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 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 GNU
18 Library General Public License for more details.
20 You should have received a copy of the GNU Library General Public
21 License 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. */
117 /* We use subtraction of (char *) 0 instead of casting to int
118 because on word-addressable machines a simple cast to int
119 may ignore the byte-within-word field of the pointer. */
122 # define __PTR_TO_INT(P) ((P) - (char *) 0)
126 #if defined __STDC__ && __STDC__
127 # define __INT_TO_PTR(P) ((void *) ((P) + (char *) 0))
129 # define __INT_TO_PTR(P) ((P) + (char *) 0)
133 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
134 defined, as with GNU C, use that; that way we don't pollute the
135 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
136 available, include it and use ptrdiff_t. In traditional C, long is
137 the best that we can do. */
139 #ifdef __PTRDIFF_TYPE__
140 # define PTR_INT_TYPE __PTRDIFF_TYPE__
142 # ifdef HAVE_STDDEF_H
144 # define PTR_INT_TYPE ptrdiff_t
146 # define PTR_INT_TYPE long
150 #if defined _LIBC || defined HAVE_STRING_H
152 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
155 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
157 # define _obstack_memcpy(To, From, N) bcopy ((From), (To), (N))
161 struct _obstack_chunk
/* Lives at front of each chunk. */
163 char *limit
; /* 1 past end of this chunk */
164 struct _obstack_chunk
*prev
; /* address of prior chunk or NULL */
165 char contents
[4]; /* objects begin here */
168 struct obstack
/* control current object in current chunk */
170 long chunk_size
; /* preferred size to allocate chunks in */
171 struct _obstack_chunk
*chunk
; /* address of current struct obstack_chunk */
172 char *object_base
; /* address of object we are building */
173 char *next_free
; /* where to add next char to current object */
174 char *chunk_limit
; /* address of char after current chunk */
175 PTR_INT_TYPE temp
; /* Temporary for some macros. */
176 int alignment_mask
; /* Mask of alignment for each object. */
177 #if defined __STDC__ && __STDC__
178 /* These prototypes vary based on `use_extra_arg', and we use
179 casts to the prototypeless function type in all assignments,
180 but having prototypes here quiets -Wstrict-prototypes. */
181 struct _obstack_chunk
*(*chunkfun
) (void *, long);
182 void (*freefun
) (void *, struct _obstack_chunk
*);
183 void *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
185 struct _obstack_chunk
*(*chunkfun
) (); /* User's fcn to allocate a chunk. */
186 void (*freefun
) (); /* User's function to free a chunk. */
187 char *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
189 unsigned use_extra_arg
:1; /* chunk alloc/dealloc funcs take extra arg */
190 unsigned maybe_empty_object
:1;/* There is a possibility that the current
191 chunk contains a zero-length object. This
192 prevents freeing the chunk if we allocate
193 a bigger chunk to replace it. */
194 unsigned alloc_failed
:1; /* No longer used, as we now call the failed
195 handler on error, but retained for binary
199 /* Declare the external functions we use; they are in obstack.c. */
201 #if defined __STDC__ && __STDC__
202 extern void _obstack_newchunk (struct obstack
*, int);
203 extern void _obstack_free (struct obstack
*, void *);
204 extern int _obstack_begin (struct obstack
*, int, int,
205 void *(*) (long), void (*) (void *));
206 extern int _obstack_begin_1 (struct obstack
*, int, int,
207 void *(*) (void *, long),
208 void (*) (void *, void *), void *);
209 extern int _obstack_memory_used (struct obstack
*);
211 extern void _obstack_newchunk ();
212 extern void _obstack_free ();
213 extern int _obstack_begin ();
214 extern int _obstack_begin_1 ();
215 extern int _obstack_memory_used ();
218 #if defined __STDC__ && __STDC__
220 /* Do the function-declarations after the structs
221 but before defining the macros. */
223 void obstack_init (struct obstack
*obstack
);
