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@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 118 because on word-addressable machines a simple cast to int 119 may ignore the byte-within-word field of the pointer. */ 120 121 #ifndef __PTR_TO_INT 122 # define __PTR_TO_INT(P) ((P) - (char *) 0) 123 #endif 124 125 #ifndef __INT_TO_PTR 126 # define __INT_TO_PTR(P) ((P) + (char *) 0) 127 #endif 128 129 /* We need the type of the resulting object. If __PTRDIFF_TYPE__ is 130 defined, as with GNU C, use that; that way we don't pollute the 131 namespace with <stddef.h>'s symbols. Otherwise, if <stddef.h> is 132 available, include it and use ptrdiff_t. In traditional C, long is 133 the best that we can do. */ 134 135 #ifdef __PTRDIFF_TYPE__ 136 # define PTR_INT_TYPE __PTRDIFF_TYPE__ 137 #else 138 # ifdef HAVE_STDDEF_H 139 # include <stddef.h> 140 # define PTR_INT_TYPE ptrdiff_t 141 # else 142 # define PTR_INT_TYPE long 143 # endif 144 #endif 145 146 #if defined _LIBC || defined HAVE_STRING_H 147 # include <string.h> 148 # define _obstack_memcpy(To, From, N) memcpy ((To), (From), (N)) 149 #else 150 # ifdef memcpy 151 # define _obstack_memcpy(To, From, N) memcpy ((To), (char *)(From), (N)) 152 # else 153 # define _obstack_memcpy(To, From, N) bcopy ((char *)(From), (To), (N)) 154 # endif 155 #endif 156 157 struct _obstack_chunk /* Lives at front of each chunk. */ 158 { 159 char *limit; /* 1 past end of this chunk */ 160 struct _obstack_chunk *prev; /* address of prior chunk or NULL */ 161 char contents[4]; /* objects begin here */ 162 }; 163 164 struct obstack /* control current object in current chunk */ 165 { 166 long chunk_size; /* preferred size to allocate chunks in */ 167 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */ 168 char *object_base; /* address of object we are building */ 169 char *next_free; /* where to add next char to current object */ 170 char *chunk_limit; /* address of char after current chunk */ 171 PTR_INT_TYPE temp; /* Temporary for some macros. */ 172 int alignment_mask; /* Mask of alignment for each object. */ 173 /* These prototypes vary based on `use_extra_arg', and we use 174 casts to the prototypeless function type in all assignments, 175 but having prototypes here quiets -Wstrict-prototypes. */ 176 struct _obstack_chunk *(*chunkfun) (void *, long); 177 void (*freefun) (void *, struct _obstack_chunk *); 178 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */ 179 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */ 180 unsigned maybe_empty_object:1;/* There is a possibility that the current 181 chunk contains a zero-length object. This 182 prevents freeing the chunk if we allocate 183 a bigger chunk to replace it. */ 184 unsigned alloc_failed:1; /* No longer used, as we now call the failed 185 handler on error, but retained for binary 186 compatibility. */ 187 }; 188 189 /* Declare the external functions we use; they are in obstack.c. */ 190 191 extern void _obstack_newchunk (struct obstack *, int); 192 extern void _obstack_free (struct obstack *, void *); 193 extern int _obstack_begin (struct obstack *, int, int, 194 void *(*) (long), void (*) (void *)); 195 extern int _obstack_begin_1 (struct obstack *, int, int, 196 void *(*) (void *, long), 197 void (*) (void *, void *), void *); 198 extern int _obstack_memory_used (struct obstack *); 199 200 /* Do the function-declarations after the structs 201 but before defining the macros. */ 202 203 void obstack_init (struct obstack *obstack); 204 205 void * obstack_alloc (struct obstack *obstack, int size); 206 207 void * obstack_copy (struct obstack *obstack, void *address, int size); 208 void * obstack_copy0 (struct obstack *obstack, void *address, int size); 209 210 void obstack_free (struct obstack *obstack, void *block); 211 212 void obstack_blank (struct obstack *obstack, int size); 213 214 void obstack_grow (struct obstack *obstack, void *data, int size); 215 void