1 /* obstack.h - object stack macros
3 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997,
4 1998, 1999, 2002 Free Software Foundation, Inc.
6 This file is part of the GNU C Library. Its master source is NOT part of
7 the C library, however. The master source lives in /gd/gnu/lib.
9 NOTE: The canonical source of this file is maintained with the GNU C Library.
10 Bugs can be reported to bug-glibc@gnu.org.
12 This program is free software; you can redistribute it and/or modify
13 it under the terms of the GNU General Public License as published by
14 the Free Software Foundation; either version 2, or (at your option)
17 This program is distributed in the hope that it will be useful,
18 but WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 GNU General Public License for more details.
22 You should have received a copy of the GNU General Public License
23 along with this program; if not, write to the Free Software Foundation,
24 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
28 All the apparent functions defined here are macros. The idea
29 is that you would use these pre-tested macros to solve a
30 very specific set of problems, and they would run fast.
31 Caution: no side-effects in arguments please!! They may be
32 evaluated MANY times!!
34 These macros operate a stack of objects. Each object starts life
35 small, and may grow to maturity. (Consider building a word syllable
36 by syllable.) An object can move while it is growing. Once it has
37 been "finished" it never changes address again. So the "top of the
38 stack" is typically an immature growing object, while the rest of the
39 stack is of mature, fixed size and fixed address objects.
41 These routines grab large chunks of memory, using a function you
42 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
43 by calling `obstack_chunk_free'. You must define them and declare
44 them before using any obstack macros.
46 Each independent stack is represented by a `struct obstack'.
47 Each of the obstack macros expects a pointer to such a structure
48 as the first argument.
50 One motivation for this package is the problem of growing char strings
51 in symbol tables. Unless you are "fascist pig with a read-only mind"
52 --Gosper's immortal quote from HAKMEM item 154, out of context--you
53 would not like to put any arbitrary upper limit on the length of your
56 In practice this often means you will build many short symbols and a
57 few long symbols. At the time you are reading a symbol you don't know
58 how long it is. One traditional method is to read a symbol into a
59 buffer, realloc()ating the buffer every time you try to read a symbol
60 that is longer than the buffer. This is beaut, but you still will
61 want to copy the symbol from the buffer to a more permanent
62 symbol-table entry say about half the time.
64 With obstacks, you can work differently. Use one obstack for all symbol
65 names. As you read a symbol, grow the name in the obstack gradually.
66 When the name is complete, finalize it. Then, if the symbol exists already,
67 free the newly read name.
69 The way we do this is to take a large chunk, allocating memory from
70 low addresses. When you want to build a symbol in the chunk you just
71 add chars above the current "high water mark" in the chunk. When you
72 have finished adding chars, because you got to the end of the symbol,
73 you know how long the chars are, and you can create a new object.
74 Mostly the chars will not burst over the highest address of the chunk,
75 because you would typically expect a chunk to be (say) 100 times as
76 long as an average object.
78 In case that isn't clear, when we have enough chars to make up
79 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
80 so we just point to it where it lies. No moving of chars is
81 needed and this is the second win: potentially long strings need
82 never be explicitly shuffled. Once an object is formed, it does not
83 change its address during its lifetime.
85 When the chars burst over a chunk boundary, we allocate a larger
86 chunk, and then copy the partly formed object from the end of the old
87 chunk to the beginning of the new larger chunk. We then carry on
88 accreting characters to the end of the object as we normally would.
90 A special macro is provided to add a single char at a time to a
91 growing object. This allows the use of register variables, which
92 break the ordinary 'growth' macro.
95 We allocate large chunks.
96 We carve out one object at a time from the current chunk.
97 Once carved, an object never moves.
98 We are free to append data of any size to the currently
100 Exactly one object is growing in an obstack at any one time.
101 You can run one obstack per control block.
102 You may have as many control blocks as you dare.
103 Because of the way we do it, you can `unwind' an obstack
104 back to a previous state. (You may remove objects much
105 as you would with a stack.)
