1 /* obstack.h - object stack macros
2 Copyright (C) 1988,89,90,91,92,93,94,96,97,98 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. */
114 /* We use subtraction of (char *) 0 instead of casting to int
115 because on word-addressable machines a simple cast to int
116 may ignore the byte-within-word field of the pointer. */
119 # define __PTR_TO_INT(P) ((P) - (char *) 0)
123 # define __INT_TO_PTR(P) ((P) + (char *) 0)
126 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is
127 defined, as with GNU C, use that; that way we don't pollute the
128 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is
129 available, include it and use ptrdiff_t. In traditional C, long is
130 the best that we can do. */
132 #ifdef __PTRDIFF_TYPE__
133 # define PTR_INT_TYPE __PTRDIFF_TYPE__
135 # ifdef HAVE_STDDEF_H
137 # define PTR_INT_TYPE ptrdiff_t
139 # define PTR_INT_TYPE long
143 #if defined _LIBC || defined HAVE_STRING_H
145 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
148 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N))
150 # define _obstack_memcpy(To, From, N) bcopy ((From), (To), (N))
154 struct _obstack_chunk
/* Lives at front of each chunk. */
156 char *limit
; /* 1 past end of this chunk */
157 struct _obstack_chunk
*prev
; /* address of prior chunk or NULL */
158 char contents
[4]; /* objects begin here */
161 struct obstack
/* control current object in current chunk */
163 long chunk_size
; /* preferred size to allocate chunks in */
164 struct _obstack_chunk
*chunk
; /* address of current struct obstack_chunk */
165 char *object_base
; /* address of object we are building */
166 char *next_free
; /* where to add next char to current object */
167 char *chunk_limit
; /* address of char after current chunk */
168 PTR_INT_TYPE temp
; /* Temporary for some macros. */
169 int alignment_mask
; /* Mask of alignment for each object. */
170 #if defined __STDC__ && __STDC__
171 /* These prototypes vary based on `use_extra_arg', and we use
172 casts to the prototypeless function type in all assignments,
173 but having prototypes here quiets -Wstrict-prototypes. */
174 struct _obstack_chunk
*(*chunkfun
) (void *, long);
175 void (*freefun
) (void *, struct _obstack_chunk
*);
176 void *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
178 struct _obstack_chunk
*(*chunkfun
) (); /* User's fcn to allocate a chunk. */
179 void (*freefun
) (); /* User's function to free a chunk. */
180 char *extra_arg
; /* first arg for chunk alloc/dealloc funcs */
182 unsigned use_extra_arg
:1; /* chunk alloc/dealloc funcs take extra arg */
183 unsigned maybe_empty_object
:1;/* There is a possibility that the current
184 chunk contains a zero-length object. This
185 prevents freeing the chunk if we allocate
186 a bigger chunk to replace it. */
187 unsigned alloc_failed
:1; /* No longer used, as we now call the failed
188 handler on error, but retained for binary
192 /* Declare the external functions we use; they are in obstack.c. */
194 #if defined __STDC__ && __STDC__
195 extern void _obstack_newchunk (struct obstack
*, int);
196 extern void _obstack_free (struct obstack
*, void *);
197 extern int _obstack_begin (struct obstack
*, int, int,
198 void *(*) (long), void (*) (void *));
199 extern int _obstack_begin_1 (struct obstack
*, int, int,
200 void *(*) (void *, long),
201 void (*) (void *, void *), void *);
202 extern int _obstack_memory_used (struct obstack
*);
204 extern void _obstack_newchunk ();
205 extern void _obstack_free ();
206 extern int _obstack_begin ();
207 extern int _obstack_begin_1 ();
208 extern int _obstack_memory_used ();
211 #if defined __STDC__ && __STDC__
213 /* Do the function-declarations after the structs
214 but before defining the macros. */
216 void obstack_init (struct obstack
*obstack
);
218 void * obstack_alloc (struct obstack
*obstack
, int size
);
220 void * obstack_copy (struct obstack
*obstack
, void *address
, int size
);
221 void * obstack_copy0 (struct obstack
*obstack
, void *address
, int size
);
223 void obstack_free (struct obstack
*obstack
, void *block
);
225 void obstack_blank (struct obstack
*obstack
, int size
);
227 void obstack_grow (struct obstack
*obstack
, void *data
, int size
);
228 void obstack_grow0 (struct obstack
*obstack
, void *data
, int size
);
230 void obstack_1grow (struct obstack
*obstack
, int data_char
);
231 void obstack_ptr_grow (struct obstack
*obstack
, void *data
);
232 void obstack_int_grow (struct obstack
*obstack
, int data
);
234 void * obstack_finish (struct obstack
*obstack
);
236 int obstack_object_size (struct obstack
*obstack
);
238 int obstack_room (struct obstack
*obstack
);
239 void obstack_make_room (struct obstack
*obstack
, int size
);
240 void obstack_1grow_fast (struct obstack
*obstack
, int data_char
);
241 void obstack_ptr_grow_fast (struct obstack
*obstack
, void *data
);
242 void obstack_int_grow_fast (struct obstack
*obstack
, int data
);
243 void obstack_blank_fast (struct obstack
*obstack
, int size
);
245 void * obstack_base (struct obstack
*obstack
);
246 void * obstack_next_free (struct obstack
*obstack
);
247 int obstack_alignment_mask (struct obstack
*obstack
);
248 int obstack_chunk_size (struct obstack
*obstack
);
249 int obstack_memory_used (struct obstack
*obstack
);
251 #endif /* __STDC__ */
253 /* Non-ANSI C cannot really support alternative functions for these macros,
254 so we do not declare them. */
256 /* Error handler called when `obstack_chunk_alloc' failed to allocate
257 more memory. This can be set to a user defined function which
258 should either abort gracefully or use longjump - but shouldn't
259 return. The default action is to print a message and abort. */
260 #if defined __STDC__ && __STDC__
261 extern void (*obstack_alloc_failed_handler
) (void);
263 extern void (*obstack_alloc_failed_handler
) ();
266 /* Exit value used when `print_and_abort' is used. */
267 extern int obstack_exit_failure
;
269 /* Pointer to beginning of object being allocated or to be allocated next.
