1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97,98,99 Free Software Foundation, Inc.
3 This file is part of the GNU C Library. Its master source is NOT part of
4 the C library, however. The master source lives in /gd/gnu/lib.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
23 All the apparent functions defined here are macros. The idea
24 is that you would use these pre-tested macros to solve a
25 very specific set of problems, and they would run fast.
26 Caution: no side-effects in arguments please!! They may be
27 evaluated MANY times!!
29 These macros operate a stack of objects. Each object starts life
30 small, and may grow to maturity. (Consider building a word syllable
31 by syllable.) An object can move while it is growing. Once it has
32 been "finished" it never changes address again. So the "top of the
33 stack" is typically an immature growing object, while the rest of the
34 stack is of mature, fixed size and fixed address objects.
36 These routines grab large chunks of memory, using a function you
37 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
38 by calling `obstack_chunk_free'. You must define them and declare
39 them before using any obstack macros.
41 Each independent stack is represented by a `struct obstack'.
42 Each of the obstack macros expects a pointer to such a structure
43 as the first argument.
45 One motivation for this package is the problem of growing char strings
46 in symbol tables. Unless you are "fascist pig with a read-only mind"
47 --Gosper's immortal quote from HAKMEM item 154, out of context--you
48 would not like to put any arbitrary upper limit on the length of your
51 In practice this often means you will build many short symbols and a
52 few long symbols. At the time you are reading a symbol you don't know
53 how long it is. One traditional method is to read a symbol into a
54 buffer, realloc()ating the buffer every time you try to read a symbol
55 that is longer than the buffer. This is beaut, but you still will
56 want to copy the symbol from the buffer to a more permanent
57 symbol-table entry say about half the time.
59 With obstacks, you can work differently. Use one obstack for all symbol
60 names. As you read a symbol, grow the name in the obstack gradually.
61 When the name is complete, finalize it. Then, if the symbol exists already,
62 free the newly read name.
64 The way we do this is to take a large chunk, allocating memory from
65 low addresses. When you want to build a symbol in the chunk you just
66 add chars above the current "high water mark" in the chunk. When you
67 have finished adding chars, because you got to the end of the symbol,
68 you know how long the chars are, and you can create a new object.
69 Mostly the chars will not burst over the highest address of the chunk,
70 because you would typically expect a chunk to be (say) 100 times as
71 long as an average object.
73 In case that isn't clear, when we have enough chars to make up
74 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
75 so we just point to it where it lies. No moving of chars is
76 needed and this is the second win: potentially long strings need
77 never be explicitly shuffled. Once an object is formed, it does not
78 change its address during its lifetime.
80 When the chars burst over a chunk boundary, we allocate a larger
81 chunk, and then copy the partly formed object from the end of the old
82 chunk to the beginning of the new larger chunk. We then carry on
83 accreting characters to the end of the object as we normally would.
85 A special macro is provided to add a single char at a time to a
86 growing object. This allows the use of register variables, which
87 break the ordinary 'growth' macro.
90 We allocate large chunks.
91 We carve out one object at a time from the current chunk.
92 Once carved, an object never moves.
93 We are free to append data of any size to the currently
95 Exactly one object is growing in an obstack at any one time.
96 You can run one obstack per control block.
97 You may have as many control blocks as you dare.
98 Because of the way we do it, you can `unwind' an obstack
99 back to a previous state. (You may remove objects much
100 as you would with a stack.)