109 /* Don't do the contents of this file more than once. */
118 /* We use subtraction of (char *) 0 instead of casting to int
119 because on word-addressable machines a simple cast to int
120 may ignore the byte-within-word field of the pointer. */
123 # define __PTR_TO_INT(P) ((P) - (char *) 0)
128 # define __INT_TO_PTR(P) ((void *) ((P) + (char *) 0))
130 # define __INT_TO_PTR(P) ((P) + (char *) 0)
134 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
135 defined, as with GNU C, use that; that way we don't pollute the
136 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
137 available, include it and use ptrdiff_t. In traditional C, long is
138 the best that we can do. */
140 #ifdef __PTRDIFF_TYPE__
141 # define PTR_INT_TYPE __PTRDIFF_TYPE__
143 # ifdef HAVE_STDDEF_H
145 # define PTR_INT_TYPE ptrdiff_t
147 # define PTR_INT_TYPE long
151 #if defined _LIBC || defined HAVE_STRING_H
153 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
156 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
158 # define _obstack_memcpy(To, From, N) bcopy ((From), (To), (N))
162 struct _obstack_chunk
/* Lives at front of each chunk. */
164 char *limit
; /* 1 past end of this chunk */
165 struct _obstack_chunk
*prev
; /* address of prior chunk or NULL */
166 char contents
[4]; /* objects begin here */
169 struct obstack
/* control current object in current chunk */
171 long chunk_size
; /* preferred size to allocate chunks in */
172 struct _obstack_chunk
*chunk
; /* address of current struct obstack_chunk */
173 char *object_base
; /* address of object we are building */
174 char *next_free
; /* where to add next char to current object */
175 char *chunk_limit
; /* address of char after current chunk */
176 PTR_INT_TYPE temp
; /* Temporary for some macros. */
177 int alignment_mask
; /* Mask of alignment for each object. */
178 #if PROTOTYPES || (defined __STDC__ && __STDC__)
179 /* These prototypes vary based on `use_extra_arg', and we use
180 casts to the prototypeless function type in all assignments,
181 but having prototypes here quiets -Wstrict-prototypes. */
182 struct _obstack_chunk
*(*chunkfun
) (void *, long);
183 void (*freefun
) (void *, struct _obstack_chunk
*);
184 void *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
186 struct _obstack_chunk
*(*chunkfun
) (); /* User's fcn to allocate a chunk. */
187 void (*freefun
) (); /* User's function to free a chunk. */
188 char *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
190 unsigned use_extra_arg
:1; /* chunk alloc/dealloc funcs take extra arg */
191 unsigned maybe_empty_object
:1;/* There is a possibility that the current
192 chunk contains a zero-length object. This
193 prevents freeing the chunk if we allocate
194 a bigger chunk to replace it. */
195 unsigned alloc_failed
:1; /* No longer used, as we now call the failed
196 handler on error, but retained for binary
200 /* Declare the external functions we use; they are in obstack.c. */
202 #if PROTOTYPES || (defined __STDC__ && __STDC__)
203 extern void _obstack_newchunk (struct obstack
*, int);
204 extern void _obstack_free (struct obstack
*, void *);
205 extern int _obstack_begin (struct obstack
*, int, int,
206 void *(*) (long), void (*) (void *));
207 extern int _obstack_begin_1 (struct obstack
*, int, int,
208 void *(*) (void *, long),
209 void (*) (void *, void *), void *);
210 extern int _obstack_memory_used (struct obstack
*);
212 extern void _obstack_newchunk ();
213 extern void _obstack_free ();
214 extern int _obstack_begin ();
215 extern int _obstack_begin_1 ();
216 extern int _obstack_memory_used ();
219 #if PROTOTYPES || (defined __STDC__ && __STDC__)
221 /* Do the function-declarations after the structs
222 but before defining the macros. */
224 void obstack_init (struct obstack
*obstack
);
226 void * obstack_alloc (struct obstack
*obstack
, int size
);
228 void * obstack_copy (struct obstack
*obstack
, const void *address
, int size
);
229 void * obstack_copy0 (struct obstack
*obstack
, const void *address
, int size
);
231 void obstack_free (struct obstack
*obstack
, void *block
);
233 void obstack_blank (struct obstack
*obstack
, int size
);
235 void obstack_grow (struct obstack
*obstack
, const void *data
, int size
);
236 void obstack_grow0 (struct obstack
*obstack
, const void *data
, int size
);
238 void obstack_1grow (struct obstack
*obstack
, int data_char
);
239 void obstack_ptr_grow (struct obstack
*obstack
, const void *data
);
240 void obstack_int_grow (struct obstack
*obstack
, int data
);
242 void * obstack_finish (struct obstack
