File: obstack.h

package info (click to toggle)
oleo 1.6-16
  • links: PTS
  • area: main
  • in suites: potato
  • size: 2,640 kB
  • ctags: 3,139
  • sloc: ansic: 39,221; yacc: 1,737; sh: 362; makefile: 88
file content (517 lines) | stat: -rw-r--r-- 19,232 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
/* obstack.h - object stack macros
   Copyright (C) 1988, 1992, 1993 Free Software Foundation, Inc.

This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */

/* Summary:

All the apparent functions defined here are macros. The idea
is that you would use these pre-tested macros to solve a
very specific set of problems, and they would run fast.
Caution: no side-effects in arguments please!! They may be
evaluated MANY times!!

These macros operate a stack of objects.  Each object starts life
small, and may grow to maturity.  (Consider building a word syllable
by syllable.)  An object can move while it is growing.  Once it has
been "finished" it never changes address again.  So the "top of the
stack" is typically an immature growing object, while the rest of the
stack is of mature, fixed size and fixed address objects.

These routines grab large chunks of memory, using a function you
supply, called `obstack_chunk_alloc'.  On occasion, they free chunks,
by calling `obstack_chunk_free'.  You must define them and declare
them before using any obstack macros.

Each independent stack is represented by a `struct obstack'.
Each of the obstack macros expects a pointer to such a structure
as the first argument.

One motivation for this package is the problem of growing char strings
in symbol tables.  Unless you are "fascist pig with a read-only mind"
--Gosper's immortal quote from HAKMEM item 154, out of context--you
would not like to put any arbitrary upper limit on the length of your
symbols.

In practice this often means you will build many short symbols and a
few long symbols.  At the time you are reading a symbol you don't know
how long it is.  One traditional method is to read a symbol into a
buffer, realloc()ating the buffer every time you try to read a symbol
that is longer than the buffer.  This is beaut, but you still will
want to copy the symbol from the buffer to a more permanent
symbol-table entry say about half the time.

With obstacks, you can work differently.  Use one obstack for all symbol
names.  As you read a symbol, grow the name in the obstack gradually.
When the name is complete, finalize it.  Then, if the symbol exists already,
free the newly read name.

The way we do this is to take a large chunk, allocating memory from
low addresses.  When you want to build a symbol in the chunk you just
add chars above the current "high water mark" in the chunk.  When you
have finished adding chars, because you got to the end of the symbol,
you know how long the chars are, and you can create a new object.
Mostly the chars will not burst over the highest address of the chunk,
because you would typically expect a chunk to be (say) 100 times as
long as an average object.

In case that isn't clear, when we have enough chars to make up
the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
so we just point to it where it lies.  No moving of chars is
needed and this is the second win: potentially long strings need
never be explicitly shuffled. Once an object is formed, it does not
change its address during its lifetime.

When the chars burst over a chunk boundary, we allocate a larger
chunk, and then copy the partly formed object from the end of the old
chunk to the beginning of the new larger chunk.  We then carry on
accreting characters to the end of the object as we normally would.

A special macro is provided to add a single char at a time to a
growing object.  This allows the use of register variables, which
break the ordinary 'growth' macro.

Summary:
	We allocate large chunks.
	We carve out one object at a time from the current chunk.
	Once carved, an object never moves.
	We are free to append data of any size to the currently
	  growing object.
	Exactly one object is growing in an obstack at any one time.
	You can run one obstack per control block.
	You may have as many control blocks as you dare.
	Because of the way we do it, you can `unwind' an obstack
	  back to a previous state. (You may remove objects much
	  as you would with a stack.)
*/


/* Don't do the contents of this file more than once.  */

#ifndef __OBSTACKS__
#define __OBSTACKS__

/* We use subtraction of (char *)0 instead of casting to int
   because on word-addressable machines a simple cast to int
   may ignore the byte-within-word field of the pointer.  */

#ifndef __PTR_TO_INT
#define __PTR_TO_INT(P) ((P) - (char *)0)
#endif

#ifndef __INT_TO_PTR
#define __INT_TO_PTR(P) ((P) + (char *)0)
#endif

/* We need the type of the resulting object.  In ANSI C it is ptrdiff_t
   but in traditional C it is usually long.  If we are in ANSI C and
   don't already have ptrdiff_t get it.  */

#if defined (__STDC__) && ! defined (offsetof)
#if defined (__GNUC__) && defined (IN_GCC)
/* On Next machine, the system's stddef.h screws up if included
   after we have defined just ptrdiff_t, so include all of gstddef.h.
   Otherwise, define just ptrdiff_t, which is all we need.  */
#ifndef __NeXT__
#define __need_ptrdiff_t
#endif

