1 /* obstack.h - object stack macros
2 Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998,
4 Free Software Foundation, Inc.
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 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
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
21 along with this program; if not, write to the Free Software
22 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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!!
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.
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.
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.
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
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.
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.
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.
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.
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.
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.
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
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.)
108 /* Don't do the contents of this file more than once. */
113 /* use function from <string.h> */
114 #define HAVE_STRING_H 1
120 /* We use subtraction of (char *) 0 instead of casting to int
121 because on word-addressable machines a simple cast to int
122 may ignore the byte-within-word field of the pointer. */
125 # define __PTR_TO_INT(P) ((P) - (char *) 0)
129 # define __INT_TO_PTR(P) ((void *)((P) + (char *) 0))
132 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
133 defined, as with GNU C, use that; that way we don't pollute the
134 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
135 available, include it and use ptrdiff_t. In traditional C, long is
136 the best that we can do. */
138 #ifdef __PTRDIFF_TYPE__
139 # define PTR_INT_TYPE __PTRDIFF_TYPE__
141 # ifdef HAVE_STDDEF_H
143 # define PTR_INT_TYPE ptrdiff_t
145 # define PTR_INT_TYPE long
149 #if defined _LIBC || defined HAVE_STRING_H
151 # if defined __STDC__
152 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
154 # define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N))
158 # define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N))
160 # define _obstack_memcpy(To, From, N) bcopy ((char *)(From), (To), (N))
164 struct _obstack_chunk /* Lives at front of each chunk. */
166 char *limit; /* 1 past end of this chunk */
167 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
168 char contents[4]; /* objects begin here */
171 struct obstack /* control current object in current chunk */
173 long chunk_size; /* preferred size to allocate chunks in */
174 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
175 char *object_base; /* address of object we are building */
176 char *next_free; /* where to add next char to current object */
177 char *chunk_limit; /* address of char after current chunk */
178 PTR_INT_TYPE temp; /* Temporary for some macros. */
179 int alignment_mask; /* Mask of alignment for each object. */
181 /* These prototypes vary based on `use_extra_arg', and we use
182 casts to the prototypeless function type in all assignments,
183 but having prototypes here quiets -Wstrict-prototypes. */
184 struct _obstack_chunk *(*chunkfun) (void *, long);
185 void (*freefun) (void *, struct _obstack_chunk *);
186 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
188 struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
189 void (*freefun) (); /* User's function to free a chunk. */
190 char *extra_arg; /* first arg for chunk alloc/dealloc funcs */
192 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
193 unsigned maybe_empty_object:1;/* There is a possibility that the current
194 chunk contains a zero-length object. This
195 prevents freeing the chunk if we allocate
196 a bigger chunk to replace it. */
197 unsigned alloc_failed:1; /* No longer used, as we now call the failed
198 handler on error, but retained for binary
202 /* Declare the external functions we use; they are in obstack.c. */
205 extern void _obstack_newchunk (struct obstack *, int);
206 extern void _obstack_free (struct obstack *, void *);
207 extern int _obstack_begin (struct obstack *, int, int,
208 void *(*) (long), void (*) (void *));
209 extern int _obstack_begin_1 (struct obstack *, int, int,
210 void *(*) (void *, long),
211 void (*) (void *, void *), void *);
212 extern int _obstack_memory_used (struct obstack *);
214 extern void _obstack_newchunk ();
215 extern void _obstack_free ();
216 extern int _obstack_begin ();
217 extern int _obstack_begin_1 ();
218 extern int _obstack_memory_used ();
223 /* Do the function-declarations after the structs
224 but before defining the macros. */
226 void obstack_init (struct obstack *obstack);
228 void * obstack_alloc (struct obstack *obstack, int size);
