include/obstack.h

   1 /* obstack.h - object stack macros
   2    Copyright (C) 1988-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /* Summary:
  20
  21    All the apparent functions defined here are macros. The idea
  22    is that you would use these pre-tested macros to solve a
  23    very specific set of problems, and they would run fast.
  24    Caution: no side-effects in arguments please!! They may be
  25    evaluated MANY times!!
  26
  27    These macros operate a stack of objects.  Each object starts life
  28    small, and may grow to maturity.  (Consider building a word syllable
  29    by syllable.)  An object can move while it is growing.  Once it has
  30    been "finished" it never changes address again.  So the "top of the
  31    stack" is typically an immature growing object, while the rest of the
  32    stack is of mature, fixed size and fixed address objects.
  33
  34    These routines grab large chunks of memory, using a function you
  35    supply, called 'obstack_chunk_alloc'.  On occasion, they free chunks,
  36    by calling 'obstack_chunk_free'.  You must define them and declare
  37    them before using any obstack macros.
  38
  39    Each independent stack is represented by a 'struct obstack'.
  40    Each of the obstack macros expects a pointer to such a structure
  41    as the first argument.
  42
  43    One motivation for this package is the problem of growing char strings
  44    in symbol tables.  Unless you are "fascist pig with a read-only mind"
  45    --Gosper's immortal quote from HAKMEM item 154, out of context--you
  46    would not like to put any arbitrary upper limit on the length of your
  47    symbols.
  48
  49    In practice this often means you will build many short symbols and a
  50    few long symbols.  At the time you are reading a symbol you don't know
  51    how long it is.  One traditional method is to read a symbol into a
  52    buffer, realloc()ating the buffer every time you try to read a symbol
  53    that is longer than the buffer.  This is beaut, but you still will
  54    want to copy the symbol from the buffer to a more permanent
  55    symbol-table entry say about half the time.
  56
  57    With obstacks, you can work differently.  Use one obstack for all symbol
  58    names.  As you read a symbol, grow the name in the obstack gradually.
  59    When the name is complete, finalize it.  Then, if the symbol exists already,
  60    free the newly read name.
  61
  62    The way we do this is to take a large chunk, allocating memory from
  63    low addresses.  When you want to build a symbol in the chunk you just
  64    add chars above the current "high water mark" in the chunk.  When you
  65    have finished adding chars, because you got to the end of the symbol,
  66    you know how long the chars are, and you can create a new object.
  67    Mostly the chars will not burst over the highest address of the chunk,
  68    because you would typically expect a chunk to be (say) 100 times as
  69    long as an average object.
  70
  71    In case that isn't clear, when we have enough chars to make up
  72    the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed)
  73    so we just point to it where it lies.  No moving of chars is
  74    needed and this is the second win: potentially long strings need
  75    never be explicitly shuffled. Once an object is formed, it does not
  76    change its address during its lifetime.
  77
  78    When the chars burst over a chunk boundary, we allocate a larger
  79    chunk, and then copy the partly formed object from the end of the old
  80    chunk to the beginning of the new larger chunk.  We then carry on
  81    accreting characters to the end of the object as we normally would.
  82
  83    A special macro is provided to add a single char at a time to a
  84    growing object.  This allows the use of register variables, which
  85    break the ordinary 'growth' macro.
  86
  87    Summary:
  88         We allocate large chunks.
  89         We carve out one object at a time from the current chunk.
  90         Once carved, an object never moves.
  91         We are free to append data of any size to the currently
  92           growing object.
  93         Exactly one object is growing in an obstack at any one time.
  94         You can run one obstack per control block.
  95         You may have as many control blocks as you dare.
  96         Because of the way we do it, you can "unwind" an obstack
  97           back to a previous state. (You may remove objects much
  98           as you would with a stack.)