/* While building GCC, the stddef.h that goes with GCC has this name.  */
#include "gstddef.h"
#else
#include <stddef.h>
#endif
#endif

#ifdef __STDC__
#define PTR_INT_TYPE ptrdiff_t
#else
#define PTR_INT_TYPE long
#endif

struct _obstack_chunk		/* Lives at front of each chunk. */
{
  char  *limit;			/* 1 past end of this chunk */
  struct _obstack_chunk *prev;	/* address of prior chunk or NULL */
  char	contents[4];		/* objects begin here */
};

struct obstack		/* control current object in current chunk */
{
  long	chunk_size;		/* preferred size to allocate chunks in */
  struct _obstack_chunk* chunk;	/* address of current struct obstack_chunk */
  char	*object_base;		/* address of object we are building */
  char	*next_free;		/* where to add next char to current object */
  char	*chunk_limit;		/* address of char after current chunk */
  PTR_INT_TYPE temp;		/* Temporary for some macros.  */
  int   alignment_mask;		/* Mask of alignment for each object. */
  struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk.  */
  void (*freefun) ();		/* User's function to free a chunk.  */
  char *extra_arg;		/* first arg for chunk alloc/dealloc funcs */
  unsigned use_extra_arg:1;	/* chunk alloc/dealloc funcs take extra arg */
  unsigned maybe_empty_object:1;/* There is a possibility that the current
				   chunk contains a zero-length object.  This
				   prevents freeing the chunk if we allocate
				   a bigger chunk to replace it. */
};

/* Declare the external functions we use; they are in obstack.c.  */

#if PROTOTYPES
extern void _obstack_newchunk (struct obstack *, int);
extern void _obstack_free (struct obstack *, VOIDSTAR);
extern void _obstack_begin (struct obstack *, int, int,
			    VOIDSTAR (*) (), void (*) ());
extern void _obstack_begin_1 (struct obstack *, int, int,
			      VOIDSTAR (*) (), void (*) (), void *);
#else /* PROTOTYPES */
extern void _obstack_newchunk ();
extern void _obstack_free ();
extern void _obstack_begin ();
extern void _obstack_begin_1 ();
#endif /* PROTOTYPES */


#ifdef PROTOTYPES

/* Do the function-declarations after the structs
   but before defining the macros.  */

void obstack_init (struct obstack *obstack);

void * obstack_alloc (struct obstack *obstack, int size);

void * obstack_copy (struct obstack *obstack, void *address, int size);
void * obstack_copy0 (struct obstack *obstack, void *address, int size);

void obstack_free (struct obstack *obstack, void *block);

void obstack_blank (struct obstack *obstack, int size);

void obstack_grow (struct obstack *obstack, void *data, int size);
void obstack_grow0 (struct obstack *obstack, void *data, int size);

void obstack_1grow (struct obstack *obstack, int data_char);
void obstack_ptr_grow (struct obstack *obstack, void *data);
void obstack_int_grow (struct obstack *obstack, int data);

void * obstack_finish (struct obstack *obstack);

int obstack_object_size (struct obstack *obstack);

int obstack_room (struct obstack *obstack);
void obstack_1grow_fast (struct obstack *obstack, int data_char);
void obstack_ptr_grow_fast (struct obstack *obstack, void *data);
void obstack_int_grow_fast (struct obstack *obstack, int data);
void obstack_blank_fast (struct obstack *obstack, int size);

void * obstack_base (struct obstack *obstack);
void * obstack_next_free (struct obstack *obstack);
int obstack_alignment_mask (struct obstack *obstack);
int obstack_chunk_size (struct obstack *obstack);
#else /* PROTOTYPES */
void obstack_init ();

void * obstack_alloc ();

void * obstack_copy ();
void * obstack_copy0 ();

void obstack_free ();

void obstack_blank ();

void obstack_grow ();
void obstack_grow0 ();

void obstack_1grow ();
void obstack_ptr_grow ();
void obstack_int_grow ();

void * obstack_finish ();

int obstack_object_size ();

int obstack_room ();
void obstack_1grow_fast ();
void obstack_ptr_grow_fast ();
void obstack_int_grow_fast ();
void obstack_blank_fast ();

void * obstack_base ();
void * obstack_next_free ();
int obstack_alignment_mask ();
int obstack_chunk_size ();
#endif /* PROTOTYPES */

/* Non-ANSI C cannot really support alternative functions for these macros,
   so we do not declare them.  */

/* Pointer to beginning of object being allocated or to be allocated next.
   Note that this might not be the final address of the object
   because a new chunk might be needed to hold the final size.  */

#define obstack_base(h) ((h)->object_base)

/* Size for allocating ordinary chunks.  */

#define obstack_chunk_size(h) ((h)->chunk_size)