*obstack
);
244 int obstack_object_size (struct obstack
*obstack
);
246 int obstack_room (struct obstack
*obstack
);
247 void obstack_make_room (struct obstack
*obstack
, int size
);
248 void obstack_1grow_fast (struct obstack
*obstack
, int data_char
);
249 void obstack_ptr_grow_fast (struct obstack
*obstack
, const void *data
);
250 void obstack_int_grow_fast (struct obstack
*obstack
, int data
);
251 void obstack_blank_fast (struct obstack
*obstack
, int size
);
253 void * obstack_base (struct obstack
*obstack
);
254 void * obstack_next_free (struct obstack
*obstack
);
255 int obstack_alignment_mask (struct obstack
*obstack
);
256 int obstack_chunk_size (struct obstack
*obstack
);
257 int obstack_memory_used (struct obstack
*obstack
);
259 #endif /* PROTOTYPES || (defined __STDC__ && __STDC__) */
261 /* Non-ANSI C cannot really support alternative functions for these macros,
262 so we do not declare them. */
264 /* Error handler called when `obstack_chunk_alloc' failed to allocate
265 more memory. This can be set to a user defined function which
266 should either abort gracefully or use longjump - but shouldn't
267 return. The default action is to print a message and abort. */
268 #if PROTOTYPES || (defined __STDC__ && __STDC__)
269 extern void (*obstack_alloc_failed_handler
) (void);
271 extern void (*obstack_alloc_failed_handler
) ();
274 /* Exit value used when `print_and_abort' is used. */
275 extern int obstack_exit_failure
;
277 /* Pointer to beginning of object being allocated or to be allocated next.
278 Note that this might not be the final address of the object
279 because a new chunk might be needed to hold the final size. */
281 #define obstack_base(h) ((h)->object_base)
283 /* Size for allocating ordinary chunks. */
285 #define obstack_chunk_size(h) ((h)->chunk_size)
287 /* Pointer to next byte not yet allocated in current chunk. */
289 #define obstack_next_free(h) ((h)->next_free)
291 /* Mask specifying low bits that should be clear in address of an object. */
293 #define obstack_alignment_mask(h) ((h)->alignment_mask)
295 /* To prevent prototype warnings provide complete argument list in
296 standard C version. */
297 #if PROTOYPES || (defined __STDC__ && __STDC__)
299 # define obstack_init(h) \
300 _obstack_begin ((h), 0, 0, \
301 (void *(*) (long)) obstack_chunk_alloc, \
302 (void (*) (void *)) obstack_chunk_free)
304 # define obstack_begin(h, size) \
305 _obstack_begin ((h), (size), 0, \
306 (void *(*) (long)) obstack_chunk_alloc, \
307 (void (*) (void *)) obstack_chunk_free)
309 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
310 _obstack_begin ((h), (size), (alignment), \
311 (void *(*) (long)) (chunkfun), \
312 (void (*) (void *)) (freefun))
314 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
315 _obstack_begin_1 ((h), (size), (alignment), \
316 (void *(*) (void *, long)) (chunkfun), \
317 (void (*) (void *, void *)) (freefun), (arg))
319 # define obstack_chunkfun(h, newchunkfun) \
320 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
322 # define obstack_freefun(h, newfreefun) \
323 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
327 # define obstack_init(h) \
328 _obstack_begin ((h), 0, 0, \
329 (void *(*) ()) obstack_chunk_alloc, \
330 (void (*) ()) obstack_chunk_free)
332 # define obstack_begin(h, size) \
333 _obstack_begin ((h), (size), 0, \
334 (void *(*) ()) obstack_chunk_alloc, \
335 (void (*) ()) obstack_chunk_free)
337 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
338 _obstack_begin ((h), (size), (alignment), \
339 (void *(*) ()) (chunkfun), \
340 (void (*) ()) (freefun))
342 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
343 _obstack_begin_1 ((h), (size), (alignment), \
344 (void *(*) ()) (chunkfun), \
345 (void (*) ()) (freefun), (arg))
347 # define obstack_chunkfun(h, newchunkfun) \
348 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
350 # define obstack_freefun(h, newfreefun) \
351 ((h) -> freefun = (void (*)()) (newfreefun))
355 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
357 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
359 #define obstack_memory_used(h) _obstack_memory_used (h)
361 #if defined __GNUC__ && defined __STDC__ && __STDC__
362 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
363 does not implement __extension__. But that compiler doesn't define
365 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
366 # define __extension__
369 /* For GNU C, if not -traditional,
370 we can define these macros to compute all args only once
371 without using a global variable.