225 void * obstack_alloc (struct obstack
*obstack
, int size
);
227 void * obstack_copy (struct obstack
*obstack
, const void *address
, int size
);
228 void * obstack_copy0 (struct obstack
*obstack
, const void *address
, int size
);
230 void obstack_free (struct obstack
*obstack
, void *block
);
232 void obstack_blank (struct obstack
*obstack
, int size
);
234 void obstack_grow (struct obstack
*obstack
, const void *data
, int size
);
235 void obstack_grow0 (struct obstack
*obstack
, const void *data
, int size
);
237 void obstack_1grow (struct obstack
*obstack
, int data_char
);
238 void obstack_ptr_grow (struct obstack
*obstack
, const void *data
);
239 void obstack_int_grow (struct obstack
*obstack
, int data
);
241 void * obstack_finish (struct obstack
*obstack
);
243 int obstack_object_size (struct obstack
*obstack
);
245 int obstack_room (struct obstack
*obstack
);
246 void obstack_make_room (struct obstack
*obstack
, int size
);
247 void obstack_1grow_fast (struct obstack
*obstack
, int data_char
);
248 void obstack_ptr_grow_fast (struct obstack
*obstack
, const void *data
);
249 void obstack_int_grow_fast (struct obstack
*obstack
, int data
);
250 void obstack_blank_fast (struct obstack
*obstack
, int size
);
252 void * obstack_base (struct obstack
*obstack
);
253 void * obstack_next_free (struct obstack
*obstack
);
254 int obstack_alignment_mask (struct obstack
*obstack
);
255 int obstack_chunk_size (struct obstack
*obstack
);
256 int obstack_memory_used (struct obstack
*obstack
);
258 #endif /* __STDC__ */
260 /* Non-ANSI C cannot really support alternative functions for these macros,
261 so we do not declare them. */
263 /* Error handler called when `obstack_chunk_alloc' failed to allocate
264 more memory. This can be set to a user defined function which
265 should either abort gracefully or use longjump - but shouldn't
266 return. The 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, \
301 (void (*) (void *)) obstack_chunk_free)
303 # define obstack_begin(h, size) \
304 _obstack_begin ((h), (size), 0, \
305 (void *(*) (long)) obstack_chunk_alloc, \
306 (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), \
311 (void (*) (void *)) (freefun))
313 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
314 _obstack_begin_1 ((h), (size), (alignment), \
315 (void *(*) (void *, long)) (chunkfun), \
316 (void (*) (void *, void *)) (freefun), (arg))
318 # define obstack_chunkfun(h, newchunkfun) \
319 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
321 # define obstack_freefun(h, newfreefun) \
322 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
326 # define obstack_init(h) \
327 _obstack_begin ((h), 0, 0, \
328 (void *(*) ()) obstack_chunk_alloc, \
329 (void (*) ()) obstack_chunk_free)
331 # define obstack_begin(h, size) \
332 _obstack_begin ((h), (size), 0, \
333 (void *(*) ()) obstack_chunk_alloc, \
334 (void (*) ()) obstack_chunk_free)
336 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
337 _obstack_begin ((h), (size), (alignment), \
338 (void *(*) ()) (chunkfun), \
339 (void (*) ()) (freefun))
341 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
342 _obstack_begin_1 ((h), (size), (alignment), \
343 (void *(*) ()) (chunkfun), \
344 (void (*) ()) (freefun), (arg))
346 # define obstack_chunkfun(h, newchunkfun) \
347 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
349 # define obstack_freefun(h, newfreefun) \
350 ((h) -> freefun = (void (*)()) (newfreefun))
354 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
356 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
358 #define obstack_memory_used(h) _obstack_memory_used (h)
360 #if defined __GNUC__ && defined __STDC__ && __STDC__
361 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
362 does not implement __extension__. But that compiler doesn't define
364 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
365 # define __extension__
368 /* For GNU C, if not -traditional,
369 we can define these macros to compute all args only once
370 without using a global variable.