obstack_grow0 (struct obstack *obstack, void *data, int size); 216 217 void obstack_1grow (struct obstack *obstack, int data_char); 218 void obstack_ptr_grow (struct obstack *obstack, void *data); 219 void obstack_int_grow (struct obstack *obstack, int data); 220 221 void * obstack_finish (struct obstack *obstack); 222 223 int obstack_object_size (struct obstack *obstack); 224 225 int obstack_room (struct obstack *obstack); 226 void obstack_make_room (struct obstack *obstack, int size); 227 void obstack_1grow_fast (struct obstack *obstack, int data_char); 228 void obstack_ptr_grow_fast (struct obstack *obstack, void *data); 229 void obstack_int_grow_fast (struct obstack *obstack, int data); 230 void obstack_blank_fast (struct obstack *obstack, int size); 231 232 void * obstack_base (struct obstack *obstack); 233 void * obstack_next_free (struct obstack *obstack); 234 int obstack_alignment_mask (struct obstack *obstack); 235 int obstack_chunk_size (struct obstack *obstack); 236 int obstack_memory_used (struct obstack *obstack); 237 238 int obstack_printf(struct obstack *obstack, const char *__restrict fmt, ...); 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. 249 Note that this might not be the final address of the object 250 because a new chunk might be needed to hold the final size. */ 251 252 #define obstack_base(h) ((h)->object_base) 253 254 /* Size for allocating ordinary chunks. */ 255 256 #define obstack_chunk_size(h) ((h)->chunk_size) 257 258 /* Pointer to next byte not yet allocated in current chunk. */ 259 260 #define obstack_next_free(h) ((h)->next_free) 261 262 /* Mask specifying low bits that should be clear in address of an object. */ 263 264 #define obstack_alignment_mask(h) ((h)->alignment_mask) 265 266 /* To prevent prototype warnings provide complete argument list in 267 standard C version. */ 268 # define obstack_init(h) \ 269 _obstack_begin ((h), 0, 0, \ 270 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 271 272 # define obstack_begin(h, size) \ 273 _obstack_begin ((h), (size), 0, \ 274 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 275 276 # define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 277 _obstack_begin ((h), (size), (alignment), \ 278 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun)) 279 280 # define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 281 _obstack_begin_1 ((h), (size), (alignment), \ 282 (void *(*) (void *, long)) (chunkfun), \ 283 (void (*) (void *, void *)) (freefun), (arg)) 284 285 # define obstack_chunkfun(h, newchunkfun) \ 286 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 287 288 # define obstack_freefun(h, newfreefun) \ 289 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 290 291 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 292 293 #define obstack_blank_fast(h,n) ((h)->next_free += (n)) 294 295 #define obstack_memory_used(h) _obstack_memory_used (h) 296 297 #if defined __GNUC__ && defined __STDC__ && __STDC__ 298 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 299 does not implement __extension__. But that compiler doesn't define 300 __GNUC_MINOR__. */ 301 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 302 # define __extension__ 303 # endif 304 305 /* For GNU C, if not -traditional, 306 we can define these macros to compute all args only once 307 without using a global variable. 