/* Pointer to next byte not yet allocated in current chunk.  */

#define obstack_next_free(h)	((h)->next_free)

/* Mask specifying low bits that should be clear in address of an object.  */

#define obstack_alignment_mask(h) ((h)->alignment_mask)

#define obstack_init(h) \
  _obstack_begin ((h), 0, 0, \
		  (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)

#define obstack_begin(h, size) \
  _obstack_begin ((h), (size), 0, \
		  (void *(*) ()) obstack_chunk_alloc, (void (*) ()) obstack_chunk_free)

#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \
  _obstack_begin ((h), (size), (alignment), \
		    (void *(*) ()) (chunkfun), (void (*) ()) (freefun))

#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
  _obstack_begin_1 ((h), (size), (alignment), \
		    (void *(*) ()) (chunkfun), (void (*) ()) (freefun), (arg))

#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = achar)

#define obstack_blank_fast(h,n) ((h)->next_free += (n))

#if defined (__GNUC__) && defined (__STDC__)
#if __GNUC__ < 2
#define __extension__
#endif

/* For GNU C, if not -traditional,
   we can define these macros to compute all args only once
   without using a global variable.
   Also, we can avoid using the `temp' slot, to make faster code.  */

#define obstack_object_size(OBSTACK)					\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     (unsigned) (__o->next_free - __o->object_base); })

#define obstack_room(OBSTACK)						\
  __extension__								\
  ({ struct obstack *__o = (OBSTACK);					\
     (unsigned) (__o->chunk_limit - __o->next_free); })

/* Note that the call to _obstack_newchunk is enclosed in (..., 0)
   so that we can avoid having void expressions
   in the arms of the conditional expression.
   Casting the third operand to void was tried before,
   but some compilers won't accept it.  */
#define obstack_grow(OBSTACK,where,length)				\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   int __len = (length);						\
   ((__o->next_free + __len > __o->chunk_limit)				\
    ? (_obstack_newchunk (__o, __len), 0) : 0);				\
   bcopy (where, __o->next_free, __len);				\
   __o->next_free += __len;						\
   (void) 0; })

#define obstack_grow0(OBSTACK,where,length)				\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   int __len = (length);						\
   ((__o->next_free + __len + 1 > __o->chunk_limit)			\
    ? (_obstack_newchunk (__o, __len + 1), 0) : 0),			\
   bcopy (where, __o->next_free, __len),				\
   __o->next_free += __len,						\
   *(__o->next_free)++ = 0;						\
   (void) 0; })

#define obstack_1grow(OBSTACK,datum)					\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   ((__o->next_free + 1 > __o->chunk_limit)				\
    ? (_obstack_newchunk (__o, 1), 0) : 0),				\
   *(__o->next_free)++ = (datum);					\
   (void) 0; })

/* These assume that the obstack alignment is good enough for pointers or ints,
   and that the data added so far to the current object
   shares that much alignment.  */
   
#define obstack_ptr_grow(OBSTACK,datum)					\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   ((__o->next_free + sizeof (void *) > __o->chunk_limit)		\
    ? (_obstack_newchunk (__o, sizeof (void *)), 0) : 0),		\
   *((void **)__o->next_free)++ = ((void *)datum);			\
   (void) 0; })

#define obstack_int_grow(OBSTACK,datum)					\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   ((__o->next_free + sizeof (int) > __o->chunk_limit)			\
    ? (_obstack_newchunk (__o, sizeof (int)), 0) : 0),			\
   *((int *)__o->next_free)++ = ((int)datum);				\
   (void) 0; })

#define obstack_ptr_grow_fast(h,aptr) (*((void **)(h)->next_free)++ = (void *)aptr)
#define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)

#define obstack_blank(OBSTACK,length)					\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   int __len = (length);						\
   ((__o->chunk_limit - __o->next_free < __len)				\
    ? (_obstack_newchunk (__o, __len), 0) : 0);				\
   __o->next_free += __len;						\
   (void) 0; })

#define obstack_alloc(OBSTACK,length)					\
__extension__								\
({ struct obstack *__h = (OBSTACK);					\
   obstack_blank (__h, (length));					\
   obstack_finish (__h); })

#define obstack_copy(OBSTACK,where,length)				\
__extension__								\
({ struct obstack *__h = (OBSTACK);					\
   obstack_grow (__h, (where), (length));				\
   obstack_finish (__h); })

#define obstack_copy0(OBSTACK,where,length)				\
__extension__								\
({ struct obstack *__h = (OBSTACK);					\
   obstack_grow0 (__h, (where), (length));				\
   obstack_finish (__h); })