371 Also, we can avoid using the `temp' slot, to make faster code. */
373 # define obstack_object_size(OBSTACK) \
375 ({ struct obstack const *__o = (OBSTACK); \
376 (unsigned) (__o->next_free - __o->object_base); })
378 # define obstack_room(OBSTACK) \
380 ({ struct obstack const *__o = (OBSTACK); \
381 (unsigned) (__o->chunk_limit - __o->next_free); })
383 # define obstack_make_room(OBSTACK,length) \
385 ({ struct obstack *__o = (OBSTACK); \
386 int __len = (length); \
387 if (__o->chunk_limit - __o->next_free < __len) \
388 _obstack_newchunk (__o, __len); \
391 # define obstack_empty_p(OBSTACK) \
393 ({ struct obstack const *__o = (OBSTACK); \
394 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
396 # define obstack_grow(OBSTACK,where,length) \
398 ({ struct obstack *__o = (OBSTACK); \
399 int __len = (length); \
400 if (__o->next_free + __len > __o->chunk_limit) \
401 _obstack_newchunk (__o, __len); \
402 _obstack_memcpy (__o->next_free, (where), __len); \
403 __o->next_free += __len; \
406 # define obstack_grow0(OBSTACK,where,length) \
408 ({ struct obstack *__o = (OBSTACK); \
409 int __len = (length); \
410 if (__o->next_free + __len + 1 > __o->chunk_limit) \
411 _obstack_newchunk (__o, __len + 1); \
412 _obstack_memcpy (__o->next_free, (where), __len); \
413 __o->next_free += __len; \
414 *(__o->next_free)++ = 0; \
417 # define obstack_1grow(OBSTACK,datum) \
419 ({ struct obstack *__o = (OBSTACK); \
420 if (__o->next_free + 1 > __o->chunk_limit) \
421 _obstack_newchunk (__o, 1); \
422 *(__o->next_free)++ = (datum); \
425 /* These assume that the obstack alignment is good enough for pointers
426 or ints, and that the data added so far to the current object
427 shares that much alignment. */
429 # define obstack_ptr_grow(OBSTACK,datum) \
431 ({ struct obstack *__o = (OBSTACK); \
432 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
433 _obstack_newchunk (__o, sizeof (void *)); \
434 *((void **)__o->next_free)++ = (datum); \
437 # define obstack_int_grow(OBSTACK,datum) \
439 ({ struct obstack *__o = (OBSTACK); \
440 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
441 _obstack_newchunk (__o, sizeof (int)); \
442 *((int *)__o->next_free)++ = (datum); \
445 # define obstack_ptr_grow_fast(h,aptr) \
446 (*((void **) (h)->next_free)++ = (aptr))
448 # define obstack_int_grow_fast(h,aint) \
449 (*((int *) (h)->next_free)++ = (aint))
451 # define obstack_blank(OBSTACK,length) \
453 ({ struct obstack *__o = (OBSTACK); \
454 int __len = (length); \
455 if (__o->chunk_limit - __o->next_free < __len) \
456 _obstack_newchunk (__o, __len); \
457 __o->next_free += __len; \
460 # define obstack_alloc(OBSTACK,length) \
462 ({ struct obstack *__h = (OBSTACK); \
463 obstack_blank (__h, (length)); \
464 obstack_finish (__h); })
466 # define obstack_copy(OBSTACK,where,length) \
468 ({ struct obstack *__h = (OBSTACK); \
469 obstack_grow (__h, (where), (length)); \
470 obstack_finish (__h); })
472 # define obstack_copy0(OBSTACK,where,length) \
474 ({ struct obstack *__h = (OBSTACK); \
475 obstack_grow0 (__h, (where), (length)); \
476 obstack_finish (__h); })
478 /* The local variable is named __o1 to avoid a name conflict
479 when obstack_blank is called. */
480 # define obstack_finish(OBSTACK) \
482 ({ struct obstack *__o1 = (OBSTACK); \
484 value = (void *) __o1->object_base; \
485 if (__o1->next_free == value) \
486 __o1->maybe_empty_object = 1; \
488 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
489 & ~ (__o1->alignment_mask)); \
490 if (__o1->next_free - (char *)__o1->chunk \
491 > __o1->chunk_limit - (char *)__o1->chunk) \
492 __o1->next_free = __o1->chunk_limit; \
493 __o1->object_base = __o1->next_free; \
496 # define obstack_free(OBSTACK, OBJ) \
498 ({ struct obstack *__o = (OBSTACK); \
499 void *__obj = (OBJ); \
