if (__o->next_free + __len > __o->chunk_limit) \
336 _obstack_newchunk (__o, __len); \
337 _obstack_memcpy (__o->next_free, (where), __len); \
338 __o->next_free += __len; \
339 (void) 0; })
340
341 # define obstack_grow0(OBSTACK,where,length) \
342 __extension__ \
343 ({ struct obstack *__o = (OBSTACK); \
344 int __len = (length); \
345 if (__o->next_free + __len + 1 > __o->chunk_limit) \
346 _obstack_newchunk (__o, __len + 1); \
347 _obstack_memcpy (__o->next_free, (where), __len); \
348 __o->next_free += __len; \
349 *(__o->next_free)++ = 0; \
350 (void) 0; })
351
352 # define obstack_1grow(OBSTACK,datum) \
353 __extension__ \
354 ({ struct obstack *__o = (OBSTACK); \
355 if (__o->next_free + 1 > __o->chunk_limit) \
356 _obstack_newchunk (__o, 1); \
357 obstack_1grow_fast (__o, datum); \
358 (void) 0; })
359
360 /* These assume that the obstack alignment is good enough for pointers or ints,
361 and that the data added so far to the current object
362 shares that much alignment. */
363
364 # define obstack_ptr_grow(OBSTACK,datum) \
365 __extension__ \
366 ({ struct obstack *__o = (OBSTACK); \
367 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
368 _obstack_newchunk (__o, sizeof (void *)); \
369 obstack_ptr_grow_fast (__o, datum); })
370
371 # define obstack_int_grow(OBSTACK,datum) \
372 __extension__ \
373 ({ struct obstack *__o = (OBSTACK); \
374 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
375 _obstack_newchunk (__o, sizeof (int)); \
376 obstack_int_grow_fast (__o, datum); })
377
378 # define obstack_ptr_grow_fast(OBSTACK,aptr) \
379 __extension__ \
380 ({ struct obstack *__o1 = (OBSTACK); \
381 *(const void **) __o1->next_free = (aptr); \
382 __o1->next_free += sizeof (const void *); \
383 (void) 0; })
384
385 # define obstack_int_grow_fast(OBSTACK,aint) \
386 __extension__ \
387 ({ struct obstack *__o1 = (OBSTACK); \
388 *(int *) __o1->next_free = (aint); \
389 __o1->next_free += sizeof (int); \
390 (void) 0; })
391
392 # define obstack_blank(OBSTACK,length) \
393 __extension__ \
394 ({ struct obstack *__o = (OBSTACK); \
395 int __len = (length); \
396 if (__o->chunk_limit - __o->next_free < __len) \
397 _obstack_newchunk (__o, __len); \
398 obstack_blank_fast (__o, __len); \
399 (void) 0; })
400
401 # define obstack_alloc(OBSTACK,length) \
402 __extension__ \
403 ({ struct obstack *__h = (OBSTACK); \
404 obstack_blank (__h, (length)); \
405 obstack_finish (__h); })
406
407 # define obstack_copy(OBSTACK,where,length) \
408 __extension__ \
409 ({ struct obstack *__h = (OBSTACK); \
410 obstack_grow (__h, (where), (length)); \
411 obstack_finish (__h); })
412
413 # define obstack_copy0(OBSTACK,where,length) \
414 __extension__ \
415 ({ struct obstack *__h = (OBSTACK); \
416 obstack_grow0 (__h, (where), (length)); \
417 obstack_finish (__h); })
418
419 /* The local variable is named __o1 to avoid a name conflict
420 when obstack_blank is called. */
421 # define obstack_finish(OBSTACK) \
422 __extension__ \
423 ({ struct obstack *__o1 = (OBSTACK); \
424 void *value; \
425 value = (void *) __o1->object_base; \
426 if (__o1->next_free == value) \
427 __o1->maybe_empty_object = 1; \
428 __o1->next_free \
429 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
430 & ~ (__o1->alignment_mask)); \
431 if (__o1->next_free - (char *)__o1->chunk \
432 > __o1->chunk_limit - (char *)__o1->chunk) \
433 __o1->next_free = __o1->chunk_limit; \
434 __o1->object_base = __o1->next_free; \
435 value; })
436
437 # define obstack_free(OBSTACK, OBJ) \
438 __extension__ \
439 ({ struct obstack *__o = (OBSTACK); \
440 void *__obj = (void *) (OBJ); \
441 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
442 __o->next_free = __o->object_base = (char *) __obj; \
443 else (obstack_free) (__o, __obj); })
444
445 #else /* not __GNUC__ or not __STDC__ */
446
447 # define obstack_object_size(h) \
448 (unsigned) ((h)->next_free - (h)->object_base)
449
450 # define obstack_room(h) \
451 (unsigned) ((h)->chunk_limit - (h)->next_free)
452
453 # define obstack_empty_p(h) \
454 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
455
456 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
457 so that we can avoid having void expressions
458 in the arms of the conditional expression.
459 Casting the third operand to void was tried before,
460 but some compilers won't accept it. */
461
462 # define obstack_make_room(h,length) \
463 ( (h)->temp = (length), \
464 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
465 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
466
467 # define obstack_grow(h,where,length) \
468 ( (h)->temp = (length), \
469 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
470 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
471 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
472 (h)->next_free += (h)->temp)
473
474 # define obstack_grow0(h,where,length) \
475 ( (h)->temp = (length), \
476 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
477 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
478 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
479 (h)->next_free += (h)->temp, \
480 *((h)->next_free)++ = 0)
481
482 # define obstack_1grow(h,datum) \
483 ( (((h)->next_free + 1 > (h)->chunk_limit) \
484 ? (_obstack_newchunk ((h), 1), 0) : 0), \
485 obstack_1grow_fast (h, datum))
486
487 # define obstack_ptr_grow(h,datum) \
488 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
489 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
490 obstack_ptr_grow_fast (h, datum))
491
492 # define obstack_int_grow(h,datum) \
493 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
494 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
495 obstack_int_grow_fast (h, datum))
496
497 # define obstack_ptr_grow_fast(h,aptr) \
498 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr))
499
500 # define obstack_int_grow_fast(h,aint) \
501 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr))
502
503 # define obstack_blank(h,length) \
504 ( (h)->temp = (length), \
505 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
506 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
507 obstack_blank_fast (h, (h)->temp))
508
509 # define obstack_alloc(h,length) \
510 (obstack_blank ((h), (length)), obstack_finish ((h)))
511
512 # define obstack_copy(h,where,length) \
513 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
514
515 # define obstack_copy0(h,where,length) \
516 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
517
518 # define obstack_finish(h) \
519 ( ((h)->next_free == (h)->object_base \
520 ? (((h)->maybe_empty_object = 1), 0) \
521 : 0), \
522 (h)->temp = __PTR_TO_INT ((h)->object_base), \
523 (h)->next_free \
524 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
525 & ~ ((h)->alignment_mask)), \
526 (((h)->next_free - (char *) (h)->chunk \
527 > (h)->chunk_limit - (char *) (h)->chunk) \
528 ? ((h)->next_free = (h)->chunk_limit) : 0), \
529 (h)->object_base = (h)->next_free, \
530 (void *) __INT_TO_PTR ((h)->temp))
531
532 # define obstack_free(h,obj) \
533 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
534 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
535 ? (int) ((h)->next_free = (h)->object_base \
536 = (h)->temp + (char *) (h)->chunk) \
537 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
538
539 #endif /* not __GNUC__ or not __STDC__ */
540
541 #ifdef __cplusplus
542 } /* C++ */
543 #endif
544
545 #endif /* obstack.h */