1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97 Free Software Foundation, Inc.
4 the C library, however. The master source lives in /gd/gnu/lib.
6 NOTE: The canonical source of this file is maintained with the GNU C Library.
7 Bugs can be reported to bug-glibc@prep.ai.mit.edu.
9 This program is free software; you can redistribute it and/or modify it
10 under the terms of the GNU General Public License as published by the
11 Free Software Foundation; either version 2, or (at your option) any
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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. In ANSI C it is ptrdiff_t
129 but in traditional C it is usually long. If we are in ANSI C and
130 don't already have ptrdiff_t get it. */
132 #if defined (__STDC__) && __STDC__ && ! defined (offsetof)
133 #if defined (__GNUC__) && defined (IN_GCC)
134 /* On Next machine, the system's stddef.h screws up if included
135 after we have defined just ptrdiff_t, so include all of stddef.h.
136 Otherwise, define just ptrdiff_t, which is all we need. */
138 #define __need_ptrdiff_t
145 #if defined (__STDC__) && __STDC__
146 #define PTR_INT_TYPE ptrdiff_t
148 #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 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 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 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
, void *address
, int size
);
229 void * obstack_copy0 (struct obstack
*obstack
, 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
, void *data
, int size
);
236 void obstack_grow0 (struct obstack
*obstack
, void *data
, int size
);
238 void obstack_1grow (struct obstack
*obstack
, int data_char
);
239 void obstack_ptr_grow (struct obstack
*obstack
, 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
, 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 /* __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. The
266 default action is to print a message and abort. */
267 #if defined (__STDC__) && __STDC__
268 extern void (*obstack_alloc_failed_handler
) (void);
270 extern void (*obstack_alloc_failed_handler
) ();
273 /* Exit value used when `print_and_abort' is used. */
274 extern int obstack_exit_failure
;
276 /* Pointer to beginning of object being allocated or to be allocated next.
277 Note that this might not be the final address of the object
278 because a new chunk might be needed to hold the final size. */
280 #define obstack_base(h) ((h)->object_base)
282 /* Size for allocating ordinary chunks. */
284 #define obstack_chunk_size(h) ((h)->chunk_size)
286 /* Pointer to next byte not yet allocated in current chunk. */
288 #define obstack_next_free(h) ((h)->next_free)
290 /* Mask specifying low bits that should be clear in address of an object. */
292 #define obstack_alignment_mask(h) ((h)->alignment_mask)
294 /* To prevent prototype warnings provide complete argument list in
295 standard C version. */
296 #if defined (__STDC__) && __STDC__
298 #define obstack_init(h) \
299 _obstack_begin ((h), 0, 0, \
300 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
302 #define obstack_begin(h, size) \
303 _obstack_begin ((h), (size), 0, \
304 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
306 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
307 _obstack_begin ((h), (size), (alignment), \
308 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
310 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
311 _obstack_begin_1 ((h), (size), (alignment), \
312 (void *(*) (void *, long)) (chunkfun), \
313 (void (*) (void *, void *)) (freefun), (arg))
315 #define obstack_chunkfun(h, newchunkfun) \
316 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
318 #define obstack_freefun(h, newfreefun) \
319 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
323 #define obstack_init(h) \
324 _obstack_begin ((h), 0, 0, \
325 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
327 #define obstack_begin(h, size) \
328 _obstack_begin ((h), (size), 0, \
329 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
331 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
332 _obstack_begin ((h), (size), (alignment), \
333 (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
335 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
336 _obstack_begin_1 ((h), (size), (alignment), \
337 (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
339 #define obstack_chunkfun(h, newchunkfun) \
340 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
342 #define obstack_freefun(h, newfreefun) \
343 ((h) -> freefun = (void (*)()) (newfreefun))
347 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
349 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
351 #define obstack_memory_used(h) _obstack_memory_used (h)
353 #if defined (__GNUC__) && defined (__STDC__) && __STDC__
354 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
355 does not implement __extension__. But that compiler doesn't define
357 #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
358 #define __extension__
361 /* For GNU C, if not -traditional,
362 we can define these macros to compute all args only once
363 without using a global variable.
