1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
20 All the apparent functions defined here are macros. The idea
21 is that you would use these pre-tested macros to solve a
22 very specific set of problems, and they would run fast.
23 Caution: no side-effects in arguments please!! They may be
24 evaluated MANY times!!
26 These macros operate a stack of objects. Each object starts life
27 small, and may grow to maturity. (Consider building a word syllable
28 by syllable.) An object can move while it is growing. Once it has
29 been "finished" it never changes address again. So the "top of the
30 stack" is typically an immature growing object, while the rest of the
31 stack is of mature, fixed size and fixed address objects.
33 These routines grab large chunks of memory, using a function you
34 supply, called `obstack_chunk_alloc'. On occasion, they free chunks,
35 by calling `obstack_chunk_free'. You must define them and declare
36 them before using any obstack macros.
38 Each independent stack is represented by a `struct obstack'.
39 Each of the obstack macros expects a pointer to such a structure
40 as the first argument.
42 One motivation for this package is the problem of growing char strings
43 in symbol tables. Unless you are "fascist pig with a read-only mind"
44 --Gosper's immortal quote from HAKMEM item 154, out of context--you
45 would not like to put any arbitrary upper limit on the length of your
48 In practice this often means you will build many short symbols and a
49 few long symbols. At the time you are reading a symbol you don't know
50 how long it is. One traditional method is to read a symbol into a
51 buffer, realloc()ating the buffer every time you try to read a symbol
52 that is longer than the buffer. This is beaut, but you still will
53 want to copy the symbol from the buffer to a more permanent
54 symbol-table entry say about half the time.
56 With obstacks, you can work differently. Use one obstack for all symbol
57 names. As you read a symbol, grow the name in the obstack gradually.
58 When the name is complete, finalize it. Then, if the symbol exists already,
59 free the newly read name.
61 The way we do this is to take a large chunk, allocating memory from
62 low addresses. When you want to build a symbol in the chunk you just
63 add chars above the current "high water mark" in the chunk. When you
64 have finished adding chars, because you got to the end of the symbol,
65 you know how long the chars are, and you can create a new object.
66 Mostly the chars will not burst over the highest address of the chunk,
67 because you would typically expect a chunk to be (say) 100 times as
68 long as an average object.
70 In case that isn't clear, when we have enough chars to make up
71 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
72 so we just point to it where it lies. No moving of chars is
73 needed and this is the second win: potentially long strings need
74 never be explicitly shuffled. Once an object is formed, it does not
75 change its address during its lifetime.
77 When the chars burst over a chunk boundary, we allocate a larger
78 chunk, and then copy the partly formed object from the end of the old
79 chunk to the beginning of the new larger chunk. We then carry on
80 accreting characters to the end of the object as we normally would.
82 A special macro is provided to add a single char at a time to a
83 growing object. This allows the use of register variables, which
84 break the ordinary 'growth' macro.
87 We allocate large chunks.
88 We carve out one object at a time from the current chunk.
89 Once carved, an object never moves.
90 We are free to append data of any size to the currently
92 Exactly one object is growing in an obstack at any one time.
93 You can run one obstack per control block.
94 You may have as many control blocks as you dare.
95 Because of the way we do it, you can `unwind' an obstack
96 back to a previous state. (You may remove objects much
97 as you would with a stack.)
101 /* Don't do the contents of this file more than once. */
103 #ifndef __OBSTACK_H__
104 #define __OBSTACK_H__
106 /* We use subtraction of (char *)0 instead of casting to int
107 because on word-addressable machines a simple cast to int
108 may ignore the byte-within-word field of the pointer. */
111 #define __PTR_TO_INT(P) ((P) - (char *)0)
115 #define __INT_TO_PTR(P) ((P) + (char *)0)
118 /* We need the type of the resulting object. In ANSI C it is ptrdiff_t
119 but in traditional C it is usually long. If we are in ANSI C and
120 don't already have ptrdiff_t get it. */
122 #if defined (__STDC__) && __STDC__ && ! defined (offsetof)
123 #if defined (__GNUC__) && defined (IN_GCC)
124 /* On Next machine, the system's stddef.h screws up if included
125 after we have defined just ptrdiff_t, so include all of stddef.h.