372 Also, we can avoid using the `temp' slot, to make faster code. */
374 # define obstack_object_size(OBSTACK) \
376 ({ struct obstack *__o = (OBSTACK); \
377 (unsigned) (__o->next_free - __o->object_base); })
379 # define obstack_room(OBSTACK) \
381 ({ struct obstack *__o = (OBSTACK); \
382 (unsigned) (__o->chunk_limit - __o->next_free); })
384 # define obstack_make_room(OBSTACK,length) \
386 ({ struct obstack *__o = (OBSTACK); \
387 int __len = (length); \
388 if (__o->chunk_limit - __o->next_free < __len) \
389 _obstack_newchunk (__o, __len); \
392 # define obstack_empty_p(OBSTACK) \
394 ({ struct obstack *__o = (OBSTACK); \
395 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
397 # define obstack_grow(OBSTACK,where,length) \
399 ({ struct obstack *__o = (OBSTACK); \
400 int __len = (length); \
401 if (__o->next_free + __len > __o->chunk_limit) \
402 _obstack_newchunk (__o, __len); \
403 _obstack_memcpy (__o->next_free, (where), __len); \
404 __o->next_free += __len; \
407 # define obstack_grow0(OBSTACK,where,length) \
409 ({ struct obstack *__o = (OBSTACK); \
410 int __len = (length); \
411 if (__o->next_free + __len + 1 > __o->chunk_limit) \
412 _obstack_newchunk (__o, __len + 1); \
413 _obstack_memcpy (__o->next_free, (where), __len); \
414 __o->next_free += __len; \
415 *(__o->next_free)++ = 0; \
418 # define obstack_1grow(OBSTACK,datum) \
420 ({ struct obstack *__o = (OBSTACK); \
421 if (__o->next_free + 1 > __o->chunk_limit) \
422 _obstack_newchunk (__o, 1); \
423 *(__o->next_free)++ = (datum); \
426 /* These assume that the obstack alignment is good enough for pointers
427 or ints, and that the data added so far to the current object
428 shares that much alignment. */
430 # define obstack_ptr_grow(OBSTACK,datum) \
432 ({ struct obstack *__o = (OBSTACK); \
433 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
434 _obstack_newchunk (__o, sizeof (void *)); \
435 *((void **)__o->next_free)++ = (datum); \
438 # define obstack_int_grow(OBSTACK,datum) \
440 ({ struct obstack *__o = (OBSTACK); \
441 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
442 _obstack_newchunk (__o, sizeof (int)); \
443 *((int *)__o->next_free)++ = (datum); \
446 # define obstack_ptr_grow_fast(h,aptr) \
447 (*((void **) (h)->next_free)++ = (aptr))
449 # define obstack_int_grow_fast(h,aint) \
450 (*((int *) (h)->next_free)++ = (aint))
452 # define obstack_blank(OBSTACK,length) \
454 ({ struct obstack *__o = (OBSTACK); \
455 int __len = (length); \
456 if (__o->chunk_limit - __o->next_free < __len) \
457 _obstack_newchunk (__o, __len); \
458 __o->next_free += __len; \
461 # define obstack_alloc(OBSTACK,length) \
463 ({ struct obstack *__h = (OBSTACK); \
464 obstack_blank (__h, (length)); \
465 obstack_finish (__h); })
467 # define obstack_copy(OBSTACK,where,length) \
469 ({ struct obstack *__h = (OBSTACK); \
470 obstack_grow (__h, (where), (length)); \
471 obstack_finish (__h); })
473 # define obstack_copy0(OBSTACK,where,length) \
475 ({ struct obstack *__h = (OBSTACK); \
476 obstack_grow0 (__h, (where), (length)); \
477 obstack_finish (__h); })
479 /* The local variable is named __o1 to avoid a name conflict
480 when obstack_blank is called. */
481 # define obstack_finish(OBSTACK) \
483 ({ struct obstack *__o1 = (OBSTACK); \
485 value = (void *) __o1->object_base; \
486 if (__o1->next_free == value) \
487 __o1->maybe_empty_object = 1; \
489 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
490 & ~ (__o1->alignment_mask)); \
491 if (__o1->next_free - (char *)__o1->chunk \
492 > __o1->chunk_limit - (char *)__o1->chunk) \
493 __o1->next_free = __o1->chunk_limit; \
494 __o1->object_base = __o1->next_free; \
497 # define obstack_free(OBSTACK, OBJ) \
499 ({ struct obstack *__o = (OBSTACK); \
500 void *__obj = (OBJ); \
501 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
502 __o->next_free = __o->object_base = (char *)__obj; \