364 Also, we can avoid using the `temp' slot, to make faster code. */
366 #define obstack_object_size(OBSTACK) \
368 ({ struct obstack *__o = (OBSTACK); \
369 (unsigned) (__o->next_free - __o->object_base); })
371 #define obstack_room(OBSTACK) \
373 ({ struct obstack *__o = (OBSTACK); \
374 (unsigned) (__o->chunk_limit - __o->next_free); })
376 #define obstack_make_room(OBSTACK,length) \
378 ({ struct obstack *__o = (OBSTACK); \
379 int __len = (length); \
380 if (__o->chunk_limit - __o->next_free < __len) \
381 _obstack_newchunk (__o, __len); \
384 #define obstack_empty_p(OBSTACK) \
386 ({ struct obstack *__o = (OBSTACK); \
387 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
389 #define obstack_grow(OBSTACK,where,length) \
391 ({ struct obstack *__o = (OBSTACK); \
392 int __len = (length); \
393 if (__o->next_free + __len > __o->chunk_limit) \
394 _obstack_newchunk (__o, __len); \
395 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
396 __o->next_free += __len; \
399 #define obstack_grow0(OBSTACK,where,length) \
401 ({ struct obstack *__o = (OBSTACK); \
402 int __len = (length); \
403 if (__o->next_free + __len + 1 > __o->chunk_limit) \
404 _obstack_newchunk (__o, __len + 1); \
405 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
406 __o->next_free += __len; \
407 *(__o->next_free)++ = 0; \
410 #define obstack_1grow(OBSTACK,datum) \
412 ({ struct obstack *__o = (OBSTACK); \
413 if (__o->next_free + 1 > __o->chunk_limit) \
414 _obstack_newchunk (__o, 1); \
415 *(__o->next_free)++ = (datum); \
418 /* These assume that the obstack alignment is good enough for pointers or ints,
419 and that the data added so far to the current object
420 shares that much alignment. */
422 #define obstack_ptr_grow(OBSTACK,datum) \
424 ({ struct obstack *__o = (OBSTACK); \
425 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
426 _obstack_newchunk (__o, sizeof (void *)); \
427 *((void **)__o->next_free)++ = ((void *)datum); \
430 #define obstack_int_grow(OBSTACK,datum) \
432 ({ struct obstack *__o = (OBSTACK); \
433 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
434 _obstack_newchunk (__o, sizeof (int)); \
435 *((int *)__o->next_free)++ = ((int)datum); \
438 #define obstack_ptr_grow_fast(h,aptr) (*((void **) (h)->next_free)++ = (void *)aptr)
439 #define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
441 #define obstack_blank(OBSTACK,length) \
443 ({ struct obstack *__o = (OBSTACK); \
444 int __len = (length); \
445 if (__o->chunk_limit - __o->next_free < __len) \
446 _obstack_newchunk (__o, __len); \
447 __o->next_free += __len; \
450 #define obstack_alloc(OBSTACK,length) \
452 ({ struct obstack *__h = (OBSTACK); \
453 obstack_blank (__h, (length)); \
454 obstack_finish (__h); })
456 #define obstack_copy(OBSTACK,where,length) \
458 ({ struct obstack *__h = (OBSTACK); \
459 obstack_grow (__h, (where), (length)); \
460 obstack_finish (__h); })
462 #define obstack_copy0(OBSTACK,where,length) \
464 ({ struct obstack *__h = (OBSTACK); \
465 obstack_grow0 (__h, (where), (length)); \
466 obstack_finish (__h); })
468 /* The local variable is named __o1 to avoid a name conflict
469 when obstack_blank is called. */
470 #define obstack_finish(OBSTACK) \
472 ({ struct obstack *__o1 = (OBSTACK); \
474 value = (void *) __o1->object_base; \
475 if (__o1->next_free == value) \
476 __o1->maybe_empty_object = 1; \
478 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
479 & ~ (__o1->alignment_mask)); \
480 if (__o1->next_free - (char *)__o1->chunk \
481 > __o1->chunk_limit - (char *)__o1->chunk) \
482 __o1->next_free = __o1->chunk_limit; \
483 __o1->object_base = __o1->next_free; \
486 #define obstack_free(OBSTACK, OBJ) \
488 ({ struct obstack *__o = (OBSTACK); \
489 void *__obj = (OBJ); \
490 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
491 __o->next_free = __o->object_base = __obj; \