126 Otherwise, define just ptrdiff_t, which is all we need. */
128 #define __need_ptrdiff_t
135 #include <sys/types.h>
137 #ifndef HAVE_PTRDIFF_T
138 # define ptrdiff_t off_t
141 #if defined (__STDC__) && __STDC__
142 #define PTR_INT_TYPE ptrdiff_t
144 #define PTR_INT_TYPE long
147 struct _obstack_chunk /* Lives at front of each chunk. */
149 char *limit; /* 1 past end of this chunk */
150 struct _obstack_chunk *prev; /* address of prior chunk or NULL */
151 char contents[4]; /* objects begin here */
154 struct obstack /* control current object in current chunk */
156 long chunk_size; /* preferred size to allocate chunks in */
157 struct _obstack_chunk* chunk; /* address of current struct obstack_chunk */
158 char *object_base; /* address of object we are building */
159 char *next_free; /* where to add next char to current object */
160 char *chunk_limit; /* address of char after current chunk */
161 PTR_INT_TYPE temp; /* Temporary for some macros. */
162 int alignment_mask; /* Mask of alignment for each object. */
163 #if defined (__STDC__) && __STDC__
164 /* These prototypes vary based on `use_extra_arg', and we use
165 casts to the prototypeless function type in all assignments,
166 but having prototypes here quiets -Wstrict-prototypes. */
167 struct _obstack_chunk *(*chunkfun) (void *, long);
168 void (*freefun) (void *, struct _obstack_chunk *);
169 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */
171 struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk. */
172 void (*freefun) (); /* User's function to free a chunk. */
173 char *extra_arg; /* first arg for chunk alloc/dealloc funcs */
175 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */
176 unsigned maybe_empty_object:1;/* There is a possibility that the current
177 chunk contains a zero-length object. This
178 prevents freeing the chunk if we allocate
179 a bigger chunk to replace it. */
180 unsigned alloc_failed:1; /* chunk alloc func returned 0 */
183 /* Declare the external functions we use; they are in obstack.c. */
185 #if defined (__STDC__) && __STDC__
186 extern void _obstack_newchunk (struct obstack *, int);
187 extern void _obstack_free (struct obstack *, void *);
188 extern int _obstack_begin (struct obstack *, int, int,
189 void *(*) (long), void (*) (void *));
190 extern int _obstack_begin_1 (struct obstack *, int, int,
191 void *(*) (void *, long),
192 void (*) (void *, void *), void *);
194 extern void _obstack_newchunk ();
195 extern void _obstack_free ();
196 extern int _obstack_begin ();
197 extern int _obstack_begin_1 ();
200 #if defined (__STDC__) && __STDC__
202 /* Do the function-declarations after the structs
203 but before defining the macros. */
205 void obstack_init (struct obstack *obstack);
207 void * obstack_alloc (struct obstack *obstack, int size);
209 void * obstack_copy (struct obstack *obstack, void *address, int size);
210 void * obstack_copy0 (struct obstack *obstack, void *address, int size);
212 void obstack_free (struct obstack *obstack, void *block);
214 void obstack_blank (struct obstack *obstack, int size);
216 void obstack_grow (struct obstack *obstack, void *data, int size);
217 void obstack_grow0 (struct obstack *obstack, void *data, int size);
219 void obstack_1grow (struct obstack *obstack, int data_char);
220 void obstack_ptr_grow (struct obstack *obstack, void *data);
221 void obstack_int_grow (struct obstack *obstack, int data);
223 void * obstack_finish (struct obstack *obstack);
225 int obstack_object_size (struct obstack *obstack);
227 int obstack_room (struct obstack *obstack);
228 void obstack_1grow_fast (struct obstack *obstack, int data_char);
229 void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
230 void obstack_int_grow_fast (struct obstack *obstack, int data);
231 void obstack_blank_fast (struct obstack *obstack, int size);
233 void * obstack_base (struct obstack *obstack);
234 void * obstack_next_free (struct obstack *obstack);
235 int obstack_alignment_mask (struct obstack *obstack);
236 int obstack_chunk_size (struct obstack *obstack);
238 #endif /* __STDC__ */
240 /* Non-ANSI C cannot really support alternative functions for these macros,
241 so we do not declare them. */
243 /* Pointer to beginning of object being allocated or to be allocated next.