500 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
501 __o->next_free = __o->object_base = (char *)__obj; \
502 else (obstack_free) (__o, __obj); })
504 #else /* not __GNUC__ or not __STDC__ */
506 # define obstack_object_size(h) \
507 (unsigned) ((h)->next_free - (h)->object_base)
509 # define obstack_room(h) \
510 (unsigned) ((h)->chunk_limit - (h)->next_free)
512 # define obstack_empty_p(h) \
513 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
515 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
516 so that we can avoid having void expressions
517 in the arms of the conditional expression.
518 Casting the third operand to void was tried before,
519 but some compilers won't accept it. */
521 # define obstack_make_room(h,length) \
522 ( (h)->temp = (length), \
523 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
524 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
526 # define obstack_grow(h,where,length) \
527 ( (h)->temp = (length), \
528 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
529 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
530 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
531 (h)->next_free += (h)->temp)
533 # define obstack_grow0(h,where,length) \
534 ( (h)->temp = (length), \
535 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
536 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
537 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
538 (h)->next_free += (h)->temp, \
539 *((h)->next_free)++ = 0)
541 # define obstack_1grow(h,datum) \
542 ( (((h)->next_free + 1 > (h)->chunk_limit) \
543 ? (_obstack_newchunk ((h), 1), 0) : 0), \
544 (*((h)->next_free)++ = (datum)))
546 # define obstack_ptr_grow(h,datum) \
547 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
548 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
549 (*((const char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = (datum)))
551 # define obstack_int_grow(h,datum) \
552 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
553 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
554 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = (datum)))
556 # define obstack_ptr_grow_fast(h,aptr) \
557 (*((const char **) (h)->next_free)++ = (aptr))
559 # define obstack_int_grow_fast(h,aint) \
560 (*((int *) (h)->next_free)++ = (aint))
562 # define obstack_blank(h,length) \
563 ( (h)->temp = (length), \
564 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
565 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
566 ((h)->next_free += (h)->temp))
568 # define obstack_alloc(h,length) \
569 (obstack_blank ((h), (length)), obstack_finish ((h)))
571 # define obstack_copy(h,where,length) \
572 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
574 # define obstack_copy0(h,where,length) \
575 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
577 # define obstack_finish(h) \
578 ( ((h)->next_free == (h)->object_base \
579 ? (((h)->maybe_empty_object = 1), 0) \
581 (h)->temp = __PTR_TO_INT ((h)->object_base), \
583 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
584 & ~ ((h)->alignment_mask)), \
585 (((h)->next_free - (char *) (h)->chunk \
586 > (h)->chunk_limit - (char *) (h)->chunk) \
587 ? ((h)->next_free = (h)->chunk_limit) : 0), \
588 (h)->object_base = (h)->next_free, \
589 __INT_TO_PTR ((h)->temp))
591 # if defined __STDC__ && __STDC__
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), 0)))
599 # define obstack_free(h,obj) \
600 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
601 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
602 ? (int) ((h)->next_free = (h)->object_base \
603 = (h)->temp + (char *) (h)->chunk) \
604 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
607 #endif /* not __GNUC__ or not __STDC__ */
613 #endif /* obstack.h */