1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97 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 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Library General Public License as
9 published by the Free Software Foundation; either version 2 of the
10 License, or (at your option) any later version.
12 The GNU C Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Library General Public License for more details.
17 You should have received a copy of the GNU Library General Public
18 License along with the GNU C Library; see the file COPYING.LIB. If not,
19 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
24 All the apparent functions defined here are macros. The idea
25 is that you would use these pre-tested macros to solve a
26 very specific set of problems, and they would run fast.
27 Caution: no side-effects in arguments please!! They may be
28 evaluated MANY times!!
30 These macros operate a stack of objects. Each object starts life
31 small, and may grow to maturity. (Consider building a word syllable
32 by syllable.) An object can move while it is growing. Once it has
33 been "finished" it never changes address again. So the "top of the
34 stack" is typically an immature growing object, while the rest of the
35 stack is of mature, fixed size and fixed address objects.
37 These routines grab large chunks of memory, using a function you
38 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
39 by calling `obstack_chunk_free'. You must define them and declare
40 them before using any obstack macros.
42 Each independent stack is represented by a `struct obstack'.
43 Each of the obstack macros expects a pointer to such a structure
44 as the first argument.
46 One motivation for this package is the problem of growing char strings
47 in symbol tables. Unless you are "fascist pig with a read-only mind"
48 --Gosper's immortal quote from HAKMEM item 154, out of context--you
49 would not like to put any arbitrary upper limit on the length of your
52 In practice this often means you will build many short symbols and a
53 few long symbols. At the time you are reading a symbol you don't know
54 how long it is. One traditional method is to read a symbol into a
55 buffer, realloc()ating the buffer every time you try to read a symbol
56 that is longer than the buffer. This is beaut, but you still will
57 want to copy the symbol from the buffer to a more permanent
58 symbol-table entry say about half the time.
60 With obstacks, you can work differently. Use one obstack for all symbol
61 names. As you read a symbol, grow the name in the obstack gradually.
62 When the name is complete, finalize it. Then, if the symbol exists already,
63 free the newly read name.
65 The way we do this is to take a large chunk, allocating memory from
66 low addresses. When you want to build a symbol in the chunk you just
67 add chars above the current "high water mark" in the chunk. When you
68 have finished adding chars, because you got to the end of the symbol,
69 you know how long the chars are, and you can create a new object.
70 Mostly the chars will not burst over the highest address of the chunk,
71 because you would typically expect a chunk to be (say) 100 times as
72 long as an average object.
74 In case that isn't clear, when we have enough chars to make up
75 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
76 so we just point to it where it lies. No moving of chars is
77 needed and this is the second win: potentially long strings need
78 never be explicitly shuffled. Once an object is formed, it does not
79 change its address during its lifetime.
81 When the chars burst over a chunk boundary, we allocate a larger
82 chunk, and then copy the partly formed object from the end of the old
83 chunk to the beginning of the new larger chunk. We then carry on
84 accreting characters to the end of the object as we normally would.
86 A special macro is provided to add a single char at a time to a
87 growing object. This allows the use of register variables, which
88 break the ordinary 'growth' macro.
91 We allocate large chunks.
92 We carve out one object at a time from the current chunk.
93 Once carved, an object never moves.
94 We are free to append data of any size to the currently
96 Exactly one object is growing in an obstack at any one time.
97 You can run one obstack per control block.
98 You may have as many control blocks as you dare.
99 Because of the way we do it, you can `unwind' an obstack
100 back to a previous state. (You may remove objects much
101 as you would with a stack.)
105 /* Don't do the contents of this file more than once. */
107 #ifndef __OBSTACK_H__
108 #define __OBSTACK_H__
110 /* We use subtraction of (char *) 0 instead of casting to int
111 because on word-addressable machines a simple cast to int
112 may ignore the byte-within-word field of the pointer. */
115 #define __PTR_TO_INT(P) ((P) - (char *) 0)
119 #define __INT_TO_PTR(P) ((P) + (char *) 0)
122 /* We need the type of the resulting object. In ANSI C it is ptrdiff_t
123 but in traditional C it is usually long. If we are in ANSI C and
124 don't already have ptrdiff_t get it. */
126 #if defined (__STDC__) && __STDC__ && ! defined (offsetof)
127 #if defined (__GNUC__) && defined (IN_GCC)
128 /* On Next machine, the system's stddef.h screws up if included
129 after we have defined just ptrdiff_t, so include all of stddef.h.