244 Note that this might not be the final address of the object
245 because a new chunk might be needed to hold the final size. */
247 #define obstack_base(h) ((h)->alloc_failed ? 0 : (h)->object_base)
249 /* Size for allocating ordinary chunks. */
251 #define obstack_chunk_size(h) ((h)->chunk_size)
253 /* Pointer to next byte not yet allocated in current chunk. */
255 #define obstack_next_free(h) ((h)->alloc_failed ? 0 : (h)->next_free)
257 /* Mask specifying low bits that should be clear in address of an object. */
259 #define obstack_alignment_mask(h) ((h)->alignment_mask)
261 /* To prevent prototype warnings provide complete argument list in
262 standard C version. */
263 #if defined (__STDC__) && __STDC__
265 #define obstack_init(h) \
266 _obstack_begin ((h), 0, 0, \
267 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
269 #define obstack_begin(h, size) \
270 _obstack_begin ((h), (size), 0, \
271 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
273 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
274 _obstack_begin ((h), (size), (alignment), \
275 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
277 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
278 _obstack_begin_1 ((h), (size), (alignment), \
279 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun), (arg))
281 #define obstack_chunkfun(h, newchunkfun) \
282 ((h) -> chunkfun = (struct _obstack_chunk *(*)(long)) (newchunkfun))
284 #define obstack_freefun(h, newfreefun) \
285 ((h) -> freefun = (void (*)(void *)) (newfreefun))
289 #define obstack_init(h) \
290 _obstack_begin ((h), 0, 0, \
291 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
293 #define obstack_begin(h, size) \
294 _obstack_begin ((h), (size), 0, \
295 (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)
297 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
298 _obstack_begin ((h), (size), (alignment), \
299 (void *(*) ()) (chunkfun), (void (*) ()) (freefun))
301 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
302 _obstack_begin_1 ((h), (size), (alignment), \
303 (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))
305 #define obstack_chunkfun(h, newchunkfun) \
306 ((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
308 #define obstack_freefun(h, newfreefun) \
309 ((h) -> freefun = (void (*)()) (newfreefun))
313 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
315 #define obstack_blank_fast(h,n) ((h)->next_free += (n))
317 #if defined (__GNUC__) && defined (__STDC__) && __STDC__
318 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
319 does not implement __extension__. But that compiler doesn't define
321 #if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
322 #define __extension__
325 /* For GNU C, if not -traditional,
326 we can define these macros to compute all args only once
327 without using a global variable.
328 Also, we can avoid using the `temp' slot, to make faster code. */
330 #define obstack_object_size(OBSTACK) \
332 ({ struct obstack *__o = (OBSTACK); \
333 __o->alloc_failed ? 0 : \
334 (unsigned) (__o->next_free - __o->object_base); })
336 #define obstack_room(OBSTACK) \
338 ({ struct obstack *__o = (OBSTACK); \
339 (unsigned) (__o->chunk_limit - __o->next_free); })
341 #define obstack_grow(OBSTACK,where,length) \
343 ({ struct obstack *__o = (OBSTACK); \
344 int __len = (length); \
345 if (__o->next_free + __len > __o->chunk_limit) \
346 _obstack_newchunk (__o, __len); \
347 if (!__o->alloc_failed) \
349 bcopy ((char *) (where), __o->next_free, __len); \
350 __o->next_free += __len; \
354 #define obstack_grow0(OBSTACK,where,length) \
356 ({ struct obstack *__o = (OBSTACK); \
357 int __len = (length); \
358 if (__o->next_free + __len + 1 > __o->chunk_limit) \
359 _obstack_newchunk (__o, __len + 1); \
360 if (!__o->alloc_failed) \
362 bcopy ((char *) (where), __o->next_free, __len); \
363 __o->next_free += __len; \
364 *(__o->next_free)++ = 0; \
368 #define obstack_1grow(OBSTACK,datum) \
370 ({ struct obstack *__o = (OBSTACK); \
371 if (__o->next_free + 1 > __o->chunk_limit) \
372 _obstack_newchunk (__o, 1); \
373 if (!__o->alloc_failed) \
374 *(__o->next_free)++ = (datum); \
377 /* These assume that the obstack alignment is good enough for pointers or ints,
378 and that the data added so far to the current object
379 shares that much alignment. */
381 #define obstack_ptr_grow(OBSTACK,datum) \
383 ({ struct obstack *__o = (OBSTACK); \
384 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
385 _obstack_newchunk (__o, sizeof (void *)); \
386 if (!__o->alloc_failed) \
387 *((void **)__o->next_free)++ = ((void *)datum); \
390 #define obstack_int_grow(OBSTACK,datum) \
392 ({ struct obstack *__o = (OBSTACK); \
393 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
394 _obstack_newchunk (__o, sizeof (int)); \
395 if (!__o->alloc_failed) \
396 *((int *)__o->next_free)++ = ((int)datum); \
399 #define obstack_ptr_grow_fast(h,aptr) (*((void **)(h)->next_free)++ = (void *)aptr)
400 #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
402 #define obstack_blank(OBSTACK,length) \
404 ({ struct obstack *__o = (OBSTACK); \
405 int __len = (length); \
406 if (__o->chunk_limit - __o->next_free < __len) \
407 _obstack_newchunk (__o, __len); \
