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
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, const void *address, int size);
221
void * obstack_copy0 (struct obstack *obstack, const 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, const void *data, int size);
228
void obstack_grow0 (struct obstack *obstack, const void *data, int size);
230
void obstack_1grow (struct obstack *obstack, int data_char);
231
void obstack_ptr_grow (struct obstack *obstack, const 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, const 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, \
294
(void (*) (void *)) obstack_chunk_free)
296
# define obstack_begin(h, size) \
297
_obstack_begin ((h), (size), 0, \
298
(void *(*) (long)) obstack_chunk_alloc, \
299
(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), \
304
(void (*) (void *)) (freefun))
306
# define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
307
_obstack_begin_1 ((h), (size), (alignment), \
308
(void *(*) (void *, long)) (chunkfun), \
309
(void (*) (void *, void *)) (freefun), (arg))
311
# define obstack_chunkfun(h, newchunkfun) \
312
((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun))
314
# define obstack_freefun(h, newfreefun) \
315
((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun))
319
# define obstack_init(h) \
320
_obstack_begin ((h), 0, 0, \
321
(void *(*) ()) obstack_chunk_alloc, \
322
(void (*) ()) obstack_chunk_free)
324
# define obstack_begin(h, size) \
325
_obstack_begin ((h), (size), 0, \
326
(void *(*) ()) obstack_chunk_alloc, \
327
(void (*) ()) obstack_chunk_free)
329
# define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
330
_obstack_begin ((h), (size), (alignment), \
331
(void *(*) ()) (chunkfun), \
332
(void (*) ()) (freefun))
334
# define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
335
_obstack_begin_1 ((h), (size), (alignment), \
336
(void *(*) ()) (chunkfun), \
337
(void (*) ()) (freefun), (arg))
339
# define obstack_chunkfun(h, newchunkfun) \
340
((h) -> chunkfun = (struct _obstack_chunk *(*)()) (newchunkfun))
342
# define obstack_freefun(h, newfreefun) \
343
((h) -> freefun = (void (*)()) (newfreefun))
347
#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)
349
#define obstack_blank_fast(h,n) ((h)->next_free += (n))
351
#define obstack_memory_used(h) _obstack_memory_used (h)
353
#if defined __GNUC__ && defined __STDC__ && __STDC__
354
/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and
355
does not implement __extension__. But that compiler doesn't define
357
# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)
358
# define __extension__
361
/* For GNU C, if not -traditional,
362
we can define these macros to compute all args only once
363
without using a global variable.
364
Also, we can avoid using the `temp' slot, to make faster code. */
366
# define obstack_object_size(OBSTACK) \
368
({ struct obstack *__o = (OBSTACK); \
369
(unsigned) (__o->next_free - __o->object_base); })
371
# define obstack_room(OBSTACK) \
373
({ struct obstack *__o = (OBSTACK); \
374
(unsigned) (__o->chunk_limit - __o->next_free); })
376
# define obstack_make_room(OBSTACK,length) \
378
({ struct obstack *__o = (OBSTACK); \
379
int __len = (length); \
380
if (__o->chunk_limit - __o->next_free < __len) \
381
_obstack_newchunk (__o, __len); \
384
# define obstack_empty_p(OBSTACK) \
386
({ struct obstack *__o = (OBSTACK); \
387
(__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
389
# define obstack_grow(OBSTACK,where,length) \
391
({ struct obstack *__o = (OBSTACK); \
392
int __len = (length); \
393
if (__o->next_free + __len > __o->chunk_limit) \
394
_obstack_newchunk (__o, __len); \
395
_obstack_memcpy (__o->next_free, (where), __len); \
396
__o->next_free += __len; \
399
# define obstack_grow0(OBSTACK,where,length) \
401
({ struct obstack *__o = (OBSTACK); \
402
int __len = (length); \
403
if (__o->next_free + __len + 1 > __o->chunk_limit) \
404
_obstack_newchunk (__o, __len + 1); \
405
_obstack_memcpy (__o->next_free, (where), __len); \
406
__o->next_free += __len; \
407
*(__o->next_free)++ = 0; \
410
# define obstack_1grow(OBSTACK,datum) \
412
({ struct obstack *__o = (OBSTACK); \
413
if (__o->next_free + 1 > __o->chunk_limit) \
414
_obstack_newchunk (__o, 1); \
415
*(__o->next_free)++ = (datum); \
418
/* These assume that the obstack alignment is good enough for pointers
419
or ints, and that the data added so far to the current object
420
shares that much alignment. */
422
# define obstack_ptr_grow(OBSTACK,datum) \
424
({ struct obstack *__o = (OBSTACK); \
425
if (__o->next_free + sizeof (void *) > __o->chunk_limit) \
426
_obstack_newchunk (__o, sizeof (void *)); \
427
*((void **)__o->next_free)++ = (datum); \
430
# define obstack_int_grow(OBSTACK,datum) \
432
({ struct obstack *__o = (OBSTACK); \
433
if (__o->next_free + sizeof (int) > __o->chunk_limit) \
434
_obstack_newchunk (__o, sizeof (int)); \
435
*((int *)__o->next_free)++ = (datum); \
438
# define obstack_ptr_grow_fast(h,aptr) \
439
(*((void **) (h)->next_free)++ = (aptr))
441
# define obstack_int_grow_fast(h,aint) \
442
(*((int *) (h)->next_free)++ = (aint))
444
# define obstack_blank(OBSTACK,length) \
446
