1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97,98,99,2003 Free Software Foundation, Inc.
4 This file is part of the GNU C Library. Its master source is NOT part of
5 the C library, however. The master source lives in /gd/gnu/lib.
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.
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 2, or (at your option)
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.
20 You should have received a copy of the GNU General Public License along
21 with this program; if not, write to the Free Software Foundation,
22 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
26 All the apparent functions defined here are macros. The idea
27 is that you would use these pre-tested macros to solve a
28 very specific set of problems, and they would run fast.
29 Caution: no side-effects in arguments please!! They may be
30 evaluated MANY times!!
32 These macros operate a stack of objects. Each object starts life
33 small, and may grow to maturity. (Consider building a word syllable
34 by syllable.) An object can move while it is growing. Once it has
35 been "finished" it never changes address again. So the "top of the
36 stack" is typically an immature growing object, while the rest of the
37 stack is of mature, fixed size and fixed address objects.
39 These routines grab large chunks of memory, using a function you
40 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
41 by calling `obstack_chunk_free'. You must define them and declare
42 them before using any obstack macros.
44 Each independent stack is represented by a `struct obstack'.
45 Each of the obstack macros expects a pointer to such a structure
46 as the first argument.
48 One motivation for this package is the problem of growing char strings
49 in symbol tables. Unless you are "fascist pig with a read-only mind"
50 --Gosper's immortal quote from HAKMEM item 154, out of context--you
51 would not like to put any arbitrary upper limit on the length of your
54 In practice this often means you will build many short symbols and a
55 few long symbols. At the time you are reading a symbol you don't know
56 how long it is. One traditional method is to read a symbol into a
57 buffer, realloc()ating the buffer every time you try to read a symbol
58 that is longer than the buffer. This is beaut, but you still will
59 want to copy the symbol from the buffer to a more permanent
60 symbol-table entry say about half the time.
62 With obstacks, you can work differently. Use one obstack for all symbol
63 names. As you read a symbol, grow the name in the obstack gradually.
64 When the name is complete, finalize it. Then, if the symbol exists already,
65 free the newly read name.
67 The way we do this is to take a large chunk, allocating memory from
68 low addresses. When you want to build a symbol in the chunk you just
69 add chars above the current "high water mark" in the chunk. When you
70 have finished adding chars, because you got to the end of the symbol,
71 you know how long the chars are, and you can create a new object.
72 Mostly the chars will not burst over the highest address of the chunk,
73 because you would typically expect a chunk to be (say) 100 times as
74 long as an average object.
76 In case that isn't clear, when we have enough chars to make up
77 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
78 so we just point to it where it lies. No moving of chars is
79 needed and this is the second win: potentially long strings need
80 never be explicitly shuffled. Once an object is formed, it does not
81 change its address during its lifetime.
83 When the chars burst over a chunk boundary, we allocate a larger
84 chunk, and then copy the partly formed object from the end of the old
85 chunk to the beginning of the new larger chunk. We then carry on
86 accreting characters to the end of the object as we normally would.
88 A special macro is provided to add a single char at a time to a
89 growing object. This allows the use of register variables, which
90 break the ordinary 'growth' macro.
93 We allocate large chunks.
94 We carve out one object at a time from the current chunk.
95 Once carved, an object never moves.
96 We are free to append data of any size to the currently
98 Exactly one object is growing in an obstack at any one time.
99 You can run one obstack per control block.
100 You may have as many control blocks as you dare.
101 Because of the way we do it, you can `unwind' an obstack
102 back to a previous state. (You may remove objects much
103 as you would with a stack.)