408 if (!__o->alloc_failed) \
409 __o->next_free += __len; \
412 #define obstack_alloc(OBSTACK,length) \
414 ({ struct obstack *__h = (OBSTACK); \
415 obstack_blank (__h, (length)); \
416 obstack_finish (__h); })
418 #define obstack_copy(OBSTACK,where,length) \
420 ({ struct obstack *__h = (OBSTACK); \
421 obstack_grow (__h, (where), (length)); \
422 obstack_finish (__h); })
424 #define obstack_copy0(OBSTACK,where,length) \
426 ({ struct obstack *__h = (OBSTACK); \
427 obstack_grow0 (__h, (where), (length)); \
428 obstack_finish (__h); })
430 /* The local variable is named __o1 to avoid a name conflict
431 when obstack_blank is called. */
432 #define obstack_finish(OBSTACK) \
434 ({ struct obstack *__o1 = (OBSTACK); \
436 if (__o1->alloc_failed) \
440 value = (void *) __o1->object_base; \
441 if (__o1->next_free == value) \
442 __o1->maybe_empty_object = 1; \
444 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
445 & ~ (__o1->alignment_mask)); \
446 if (__o1->next_free - (char *)__o1->chunk \
447 > __o1->chunk_limit - (char *)__o1->chunk) \
448 __o1->next_free = __o1->chunk_limit; \
449 __o1->object_base = __o1->next_free; \
453 #define obstack_free(OBSTACK, OBJ) \
455 ({ struct obstack *__o = (OBSTACK); \
456 void *__obj = (OBJ); \
457 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
458 __o->next_free = __o->object_base = __obj; \
459 else (obstack_free) (__o, __obj); })
461 #else /* not __GNUC__ or not __STDC__ */
463 #define obstack_object_size(h) \
464 (unsigned) ((h)->alloc_failed ? 0 : (h)->next_free - (h)->object_base)
466 #define obstack_room(h) \
467 (unsigned) ((h)->chunk_limit - (h)->next_free)
469 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
470 so that we can avoid having void expressions
471 in the arms of the conditional expression.
472 Casting the third operand to void was tried before,
473 but some compilers won't accept it. */
475 #define obstack_grow(h,where,length) \
476 ( (h)->temp = (length), \
477 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
478 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
479 ((h)->alloc_failed ? 0 : \
480 (bcopy ((char *) (where), (h)->next_free, (h)->temp), \
481 (h)->next_free += (h)->temp)))
483 #define obstack_grow0(h,where,length) \
484 ( (h)->temp = (length), \
485 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
486 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
487 ((h)->alloc_failed ? 0 : \
488 (bcopy ((char *) (where), (h)->next_free, (h)->temp), \
489 (h)->next_free += (h)->temp, \
490 *((h)->next_free)++ = 0)))
492 #define obstack_1grow(h,datum) \
493 ( (((h)->next_free + 1 > (h)->chunk_limit) \
494 ? (_obstack_newchunk ((h), 1), 0) : 0), \
495 ((h)->alloc_failed ? 0 : \
496 (*((h)->next_free)++ = (datum))))
498 #define obstack_ptr_grow(h,datum) \
499 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
500 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
501 ((h)->alloc_failed ? 0 : \
502 (*((char **)(((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *)datum))))
504 #define obstack_int_grow(h,datum) \
505 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
506 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
507 ((h)->alloc_failed ? 0 : \
508 (*((int *)(((h)->next_free+=sizeof(int))-sizeof(int))) = ((int)datum))))
510 #define obstack_ptr_grow_fast(h,aptr) (*((char **)(h)->next_free)++ = (char *)aptr)
511 #define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)
513 #define obstack_blank(h,length) \
514 ( (h)->temp = (length), \
515 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
516 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
517 ((h)->alloc_failed ? 0 : \
518 ((h)->next_free += (h)->temp)))
520 #define obstack_alloc(h,length) \
521 (obstack_blank ((h), (length)), obstack_finish ((h)))
523 #define obstack_copy(h,where,length) \
524 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
526 #define obstack_copy0(h,where,length) \
527 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
529 #define obstack_finish(h) \
530 ( (h)->alloc_failed ? 0 : \
531 (((h)->next_free == (h)->object_base \
532 ? (((h)->maybe_empty_object = 1), 0) \
534 (h)->temp = __PTR_TO_INT ((h)->object_base), \
536 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
537 & ~ ((h)->alignment_mask)), \
538 (((h)->next_free - (char *)(h)->chunk \
539 > (h)->chunk_limit - (char *)(h)->chunk) \
540 ? ((h)->next_free = (h)->chunk_limit) : 0), \
541 (h)->object_base = (h)->next_free, \
542 __INT_TO_PTR ((h)->temp)))
544 #if defined (__STDC__) && __STDC__
545 #define obstack_free(h,obj) \
546 ( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
547 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
548 ? (int) ((h)->next_free = (h)->object_base \
549 = (h)->temp + (char *) (h)->chunk) \
550 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
552 #define obstack_free(h,obj) \
553 ( (h)->temp = (char *)(obj) - (char *) (h)->chunk, \
554 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
555 ? (int) ((h)->next_free = (h)->object_base \
556 = (h)->temp + (char *) (h)->chunk) \
557 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
560 #endif /* not __GNUC__ or not __STDC__ */
562 #endif /* not __OBSTACK_H__ */