230 void * obstack_copy (struct obstack *obstack, void *address, int size);
231 void * obstack_copy0 (struct obstack *obstack, void *address, int size);
233 void obstack_free (struct obstack *obstack, void *block);
235 void obstack_blank (struct obstack *obstack, int size);
237 void obstack_grow (struct obstack *obstack, void *data, int size);
238 void obstack_grow0 (struct obstack *obstack, void *data, int size);
240 void obstack_1grow (struct obstack *obstack, int data_char);
241 void obstack_ptr_grow (struct obstack *obstack, void *data);
242 void obstack_int_grow (struct obstack *obstack, int data);
244 void * obstack_finish (struct obstack *obstack);
246 int obstack_object_size (struct obstack *obstack);
248 int obstack_room (struct obstack *obstack);
249 void obstack_make_room (struct obstack *obstack, int size);
250 void obstack_1grow_fast (struct obstack *obstack, int data_char);
251 void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
252 void obstack_int_grow_fast (struct obstack *obstack, int data);
253 void obstack_blank_fast (struct obstack *obstack, int size);
255 void * obstack_base (struct obstack *obstack);
256 void * obstack_next_free (struct obstack *obstack);
257 int obstack_alignment_mask (struct obstack *obstack);
258 int obstack_chunk_size (struct obstack *obstack);
259 int obstack_memory_used (struct obstack *obstack);
261 #endif /* __STDC__ */
263 /* Non-ANSI C cannot really support alternative functions for these macros,
264 so we do not declare them. */
266 /* Error handler called when `obstack_chunk_alloc' failed to allocate
267 more memory. This can be set to a user defined function. The
268 default action is to print a message and abort. */
270 extern void (*obstack_alloc_failed_handler) (void);
272 extern void (*obstack_alloc_failed_handler) ();
275 /* Exit value used when `print_and_abort' is used. */
276 extern int obstack_exit_failure;
278 /* Pointer to beginning of object being allocated or to be allocated next.
279 Note that this might not be the final address of the object
280 because a new chunk might be needed to hold the final size. */
282 #define obstack_base(h) ((h)->object_base)
284 /* Size for allocating ordinary chunks. */
286 #define obstack_chunk_size(h) ((h)->chunk_size)
288 /* Pointer to next byte not yet allocated in current chunk. */
290 #define obstack_next_free(h) ((h)->next_free)
292 /* Mask specifying low bits that should be clear in address of an object. */
294 #define obstack_alignment_mask(h) ((h)->alignment_mask)
296 /* To prevent prototype warnings provide complete argument list in
297 standard C version. */
300 # define obstack_init(h) \
301 _obstack_begin ((h), 0, 0, \
302 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
304 # define obstack_begin(h, size) \
305 _obstack_begin ((h), (size), 0, \
306 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
308 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
309 _obstack_begin ((h), (size), (alignment), \
310 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
312 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
313 _obstack_begin_1 ((h), (size), (alignment), \
314 (void *(*) (void *, long)) (chunkfun), \
315 (void (*) (void *, void *)) (freefun), (arg))
317 # define obstack_chunkfun(h, newchunkfun) \
318 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
320 # define obstack_freefun(h, newfreefun) \
321 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
325 # define obstack_init(h) \
326 _obstack_begin ((h), 0, 0, \
327 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
329 # define obstack_begin(h, size) \
330 _obstack_begin ((h), (size), 0, \
331 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
333 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
334 _obstack_begin ((h), (size), (alignment), \
335 (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
337 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
338 _obstack_begin_1 ((h), (size), (alignment), \
339 (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
341 # define obstack_chunkfun(h, newchunkfun) \
342 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
344 # define obstack_freefun(h, newfreefun) \
345 ((h) -> freefun = (void (*)()) (newfreefun))
349 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
351 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
353 #define obstack_memory_used(h) _obstack_memory_used (h)
355 #if defined __GNUC__ && defined __STDC__ && __STDC__
356 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
357 does not implement __extension__. But that compiler doesn't define
359 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
360 # define __extension__
363 /* For GNU C, if not -traditional,
364 we can define these macros to compute all args only once
365 without using a global variable.