  99  */
 100
 101
 102 /* Don't do the contents of this file more than once.  */
 103
 104 #ifndef _OBSTACK_H
 105 #define _OBSTACK_H 1
 106
 107 #ifndef _OBSTACK_INTERFACE_VERSION
 108 # define _OBSTACK_INTERFACE_VERSION 2
 109 #endif
 110
 111 #include <stddef.h>             /* For size_t and ptrdiff_t.  */
 112 #include <string.h>             /* For __GNU_LIBRARY__, and memcpy.  */
 113
 114 #if _OBSTACK_INTERFACE_VERSION == 1
 115 /* For binary compatibility with obstack version 1, which used "int"
 116    and "long" for these two types.  */
 117 # define _OBSTACK_SIZE_T unsigned int
 118 # define _CHUNK_SIZE_T unsigned long
 119 # define _OBSTACK_CAST(type, expr) ((type) (expr))
 120 #else
 121 /* Version 2 with sane types, especially for 64-bit hosts.  */
 122 # define _OBSTACK_SIZE_T size_t
 123 # define _CHUNK_SIZE_T size_t
 124 # define _OBSTACK_CAST(type, expr) (expr)
 125 #endif
 126
 127 /* If B is the base of an object addressed by P, return the result of
 128    aligning P to the next multiple of A + 1.  B and P must be of type
 129    char *.  A + 1 must be a power of 2.  */
 130
 131 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
 132
 133 /* Similar to __BPTR_ALIGN (B, P, A), except optimize the common case
 134    where pointers can be converted to integers, aligned as integers,
 135    and converted back again.  If ptrdiff_t is narrower than a
 136    pointer (e.g., the AS/400), play it safe and compute the alignment
 137    relative to B.  Otherwise, use the faster strategy of computing the
 138    alignment relative to 0.  */
 139
 140 #define __PTR_ALIGN(B, P, A)                                                  \
 141   __BPTR_ALIGN (sizeof (ptrdiff_t) < sizeof (void *) ? (B) : (char *) 0,      \
 142                 P, A)
 143
 144 #ifndef __attribute_pure__
 145 # if defined __GNUC_MINOR__ && __GNUC__ * 1000 + __GNUC_MINOR__ >= 2096
 146 #  define __attribute_pure__ __attribute__ ((__pure__))
 147 # else
 148 #  define __attribute_pure__
 149 # endif
 150 #endif
 151
 152 #ifdef __cplusplus
 153 extern "C" {
 154 #endif
 155
 156 struct _obstack_chunk           /* Lives at front of each chunk. */
 157 {
 158   char *limit;                  /* 1 past end of this chunk */
 159   struct _obstack_chunk *prev;  /* address of prior chunk or NULL */
 160   char contents[4];             /* objects begin here */
 161 };
 162
 163 struct obstack          /* control current object in current chunk */
 164 {
 165   _CHUNK_SIZE_T chunk_size;     /* preferred size to allocate chunks in */
 166   struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */
 167   char *object_base;            /* address of object we are building */
 168   char *next_free;              /* where to add next char to current object */
 169   char *chunk_limit;            /* address of char after current chunk */
 170   union
 171   {
 172     _OBSTACK_SIZE_T i;
 173     void *p;
 174   } temp;                       /* Temporary for some macros.  */
 175   _OBSTACK_SIZE_T alignment_mask;  /* Mask of alignment for each object. */
 176
 177   /* These prototypes vary based on 'use_extra_arg'.  */
 178   union
 179   {
 180     void *(*plain) (size_t);
 181     void *(*extra) (void *, size_t);
 182   } chunkfun;
 183   union
 184   {
 185     void (*plain) (void *);
 186     void (*extra) (void *, void *);
 187   } freefun;
 188
 189   void *extra_arg;              /* first arg for chunk alloc/dealloc funcs */
 190   unsigned use_extra_arg : 1;     /* chunk alloc/dealloc funcs take extra arg */
 191   unsigned maybe_empty_object : 1; /* There is a possibility that the current
 192                                       chunk contains a zero-length object.  This
 193                                       prevents freeing the chunk if we allocate
 194                                       a bigger chunk to replace it. */
 195   unsigned alloc_failed : 1;      /* No longer used, as we now call the failed
 196                                      handler on error, but retained for binary
 197                                      compatibility.  */
 198 };
 199
 200 /* Declare the external functions we use; they are in obstack.c.  */
 201
 202 extern void _obstack_newchunk (struct obstack *, _OBSTACK_SIZE_T);
 203 extern void _obstack_free (struct obstack *, void *);
 204 extern int _obstack_begin (struct obstack *,
 205                            _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
 206                            void *(*) (size_t), void (*) (void *));
 207 extern int _obstack_begin_1 (struct obstack *,
 208                              _OBSTACK_SIZE_T, _OBSTACK_SIZE_T,
 209                              void *(*) (void *, size_t),
 210                              void (*) (void *, void *), void *);
 211 extern _OBSTACK_SIZE_T _obstack_memory_used (struct obstack *)
 212   __attribute_pure__;
 213
 214
 215 /* Error handler called when 'obstack_chunk_alloc' failed to allocate
 216    more memory.  This can be set to a user defined function which
 217    should either abort gracefully or use longjump - but shouldn't
 218    return.  The default action is to print a message and abort.  */
 219 extern void (*obstack_alloc_failed_handler) (void);
 220
 221 /* Exit value used when 'print_and_abort' is used.  */
 222 extern int obstack_exit_failure;
 223
 224 /* Pointer to beginning of object being allocated or to be allocated next.
