1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97,98,99 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 GNU
17 Library General Public License for more details.
19 You should have received a copy of the GNU Library General Public
20 License 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. If __PTRDIFF_TYPE__ is
129 defined, as with GNU C, use that; that way we don't pollute the
130 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
131 available, include it and use ptrdiff_t. In traditional C, long is
132 the best that we can do. */
134 #ifdef __PTRDIFF_TYPE__
135 # define PTR_INT_TYPE __PTRDIFF_TYPE__
137 # ifdef HAVE_STDDEF_H
139 # define PTR_INT_TYPE ptrdiff_t
141 # 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, const void *address, int size);
223 void * obstack_copy0 (struct obstack *obstack, const 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, const void *data, int size);
230 void obstack_grow0 (struct obstack *obstack, const void *data, int size);
232 void obstack_1grow (struct obstack *obstack, int data_char);
233 void obstack_ptr_grow (struct obstack *obstack, const 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, const 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 which
260 should either abort gracefully or use longjump - but shouldn't
261 return. The default action is to print a message and abort. */
262 #if defined __STDC__ && __STDC__
263 extern void (*obstack_alloc_failed_handler) (void);
265 extern void (*obstack_alloc_failed_handler) ();
268 /* Exit value used when `print_and_abort' is used. */
269 extern int obstack_exit_failure;
271 /* Pointer to beginning of object being allocated or to be allocated next.
272 Note that this might not be the final address of the object
273 because a new chunk might be needed to hold the final size. */
275 #define obstack_base(h) ((h)->object_base)
277 /* Size for allocating ordinary chunks. */
279 #define obstack_chunk_size(h) ((h)->chunk_size)
281 /* Pointer to next byte not yet allocated in current chunk. */
283 #define obstack_next_free(h) ((h)->next_free)
285 /* Mask specifying low bits that should be clear in address of an object. */
287 #define obstack_alignment_mask(h) ((h)->alignment_mask)
289 /* To prevent prototype warnings provide complete argument list in
290 standard C version. */
291 #if defined __STDC__ && __STDC__
293 # define obstack_init(h) \
294 _obstack_begin ((h), 0, 0, \
295 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
297 # define obstack_begin(h, size) \
298 _obstack_begin ((h), (size), 0, \
299 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
301 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
302 _obstack_begin ((h), (size), (alignment), \
303 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
305 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
306 _obstack_begin_1 ((h), (size), (alignment), \
307 (void *(*) (void *, long)) (chunkfun), \
308 (void (*) (void *, void *)) (freefun), (arg))
310 # define obstack_chunkfun(h, newchunkfun) \
311 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
313 # define obstack_freefun(h, newfreefun) \
314 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
318 # define obstack_init(h) \
319 _obstack_begin ((h), 0, 0, \
320 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
322 # define obstack_begin(h, size) \
323 _obstack_begin ((h), (size), 0, \
324 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
326 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
327 _obstack_begin ((h), (size), (alignment), \
328 (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
330 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
331 _obstack_begin_1 ((h), (size), (alignment), \
332 (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
334 # define obstack_chunkfun(h, newchunkfun) \
335 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
337 # define obstack_freefun(h, newfreefun) \
338 ((h) -> freefun = (void (*)()) (newfreefun))
342 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
344 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
346 #define obstack_memory_used(h) _obstack_memory_used (h)
348 #if defined __GNUC__ && defined __STDC__ && __STDC__
349 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
350 does not implement __extension__. But that compiler doesn't define
352 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
353 # define __extension__
356 /* For GNU C, if not -traditional,
357 we can define these macros to compute all args only once
358 without using a global variable.
359 Also, we can avoid using the `temp' slot, to make faster code. */
361 # define obstack_object_size(OBSTACK) \
363 ({ struct obstack *__o = (OBSTACK); \
364 (unsigned) (__o->next_free - __o->object_base); })
366 # define obstack_room(OBSTACK) \
368 ({ struct obstack *__o = (OBSTACK); \
369 (unsigned) (__o->chunk_limit - __o->next_free); })
371 # define obstack_make_room(OBSTACK,length) \
373 ({ struct obstack *__o = (OBSTACK); \
374 int __len = (length); \
375 if (__o->chunk_limit - __o->next_free < __len) \
376 _obstack_newchunk (__o, __len); \
379 # define obstack_empty_p(OBSTACK) \
381 ({ struct obstack *__o = (OBSTACK); \
382 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
384 # define obstack_grow(OBSTACK,where,length) \
386 ({ struct obstack *__o = (OBSTACK); \
387 int __len = (length); \
388 if (__o->next_free + __len > __o->chunk_limit) \
389 _obstack_newchunk (__o, __len); \
390 _obstack_memcpy (__o->next_free, (const char *) (where), __len); \
391 __o->next_free += __len; \
394 # define obstack_grow0(OBSTACK,where,length) \
396 ({ struct obstack *__o = (OBSTACK); \
397 int __len = (length); \
398 if (__o->next_free + __len + 1 > __o->chunk_limit) \
399 _obstack_newchunk (__o, __len + 1); \
400 _obstack_memcpy (__o->next_free, (const char *) (where), __len); \
401 __o->next_free += __len; \
402 *(__o->next_free)++ = 0; \
405 # define obstack_1grow(OBSTACK,datum) \
407 ({ struct obstack *__o = (OBSTACK); \
408 if (__o->next_free + 1 > __o->chunk_limit) \
409 _obstack_newchunk (__o, 1); \
410 *(__o->next_free)++ = (datum); \