107 /* Don't do the contents of this file more than once. */
116 /* We use subtraction of (char *) 0 instead of casting to int
117 because on word-addressable machines a simple cast to int
118 may ignore the byte-within-word field of the pointer. */
121 # define __PTR_TO_INT(P) ((P) - (char *) 0)
125 # define __INT_TO_PTR(P) ((P) + (char *) 0)
128 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
129 defined, as with GNU C, use that; that way we don't pollute the
130 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h>
131 and use ptrdiff_t. */
133 #ifdef __PTRDIFF_TYPE__
134 # define PTR_INT_TYPE __PTRDIFF_TYPE__
137 # define PTR_INT_TYPE ptrdiff_t
142 struct _obstack_chunk /* Lives at front of each chunk. */
144 char *limit; /* 1 past end of this chunk */
145 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
146 char contents[4]; /* objects begin here */
149 struct obstack /* control current object in current chunk */
151 long chunk_size; /* preferred size to allocate chunks in */
152 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
153 char *object_base; /* address of object we are building */
154 char *next_free; /* where to add next char to current object */
155 char *chunk_limit; /* address of char after current chunk */
156 PTR_INT_TYPE temp; /* Temporary for some macros. */
157 int alignment_mask; /* Mask of alignment for each object. */
158 /* These prototypes vary based on `use_extra_arg', and we use
159 casts to the prototypeless function type in all assignments,
160 but having prototypes here quiets -Wstrict-prototypes. */
161 struct _obstack_chunk *(*chunkfun) (void *, long);
162 void (*freefun) (void *, struct _obstack_chunk *);
163 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
164 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
165 unsigned maybe_empty_object:1;/* There is a possibility that the current
166 chunk contains a zero-length object. This
167 prevents freeing the chunk if we allocate
168 a bigger chunk to replace it. */
169 unsigned alloc_failed:1; /* No longer used, as we now call the failed
170 handler on error, but retained for binary
174 /* Declare the external functions we use; they are in obstack.c. */
176 extern void _obstack_newchunk (struct obstack *, int);
177 extern void _obstack_free (struct obstack *, void *);
178 extern int _obstack_begin (struct obstack *, int, int,
179 void *(*) (long), void (*) (void *));
180 extern int _obstack_begin_1 (struct obstack *, int, int,
181 void *(*) (void *, long),
182 void (*) (void *, void *), void *);
183 extern int _obstack_memory_used (struct obstack *);
185 /* Do the function-declarations after the structs
186 but before defining the macros. */
188 void obstack_init (struct obstack *obstack);
190 void * obstack_alloc (struct obstack *obstack, int size);
192 void * obstack_copy (struct obstack *obstack, const void *address, int size);
193 void * obstack_copy0 (struct obstack *obstack, const void *address, int size);
195 void obstack_free (struct obstack *obstack, void *block);
197 void obstack_blank (struct obstack *obstack, int size);
199 void obstack_grow (struct obstack *obstack, const void *data, int size);
200 void obstack_grow0 (struct obstack *obstack, const void *data, int size);
202 void obstack_1grow (struct obstack *obstack, int data_char);
203 void obstack_ptr_grow (struct obstack *obstack, const void *data);
204 void obstack_int_grow (struct obstack *obstack, int data);
206 void * obstack_finish (struct obstack *obstack);
208 int obstack_object_size (struct obstack *obstack);
210 int obstack_room (struct obstack *obstack);
211 void obstack_make_room (struct obstack *obstack, int size);
212 void obstack_1grow_fast (struct obstack *obstack, int data_char);
213 void obstack_ptr_grow_fast (struct obstack *obstack, const void *data);
214 void obstack_int_grow_fast (struct obstack *obstack, int data);
215 void obstack_blank_fast (struct obstack *obstack, int size);
217 void * obstack_base (struct obstack *obstack);
218 void * obstack_next_free (struct obstack *obstack);
219 int obstack_alignment_mask (struct obstack *obstack);
220 int obstack_chunk_size (struct obstack *obstack);
221 int obstack_memory_used (struct obstack *obstack);
223 /* Error handler called when `obstack_chunk_alloc' failed to allocate
224 more memory. This can be set to a user defined function which
225 should either abort gracefully or use longjump - but shouldn't
226 return. The default action is to print a message and abort. */
227 extern void (*obstack_alloc_failed_handler) (void);
229 /* Exit value used when `print_and_abort' is used. */
230 extern int obstack_exit_failure;
232 /* Pointer to beginning of object being allocated or to be allocated next.