130 Otherwise, define just ptrdiff_t, which is all we need. */
132 #define __need_ptrdiff_t
139 #if defined (__STDC__) && __STDC__
140 #define PTR_INT_TYPE ptrdiff_t
142 #define PTR_INT_TYPE long
145 #if defined (_LIBC) || defined (HAVE_STRING_H)
147 #define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
150 #define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
152 #define _obstack_memcpy(To, From, N) bcopy ((From), (To), (N))
156 struct _obstack_chunk /* Lives at front of each chunk. */
158 char *limit; /* 1 past end of this chunk */
159 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
160 char contents[4]; /* objects begin here */
163 struct obstack /* control current object in current chunk */
165 long chunk_size; /* preferred size to allocate chunks in */
166 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
167 char *object_base; /* address of object we are building */
168 char *next_free; /* where to add next char to current object */
169 char *chunk_limit; /* address of char after current chunk */
170 PTR_INT_TYPE temp; /* Temporary for some macros. */
171 int alignment_mask; /* Mask of alignment for each object. */
172 #if defined (__STDC__) && __STDC__
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 */
180 struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
181 void (*freefun) (); /* User's function to free a chunk. */
182 char *extra_arg; /* first arg for chunk alloc/dealloc funcs */
184 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
185 unsigned maybe_empty_object:1;/* There is a possibility that the current
186 chunk contains a zero-length object. This
187 prevents freeing the chunk if we allocate
188 a bigger chunk to replace it. */
189 unsigned alloc_failed:1; /* No longer used, as we now call the failed
190 handler on error, but retained for binary
194 /* Declare the external functions we use; they are in obstack.c. */
196 #if defined (__STDC__) && __STDC__
197 extern void _obstack_newchunk (struct obstack *, int);
198 extern void _obstack_free (struct obstack *, void *);
199 extern int _obstack_begin (struct obstack *, int, int,
200 void *(*) (long), void (*) (void *));
201 extern int _obstack_begin_1 (struct obstack *, int, int,
202 void *(*) (void *, long),
203 void (*) (void *, void *), void *);
204 extern int _obstack_memory_used (struct obstack *);
206 extern void _obstack_newchunk ();
207 extern void _obstack_free ();
208 extern int _obstack_begin ();
209 extern int _obstack_begin_1 ();
210 extern int _obstack_memory_used ();
213 #if defined (__STDC__) && __STDC__
215 /* Do the function-declarations after the structs
216 but before defining the macros. */
218 void obstack_init (struct obstack *obstack);
220 void * obstack_alloc (struct obstack *obstack, int size);
222 void * obstack_copy (struct obstack *obstack, void *address, int size);
223 void * obstack_copy0 (struct obstack *obstack, void *address, int size);
225 void obstack_free (struct obstack *obstack, void *block);
227 void obstack_blank (struct obstack *obstack, int size);
229 void obstack_grow (struct obstack *obstack, void *data, int size);
230 void obstack_grow0 (struct obstack *obstack, void *data, int size);
232 void obstack_1grow (struct obstack *obstack, int data_char);
233 void obstack_ptr_grow (struct obstack *obstack, void *data);
234 void obstack_int_grow (struct obstack *obstack, int data);
236 void * obstack_finish (struct obstack *obstack);
238 int obstack_object_size (struct obstack *obstack);
240 int obstack_room (struct obstack *obstack);
241 void obstack_make_room (struct obstack *obstack, int size);
242 void obstack_1grow_fast (struct obstack *obstack, int data_char);
243 void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
244 void obstack_int_grow_fast (struct obstack *obstack, int data);
245 void obstack_blank_fast (struct obstack *obstack, int size);
247 void * obstack_base (struct obstack *obstack);
248 void * obstack_next_free (struct obstack *obstack);
249 int obstack_alignment_mask (struct obstack *obstack);
250 int obstack_chunk_size (struct obstack *obstack);
251 int obstack_memory_used (struct obstack *obstack);
253 #endif /* __STDC__ */
255 /* Non-ANSI C cannot really support alternative functions for these macros,
256 so we do not declare them. */
258 /* Error handler called when `obstack_chunk_alloc' failed to allocate
259 more memory. This can be set to a user defined function. The
260 default action is to print a message and abort. */
261 #if defined (__STDC__) && __STDC__
262 extern void (*obstack_alloc_failed_handler) (void);
264 extern void (*obstack_alloc_failed_handler) ();
267 /* Exit value used when `print_and_abort' is used. */
268 extern int obstack_exit_failure;
270 /* Pointer to beginning of object being allocated or to be allocated next.