 225    Note that this might not be the final address of the object
 226    because a new chunk might be needed to hold the final size.  */
 227
 228 #define obstack_base(h) ((void *) (h)->object_base)
 229
 230 /* Size for allocating ordinary chunks.  */
 231
 232 #define obstack_chunk_size(h) ((h)->chunk_size)
 233
 234 /* Pointer to next byte not yet allocated in current chunk.  */
 235
 236 #define obstack_next_free(h) ((void *) (h)->next_free)
 237
 238 /* Mask specifying low bits that should be clear in address of an object.  */
 239
 240 #define obstack_alignment_mask(h) ((h)->alignment_mask)
 241
 242 /* To prevent prototype warnings provide complete argument list.  */
 243 #define obstack_init(h)                                                       \
 244   _obstack_begin ((h), 0, 0,                                                  \
 245                   _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc),    \
 246                   _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
 247
 248 #define obstack_begin(h, size)                                                \
 249   _obstack_begin ((h), (size), 0,                                             \
 250                   _OBSTACK_CAST (void *(*) (size_t), obstack_chunk_alloc), \
 251                   _OBSTACK_CAST (void (*) (void *), obstack_chunk_free))
 252
 253 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun)     \
 254   _obstack_begin ((h), (size), (alignment),                                   \
 255                   _OBSTACK_CAST (void *(*) (size_t), chunkfun),               \
 256                   _OBSTACK_CAST (void (*) (void *), freefun))
 257
 258 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \
 259   _obstack_begin_1 ((h), (size), (alignment),                                 \
 260                     _OBSTACK_CAST (void *(*) (void *, size_t), chunkfun),     \
 261                     _OBSTACK_CAST (void (*) (void *, void *), freefun), arg)
 262
 263 #define obstack_chunkfun(h, newchunkfun)                                      \
 264   ((void) ((h)->chunkfun.extra = (void *(*) (void *, size_t)) (newchunkfun)))
 265
 266 #define obstack_freefun(h, newfreefun)                                        \
 267   ((void) ((h)->freefun.extra = (void *(*) (void *, void *)) (newfreefun)))
 268
 269 #define obstack_1grow_fast(h, achar) ((void) (*((h)->next_free)++ = (achar)))
 270
 271 #define obstack_blank_fast(h, n) ((void) ((h)->next_free += (n)))
 272
 273 #define obstack_memory_used(h) _obstack_memory_used (h)
 274
 275 #if defined __GNUC__
 276 # if !defined __GNUC_MINOR__ || __GNUC__ * 1000 + __GNUC_MINOR__ < 2008
 277 #  define __extension__
 278 # endif
 279
 280 /* For GNU C, if not -traditional,
 281    we can define these macros to compute all args only once
 282    without using a global variable.