233 Note that this might not be the final address of the object
234 because a new chunk might be needed to hold the final size. */
236 #define obstack_base(h) ((h)->object_base)
238 /* Size for allocating ordinary chunks. */
240 #define obstack_chunk_size(h) ((h)->chunk_size)
242 /* Pointer to next byte not yet allocated in current chunk. */
244 #define obstack_next_free(h) ((h)->next_free)
246 /* Mask specifying low bits that should be clear in address of an object. */
248 #define obstack_alignment_mask(h) ((h)->alignment_mask)
250 /* To prevent prototype warnings provide complete argument list. */
251 # define obstack_init(h) \
252 _obstack_begin ((h), 0, 0, \
253 (void *(*) (long)) obstack_chunk_alloc, \
254 (void (*) (void *)) obstack_chunk_free)
256 # define obstack_begin(h, size) \
257 _obstack_begin ((h), (size), 0, \
258 (void *(*) (long)) obstack_chunk_alloc, \
259 (void (*) (void *)) obstack_chunk_free)
261 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
262 _obstack_begin ((h), (size), (alignment), \
263 (void *(*) (long)) (chunkfun), \
264 (void (*) (void *)) (freefun))
266 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
267 _obstack_begin_1 ((h), (size), (alignment), \
268 (void *(*) (void *, long)) (chunkfun), \
269 (void (*) (void *, void *)) (freefun), (arg))
271 # define obstack_chunkfun(h, newchunkfun) \
272 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
274 # define obstack_freefun(h, newfreefun) \
275 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
277 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
279 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
281 #define obstack_memory_used(h) _obstack_memory_used (h)
283 #if defined __GNUC__ && defined __STDC__ && __STDC__
284 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
285 does not implement __extension__. But that compiler doesn't define
287 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
288 # define __extension__
291 /* For GNU C, if not -traditional,
292 we can define these macros to compute all args only once
293 without using a global variable.
294 Also, we can avoid using the `temp' slot, to make faster code. */
296 # define obstack_object_size(OBSTACK) \
298 ({ struct obstack const *__o = (OBSTACK); \
299 (unsigned) (__o->next_free - __o->object_base); })
301 # define obstack_room(OBSTACK) \
303 ({ struct obstack const *__o = (OBSTACK); \
304 (unsigned) (__o->chunk_limit - __o->next_free); })
306 # define obstack_make_room(OBSTACK,length) \
308 ({ struct obstack *__o = (OBSTACK); \
309 int __len = (length); \
310 if (__o->chunk_limit - __o->next_free < __len) \
311 _obstack_newchunk (__o, __len); \
314 # define obstack_empty_p(OBSTACK) \
316 ({ struct obstack const *__o = (OBSTACK); \
317 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
319 # define obstack_grow(OBSTACK,where,length) \
321 ({ struct obstack *__o = (OBSTACK); \
322 int __len = (length); \
323 if (__o->next_free + __len > __o->chunk_limit) \
324 _obstack_newchunk (__o, __len); \
325 memcpy (__o->next_free, (where), __len); \
326 __o->next_free += __len; \
329 # define obstack_grow0(OBSTACK,where,length) \
331 ({ struct obstack *__o = (OBSTACK); \
332 int __len = (length); \
333 if (__o->next_free + __len + 1 > __o->chunk_limit) \
334 _obstack_newchunk (__o, __len + 1); \
335 memcpy (__o->next_free, (where), __len); \
336 __o->next_free += __len; \
337 *(__o->next_free)++ = 0; \
340 # define obstack_1grow(OBSTACK,datum) \
342 ({ struct obstack *__o = (OBSTACK); \
343 if (__o->next_free + 1 > __o->chunk_limit) \
344 _obstack_newchunk (__o, 1); \
345 *(__o->next_free)++ = (datum); \
348 /* These assume that the obstack alignment is good enough for pointers
349 or ints, and that the data added so far to the current object
350 shares that much alignment. */
352 # define obstack_ptr_grow(OBSTACK,datum) \
354 ({ struct obstack *__o = (OBSTACK); \
355 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
356 _obstack_newchunk (__o, sizeof (void *)); \
357 *((void **)__o->next_free)++ = (datum); \
360 # define obstack_int_grow(OBSTACK,datum) \
362 ({ struct obstack *__o = (OBSTACK); \
363 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
364 _obstack_newchunk (__o, sizeof (int)); \
365 *((int *)__o->next_free)++ = (datum); \
368 # define obstack_ptr_grow_fast(h,aptr) \
369 (*((void **) (h)->next_free)++ = (aptr))
371 # define obstack_int_grow_fast(h,aint) \
372 (*((int *) (h)->next_free)++ = (aint))
374 # define obstack_blank(OBSTACK,length) \
376 ({ struct obstack *__o = (OBSTACK); \
377 int __len = (length); \
378 if (__o->chunk_limit - __o->next_free < __len) \
379 _obstack_newchunk (__o, __len); \
380 __o->next_free += __len; \
383 # define obstack_alloc(OBSTACK,length) \
385 ({ struct obstack *__h = (OBSTACK); \