366 Also, we can avoid using the `temp' slot, to make faster code. */
368 # define obstack_object_size(OBSTACK) \
370 ({ struct obstack *__o = (OBSTACK); \
371 (unsigned) (__o->next_free - __o->object_base); })
373 # define obstack_room(OBSTACK) \
375 ({ struct obstack *__o = (OBSTACK); \
376 (unsigned) (__o->chunk_limit - __o->next_free); })
378 # define obstack_make_room(OBSTACK,length) \
380 ({ struct obstack *__o = (OBSTACK); \
381 int __len = (length); \
382 if (__o->chunk_limit - __o->next_free < __len) \
383 _obstack_newchunk (__o, __len); \
386 # define obstack_empty_p(OBSTACK) \
388 ({ struct obstack *__o = (OBSTACK); \
389 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
391 # define obstack_grow(OBSTACK,where,length) \
393 ({ struct obstack *__o = (OBSTACK); \
394 int __len = (length); \
395 if (__o->next_free + __len > __o->chunk_limit) \
396 _obstack_newchunk (__o, __len); \
397 _obstack_memcpy (__o->next_free, (where), __len); \
398 __o->next_free += __len; \
401 # define obstack_grow0(OBSTACK,where,length) \
403 ({ struct obstack *__o = (OBSTACK); \
404 int __len = (length); \
405 if (__o->next_free + __len + 1 > __o->chunk_limit) \
406 _obstack_newchunk (__o, __len + 1); \
407 _obstack_memcpy (__o->next_free, (where), __len); \
408 __o->next_free += __len; \
409 *(__o->next_free)++ = 0; \
412 # define obstack_1grow(OBSTACK,datum) \
414 ({ struct obstack *__o = (OBSTACK); \
415 if (__o->next_free + 1 > __o->chunk_limit) \
416 _obstack_newchunk (__o, 1); \
417 *(__o->next_free)++ = (datum); \
420 /* These assume that the obstack alignment is good enough for pointers or ints,
421 and that the data added so far to the current object
422 shares that much alignment. */
424 # define obstack_ptr_grow(OBSTACK,datum) \
426 ({ struct obstack *__o = (OBSTACK); \
427 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
428 _obstack_newchunk (__o, sizeof (void *)); \
429 *((void **)__o->next_free)++ = ((void *)datum); \
432 # define obstack_int_grow(OBSTACK,datum) \
434 ({ struct obstack *__o = (OBSTACK); \
435 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
436 _obstack_newchunk (__o, sizeof (int)); \
437 *((int *)__o->next_free)++ = ((int)datum); \
440 # define obstack_ptr_grow_fast(h,aptr) (*((void **) (h)->next_free)++ = (void *)aptr)
441 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
443 # define obstack_blank(OBSTACK,length) \
445 ({ struct obstack *__o = (OBSTACK); \
446 int __len = (length); \
447 if (__o->chunk_limit - __o->next_free < __len) \
448 _obstack_newchunk (__o, __len); \
449 __o->next_free += __len; \
452 # define obstack_alloc(OBSTACK,length) \
454 ({ struct obstack *__h = (OBSTACK); \
455 obstack_blank (__h, (length)); \
456 obstack_finish (__h); })
458 # define obstack_copy(OBSTACK,where,length) \
460 ({ struct obstack *__h = (OBSTACK); \
461 obstack_grow (__h, (where), (length)); \
462 obstack_finish (__h); })
464 # define obstack_copy0(OBSTACK,where,length) \
466 ({ struct obstack *__h = (OBSTACK); \
467 obstack_grow0 (__h, (where), (length)); \
468 obstack_finish (__h); })
470 /* The local variable is named __o1 to avoid a name conflict
471 when obstack_blank is called. */
472 # define obstack_finish(OBSTACK) \
474 ({ struct obstack *__o1 = (OBSTACK); \
476 value = (void *) __o1->object_base; \
477 if (__o1->next_free == value) \
478 __o1->maybe_empty_object = 1; \
480 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
481 & ~ (__o1->alignment_mask)); \
482 if (__o1->next_free - (char *)__o1->chunk \
483 > __o1->chunk_limit - (char *)__o1->chunk) \
484 __o1->next_free = __o1->chunk_limit; \
485 __o1->object_base = __o1->next_free; \
488 # define obstack_free(OBSTACK, OBJ) \
490 ({ struct obstack *__o = (OBSTACK); \
491 void *__obj = (OBJ); \
492 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
493 __o->next_free = __o->object_base = __obj; \
494 else (obstack_free) (__o, __obj); })
496 extern int obstack_printf (struct obstack *obst, const char *fmt, ...)