({ struct obstack *__o = (OBSTACK); \
447
int __len = (length); \
448
if (__o->chunk_limit - __o->next_free < __len) \
449
_obstack_newchunk (__o, __len); \
450
__o->next_free += __len; \
453
# define obstack_alloc(OBSTACK,length) \
455
({ struct obstack *__h = (OBSTACK); \
456
obstack_blank (__h, (length)); \
457
obstack_finish (__h); })
459
# define obstack_copy(OBSTACK,where,length) \
461
({ struct obstack *__h = (OBSTACK); \
462
obstack_grow (__h, (where), (length)); \
463
obstack_finish (__h); })
465
# define obstack_copy0(OBSTACK,where,length) \
467
({ struct obstack *__h = (OBSTACK); \
468
obstack_grow0 (__h, (where), (length)); \
469
obstack_finish (__h); })
471
/* The local variable is named __o1 to avoid a name conflict
472
when obstack_blank is called. */
473
# define obstack_finish(OBSTACK) \
475
({ struct obstack *__o1 = (OBSTACK); \
477
value = (void *) __o1->object_base; \
478
if (__o1->next_free == value) \
479
__o1->maybe_empty_object = 1; \
481
= __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
482
& ~ (__o1->alignment_mask)); \
483
if (__o1->next_free - (char *)__o1->chunk \
484
> __o1->chunk_limit - (char *)__o1->chunk) \
485
__o1->next_free = __o1->chunk_limit; \
486
__o1->object_base = __o1->next_free; \
489
# define obstack_free(OBSTACK, OBJ) \
491
({ struct obstack *__o = (OBSTACK); \
492
void *__obj = (OBJ); \
493
if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \
494
__o->next_free = __o->object_base = (char *)__obj; \
495
else (obstack_free) (__o, __obj); })
497
#else /* not __GNUC__ or not __STDC__ */
499
# define obstack_object_size(h) \
500
(unsigned) ((h)->next_free - (h)->object_base)
502
# define obstack_room(h) \
503
(unsigned) ((h)->chunk_limit - (h)->next_free)
505
# define obstack_empty_p(h) \
506
((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
508
/* Note that the call to _obstack_newchunk is enclosed in (..., 0)
509
so that we can avoid having void expressions
510
in the arms of the conditional expression.
511
Casting the third operand to void was tried before,
512
but some compilers won't accept it. */
514
# define obstack_make_room(h,length) \
515
( (h)->temp = (length), \
516
(((h)->next_free + (h)->temp > (h)->chunk_limit) \
517
? (_obstack_newchunk ((h), (h)->temp), 0) : 0))
519
# define obstack_grow(h,where,length) \
520
( (h)->temp = (length), \
521
(((h)->next_free + (h)->temp > (h)->chunk_limit) \
522
? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
523
_obstack_memcpy ((h)->next_free, (where), (h)->temp), \
524
(h)->next_free += (h)->temp)
526
# define obstack_grow0(h,where,length) \
527
( (h)->temp = (length), \
528
(((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \
529
? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \
530
_obstack_memcpy ((h)->next_free, (where), (h)->temp), \
531
(h)->next_free += (h)->temp, \
532
*((h)->next_free)++ = 0)
534
# define obstack_1grow(h,datum) \
535
( (((h)->next_free + 1 > (h)->chunk_limit) \
536
? (_obstack_newchunk ((h), 1), 0) : 0), \
537
(*((h)->next_free)++ = (datum)))
539
# define obstack_ptr_grow(h,datum) \
540
( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \
541
? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \
542
(*((const char **) (((h)->next_free+=sizeof(char *))-sizeof(char *))) = (datum)))
544
# define obstack_int_grow(h,datum) \
545
( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \
546
? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \
547
(*((int *) (((h)->next_free+=sizeof(int))-sizeof(int))) = (datum)))
549
# define obstack_ptr_grow_fast(h,aptr) \
550
(*((const char **) (h)->next_free)++ = (aptr))
552
# define obstack_int_grow_fast(h,aint) \
553
(*((int *) (h)->next_free)++ = (aint))
555
# define obstack_blank(h,length) \
556
( (h)->temp = (length), \
557
(((h)->chunk_limit - (h)->next_free < (h)->temp) \
558
? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \
559
((h)->next_free += (h)->temp))
561
# define obstack_alloc(h,length) \
562
(obstack_blank ((h), (length)), obstack_finish ((h)))
564
# define obstack_copy(h,where,length) \
565
(obstack_grow ((h), (where), (length)), obstack_finish ((h)))
567
# define obstack_copy0(h,where,length) \
568
(obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
570
# define obstack_finish(h) \
571
( ((h)->next_free == (h)->object_base \
572
? (((h)->maybe_empty_object = 1), 0) \
574
(h)->temp = __PTR_TO_INT ((h)->object_base), \
576
= __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \
577
& ~ ((h)->alignment_mask)), \
578
(((h)->next_free - (char *) (h)->chunk \
579
> (h)->chunk_limit - (char *) (h)->chunk) \
580
? ((h)->next_free = (h)->chunk_limit) : 0), \
581
(h)->object_base = (h)->next_free, \
582
__INT_TO_PTR ((h)->temp))
584
# if defined __STDC__ && __STDC__
585
# define obstack_free(h,obj) \
586
( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \
587
(((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
588
? (int) ((h)->next_free = (h)->object_base \
589
= (h)->temp + (char *) (h)->chunk) \
590
: (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
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)))
600
#endif /* not __GNUC__ or not __STDC__ */
606
#endif /* obstack.h */