271 Note that this might not be the final address of the object
272 because a new chunk might be needed to hold the final size. */
274 #define obstack_base(h) ((h)->object_base)
276 /* Size for allocating ordinary chunks. */
278 #define obstack_chunk_size(h) ((h)->chunk_size)
280 /* Pointer to next byte not yet allocated in current chunk. */
282 #define obstack_next_free(h) ((h)->next_free)
284 /* Mask specifying low bits that should be clear in address of an object. */
286 #define obstack_alignment_mask(h) ((h)->alignment_mask)
288 /* To prevent prototype warnings provide complete argument list in
289 standard C version. */
290 #if defined (__STDC__) && __STDC__
292 #define obstack_init(h) \
293 _obstack_begin ((h), 0, 0, \
294 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
296 #define obstack_begin(h, size) \
297 _obstack_begin ((h), (size), 0, \
298 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
300 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
301 _obstack_begin ((h), (size), (alignment), \
302 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
304 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
305 _obstack_begin_1 ((h), (size), (alignment), \
306 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun), (arg))
308 #define obstack_chunkfun(h, newchunkfun) \
309 ((h) -> chunkfun = (struct _obstack_chunk *(*)(long)) (newchunkfun))
311 #define obstack_freefun(h, newfreefun) \
312 ((h) -> freefun = (void (*)(void *)) (newfreefun))
316 #define obstack_init(h) \
317 _obstack_begin ((h), 0, 0, \
318 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
320 #define obstack_begin(h, size) \
321 _obstack_begin ((h), (size), 0, \
322 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
324 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
325 _obstack_begin ((h), (size), (alignment), \
326 (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
328 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
329 _obstack_begin_1 ((h), (size), (alignment), \
330 (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
332 #define obstack_chunkfun(h, newchunkfun) \
333 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
335 #define obstack_freefun(h, newfreefun) \
336 ((h) -> freefun = (void (*)()) (newfreefun))
340 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
342 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
344 #define obstack_memory_used(h) _obstack_memory_used (h)
346 #if defined (__GNUC__) && defined (__STDC__) && __STDC__
347 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
348 does not implement __extension__. But that compiler doesn't define
350 #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
351 #define __extension__
354 /* For GNU C, if not -traditional,
355 we can define these macros to compute all args only once
356 without using a global variable.
357 Also, we can avoid using the `temp' slot, to make faster code. */
359 #define obstack_object_size(OBSTACK) \
361 ({ struct obstack *__o = (OBSTACK); \
362 (unsigned) (__o->next_free - __o->object_base); })
364 #define obstack_room(OBSTACK) \
366 ({ struct obstack *__o = (OBSTACK); \
367 (unsigned) (__o->chunk_limit - __o->next_free); })
369 #define obstack_make_room(OBSTACK,length) \
371 ({ struct obstack *__o = (OBSTACK); \
372 int __len = (length); \
373 if (__o->chunk_limit - __o->next_free < __len) \
374 _obstack_newchunk (__o, __len); \
377 #define obstack_grow(OBSTACK,where,length) \
379 ({ struct obstack *__o = (OBSTACK); \
380 int __len = (length); \
381 if (__o->next_free + __len > __o->chunk_limit) \
382 _obstack_newchunk (__o, __len); \
383 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
384 __o->next_free += __len; \
387 #define obstack_grow0(OBSTACK,where,length) \
389 ({ struct obstack *__o = (OBSTACK); \
390 int __len = (length); \
391 if (__o->next_free + __len + 1 > __o->chunk_limit) \
392 _obstack_newchunk (__o, __len + 1); \
393 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
394 __o->next_free += __len; \
395 *(__o->next_free)++ = 0; \
398 #define obstack_1grow(OBSTACK,datum) \
400 ({ struct obstack *__o = (OBSTACK); \
401 if (__o->next_free + 1 > __o->chunk_limit) \
402 _obstack_newchunk (__o, 1); \
403 *(__o->next_free)++ = (datum); \
406 /* These assume that the obstack alignment is good enough for pointers or ints,
407 and that the data added so far to the current object
408 shares that much alignment. */
410 #define obstack_ptr_grow(OBSTACK,datum) \
412 ({ struct obstack *__o = (OBSTACK); \
413 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
414 _obstack_newchunk (__o, sizeof (void *)); \
415 *((void **)__o->next_free)++ = ((void *)datum); \
418 #define obstack_int_grow(OBSTACK,datum) \
420 ({ struct obstack *__o = (OBSTACK); \
421 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
422 _obstack_newchunk (__o, sizeof (int)); \
423 *((int *)__o->next_free)++ = ((int)datum); \
426 #define obstack_ptr_grow_fast(h,aptr) (*((void **) (h)->next_free)++ = (void *)aptr)
427 #define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
429 #define obstack_blank(OBSTACK,length) \
431 ({ struct obstack *__o = (OBSTACK); \
432 int __len = (length); \