497 __attribute__ ((__format__ (__printf__, 2, 3)));
500 #else /* not __GNUC__ or not __STDC__ */
502 # define obstack_object_size(h) \
503 (unsigned) ((h)->next_free - (h)->object_base)
505 # define obstack_room(h) \
506 (unsigned) ((h)->chunk_limit - (h)->next_free)
508 # define obstack_empty_p(h) \
509 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
511 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
512 so that we can avoid having void expressions
513 in the arms of the conditional expression.
514 Casting the third operand to void was tried before,
515 but some compilers won't accept it. */
517 # define obstack_make_room(h,length) \
518 ( (h)->temp = (length), \
519 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
520 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
522 # define obstack_grow(h,where,length) \
523 ( (h)->temp = (length), \
524 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
525 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
526 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
527 (h)->next_free += (h)->temp)
529 # define obstack_grow0(h,where,length) \
530 ( (h)->temp = (length), \
531 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
532 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
533 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
534 (h)->next_free += (h)->temp, \
535 *((h)->next_free)++ = 0)
537 # define obstack_1grow(h,datum) \
538 ( (((h)->next_free + 1 > (h)->chunk_limit) \
539 ? (_obstack_newchunk ((h), 1), 0) : 0), \
540 (*((h)->next_free)++ = (datum)))
542 # define obstack_ptr_grow(h,datum) \
543 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
544 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
545 (*((char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *) datum)))
547 # define obstack_int_grow(h,datum) \
548 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
549 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
550 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = ((int) datum)))
552 # define obstack_ptr_grow_fast(h,aptr) (*((char **) (h)->next_free)++ = (char *) aptr)
553 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
555 # define obstack_blank(h,length) \
556 ( (h)->temp = (length), \
557 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
558 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
559 ((h)->next_free += (h)->temp))
561 # define obstack_alloc(h,length) \
562 (obstack_blank ((h), (length)), obstack_finish ((h)))
564 # define obstack_copy(h,where,length) \
565 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
567 # define obstack_copy0(h,where,length) \
568 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
570 # define obstack_finish(h) \
571 ( ((h)->next_free == (h)->object_base \
572 ? (((h)->maybe_empty_object = 1), 0) \
574 (h)->temp = __PTR_TO_INT ((h)->object_base), \
576 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
577 & ~ ((h)->alignment_mask)), \
578 (((h)->next_free - (char *) (h)->chunk \
579 > (h)->chunk_limit - (char *) (h)->chunk) \
580 ? ((h)->next_free = (h)->chunk_limit) : 0), \
581 (h)->object_base = (h)->next_free, \
582 __INT_TO_PTR ((h)->temp))
584 # if defined __STDC__
585 # define obstack_free(h,obj) \
586 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
587 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
588 ? (int) ((h)->next_free = (h)->object_base \
589 = (h)->temp + (char *) (h)->chunk) \
590 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
592 # define obstack_free(h,obj) \
593 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
594 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
595 ? (int) ((h)->next_free = (h)->object_base \
596 = (h)->temp + (char *) (h)->chunk) \
597 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
600 extern int obstack_printf (struct obstack *obst, const char *fmt, ...);
602 #endif /* not __GNUC__ or not __STDC__ */
608 #endif /* obstack.h */