386 obstack_blank (__h, (length)); \
387 obstack_finish (__h); })
389 # define obstack_copy(OBSTACK,where,length) \
391 ({ struct obstack *__h = (OBSTACK); \
392 obstack_grow (__h, (where), (length)); \
393 obstack_finish (__h); })
395 # define obstack_copy0(OBSTACK,where,length) \
397 ({ struct obstack *__h = (OBSTACK); \
398 obstack_grow0 (__h, (where), (length)); \
399 obstack_finish (__h); })
401 /* The local variable is named __o1 to avoid a name conflict
402 when obstack_blank is called. */
403 # define obstack_finish(OBSTACK) \
405 ({ struct obstack *__o1 = (OBSTACK); \
407 value = (void *) __o1->object_base; \
408 if (__o1->next_free == value) \
409 __o1->maybe_empty_object = 1; \
411 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
412 & ~ (__o1->alignment_mask)); \
413 if (__o1->next_free - (char *)__o1->chunk \
414 > __o1->chunk_limit - (char *)__o1->chunk) \
415 __o1->next_free = __o1->chunk_limit; \
416 __o1->object_base = __o1->next_free; \
419 # define obstack_free(OBSTACK, OBJ) \
421 ({ struct obstack *__o = (OBSTACK); \
422 void *__obj = (OBJ); \
423 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
424 __o->next_free = __o->object_base = (char *)__obj; \
425 else (obstack_free) (__o, __obj); })
427 #else /* not __GNUC__ or not __STDC__ */
429 # define obstack_object_size(h) \
430 (unsigned) ((h)->next_free - (h)->object_base)
432 # define obstack_room(h) \
433 (unsigned) ((h)->chunk_limit - (h)->next_free)
435 # define obstack_empty_p(h) \
436 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
438 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
439 so that we can avoid having void expressions
440 in the arms of the conditional expression.
441 Casting the third operand to void was tried before,
442 but some compilers won't accept it. */
444 # define obstack_make_room(h,length) \
445 ( (h)->temp = (length), \
446 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
447 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
449 # define obstack_grow(h,where,length) \
450 ( (h)->temp = (length), \
451 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
452 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
453 memcpy ((h)->next_free, (where), (h)->temp), \
454 (h)->next_free += (h)->temp)
456 # define obstack_grow0(h,where,length) \
457 ( (h)->temp = (length), \
458 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
459 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
460 memcpy ((h)->next_free, (where), (h)->temp), \
461 (h)->next_free += (h)->temp, \
462 *((h)->next_free)++ = 0)
464 # define obstack_1grow(h,datum) \
465 ( (((h)->next_free + 1 > (h)->chunk_limit) \
466 ? (_obstack_newchunk ((h), 1), 0) : 0), \
467 (*((h)->next_free)++ = (datum)))
469 # define obstack_ptr_grow(h,datum) \
470 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
471 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
472 (*((const char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = (datum)))
474 # define obstack_int_grow(h,datum) \
475 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
476 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
477 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = (datum)))
479 # define obstack_ptr_grow_fast(h,aptr) \
480 (*((const char **) (h)->next_free)++ = (aptr))
482 # define obstack_int_grow_fast(h,aint) \
483 (*((int *) (h)->next_free)++ = (aint))
485 # define obstack_blank(h,length) \
486 ( (h)->temp = (length), \
487 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
488 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
489 ((h)->next_free += (h)->temp))
491 # define obstack_alloc(h,length) \
492 (obstack_blank ((h), (length)), obstack_finish ((h)))
494 # define obstack_copy(h,where,length) \
495 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
497 # define obstack_copy0(h,where,length) \
498 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
500 # define obstack_finish(h) \
501 ( ((h)->next_free == (h)->object_base \
502 ? (((h)->maybe_empty_object = 1), 0) \
504 (h)->temp = __PTR_TO_INT ((h)->object_base), \
506 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
507 & ~ ((h)->alignment_mask)), \
508 (((h)->next_free - (char *) (h)->chunk \
509 > (h)->chunk_limit - (char *) (h)->chunk) \
510 ? ((h)->next_free = (h)->chunk_limit) : 0), \
511 (h)->object_base = (h)->next_free, \
512 (void *) __INT_TO_PTR ((h)->temp))
514 # define obstack_free(h,obj) \
515 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
516 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
517 ? (int) ((h)->next_free = (h)->object_base \
518 = (h)->temp + (char *) (h)->chunk) \
519 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
521 #endif /* not __GNUC__ or not __STDC__ */
527 #endif /* obstack.h */