1 /* obstack.h - object stack macros 2 Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1996, 1997, 1998, 3 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2008 4 Free Software Foundation, Inc. 5 6 7 NOTE: The canonical source of this file is maintained with the GNU C Library. 8 Bugs can be reported to bug-glibc (at) gnu.org. 9 10 This program is free software; you can redistribute it and/or modify it 11 under the terms of the GNU General Public License as published by the 12 Free Software Foundation; either version 2, or (at your option) any 13 later version. 14 15 This program is distributed in the hope that it will be useful, 16 but WITHOUT ANY WARRANTY; without even the implied warranty of 17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18 GNU General Public License for more details. 19 20 You should have received a copy of the GNU General Public License 21 along with this program; if not, write to the Free Software 22 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, 23 USA. */ 24 25 /* Summary: 26 27 All the apparent functions defined here are macros. The idea 28 is that you would use these pre-tested macros to solve a 29 very specific set of problems, and they would run fast. 30 Caution: no side-effects in arguments please!! They may be 31 evaluated MANY times!! 32 33 These macros operate a stack of objects. Each object starts life 34 small, and may grow to maturity. (Consider building a word syllable 35 by syllable.) An object can move while it is growing. Once it has 36 been "finished" it never changes address again. So the "top of the 37 stack" is typically an immature growing object, while the rest of the 38 stack is of mature, fixed size and fixed address objects. 39 40 These routines grab large chunks of memory, using a function you 41 supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 42 by calling `obstack_chunk_free'. You must define them and declare 43 them before using any obstack macros. 44 45 Each independent stack is represented by a `struct obstack'. 46 Each of the obstack macros expects a pointer to such a structure 47 as the first argument. 48 49 One motivation for this package is the problem of growing char strings 50 in symbol tables. Unless you are "fascist pig with a read-only mind" 51 --Gosper's immortal quote from HAKMEM item 154, out of context--you 52 would not like to put any arbitrary upper limit on the length of your 53 symbols. 54 55 In practice this often means you will build many short symbols and a 56 few long symbols. At the time you are reading a symbol you don't know 57 how long it is. One traditional method is to read a symbol into a 58 buffer, realloc()ating the buffer every time you try to read a symbol 59 that is longer than the buffer. This is beaut, but you still will 60 want to copy the symbol from the buffer to a more permanent 61 symbol-table entry say about half the time. 62 63 With obstacks, you can work differently. Use one obstack for all symbol 64 names. As you read a symbol, grow the name in the obstack gradually. 65 When the name is complete, finalize it. Then, if the symbol exists already, 66 free the newly read name. 67 68 The way we do this is to take a large chunk, allocating memory from 69 low addresses. When you want to build a symbol in the chunk you just 70 add chars above the current "high water mark" in the chunk. When you 71 have finished adding chars, because you got to the end of the symbol, 72 you know how long the chars are, and you can create a new object. 73 Mostly the chars will not burst over the highest address of the chunk, 74 because you would typically expect a chunk to be (say) 100 times as 75 long as an average object. 76 77 In case that isn't clear, when we have enough chars to make up 78 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 79 so we just point to it where it lies. No moving of chars is 80 needed and this is the second win: potentially long strings need 81 never be explicitly shuffled. Once an object is formed, it does not 82 change its address during its lifetime. 83 84 When the chars burst over a chunk boundary, we allocate a larger 85 chunk, and then copy the partly formed object from the end of the old 86 chunk to the beginning of the new larger chunk. We then carry on 87 accreting characters to the end of the object as we normally would. 