270 Note that this might not be the final address of the object
271 because a new chunk might be needed to hold the final size. */
273 #define obstack_base(h) ((h)->object_base)
275 /* Size for allocating ordinary chunks. */
277 #define obstack_chunk_size(h) ((h)->chunk_size)
279 /* Pointer to next byte not yet allocated in current chunk. */
281 #define obstack_next_free(h) ((h)->next_free)
283 /* Mask specifying low bits that should be clear in address of an object. */
285 #define obstack_alignment_mask(h) ((h)->alignment_mask)
287 /* To prevent prototype warnings provide complete argument list in
288 standard C version. */
289 #if defined __STDC__ && __STDC__
291 # define obstack_init(h) \
292 _obstack_begin ((h), 0, 0, \
293 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
295 # define obstack_begin(h, size) \
296 _obstack_begin ((h), (size), 0, \
297 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free)
299 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
300 _obstack_begin ((h), (size), (alignment), \
301 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun))
303 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
304 _obstack_begin_1 ((h), (size), (alignment), \
305 (void *(*) (void *, long)) (chunkfun), \
306 (void (*) (void *, void *)) (freefun), (arg))
308 # define obstack_chunkfun(h, newchunkfun) \
309 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
311 # define obstack_freefun(h, newfreefun) \
312 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (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_empty_p(OBSTACK) \
379 ({ struct obstack *__o = (OBSTACK); \
380 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
382 # define obstack_grow(OBSTACK,where,length) \
384 ({ struct obstack *__o = (OBSTACK); \
385 int __len = (length); \
386 if (__o->next_free + __len > __o->chunk_limit) \
387 _obstack_newchunk (__o, __len); \
388 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
389 __o->next_free += __len; \
392 # define obstack_grow0(OBSTACK,where,length) \
394 ({ struct obstack *__o = (OBSTACK); \
395 int __len = (length); \
396 if (__o->next_free + __len + 1 > __o->chunk_limit) \
397 _obstack_newchunk (__o, __len + 1); \
398 _obstack_memcpy (__o->next_free, (char *) (where), __len); \
399 __o->next_free += __len; \
400 *(__o->next_free)++ = 0; \
403 # define obstack_1grow(OBSTACK,datum) \
405 ({ struct obstack *__o = (OBSTACK); \
406 if (__o->next_free + 1 > __o->chunk_limit) \
407 _obstack_newchunk (__o, 1); \
408 *(__o->next_free)++ = (datum); \
411 /* These assume that the obstack alignment is good enough for pointers or ints,
412 and that the data added so far to the current object
413 shares that much alignment. */
415 # define obstack_ptr_grow(OBSTACK,datum) \
417 ({ struct obstack *__o = (OBSTACK); \
418 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
419 _obstack_newchunk (__o, sizeof (void *)); \
420 *((void **)__o->next_free)++ = ((void *)datum); \
423 # define obstack_int_grow(OBSTACK,datum) \
425 ({ struct obstack *__o = (OBSTACK); \
426 if (__o->next_free + sizeof (int) > __o->chunk_limit) \
427 _obstack_newchunk (__o, sizeof (int)); \
428 *((int *)__o->next_free)++ = ((int)datum); \
431 # define obstack_ptr_grow_fast(h,aptr) (*((void **) (h)->next_free)++ = (void *)aptr)
432 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
434 # define obstack_blank(OBSTACK,length) \
436 ({ struct obstack *__o = (OBSTACK); \
437 int __len = (length); \
438 if (__o->chunk_limit - __o->next_free < __len) \
439 _obstack_newchunk (__o, __len); \
440 __o->next_free += __len; \
443 # define obstack_alloc(OBSTACK,length) \
445 ({ struct obstack *__h = (OBSTACK); \
446 obstack_blank (__h, (length)); \
447 obstack_finish (__h); })
449 # define obstack_copy(OBSTACK,where,length) \
451 ({ struct obstack *__h = (OBSTACK); \
452 obstack_grow (__h, (where), (length)); \
453 obstack_finish (__h); })
455 # define obstack_copy0(OBSTACK,where,length) \
457 ({ struct obstack *__h = (OBSTACK); \
458 obstack_grow0 (__h, (where), (length)); \
459 obstack_finish (__h); })
461 /* The local variable is named __o1 to avoid a name conflict
462 when obstack_blank is called. */
463 # define obstack_finish(OBSTACK) \
465 ({ struct obstack *__o1 = (OBSTACK); \
467 value = (void *) __o1->object_base; \
468 if (__o1->next_free == value) \
469 __o1->maybe_empty_object = 1; \