308 Also, we can avoid using the `temp' slot, to make faster code. */ 309 310 # define obstack_object_size(OBSTACK) \ 311 __extension__ \ 312 ({ struct obstack *__o = (OBSTACK); \ 313 (unsigned) (__o->next_free - __o->object_base); }) 314 315 # define obstack_room(OBSTACK) \ 316 __extension__ \ 317 ({ struct obstack *__o = (OBSTACK); \ 318 (unsigned) (__o->chunk_limit - __o->next_free); }) 319 320 # define obstack_make_room(OBSTACK,length) \ 321 __extension__ \ 322 ({ struct obstack *__o = (OBSTACK); \ 323 int __len = (length); \ 324 if (__o->chunk_limit - __o->next_free < __len) \ 325 _obstack_newchunk (__o, __len); \ 326 (void) 0; }) 327 328 # define obstack_empty_p(OBSTACK) \ 329 __extension__ \ 330 ({ struct obstack *__o = (OBSTACK); \ 331 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); }) 332 333 # define obstack_grow(OBSTACK,where,length) \ 334 __extension__ \ 335 ({ struct obstack *__o = (OBSTACK); \ 336 int __len = (length); \ 337 if (__o->next_free + __len > __o->chunk_limit) \ 338 _obstack_newchunk (__o, __len); \ 339 _obstack_memcpy (__o->next_free, (where), __len); \ 340 __o->next_free += __len; \ 341 (void) 0; }) 342 343 # define obstack_grow0(OBSTACK,where,length) \ 344 __extension__ \ 345 ({ struct obstack *__o = (OBSTACK); \ 346 int __len = (length); \ 347 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 348 _obstack_newchunk (__o, __len + 1); \ 349 _obstack_memcpy (__o->next_free, (where), __len); \ 350 __o->next_free += __len; \ 351 *(__o->next_free)++ = 0; \ 352 (void) 0; }) 353 354 # define obstack_1grow(OBSTACK,datum) \ 355 __extension__ \ 356 ({ struct obstack *__o = (OBSTACK); \ 357 if (__o->next_free + 1 > __o->chunk_limit) \ 358 _obstack_newchunk (__o, 1); \ 359 obstack_1grow_fast (__o, datum); \ 360 (void) 0; }) 361 362 /* These assume that the obstack alignment is good enough for pointers or ints, 363 and that the data added so far to the current object 364 shares that much alignment. */ 365 366 # define obstack_ptr_grow(OBSTACK,datum) \ 367 __extension__ \ 368 ({ struct obstack *__o = (OBSTACK); \ 369 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 370 _obstack_newchunk (__o, sizeof (void *)); \ 371 obstack_ptr_grow_fast (__o, datum); }) 372 373 # define obstack_int_grow(OBSTACK,datum) \ 374 __extension__ \ 375 ({ struct obstack *__o = (OBSTACK); \ 376 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 377 _obstack_newchunk (__o, sizeof (int)); \ 378 obstack_int_grow_fast (__o, datum); }) 379 380 # define obstack_ptr_grow_fast(OBSTACK,aptr) \ 381 __extension__ \ 382 ({ struct obstack *__o1 = (OBSTACK); \ 383 *(const void **) __o1->next_free = (aptr); \ 384 __o1->next_free += sizeof (const void *); \ 385 (void) 0; }) 386 387 # define obstack_int_grow_fast(OBSTACK,aint) \ 388 __extension__ \ 389 ({ struct obstack *__o1 = (OBSTACK); \ 390 *(int *) __o1->next_free = (aint); \ 391 __o1->next_free += sizeof (int); \ 392 (void) 0; }) 393 394 # define obstack_blank(OBSTACK,length) \ 395 __extension__ \ 396 ({ struct obstack *__o = (OBSTACK); \ 397 int __len = (length); \ 398 if (__o->chunk_limit - __o->next_free < __len) \ 399 _obstack_newchunk (__o, __len); \ 400 obstack_blank_fast (__o, __len); \ 401 (void) 0; }) 402 403 # define obstack_alloc(OBSTACK,length) \ 404 __extension__ \ 405 ({ struct obstack *__h = (OBSTACK); \ 406 obstack_blank (__h, (length)); \ 407 obstack_finish (__h); }) 408 409 # define obstack_copy(OBSTACK,where,length) \ 410 __extension__ \ 411 ({ struct obstack *__h = (OBSTACK); \ 412 obstack_grow (__h, (where), (length)); \ 413 obstack_finish (__h); }) 414 415 # define obstack_copy0(OBSTACK,where,length) \ 416 __extension__ \ 417 ({ struct obstack *__h = (OBSTACK); \ 418 obstack_grow0 (__h, (where), (length)); \ 419 obstack_finish (__h); }) 420 421 /* The local variable is named __o1 to avoid a name conflict 422 when obstack_blank is called. */ 423 # define obstack_finish(OBSTACK) \ 424 __extension__ \ 425 ({ struct obstack *__o1 = (OBSTACK); \ 426 void *value; \ 427 value = (void *) __o1->object_base; \ 428 if (__o1->next_free == value) \ 429 __o1->maybe_empty_object = 1; \ 430 __o1->next_free \ 431 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\ 432 & ~ (__o1->alignment_mask)); \ 433 if (__o1->next_free - (char *)__o1->chunk \ 434 > __o1->chunk_limit - (char *)__o1->chunk) \ 435 __o1->next_free = __o1->chunk_limit; \ 436 __o1->object_base = __o1->next_free; \ 437 value; }) 438 439 # define obstack_free(OBSTACK, OBJ) \ 440 __extension__ \ 441 ({ struct