88 89 A special macro is provided to add a single char at a time to a 90 growing object. This allows the use of register variables, which 91 break the ordinary 'growth' macro. 92 93 Summary: 94 We allocate large chunks. 95 We carve out one object at a time from the current chunk. 96 Once carved, an object never moves. 97 We are free to append data of any size to the currently 98 growing object. 99 Exactly one object is growing in an obstack at any one time. 100 You can run one obstack per control block. 101 You may have as many control blocks as you dare. 102 Because of the way we do it, you can `unwind' an obstack 103 back to a previous state. (You may remove objects much 104 as you would with a stack.) 105 */ 106 107 108 /* Don't do the contents of this file more than once. */ 109 110 #ifndef _OBSTACK_H 111 #define _OBSTACK_H 1 112 113 #ifdef __cplusplus 114 extern "C" { 115 #endif 116 117 /* We use subtraction of (char *) 0 instead of casting to int 119 because on word-addressable machines a simple cast to int 120 may ignore the byte-within-word field of the pointer. */ 121 122 #ifndef __PTR_TO_INT 123 # define __PTR_TO_INT(P) ((P) - (char *) 0) 124 #endif 125 126 #ifndef __INT_TO_PTR 127 # define __INT_TO_PTR(P) ((P) + (char *) 0) 128 #endif 129 130 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is 131 defined, as with GNU C, use that; that way we don't pollute the 132 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is 133 available, include it and use ptrdiff_t. In traditional C, long is 134 the best that we can do. */ 135 136 #ifdef __PTRDIFF_TYPE__ 137 # define PTR_INT_TYPE __PTRDIFF_TYPE__ 138 #else 139 # ifdef HAVE_STDDEF_H 140 # include <stddef.h> 141 # define PTR_INT_TYPE ptrdiff_t 142 # else 143 # define PTR_INT_TYPE long 144 # endif 145 #endif 146 147 #if defined _LIBC || defined HAVE_STRING_H 148 # include <string.h> 149 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N)) 150 #else 151 # ifdef memcpy 152 # define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N)) 153 # else 154 # define _obstack_memcpy(To, From, N) bcopy ((char *)(From), (To), (N)) 155 # endif 156 #endif 157 158 struct _obstack_chunk /* Lives at front of each chunk. */ 159 { 160 char *limit; /* 1 past end of this chunk */ 161 struct _obstack_chunk *prev; /* address of prior chunk or NULL */ 162 char contents[4]; /* objects begin here */ 163 }; 164 165 struct obstack /* control current object in current chunk */ 166 { 167 long chunk_size; /* preferred size to allocate chunks in */ 168 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */ 169 char *object_base; /* address of object we are building */ 170 char *next_free; /* where to add next char to current object */ 171 char *chunk_limit; /* address of char after current chunk */ 172 PTR_INT_TYPE temp; /* Temporary for some macros. */ 173 int alignment_mask; /* Mask of alignment for each object. */ 174 /* These prototypes vary based on `use_extra_arg', and we use 175 casts to the prototypeless function type in all assignments, 176 but having prototypes here quiets -Wstrict-prototypes. */ 177 struct _obstack_chunk *(*chunkfun) (void *, long); 178 void (*freefun) (void *, struct _obstack_chunk *); 179 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */ 180 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */ 181 unsigned maybe_empty_object:1;/* There is a possibility that the current 182 chunk contains a zero-length object. This 183 prevents freeing the chunk if we allocate 184 a bigger chunk to replace it. */ 185 unsigned alloc_failed:1; /* No longer used, as we now call the failed 186 handler on error, but retained for binary 187 compatibility. */ 188 }; 189 190 /* Declare the external functions we use; they are in obstack.c. */ 191 192 extern void _obstack_newchunk (struct obstack *, int); 193 extern void _obstack_free (struct obstack *, void *); 194 extern int _obstack_begin (struct obstack *, int, int, 195 void *(*) (long), void (*) (void *)); 196 extern int _obstack_begin_1 (struct obstack *, int, int, 197 void *(*) (void *, long), 198 void (*) (void *, void *), void *); 199 extern int _obstack_memory_used (struct obstack *); 200 201 /* Do the function-declarations after the structs 203 but before defining the macros. */ 204 205 void obstack_init (struct obstack *obstack); 206 207 void * obstack_alloc (struct obstack *obstack, int size); 208 209 void * obstack_copy (struct obstack *obstack, void *address, int size); 210 void * obstack_copy0 (struct obstack *obstack, void *address, int size); 211 212 void obstack_free (struct obstack *obstack, void *block); 213 214 void obstack_blank (struct obstack *obstack, int size); 215 216 void obstack_grow (struct obstack *obstack, void *data, int size); 217 void obstack_grow0 (struct obstack *obstack, void *data, int size); 218 219 void obstack_1grow (struct obstack *obstack, int data_char); 220 void obstack_ptr_grow (struct obstack *obstack, void *data); 221 void obstack_int_grow (struct obstack *obstack, int data); 222 223 void * obstack_finish (struct obstack *obstack); 224 225 int obstack_object_size (struct obstack *obstack); 226 227 int obstack_room (struct obstack *obstack); 228 void obstack_make_room (struct obstack *obstack, int size); 229 void obstack_1grow_fast (struct obstack *obstack, int data_char); 230 void obstack_ptr_grow_fast (struct obstack *obstack, void *data); 231 void obstack_int_grow_fast (struct obstack *obstack, int data); 232 void obstack_blank_fast (struct obstack *obstack, int size); 233 234 void * obstack_base (struct obstack *obstack); 235 void * obstack_next_free (struct obstack *obstack); 236 int obstack_alignment_mask (struct obstack *obstack); 237 int obstack_chunk_size (struct obstack *obstack); 238 int obstack_memory_used (struct obstack *obstack); 239 240 /* Error handler called when `obstack_chunk_alloc' failed to allocate 241 more memory. This can be set to a user defined function. The 242 default action is to print a message and abort. */ 243 extern void (*obstack_alloc_failed_handler) (void); 244 245 /* Exit value used when `print_and_abort' is used. */ 246 extern int obstack_exit_failure; 247 248 /* Pointer to beginning of object being allocated or to be allocated next. 250 Note that this might not be the final address of the object 251 because a new chunk might be needed to hold the final size. */ 252 253 #define obstack_base(h) ((h)->object_base) 254 255 /* Size for allocating ordinary chunks. */ 256 257 #define obstack_chunk_size(h) ((h)->chunk_size) 258 259 /* Pointer to next byte not yet allocated in current chunk. */ 260 261 #define obstack_next_free(h) ((h)->next_free) 262 263 /* Mask specifying low bits that should be clear in address of an object. */ 264 265 #define obstack_alignment_mask(h) ((h)->alignment_mask) 266 267 /* To prevent prototype warnings provide complete argument list in 268 standard C version. */ 269 # define obstack_init(h) \ 270 _obstack_begin ((h), 0, 0, \ 271 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 272 273 # define obstack_begin(h, size) \ 274 _obstack_begin ((h), (size), 0, \ 275 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 276 277 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 278 _obstack_begin ((h), (size), (alignment), \ 279 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun)) 280 281 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 282 _obstack_begin_1 ((h), (size), (alignment), \ 283 (void *(*) (void *, long)) (chunkfun), \ 284 (void (*) (void *, void *)) (freefun), (arg)) 285 286 # define obstack_chunkfun(h, newchunkfun) \ 287 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 288 289 # define obstack_freefun(h, newfreefun) \ 290 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 291 292 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 293 294 #define obstack_blank_fast(h,n) ((h)->next_free += (n)) 295 296 #define obstack_memory_used(h) _obstack_memory_used (h) 297 298 #if defined __GNUC__ && defined __STDC__ && __STDC__ 300 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 301 does not implement __extension__. But that compiler doesn't define 302 __GNUC_MINOR__. */ 303 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 304 # define __extension__ 305 # endif 306 307 /* For GNU C, if not -traditional, 308 we can define these macros to compute all args only once 309 without using a global variable. 