 283    Also, we can avoid using the 'temp' slot, to make faster code.  */
 284
 285 # define obstack_object_size(OBSTACK)                                         \
 286   __extension__                                                               \
 287     ({ struct obstack const *__o = (OBSTACK);                                 \
 288        (_OBSTACK_SIZE_T) (__o->next_free - __o->object_base); })
 289
 290 /* The local variable is named __o1 to avoid a shadowed variable
 291    warning when invoked from other obstack macros.  */
 292 # define obstack_room(OBSTACK)                                                \
 293   __extension__                                                               \
 294     ({ struct obstack const *__o1 = (OBSTACK);                                \
 295        (_OBSTACK_SIZE_T) (__o1->chunk_limit - __o1->next_free); })
 296
 297 # define obstack_make_room(OBSTACK, length)                                   \
 298   __extension__                                                               \
 299     ({ struct obstack *__o = (OBSTACK);                                       \
 300        _OBSTACK_SIZE_T __len = (length);                                      \
 301        if (obstack_room (__o) < __len)                                        \
 302          _obstack_newchunk (__o, __len);                                      \
 303        (void) 0; })
 304
 305 # define obstack_empty_p(OBSTACK)                                             \
 306   __extension__                                                               \
 307     ({ struct obstack const *__o = (OBSTACK);                                 \
 308        (__o->chunk->prev == 0                                                 \
 309         && __o->next_free == __PTR_ALIGN ((char *) __o->chunk,                \
 310                                           __o->chunk->contents,               \
 311                                           __o->alignment_mask)); })
 312
 313 # define obstack_grow(OBSTACK, where, length)                                 \
 314   __extension__                                                               \
 315     ({ struct obstack *__o = (OBSTACK);                                       \
 316        _OBSTACK_SIZE_T __len = (length);                                      \
 317        if (obstack_room (__o) < __len)                                        \
 318          _obstack_newchunk (__o, __len);                                      \
 319        memcpy (__o->next_free, where, __len);                                 \
 320        __o->next_free += __len;                                               \
 321        (void) 0; })
 322
 323 # define obstack_grow0(OBSTACK, where, length)                                \
 324   __extension__                                                               \
 325     ({ struct obstack *__o = (OBSTACK);                                       \
 326        _OBSTACK_SIZE_T __len = (length);                                      \
 327        if (obstack_room (__o) < __len + 1)                                    \
 328          _obstack_newchunk (__o, __len + 1);                                  \
 329        memcpy (__o->next_free, where, __len);                                 \
 330        __o->next_free += __len;                                               \
 331        *(__o->next_free)++ = 0;                                               \
 332        (void) 0; })
 333
 334 # define obstack_1grow(OBSTACK, datum)                                        \
 335   __extension__                                                               \
 336     ({ struct obstack *__o = (OBSTACK);                                       \
 337        if (obstack_room (__o) < 1)                                            \
 338          _obstack_newchunk (__o, 1);                                          \
 339        obstack_1grow_fast (__o, datum); })
 340
 341 /* These assume that the obstack alignment is good enough for pointers
 342    or ints, and that the data added so far to the current object
 343    shares that much alignment.  */
 344
 345 # define obstack_ptr_grow(OBSTACK, datum)                                     \
 346   __extension__                                                               \
 347     ({ struct obstack *__o = (OBSTACK);                                       \
 348        if (obstack_room (__o) < sizeof (void *))                              \
 349          _obstack_newchunk (__o, sizeof (void *));                            \
 350        obstack_ptr_grow_fast (__o, datum); })
 351
 352 # define obstack_int_grow(OBSTACK, datum)                                     \
 353   __extension__                                                               \
 354     ({ struct obstack *__o = (OBSTACK);                                       \
 355        if (obstack_room (__o) < sizeof (int))                                 \
 356          _obstack_newchunk (__o, sizeof (int));                               \
 357        obstack_int_grow_fast (__o, datum); })
 358
 359 # define obstack_ptr_grow_fast(OBSTACK, aptr)                                 \
 360   __extension__                                                               \
 361     ({ struct obstack *__o1 = (OBSTACK);                                      \