obstack *__o = (OBSTACK); \ 442 void *__obj = (void *) (OBJ); \ 443 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 444 __o->next_free = __o->object_base = (char *) __obj; \ 445 else (obstack_free) (__o, __obj); }) 446 447 #else /* not __GNUC__ or not __STDC__ */ 448 449 # define obstack_object_size(h) \ 450 (unsigned) ((h)->next_free - (h)->object_base) 451 452 # define obstack_room(h) \ 453 (unsigned) ((h)->chunk_limit - (h)->next_free) 454 455 # define obstack_empty_p(h) \ 456 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0) 457 458 /* Note that the call to _obstack_newchunk is enclosed in (..., 0) 459 so that we can avoid having void expressions 460 in the arms of the conditional expression. 461 Casting the third operand to void was tried before, 462 but some compilers won't accept it. */ 463 464 # define obstack_make_room(h,length) \ 465 ( (h)->temp = (length), \ 466 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 467 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0)) 468 469 # define obstack_grow(h,where,length) \ 470 ( (h)->temp = (length), \ 471 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 472 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 473 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 474 (h)->next_free += (h)->temp) 475 476 # define obstack_grow0(h,where,length) \ 477 ( (h)->temp = (length), \ 478 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \ 479 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \ 480 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 481 (h)->next_free += (h)->temp, \ 482 *((h)->next_free)++ = 0) 483 484 # define obstack_1grow(h,datum) \ 485 ( (((h)->next_free + 1 > (h)->chunk_limit) \ 486 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 487 obstack_1grow_fast (h, datum)) 488 489 # define obstack_ptr_grow(h,datum) \ 490 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 491 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 492 obstack_ptr_grow_fast (h, datum)) 493 494 # define obstack_int_grow(h,datum) \ 495 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 496 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 497 obstack_int_grow_fast (h, datum)) 498 499 # define obstack_ptr_grow_fast(h,aptr) \ 500 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 501 502 # define obstack_int_grow_fast(h,aint) \ 503 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr)) 504 505 # define obstack_blank(h,length) \ 506 ( (h)->temp = (length), \ 507 (((h)->chunk_limit - (h)->next_free < (h)->temp) \ 508 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 509 obstack_blank_fast (h, (h)->temp)) 510 511 # define obstack_alloc(h,length) \ 512 (obstack_blank ((h), (length)), obstack_finish ((h))) 513 514 # define obstack_copy(h,where,length) \ 515 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 516 517 # define obstack_copy0(h,where,length) \ 518 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 519 520 # define obstack_finish(h) \ 521 ( ((h)->next_free == (h)->object_base \ 522 ? (((h)->maybe_empty_object = 1), 0) \ 523 : 0), \ 524 (h)->temp = __PTR_TO_INT ((h)->object_base), \ 525 (h)->next_free \ 526 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \ 527 & ~ ((h)->alignment_mask)), \ 528 (((h)->next_free - (char *) (h)->chunk \ 529 > (h)->chunk_limit - (char *) (h)->chunk) \ 530 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 531 (h)->object_base = (h)->next_free, \ 532 (void *) __INT_TO_PTR ((h)->temp)) 533 534 # define obstack_free(h,obj) \ 535 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \ 536 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\ 537 ? (((h)->next_free = (h)->object_base \ 538 = (h)->temp + (char *) (h)->chunk), 0) \ 539 : ((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0))) 540 541 #endif /* not __GNUC__ or not __STDC__ */ 542 543 #ifdef __cplusplus 544 } /* C++ */ 545 #endif 546 547 #endif /* obstack.h */ 548