310 Also, we can avoid using the `temp' slot, to make faster code. */ 311 312 # define obstack_object_size(OBSTACK) \ 313 __extension__ \ 314 ({ struct obstack *__o = (OBSTACK); \ 315 (unsigned) (__o->next_free - __o->object_base); }) 316 317 # define obstack_room(OBSTACK) \ 318 __extension__ \ 319 ({ struct obstack *__o = (OBSTACK); \ 320 (unsigned) (__o->chunk_limit - __o->next_free); }) 321 322 # define obstack_make_room(OBSTACK,length) \ 323 __extension__ \ 324 ({ struct obstack *__o = (OBSTACK); \ 325 int __len = (length); \ 326 if (__o->chunk_limit - __o->next_free < __len) \ 327 _obstack_newchunk (__o, __len); \ 328 (void) 0; }) 329 330 # define obstack_empty_p(OBSTACK) \ 331 __extension__ \ 332 ({ struct obstack *__o = (OBSTACK); \ 333 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); }) 334 335 # define obstack_grow(OBSTACK,where,length) \ 336 __extension__ \ 337 ({ struct obstack *__o = (OBSTACK); \ 338 int __len = (length); \ 339 if (__o->next_free + __len > __o->chunk_limit) \ 340 _obstack_newchunk (__o, __len); \ 341 _obstack_memcpy (__o->next_free, (where), __len); \ 342 __o->next_free += __len; \ 343 (void) 0; }) 344 345 # define obstack_grow0(OBSTACK,where,length) \ 346 __extension__ \ 347 ({ struct obstack *__o = (OBSTACK); \ 348 int __len = (length); \ 349 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 350 _obstack_newchunk (__o, __len + 1); \ 351 _obstack_memcpy (__o->next_free, (where), __len); \ 352 __o->next_free += __len; \ 353 *(__o->next_free)++ = 0; \ 354 (void) 0; }) 355 356 # define obstack_1grow(OBSTACK,datum) \ 357 __extension__ \ 358 ({ struct obstack *__o = (OBSTACK); \ 359 if (__o->next_free + 1 > __o->chunk_limit) \ 360 _obstack_newchunk (__o, 1); \ 361 obstack_1grow_fast (__o, datum); \ 362 (void) 0; }) 363 364 /* These assume that the obstack alignment is good enough for pointers or ints, 365 and that the data added so far to the current object 366 shares that much alignment. */ 367 368 # define obstack_ptr_grow(OBSTACK,datum) \ 369 __extension__ \ 370 ({ struct obstack *__o = (OBSTACK); \ 371 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 372 _obstack_newchunk (__o, sizeof (void *)); \ 373 obstack_ptr_grow_fast (__o, datum); }) 374 375 # define obstack_int_grow(OBSTACK,datum) \ 376 __extension__ \ 377 ({ struct obstack *__o = (OBSTACK); \ 378 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 379 _obstack_newchunk (__o, sizeof (int)); \ 380 obstack_int_grow_fast (__o, datum); }) 381 382 # define obstack_ptr_grow_fast(OBSTACK,aptr) \ 383 __extension__ \ 384 ({ struct obstack *__o1 = (OBSTACK); \ 385 *(const void **) __o1->next_free = (aptr); \ 386 __o1->next_free += sizeof (const void *); \ 387 (void) 0; }) 388 389 # define obstack_int_grow_fast(OBSTACK,aint) \ 390 __extension__ \ 391 ({ struct obstack *__o1 = (OBSTACK); \ 392 *(int *) __o1->next_free = (aint); \ 393 __o1->next_free += sizeof (int); \ 394 (void) 0; }) 395 396 # define obstack_blank(OBSTACK,length) \ 397 __extension__ \ 398 ({ struct obstack *__o = (OBSTACK); \ 399 int __len = (length); \ 400 if (__o->chunk_limit - __o->next_free < __len) \ 401 _obstack_newchunk (__o, __len); \ 402 obstack_blank_fast (__o, __len); \ 403 (void) 0; }) 404 405 # define obstack_alloc(OBSTACK,length) \ 406 __extension__ \ 407 ({ struct obstack *__h = (OBSTACK); \ 408 obstack_blank (__h, (length)); \ 409 obstack_finish (__h); }) 410 411 # define obstack_copy(OBSTACK,where,length) \ 412 __extension__ \ 413 ({ struct obstack *__h = (OBSTACK); \ 414 obstack_grow (__h, (where), (length)); \ 415 obstack_finish (__h); }) 416 417 # define obstack_copy0(OBSTACK,where,length) \ 418 __extension__ \ 419 ({ struct obstack *__h = (OBSTACK); \ 420 obstack_grow0 (__h, (where), (length)); \ 421 obstack_finish (__h); }) 422 423 /* The local variable is named __o1 to avoid a name conflict 424 when obstack_blank is called. */ 425 # define obstack_finish(OBSTACK) \ 426 __extension__ \ 427 ({ struct obstack *__o1 = (OBSTACK); \ 428 void *value; \ 429 value = (void *) __o1->object_base; \ 430 if (__o1->next_free == value) \ 431 __o1->maybe_empty_object = 1; \ 432 __o1->next_free \ 433 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\ 434 & ~ (__o1->alignment_mask)); \ 435 if (__o1->next_free - (char *)__o1->chunk \ 436 > __o1->chunk_limit - (char *)__o1->chunk) \ 437 __o1->next_free = __o1->chunk_limit; \ 438 __o1->object_base = __o1->next_free; \ 439 value; }) 440 441 # define obstack_free(OBSTACK, OBJ) \ 442 __extension__ \ 443 ({ struct obstack *__o = (OBSTACK); \ 444 void *__obj = (void *) (OBJ); \ 445 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 446 __o->next_free = __o->object_base = (char *) __obj; \ 447 else (obstack_free) (__o, __obj); }) 448 449 #else /* not __GNUC__ or not __STDC__ */ 451 452 # define obstack_object_size(h) \ 453 (unsigned) ((h)->next_free - (h)->object_base) 454 455 # define obstack_room(h) \ 456 (unsigned) ((h)->chunk_limit - (h)->next_free) 457 458 # define obstack_empty_p(h) \ 459 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0) 460 461 /* Note that the call to _obstack_newchunk is enclosed in (..., 0) 462 so that we can avoid having void expressions 463 in the arms of the conditional expression. 464 Casting the third operand to void was tried before, 465 but some compilers won't accept it. */ 466 467 # define obstack_make_room(h,length) \ 468 ( (h)->temp = (length), \ 469 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 470 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0)) 471 472 # define obstack_grow(h,where,length) \ 473 ( (h)->temp = (length), \ 474 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 475 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 476 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 477 (h)->next_free += (h)->temp) 478 479 # define obstack_grow0(h,where,length) \ 480 ( (h)->temp = (length), \ 481 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \ 482 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \ 483 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 484 (h)->next_free += (h)->temp, \ 485 *((h)->next_free)++ = 0) 486 487 # define obstack_1grow(h,datum) \ 488 ( (((h)->next_free + 1 > (h)->chunk_limit) \ 489 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 490 obstack_1grow_fast (h, datum)) 491 492 # define obstack_ptr_grow(h,datum) \ 493 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 494 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 495 obstack_ptr_grow_fast (h, datum)) 496 497 # define obstack_int_grow(h,datum) \ 498 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 499 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 500 obstack_int_grow_fast (h, datum)) 501 502 # define obstack_ptr_grow_fast(h,aptr) \ 503 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 504 505 # define obstack_int_grow_fast(h,aint) \ 506 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr)) 507 508 # define obstack_blank(h,length) \ 509 ( (h)->temp = (length), \ 510 (((h)->chunk_limit - (h)->next_free < (h)->temp) \ 511 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 512 obstack_blank_fast (h, (h)->temp)) 513 514 # define obstack_alloc(h,length) \ 515 (obstack_blank ((h), (length)), obstack_finish ((h))) 516 517 # define obstack_copy(h,where,length) \ 518 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 519 520 # define obstack_copy0(h,where,length) \ 521 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 522 523 # define obstack_finish(h) \ 524 ( ((h)->next_free == (h)->object_base \ 525 ? (((h)->maybe_empty_object = 1), 0) \ 526 : 0), \ 527 (h)->temp = __PTR_TO_INT ((h)->object_base), \ 528 (h)->next_free \ 529 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \ 530 & ~ ((h)->alignment_mask)), \ 531 (((h)->next_free - (char *) (h)->chunk \ 532 > (h)->chunk_limit - (char *) (h)->chunk) \ 533 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 534 (h)->object_base = (h)->next_free, \ 535 (void *) __INT_TO_PTR ((h)->temp)) 536 537 # define obstack_free(h,obj) \ 538 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \ 539 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\ 540 ? (((h)->next_free = (h)->object_base \ 541 = (h)->temp + (char *) (h)->chunk), 0) \ 542 : ((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0))) 543 544 #endif /* not __GNUC__ or not __STDC__ */ 545 546 #ifdef __cplusplus 547 } /* C++ */ 548 #endif 549 550 #endif /* obstack.h */ 551