104 /* Don't do the contents of this file more than once. */
113 /* We use subtraction of (char *) 0 instead of casting to int
114 because on word-addressable machines a simple cast to int
115 may ignore the byte-within-word field of the pointer. */
118 # define __PTR_TO_INT(P) ((P) - (char *) 0)
122 # define __INT_TO_PTR(P) ((P) + (char *) 0)
125 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
126 defined, as with GNU C, use that; that way we don't pollute the
127 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
128 available, include it and use ptrdiff_t. In traditional C, long is
129 the best that we can do. */
131 #ifdef __PTRDIFF_TYPE__
132 # define PTR_INT_TYPE __PTRDIFF_TYPE__
134 # ifdef HAVE_STDDEF_H
136 # define PTR_INT_TYPE ptrdiff_t
138 # define PTR_INT_TYPE long
142 #if defined _LIBC || defined HAVE_STRING_H
144 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
147 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
149 # define _obstack_memcpy(To, From, N) bcopy ((From), (To), (N))
153 struct _obstack_chunk /* Lives at front of each chunk. */
155 char *limit; /* 1 past end of this chunk */
156 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
157 char contents[4]; /* objects begin here */
160 struct obstack /* control current object in current chunk */
162 long chunk_size; /* preferred size to allocate chunks in */
163 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
164 char *object_base; /* address of object we are building */
165 char *next_free; /* where to add next char to current object */
166 char *chunk_limit; /* address of char after current chunk */
167 PTR_INT_TYPE temp; /* Temporary for some macros. */
168 int alignment_mask; /* Mask of alignment for each object. */
169 #if defined __STDC__ && __STDC__
170 /* These prototypes vary based on `use_extra_arg', and we use
171 casts to the prototypeless function type in all assignments,
172 but having prototypes here quiets -Wstrict-prototypes. */
173 struct _obstack_chunk *(*chunkfun) (void *, long);
174 void (*freefun) (void *, struct _obstack_chunk *);
175 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
177 struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
178 void (*freefun) (); /* User's function to free a chunk. */
179 char *extra_arg; /* first arg for chunk alloc/dealloc funcs */
181 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
182 unsigned maybe_empty_object:1;/* There is a possibility that the current
183 chunk contains a zero-length object. This
184 prevents freeing the chunk if we allocate
185 a bigger chunk to replace it. */
186 unsigned alloc_failed:1; /* No longer used, as we now call the failed
187 handler on error, but retained for binary
191 /* Declare the external functions we use; they are in obstack.c. */
193 #if defined __STDC__ && __STDC__
194 extern void _obstack_newchunk (struct obstack *, int);
195 extern void _obstack_free (struct obstack *, void *);
196 extern int _obstack_begin (struct obstack *, int, int,
197 void *(*) (long), void (*) (void *));
198 extern int _obstack_begin_1 (struct obstack *, int, int,
199 void *(*) (void *, long),
200 void (*) (void *, void *), void *);
201 extern int _obstack_memory_used (struct obstack *);
203 extern void _obstack_newchunk ();
204 extern void _obstack_free ();
205 extern int _obstack_begin ();
206 extern int _obstack_begin_1 ();
207 extern int _obstack_memory_used ();
210 #if defined __STDC__ && __STDC__
212 /* Do the function-declarations after the structs
213 but before defining the macros. */
215 void obstack_init (struct obstack *obstack);
217 void * obstack_alloc (struct obstack *obstack, int size);
219 void * obstack_copy (struct obstack *obstack, const void *address, int size);
220 void * obstack_copy0 (struct obstack *obstack, const void *address, int size);
222 void obstack_free (struct obstack *obstack, void *block);
224 void obstack_blank (struct obstack *obstack, int size);
226 void obstack_grow (struct obstack *obstack, const void *data, int size);
227 void obstack_grow0 (struct obstack *obstack, const void *data, int size);
229 void obstack_1grow (struct obstack *obstack, int data_char);
230 void obstack_ptr_grow (struct obstack *obstack, const void *data);
231 void obstack_int_grow (struct obstack *obstack, int data);
233 void * obstack_finish (struct obstack *obstack);
235 int obstack_object_size (struct obstack *obstack);
237 int obstack_room (struct obstack *obstack);
238 void obstack_make_room (struct obstack *obstack, int size);
239 void obstack_1grow_fast (struct obstack *obstack, int data_char);
240 void obstack_ptr_grow_fast (struct obstack *obstack, const void *data);
241 void obstack_int_grow_fast (struct obstack *obstack, int data);
242 void obstack_blank_fast (struct obstack *obstack, int size);
244 void * obstack_base (struct obstack *obstack);
245 void * obstack_next_free (struct obstack *obstack);
246 int obstack_alignment_mask (struct obstack *obstack);
247 int obstack_chunk_size (struct obstack *obstack);
248 int obstack_memory_used (struct obstack *obstack);
250 #endif /* __STDC__ */
252 /* Non-ANSI C cannot really support alternative functions for these macros,
253 so we do not declare them. */
255 /* Error handler called when `obstack_chunk_alloc' failed to allocate
256 more memory. This can be set to a user defined function which
257 should either abort gracefully or use longjump - but shouldn't
258 return. The default action is to print a message and abort. */
259 #if defined __STDC__ && __STDC__
260 extern void (*obstack_alloc_failed_handler) (void);
262 extern void (*obstack_alloc_failed_handler) ();
265 /* Exit value used when `print_and_abort' is used. */
266 extern int obstack_exit_failure;
268 /* Pointer to beginning of object being allocated or to be allocated next.