 362        void *__p1 = __o1->next_free;                                          \
 363        *(const void **) __p1 = (aptr);                                        \
 364        __o1->next_free += sizeof (const void *);                              \
 365        (void) 0; })
 366
 367 # define obstack_int_grow_fast(OBSTACK, aint)                                 \
 368   __extension__                                                               \
 369     ({ struct obstack *__o1 = (OBSTACK);                                      \
 370        void *__p1 = __o1->next_free;                                          \
 371        *(int *) __p1 = (aint);                                                \
 372        __o1->next_free += sizeof (int);                                       \
 373        (void) 0; })
 374
 375 # define obstack_blank(OBSTACK, length)                                       \
 376   __extension__                                                               \
 377     ({ struct obstack *__o = (OBSTACK);                                       \
 378        _OBSTACK_SIZE_T __len = (length);                                      \
 379        if (obstack_room (__o) < __len)                                        \
 380          _obstack_newchunk (__o, __len);                                      \
 381        obstack_blank_fast (__o, __len); })
 382
 383 # define obstack_alloc(OBSTACK, length)                                       \
 384   __extension__                                                               \
 385     ({ struct obstack *__h = (OBSTACK);                                       \
 386        obstack_blank (__h, (length));                                         \
 387        obstack_finish (__h); })
 388
 389 # define obstack_copy(OBSTACK, where, length)                                 \
 390   __extension__                                                               \
 391     ({ struct obstack *__h = (OBSTACK);                                       \
 392        obstack_grow (__h, (where), (length));                                 \
 393        obstack_finish (__h); })
 394
 395 # define obstack_copy0(OBSTACK, where, length)                                \
 396   __extension__                                                               \
 397     ({ struct obstack *__h = (OBSTACK);                                       \
 398        obstack_grow0 (__h, (where), (length));                                \
 399        obstack_finish (__h); })
 400
 401 /* The local variable is named __o1 to avoid a shadowed variable
 402    warning when invoked from other obstack macros, typically obstack_free.  */
 403 # define obstack_finish(OBSTACK)                                              \
 404   __extension__                                                               \
 405     ({ struct obstack *__o1 = (OBSTACK);                                      \
 406        void *__value = (void *) __o1->object_base;                            \
 407        if (__o1->next_free == __value)                                        \
 408          __o1->maybe_empty_object = 1;                                        \
 409        __o1->next_free                                                        \
 410          = __PTR_ALIGN (__o1->object_base, __o1->next_free,                   \
 411                         __o1->alignment_mask);                                \
 412        if ((size_t) (__o1->next_free - (char *) __o1->chunk)                  \
 413            > (size_t) (__o1->chunk_limit - (char *) __o1->chunk))             \
 414          __o1->next_free = __o1->chunk_limit;                                 \
 415        __o1->object_base = __o1->next_free;                                   \
 416        __value; })
 417
 418 # define obstack_free(OBSTACK, OBJ)                                           \
 419   __extension__                                                               \
 420     ({ struct obstack *__o = (OBSTACK);                                       \
 421        void *__obj = (void *) (OBJ);                                          \
 422        if (__obj > (void *) __o->chunk && __obj < (void *) __o->chunk_limit)  \
 423          __o->next_free = __o->object_base = (char *) __obj;                  \
 424        else                                                                   \
 425          _obstack_free (__o, __obj); })
 426
 427 #else /* not __GNUC__ */
 428
 429 # define obstack_object_size(h)                                               \
 430   ((_OBSTACK_SIZE_T) ((h)->next_free - (h)->object_base))
 431
 432 # define obstack_room(h)                                                      \
 433   ((_OBSTACK_SIZE_T) ((h)->chunk_limit - (h)->next_free))
 434
 435 # define obstack_empty_p(h)                                                   \
 436   ((h)->chunk->prev == 0                                                      \
 437    && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk,                     \
 438                                      (h)->chunk->contents,                    \
 439                                      (h)->alignment_mask))
 440
 441 /* Note that the call to _obstack_newchunk is enclosed in (..., 0)
 442    so that we can avoid having void expressions
 443    in the arms of the conditional expression.