492 else (obstack_free) (__o, __obj); })
494 #else /* not __GNUC__ or not __STDC__ */
496 #define obstack_object_size(h) \
497 (unsigned) ((h)->next_free - (h)->object_base)
499 #define obstack_room(h) \
500 (unsigned) ((h)->chunk_limit - (h)->next_free)
502 #define obstack_empty_p(h) \
503 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
505 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
506 so that we can avoid having void expressions
507 in the arms of the conditional expression.
508 Casting the third operand to void was tried before,
509 but some compilers won't accept it. */
511 #define obstack_make_room(h,length) \
512 ( (h)->temp = (length), \
513 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
514 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
516 #define obstack_grow(h,where,length) \
517 ( (h)->temp = (length), \
518 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
519 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
520 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
521 (h)->next_free += (h)->temp)
523 #define obstack_grow0(h,where,length) \
524 ( (h)->temp = (length), \
525 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
526 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
527 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
528 (h)->next_free += (h)->temp, \
529 *((h)->next_free)++ = 0)
531 #define obstack_1grow(h,datum) \
532 ( (((h)->next_free + 1 > (h)->chunk_limit) \
533 ? (_obstack_newchunk ((h), 1), 0) : 0), \
534 (*((h)->next_free)++ = (datum)))
536 #define obstack_ptr_grow(h,datum) \
537 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
538 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
539 (*((char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *) datum)))
541 #define obstack_int_grow(h,datum) \
542 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
543 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
544 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = ((int) datum)))
546 #define obstack_ptr_grow_fast(h,aptr) (*((char **) (h)->next_free)++ = (char *) aptr)
547 #define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
549 #define obstack_blank(h,length) \
550 ( (h)->temp = (length), \
551 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
552 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
553 ((h)->next_free += (h)->temp))
555 #define obstack_alloc(h,length) \
556 (obstack_blank ((h), (length)), obstack_finish ((h)))
558 #define obstack_copy(h,where,length) \
559 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
561 #define obstack_copy0(h,where,length) \
562 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
564 #define obstack_finish(h) \
565 ( ((h)->next_free == (h)->object_base \
566 ? (((h)->maybe_empty_object = 1), 0) \
568 (h)->temp = __PTR_TO_INT ((h)->object_base), \
570 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
571 & ~ ((h)->alignment_mask)), \
572 (((h)->next_free - (char *) (h)->chunk \
573 > (h)->chunk_limit - (char *) (h)->chunk) \
574 ? ((h)->next_free = (h)->chunk_limit) : 0), \
575 (h)->object_base = (h)->next_free, \
576 __INT_TO_PTR ((h)->temp))
578 #if defined (__STDC__) && __STDC__
579 #define obstack_free(h,obj) \
580 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
581 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
582 ? (int) ((h)->next_free = (h)->object_base \
583 = (h)->temp + (char *) (h)->chunk) \
584 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
586 #define obstack_free(h,obj) \
587 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
588 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
589 ? (int) ((h)->next_free = (h)->object_base \
590 = (h)->temp + (char *) (h)->chunk) \
591 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
594 #endif /* not __GNUC__ or not __STDC__ */
600 #endif /* obstack.h */