269 Note that this might not be the final address of the object
270 because a new chunk might be needed to hold the final size. */
272 #define obstack_base(h) ((h)->object_base)
274 /* Size for allocating ordinary chunks. */
276 #define obstack_chunk_size(h) ((h)->chunk_size)
278 /* Pointer to next byte not yet allocated in current chunk. */
280 #define obstack_next_free(h) ((h)->next_free)
282 /* Mask specifying low bits that should be clear in address of an object. */
284 #define obstack_alignment_mask(h) ((h)->alignment_mask)
286 /* To prevent prototype warnings provide complete argument list in
287 standard C version. */
288 #if defined __STDC__ && __STDC__
290 # define obstack_init(h) \
291 _obstack_begin ((h), 0, 0, \
292 (void *(*) (long)) obstack_chunk_alloc, \
293 (void (*) (void *)) obstack_chunk_free)
295 # define obstack_begin(h, size) \
296 _obstack_begin ((h), (size), 0, \
297 (void *(*) (long)) obstack_chunk_alloc, \
298 (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), \
303 (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, \
321 (void (*) ()) obstack_chunk_free)
323 # define obstack_begin(h, size) \
324 _obstack_begin ((h), (size), 0, \
325 (void *(*) ()) obstack_chunk_alloc, \
326 (void (*) ()) obstack_chunk_free)
328 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
329 _obstack_begin ((h), (size), (alignment), \
330 (void *(*) ()) (chunkfun), \
331 (void (*) ()) (freefun))
333 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
334 _obstack_begin_1 ((h), (size), (alignment), \
335 (void *(*) ()) (chunkfun), \
336 (void (*) ()) (freefun), (arg))
338 # define obstack_chunkfun(h, newchunkfun) \
339 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
341 # define obstack_freefun(h, newfreefun) \
342 ((h) -> freefun = (void (*)()) (newfreefun))
346 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
348 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
350 #define obstack_memory_used(h) _obstack_memory_used (h)
352 #if defined __GNUC__ && defined __STDC__ && __STDC__
353 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
354 does not implement __extension__. But that compiler doesn't define
356 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
357 # define __extension__
360 /* For GNU C, if not -traditional,
361 we can define these macros to compute all args only once
362 without using a global variable.
363 Also, we can avoid using the `temp' slot, to make faster code. */
365 # define obstack_object_size(OBSTACK) \
367 ({ struct obstack *__o = (OBSTACK); \
368 (unsigned) (__o->next_free - __o->object_base); })
370 # define obstack_room(OBSTACK) \
372 ({ struct obstack *__o = (OBSTACK); \
373 (unsigned) (__o->chunk_limit - __o->next_free); })
375 # define obstack_make_room(OBSTACK,length) \
377 ({ struct obstack *__o = (OBSTACK); \
378 int __len = (length); \
379 if (__o->chunk_limit - __o->next_free < __len) \
380 _obstack_newchunk (__o, __len); \
383 # define obstack_empty_p(OBSTACK) \
385 ({ struct obstack *__o = (OBSTACK); \
386 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
388 # define obstack_grow(OBSTACK,where,length) \
390 ({ struct obstack *__o = (OBSTACK); \
391 int __len = (length); \
392 if (__o->next_free + __len > __o->chunk_limit) \
393 _obstack_newchunk (__o, __len); \
394 _obstack_memcpy (__o->next_free, (where), __len); \
395 __o->next_free += __len; \
398 # define obstack_grow0(OBSTACK,where,length) \
400 ({ struct obstack *__o = (OBSTACK); \
401 int __len = (length); \
402 if (__o->next_free + __len + 1 > __o->chunk_limit) \
403 _obstack_newchunk (__o, __len + 1); \
404 _obstack_memcpy (__o->next_free, (where), __len); \
405 __o->next_free += __len; \
406 *(__o->next_free)++ = 0; \
409 # define obstack_1grow(OBSTACK,datum) \
411 ({ struct obstack *__o = (OBSTACK); \
412 if (__o->next_free + 1 > __o->chunk_limit) \
413 _obstack_newchunk (__o, 1); \
414 *(__o->next_free)++ = (datum); \
417 /* These assume that the obstack alignment is good enough for pointers
418 or ints, and that the data added so far to the current object
419 shares that much alignment. */
421 # define obstack_ptr_grow(OBSTACK,datum) \
423 ({ struct obstack *__o = (OBSTACK); \
424 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
425 _obstack_newchunk (__o, sizeof (void *)); \
426 *((void **)__o->next_free)++ = (datum); \
429 # define obstack_int_grow(OBSTACK,datum) \
431 ({ struct obstack *__o = (OBSTACK); \
432 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
433 _obstack_newchunk (__o, sizeof (int)); \
434 *((int *)__o->next_free)++ = (datum); \
437 # define obstack_ptr_grow_fast(h,aptr) \
438 (*((void **) (h)->next_free)++ = (aptr))
440 # define obstack_int_grow_fast(h,aint) \
441 (*((int *) (h)->next_free)++ = (aint))
443 # define obstack_blank(OBSTACK,length) \
445 ({ struct obstack *__o = (OBSTACK); \
446 int __len = (length); \
447 if (__o->chunk_limit - __o->next_free < __len) \
448 _obstack_newchunk (__o, __len); \
449 __o->next_free += __len; \
452 # define obstack_alloc(OBSTACK,length) \
454 ({ struct obstack *__h = (OBSTACK); \