433 if (__o->chunk_limit - __o->next_free < __len) \
434 _obstack_newchunk (__o, __len); \
435 __o->next_free += __len; \
438 #define obstack_alloc(OBSTACK,length) \
440 ({ struct obstack *__h = (OBSTACK); \
441 obstack_blank (__h, (length)); \
442 obstack_finish (__h); })
444 #define obstack_copy(OBSTACK,where,length) \
446 ({ struct obstack *__h = (OBSTACK); \
447 obstack_grow (__h, (where), (length)); \
448 obstack_finish (__h); })
450 #define obstack_copy0(OBSTACK,where,length) \
452 ({ struct obstack *__h = (OBSTACK); \
453 obstack_grow0 (__h, (where), (length)); \
454 obstack_finish (__h); })
456 /* The local variable is named __o1 to avoid a name conflict
457 when obstack_blank is called. */
458 #define obstack_finish(OBSTACK) \
460 ({ struct obstack *__o1 = (OBSTACK); \
462 value = (void *) __o1->object_base; \
463 if (__o1->next_free == value) \
464 __o1->maybe_empty_object = 1; \
466 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
467 & ~ (__o1->alignment_mask)); \
468 if (__o1->next_free - (char *)__o1->chunk \
469 > __o1->chunk_limit - (char *)__o1->chunk) \
470 __o1->next_free = __o1->chunk_limit; \
471 __o1->object_base = __o1->next_free; \
474 #define obstack_free(OBSTACK, OBJ) \
476 ({ struct obstack *__o = (OBSTACK); \
477 void *__obj = (OBJ); \
478 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
479 __o->next_free = __o->object_base = __obj; \
480 else (obstack_free) (__o, __obj); })
482 #else /* not __GNUC__ or not __STDC__ */
484 #define obstack_object_size(h) \
485 (unsigned) ((h)->next_free - (h)->object_base)
487 #define obstack_room(h) \
488 (unsigned) ((h)->chunk_limit - (h)->next_free)
490 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
491 so that we can avoid having void expressions
492 in the arms of the conditional expression.
493 Casting the third operand to void was tried before,
494 but some compilers won't accept it. */
496 #define obstack_make_room(h,length) \
497 ( (h)->temp = (length), \
498 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
499 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
501 #define obstack_grow(h,where,length) \
502 ( (h)->temp = (length), \
503 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
504 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
505 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
506 (h)->next_free += (h)->temp)
508 #define obstack_grow0(h,where,length) \
509 ( (h)->temp = (length), \
510 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
511 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
512 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
513 (h)->next_free += (h)->temp, \
514 *((h)->next_free)++ = 0)
516 #define obstack_1grow(h,datum) \
517 ( (((h)->next_free + 1 > (h)->chunk_limit) \
518 ? (_obstack_newchunk ((h), 1), 0) : 0), \
519 (*((h)->next_free)++ = (datum)))
521 #define obstack_ptr_grow(h,datum) \
522 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
523 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
524 (*((char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *) datum)))
526 #define obstack_int_grow(h,datum) \
527 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
528 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
529 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = ((int) datum)))
531 #define obstack_ptr_grow_fast(h,aptr) (*((char **) (h)->next_free)++ = (char *) aptr)
532 #define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
534 #define obstack_blank(h,length) \
535 ( (h)->temp = (length), \
536 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
537 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
538 ((h)->next_free += (h)->temp))
540 #define obstack_alloc(h,length) \
541 (obstack_blank ((h), (length)), obstack_finish ((h)))
543 #define obstack_copy(h,where,length) \
544 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
546 #define obstack_copy0(h,where,length) \
547 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
549 #define obstack_finish(h) \
550 ( ((h)->next_free == (h)->object_base \
551 ? (((h)->maybe_empty_object = 1), 0) \
553 (h)->temp = __PTR_TO_INT ((h)->object_base), \
555 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
556 & ~ ((h)->alignment_mask)), \
557 (((h)->next_free - (char *) (h)->chunk \
558 > (h)->chunk_limit - (char *) (h)->chunk) \
559 ? ((h)->next_free = (h)->chunk_limit) : 0), \
560 (h)->object_base = (h)->next_free, \
561 __INT_TO_PTR ((h)->temp))
563 #if defined (__STDC__) && __STDC__
564 #define obstack_free(h,obj) \
565 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
566 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
567 ? (int) ((h)->next_free = (h)->object_base \
568 = (h)->temp + (char *) (h)->chunk) \
569 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
571 #define obstack_free(h,obj) \
572 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
573 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
574 ? (int) ((h)->next_free = (h)->object_base \
575 = (h)->temp + (char *) (h)->chunk) \
576 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
579 #endif /* not __GNUC__ or not __STDC__ */
581 #endif /* not __OBSTACK_H__ */