503 else (obstack_free) (__o, __obj); })
505 #else /* not __GNUC__ or not __STDC__ */
507 # define obstack_object_size(h) \
508 (unsigned) ((h)->next_free - (h)->object_base)
510 # define obstack_room(h) \
511 (unsigned) ((h)->chunk_limit - (h)->next_free)
513 # define obstack_empty_p(h) \
514 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
516 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
517 so that we can avoid having void expressions
518 in the arms of the conditional expression.
519 Casting the third operand to void was tried before,
520 but some compilers won't accept it. */
522 # define obstack_make_room(h,length) \
523 ( (h)->temp = (length), \
524 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
525 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
527 # define obstack_grow(h,where,length) \
528 ( (h)->temp = (length), \
529 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
530 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
531 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
532 (h)->next_free += (h)->temp)
534 # define obstack_grow0(h,where,length) \
535 ( (h)->temp = (length), \
536 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
537 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
538 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
539 (h)->next_free += (h)->temp, \
540 *((h)->next_free)++ = 0)
542 # define obstack_1grow(h,datum) \
543 ( (((h)->next_free + 1 > (h)->chunk_limit) \
544 ? (_obstack_newchunk ((h), 1), 0) : 0), \
545 (*((h)->next_free)++ = (datum)))
547 # define obstack_ptr_grow(h,datum) \
548 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
549 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
550 (*((const char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = (datum)))
552 # define obstack_int_grow(h,datum) \
553 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
554 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
555 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = (datum)))
557 # define obstack_ptr_grow_fast(h,aptr) \
558 (*((const char **) (h)->next_free)++ = (aptr))
560 # define obstack_int_grow_fast(h,aint) \
561 (*((int *) (h)->next_free)++ = (aint))
563 # define obstack_blank(h,length) \
564 ( (h)->temp = (length), \
565 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
566 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
567 ((h)->next_free += (h)->temp))
569 # define obstack_alloc(h,length) \
570 (obstack_blank ((h), (length)), obstack_finish ((h)))
572 # define obstack_copy(h,where,length) \
573 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
575 # define obstack_copy0(h,where,length) \
576 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
578 # define obstack_finish(h) \
579 ( ((h)->next_free == (h)->object_base \
580 ? (((h)->maybe_empty_object = 1), 0) \
582 (h)->temp = __PTR_TO_INT ((h)->object_base), \
584 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
585 & ~ ((h)->alignment_mask)), \
586 (((h)->next_free - (char *) (h)->chunk \
587 > (h)->chunk_limit - (char *) (h)->chunk) \
588 ? ((h)->next_free = (h)->chunk_limit) : 0), \
589 (h)->object_base = (h)->next_free, \
590 __INT_TO_PTR ((h)->temp))
592 # if PROTOTYPES || (defined __STDC__ && __STDC__)
593 # define obstack_free(h,obj) \
594 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
595 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
596 ? (int) ((h)->next_free = (h)->object_base \
597 = (h)->temp + (char *) (h)->chunk) \
598 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
600 # define obstack_free(h,obj) \
601 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
602 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
603 ? (int) ((h)->next_free = (h)->object_base \
604 = (h)->temp + (char *) (h)->chunk) \
605 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
608 #endif /* not __GNUC__ or not __STDC__ */
614 #endif /* obstack.h */