455 obstack_blank (__h, (length)); \
456 obstack_finish (__h); })
458 # define obstack_copy(OBSTACK,where,length) \
460 ({ struct obstack *__h = (OBSTACK); \
461 obstack_grow (__h, (where), (length)); \
462 obstack_finish (__h); })
464 # define obstack_copy0(OBSTACK,where,length) \
466 ({ struct obstack *__h = (OBSTACK); \
467 obstack_grow0 (__h, (where), (length)); \
468 obstack_finish (__h); })
470 /* The local variable is named __o1 to avoid a name conflict
471 when obstack_blank is called. */
472 # define obstack_finish(OBSTACK) \
474 ({ struct obstack *__o1 = (OBSTACK); \
476 value = (void *) __o1->object_base; \
477 if (__o1->next_free == value) \
478 __o1->maybe_empty_object = 1; \
480 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
481 & ~ (__o1->alignment_mask)); \
482 if (__o1->next_free - (char *)__o1->chunk \
483 > __o1->chunk_limit - (char *)__o1->chunk) \
484 __o1->next_free = __o1->chunk_limit; \
485 __o1->object_base = __o1->next_free; \
488 # define obstack_free(OBSTACK, OBJ) \
490 ({ struct obstack *__o = (OBSTACK); \
491 void *__obj = (OBJ); \
492 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
493 __o->next_free = __o->object_base = (char *)__obj; \
494 else (obstack_free) (__o, __obj); })
496 #else /* not __GNUC__ or not __STDC__ */
498 # define obstack_object_size(h) \
499 (unsigned) ((h)->next_free - (h)->object_base)
501 # define obstack_room(h) \
502 (unsigned) ((h)->chunk_limit - (h)->next_free)
504 # define obstack_empty_p(h) \
505 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
507 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
508 so that we can avoid having void expressions
509 in the arms of the conditional expression.
510 Casting the third operand to void was tried before,
511 but some compilers won't accept it. */
513 # define obstack_make_room(h,length) \
514 ( (h)->temp = (length), \
515 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
516 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
518 # define obstack_grow(h,where,length) \
519 ( (h)->temp = (length), \
520 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
521 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
522 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
523 (h)->next_free += (h)->temp)
525 # define obstack_grow0(h,where,length) \
526 ( (h)->temp = (length), \
527 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
528 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
529 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \
530 (h)->next_free += (h)->temp, \
531 *((h)->next_free)++ = 0)
533 # define obstack_1grow(h,datum) \
534 ( (((h)->next_free + 1 > (h)->chunk_limit) \
535 ? (_obstack_newchunk ((h), 1), 0) : 0), \
536 (*((h)->next_free)++ = (datum)))
538 # define obstack_ptr_grow(h,datum) \
539 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
540 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
541 (*((const char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = (datum)))
543 # define obstack_int_grow(h,datum) \
544 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
545 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
546 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = (datum)))
548 # define obstack_ptr_grow_fast(h,aptr) \
549 (*((const char **) (h)->next_free)++ = (aptr))
551 # define obstack_int_grow_fast(h,aint) \
552 (*((int *) (h)->next_free)++ = (aint))
554 # define obstack_blank(h,length) \
555 ( (h)->temp = (length), \
556 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
557 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
558 ((h)->next_free += (h)->temp))
560 # define obstack_alloc(h,length) \
561 (obstack_blank ((h), (length)), obstack_finish ((h)))
563 # define obstack_copy(h,where,length) \
564 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
566 # define obstack_copy0(h,where,length) \
567 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
569 # define obstack_finish(h) \
570 ( ((h)->next_free == (h)->object_base \
571 ? (((h)->maybe_empty_object = 1), 0) \
573 (h)->temp = __PTR_TO_INT ((h)->object_base), \
575 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
576 & ~ ((h)->alignment_mask)), \
577 (((h)->next_free - (char *) (h)->chunk \
578 > (h)->chunk_limit - (char *) (h)->chunk) \
579 ? ((h)->next_free = (h)->chunk_limit) : 0), \
580 (h)->object_base = (h)->next_free, \
581 __INT_TO_PTR ((h)->temp))
583 # if defined __STDC__ && __STDC__
584 # define obstack_free(h,obj) \
585 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
586 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
587 ? (int) ((h)->next_free = (h)->object_base \
588 = (h)->temp + (char *) (h)->chunk) \
589 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
591 # define obstack_free(h,obj) \
592 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
593 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
594 ? (int) ((h)->next_free = (h)->object_base \
595 = (h)->temp + (char *) (h)->chunk) \
596 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
599 #endif /* not __GNUC__ or not __STDC__ */
605 #endif /* obstack.h */