 444    Casting the third operand to void was tried before,
 445    but some compilers won't accept it.  */
 446
 447 # define obstack_make_room(h, length)                                         \
 448   ((h)->temp.i = (length),                                                    \
 449    ((obstack_room (h) < (h)->temp.i)                                          \
 450     ? (_obstack_newchunk (h, (h)->temp.i), 0) : 0),                           \
 451    (void) 0)
 452
 453 # define obstack_grow(h, where, length)                                       \
 454   ((h)->temp.i = (length),                                                    \
 455    ((obstack_room (h) < (h)->temp.i)                                          \
 456    ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),                          \
 457    memcpy ((h)->next_free, where, (h)->temp.i),                               \
 458    (h)->next_free += (h)->temp.i,                                             \
 459    (void) 0)
 460
 461 # define obstack_grow0(h, where, length)                                      \
 462   ((h)->temp.i = (length),                                                    \
 463    ((obstack_room (h) < (h)->temp.i + 1)                                      \
 464    ? (_obstack_newchunk ((h), (h)->temp.i + 1), 0) : 0),                      \
 465    memcpy ((h)->next_free, where, (h)->temp.i),                               \
 466    (h)->next_free += (h)->temp.i,                                             \
 467    *((h)->next_free)++ = 0,                                                   \
 468    (void) 0)
 469
 470 # define obstack_1grow(h, datum)                                              \
 471   (((obstack_room (h) < 1)                                                    \
 472     ? (_obstack_newchunk ((h), 1), 0) : 0),                                   \
 473    obstack_1grow_fast (h, datum))
 474
 475 # define obstack_ptr_grow(h, datum)                                           \
 476   (((obstack_room (h) < sizeof (char *))                                      \
 477     ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0),                     \
 478    obstack_ptr_grow_fast (h, datum))
 479
 480 # define obstack_int_grow(h, datum)                                           \
 481   (((obstack_room (h) < sizeof (int))                                         \
 482     ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0),                        \
 483    obstack_int_grow_fast (h, datum))
 484
 485 # define obstack_ptr_grow_fast(h, aptr)                                       \
 486   (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr),        \
 487    (void) 0)
 488
 489 # define obstack_int_grow_fast(h, aint)                                       \
 490   (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint),                   \
 491    (void) 0)
 492
 493 # define obstack_blank(h, length)                                             \
 494   ((h)->temp.i = (length),                                                    \
 495    ((obstack_room (h) < (h)->temp.i)                                          \
 496    ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),                          \
 497    obstack_blank_fast (h, (h)->temp.i))
 498
 499 # define obstack_alloc(h, length)                                             \
 500   (obstack_blank ((h), (length)), obstack_finish ((h)))
 501
 502 # define obstack_copy(h, where, length)                                       \
 503   (obstack_grow ((h), (where), (length)), obstack_finish ((h)))
 504
 505 # define obstack_copy0(h, where, length)                                      \
 506   (obstack_grow0 ((h), (where), (length)), obstack_finish ((h)))
 507
 508 # define obstack_finish(h)                                                    \
 509   (((h)->next_free == (h)->object_base                                        \
 510     ? (((h)->maybe_empty_object = 1), 0)                                      \
 511     : 0),                                                                     \
 512    (h)->temp.p = (h)->object_base,                                            \
 513    (h)->next_free                                                             \
 514      = __PTR_ALIGN ((h)->object_base, (h)->next_free,                         \
 515                     (h)->alignment_mask),                                     \
 516    (((size_t) ((h)->next_free - (char *) (h)->chunk)                          \
 517      > (size_t) ((h)->chunk_limit - (char *) (h)->chunk))                     \
 518    ? ((h)->next_free = (h)->chunk_limit) : 0),                                \
 519    (h)->object_base = (h)->next_free,                                         \
 520    (h)->temp.p)
 521
 522 # define obstack_free(h, obj)                                                 \
 523   ((h)->temp.p = (void *) (obj),                                              \
 524    (((h)->temp.p > (void *) (h)->chunk                                        \
 525      && (h)->temp.p < (void *) (h)->chunk_limit)                              \
 526     ? (void) ((h)->next_free = (h)->object_base = (char *) (h)->temp.p)       \
 527     : _obstack_free ((h), (h)->temp.p)))
 528
 529 #endif /* not __GNUC__ */
 530
 531 #ifdef __cplusplus
 532 }       /* C++ */
 533 #endif
 534
 535 #endif /* _OBSTACK_H */