471 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
472 & ~ (__o1->alignment_mask)); \
473 if (__o1->next_free - (char *)__o1->chunk \
474 > __o1->chunk_limit - (char *)__o1->chunk) \
475 __o1->next_free = __o1->chunk_limit; \
476 __o1->object_base = __o1->next_free; \
479 # define obstack_free(OBSTACK, OBJ) \
481 ({ struct obstack *__o = (OBSTACK); \
482 void *__obj = (OBJ); \
483 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
484 __o->next_free = __o->object_base = __obj; \
485 else (obstack_free) (__o, __obj); })
487 #else /* not __GNUC__ or not __STDC__ */
489 # define obstack_object_size(h) \
490 (unsigned) ((h)->next_free - (h)->object_base)
492 # define obstack_room(h) \
493 (unsigned) ((h)->chunk_limit - (h)->next_free)
495 # define obstack_empty_p(h) \
496 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
498 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
499 so that we can avoid having void expressions
500 in the arms of the conditional expression.
501 Casting the third operand to void was tried before,
502 but some compilers won't accept it. */
504 # define obstack_make_room(h,length) \
505 ( (h)->temp = (length), \
506 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
507 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
509 # define obstack_grow(h,where,length) \
510 ( (h)->temp = (length), \
511 (((h)->next_free + (h)->temp > (h)->chunk_limit) \
512 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
513 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
514 (h)->next_free += (h)->temp)
516 # define obstack_grow0(h,where,length) \
517 ( (h)->temp = (length), \
518 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
519 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
520 _obstack_memcpy ((h)->next_free, (char *) (where), (h)->temp), \
521 (h)->next_free += (h)->temp, \
522 *((h)->next_free)++ = 0)
524 # define obstack_1grow(h,datum) \
525 ( (((h)->next_free + 1 > (h)->chunk_limit) \
526 ? (_obstack_newchunk ((h), 1), 0) : 0), \
527 (*((h)->next_free)++ = (datum)))
529 # define obstack_ptr_grow(h,datum) \
530 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
531 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
532 (*((char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *) datum)))
534 # define obstack_int_grow(h,datum) \
535 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
536 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
537 (*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = ((int) datum)))
539 # define obstack_ptr_grow_fast(h,aptr) (*((char **) (h)->next_free)++ = (char *) aptr)
540 # define obstack_int_grow_fast(h,aint) (*((int *) (h)->next_free)++ = (int) aint)
542 # define obstack_blank(h,length) \
543 ( (h)->temp = (length), \
544 (((h)->chunk_limit - (h)->next_free < (h)->temp) \
545 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
546 ((h)->next_free += (h)->temp))
548 # define obstack_alloc(h,length) \
549 (obstack_blank ((h), (length)), obstack_finish ((h)))
551 # define obstack_copy(h,where,length) \
552 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
554 # define obstack_copy0(h,where,length) \
555 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
557 # define obstack_finish(h) \
558 ( ((h)->next_free == (h)->object_base \
559 ? (((h)->maybe_empty_object = 1), 0) \
561 (h)->temp = __PTR_TO_INT ((h)->object_base), \
563 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
564 & ~ ((h)->alignment_mask)), \
565 (((h)->next_free - (char *) (h)->chunk \
566 > (h)->chunk_limit - (char *) (h)->chunk) \
567 ? ((h)->next_free = (h)->chunk_limit) : 0), \
568 (h)->object_base = (h)->next_free, \
569 __INT_TO_PTR ((h)->temp))
571 # if defined __STDC__ && __STDC__
572 # define obstack_free(h,obj) \
573 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
574 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
575 ? (int) ((h)->next_free = (h)->object_base \
576 = (h)->temp + (char *) (h)->chunk) \
577 : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
579 # define obstack_free(h,obj) \
580 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
581 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
582 ? (int) ((h)->next_free = (h)->object_base \
583 = (h)->temp + (char *) (h)->chunk) \
584 : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
587 #endif /* not __GNUC__ or not __STDC__ */
593 #endif /* obstack.h */