/* The local variable is named __o1 to avoid a name conflict
   when obstack_blank is called.  */
#define obstack_finish(OBSTACK)  					\
__extension__								\
({ struct obstack *__o1 = (OBSTACK);					\
   void *value = (void *) __o1->object_base;				\
   if (__o1->next_free == value)					\
     __o1->maybe_empty_object = 1;					\
   __o1->next_free							\
     = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\
		     & ~ (__o1->alignment_mask));			\
   ((__o1->next_free - (char *)__o1->chunk				\
     > __o1->chunk_limit - (char *)__o1->chunk)				\
    ? (__o1->next_free = __o1->chunk_limit) : 0);			\
   __o1->object_base = __o1->next_free;					\
   value; })

#define obstack_free(OBSTACK, OBJ)					\
__extension__								\
({ struct obstack *__o = (OBSTACK);					\
   void *__obj = (OBJ);							\
   if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit)  \
     __o->next_free = __o->object_base = __obj;				\
   else (obstack_free) (__o, __obj); })

#else /* not __GNUC__ or not __STDC__ */

#define obstack_object_size(h) \
 (unsigned) ((h)->next_free - (h)->object_base)

#define obstack_room(h)		\
 (unsigned) ((h)->chunk_limit - (h)->next_free)

#define obstack_grow(h,where,length)					\
( (h)->temp = (length),							\
  (((h)->next_free + (h)->temp > (h)->chunk_limit)			\
   ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),			\
  bcopy (where, (h)->next_free, (h)->temp),				\
  (h)->next_free += (h)->temp)

#define obstack_grow0(h,where,length)					\
( (h)->temp = (length),							\
  (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit)			\
   ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0),			\
  bcopy (where, (h)->next_free, (h)->temp),				\
  (h)->next_free += (h)->temp,						\
  *((h)->next_free)++ = 0)

#define obstack_1grow(h,datum)						\
( (((h)->next_free + 1 > (h)->chunk_limit)				\
   ? (_obstack_newchunk ((h), 1), 0) : 0),				\
  *((h)->next_free)++ = (datum))

#define obstack_ptr_grow(h,datum)					\
( (((h)->next_free + sizeof (char *) > (h)->chunk_limit)		\
   ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0),		\
  *((char **)(((h)->next_free+=sizeof(char *))-sizeof(char *))) = ((char *)datum))

#define obstack_int_grow(h,datum)					\
( (((h)->next_free + sizeof (int) > (h)->chunk_limit)			\
   ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0),			\
  *((int *)(((h)->next_free+=sizeof(int))-sizeof(int))) = ((int)datum))

#define obstack_ptr_grow_fast(h,aptr) (*((char **)(h)->next_free)++ = (char *)aptr)
#define obstack_int_grow_fast(h,aint) (*((int *)(h)->next_free)++ = (int)aint)

#define obstack_blank(h,length)						\
( (h)->temp = (length),							\
  (((h)->chunk_limit - (h)->next_free < (h)->temp)			\
   ? (_obstack_newchunk ((h), (h)->temp), 0) : 0),			\
  (h)->next_free += (h)->temp)

#define obstack_alloc(h,length)						\
 (obstack_blank ((h), (length)), obstack_finish ((h)))

#define obstack_copy(h,where,length)					\
 (obstack_grow ((h), (where), (length)), obstack_finish ((h)))

#define obstack_copy0(h,where,length)					\
 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))

#define obstack_finish(h)  						\
( ((h)->next_free == (h)->object_base					\
   ? (((h)->maybe_empty_object = 1), 0)					\
   : 0),								\
  (h)->temp = __PTR_TO_INT ((h)->object_base),				\
  (h)->next_free							\
    = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask)	\
		    & ~ ((h)->alignment_mask)),				\
  (((h)->next_free - (char *)(h)->chunk					\
    > (h)->chunk_limit - (char *)(h)->chunk)				\
   ? ((h)->next_free = (h)->chunk_limit) : 0),				\
  (h)->object_base = (h)->next_free,					\
  __INT_TO_PTR ((h)->temp))

#ifdef __STDC__
#define obstack_free(h,obj)						\
( (h)->temp = (char *)(obj) - (char *) (h)->chunk,			\
  (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
   ? (int) ((h)->next_free = (h)->object_base				\
	    = (h)->temp + (char *) (h)->chunk)				\
   : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
#else
#define obstack_free(h,obj)						\
( (h)->temp = (char *)(obj) - (char *) (h)->chunk,			\
  (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
   ? (int) ((h)->next_free = (h)->object_base				\
	    = (h)->temp + (char *) (h)->chunk)				\
   : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))
#endif

#endif /* not __GNUC__ or not __STDC__ */

#endif /* not __OBSTACKS__ */