413 /* These assume that the obstack alignment is good enough for pointers or ints,
414 and that the data added so far to the current object
415 shares that much alignment. */
417 # define obstack_ptr_grow(OBSTACK,datum) \
419 ({ struct obstack *__o = (OBSTACK); \
420 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
421 _obstack_newchunk (__o, sizeof (void *)); \
422 *((void **)__o->next_free)++ = ((const void *)datum); \
425 # define obstack_int_grow(OBSTACK,datum) \
427 ({ struct obstack *__o = (OBSTACK); \
428 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
429 _obstack_newchunk (__o, sizeof (int)); \
430 *((int *)__o->next_free)++ = ((int)datum); \
433 # define obstack_ptr_grow_fast(h,aptr) (*((void **) (h)->next_free)++ = (void *)aptr)
434 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
436 # define obstack_blank(OBSTACK,length) \
438 ({ struct obstack *__o = (OBSTACK); \
439 int __len = (length); \
440 if (__o->chunk_limit - __o->next_free < __len) \
441 _obstack_newchunk (__o, __len); \
442 __o->next_free += __len; \
445 # define obstack_alloc(OBSTACK,length) \
447 ({ struct obstack *__h = (OBSTACK); \
448 obstack_blank (__h, (length)); \
449 obstack_finish (__h); })
451 # define obstack_copy(OBSTACK,where,length) \
453 ({ struct obstack *__h = (OBSTACK); \
454 obstack_grow (__h, (where), (length)); \
455 obstack_finish (__h); })
457 # define obstack_copy0(OBSTACK,where,length) \
459 ({ struct obstack *__h = (OBSTACK); \
460 obstack_grow0 (__h, (where), (length)); \
461 obstack_finish (__h); })
463 /* The local variable is named __o1 to avoid a name conflict
464 when obstack_blank is called. */
465 # define obstack_finish(OBSTACK) \
467 ({ struct obstack *__o1 = (OBSTACK); \
469 value = (void *) __o1->object_base; \
470 if (__o1->next_free == value) \
471 __o1->maybe_empty_object = 1; \
473 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
474 & ~ (__o1->alignment_mask)); \
475 if (__o1->next_free - (char *)__o1->chunk \
476 > __o1->chunk_limit - (char *)__o1->chunk) \
477 __o1->next_free = __o1->chunk_limit; \
478 __o1->object_base = __o1->next_free; \
481 # define obstack_free(OBSTACK, OBJ) \
483 ({ struct obstack *__o = (OBSTACK); \
484 void *__obj = (OBJ); \
485 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
486 __o->next_free = __o->object_base = (char *)__obj; \
487 else (obstack_free) (__o, __obj); })
489 #else /* not __GNUC__ or not __STDC__ */
491 # define obstack_object_size(h) \
492 (unsigned) ((h)->next_free - (h)->object_base)
494 # define obstack_room(h) \
495 (unsigned) ((h)->chunk_limit - (h)->next_free)
497 # define obstack_empty_p(h) \
498 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
500 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
501 so that we can avoid having void expressions
502 in the arms of the conditional expression.
503 Casting the third operand to void was tried before,
504 but some compilers won't accept it. */
506 # define obstack_make_room(h,length) \
507 ( (h)->temp = (length), \
508 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
509 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
511 # define obstack_grow(h,where,length) \
512 ( (h)->temp = (length), \
513 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
514 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
515 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
516 (h)->next_free += (h)->temp)
518 # define obstack_grow0(h,where,length) \
519 ( (h)->temp = (length), \
520 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
521 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
522 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
523 (h)->next_free += (h)->temp, \
524 *((h)->next_free)++ = 0)
526 # define obstack_1grow(h,datum) \
527 ( (((h)->next_free + 1 > (h)->chunk_limit) \
528 ? (_obstack_newchunk ((h), 1), 0) : 0), \
529 (*((h)->next_free)++ = (datum)))
531 # define obstack_ptr_grow(h,datum) \
532 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
533 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
534 (*((char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *) datum)))
536 # define obstack_int_grow(h,datum) \
537 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
538 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
539 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = ((int) datum)))
541 # define obstack_ptr_grow_fast(h,aptr) (*((char **) (h)->next_free)++ = (char *) aptr)
542 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
544 # define obstack_blank(h,length) \
545 ( (h)->temp = (length), \
546 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
547 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
548 ((h)->next_free += (h)->temp))
550 # define obstack_alloc(h,length) \
551 (obstack_blank ((h), (length)), obstack_finish ((h)))
553 # define obstack_copy(h,where,length) \
554 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
556 # define obstack_copy0(h,where,length) \
557 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
559 # define obstack_finish(h) \
560 ( ((h)->next_free == (h)->object_base \
561 ? (((h)->maybe_empty_object = 1), 0) \
563 (h)->temp = __PTR_TO_INT ((h)->object_base), \
565 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
566 & ~ ((h)->alignment_mask)), \
567 (((h)->next_free - (char *) (h)->chunk \
568 > (h)->chunk_limit - (char *) (h)->chunk) \
569 ? ((h)->next_free = (h)->chunk_limit) : 0), \
570 (h)->object_base = (h)->next_free, \
571 __INT_TO_PTR ((h)->temp))
573 # if defined __STDC__ && __STDC__
574 # define obstack_free(h,obj) \
575 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
576 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
577 ? (int) ((h)->next_free = (h)->object_base \
578 = (h)->temp + (char *) (h)->chunk) \
579 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
581 # define obstack_free(h,obj) \
582 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
583 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
584 ? (int) ((h)->next_free = (h)->object_base \
585 = (h)->temp + (char *) (h)->chunk) \
586 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
589 #endif /* not __GNUC__ or not __STDC__ */
595 #endif /* obstack.h */