1 /* obstack.h - object stack macros 2 Copyright (C) 1988-1994,1996-1999,2003,2004,2005,2009,2011 3 Free Software Foundation, Inc. 4 This file is part of the GNU C Library. 5 6 The GNU C Library is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 The GNU C Library is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, write to the Free 18 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 Boston, MA 02110-1301, USA. */ 20 21 /* Summary: 22 23 All the apparent functions defined here are macros. The idea 24 is that you would use these pre-tested macros to solve a 25 very specific set of problems, and they would run fast. 26 Caution: no side-effects in arguments please!! They may be 27 evaluated MANY times!! 28 29 These macros operate a stack of objects. Each object starts life 30 small, and may grow to maturity. (Consider building a word syllable 31 by syllable.) An object can move while it is growing. Once it has 32 been "finished" it never changes address again. So the "top of the 33 stack" is typically an immature growing object, while the rest of the 34 stack is of mature, fixed size and fixed address objects. 35 36 These routines grab large chunks of memory, using a function you 37 supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 38 by calling `obstack_chunk_free'. You must define them and declare 39 them before using any obstack macros. 40 41 Each independent stack is represented by a `struct obstack'. 42 Each of the obstack macros expects a pointer to such a structure 43 as the first argument. 44 45 One motivation for this package is the problem of growing char strings 46 in symbol tables. Unless you are "fascist pig with a read-only mind" 47 --Gosper's immortal quote from HAKMEM item 154, out of context--you 48 would not like to put any arbitrary upper limit on the length of your 49 symbols. 50 51 In practice this often means you will build many short symbols and a 52 few long symbols. At the time you are reading a symbol you don't know 53 how long it is. One traditional method is to read a symbol into a 54 buffer, realloc()ating the buffer every time you try to read a symbol 55 that is longer than the buffer. This is beaut, but you still will 56 want to copy the symbol from the buffer to a more permanent 57 symbol-table entry say about half the time. 58 59 With obstacks, you can work differently. Use one obstack for all symbol 60 names. As you read a symbol, grow the name in the obstack gradually. 61 When the name is complete, finalize it. Then, if the symbol exists already, 62 free the newly read name. 63 64 The way we do this is to take a large chunk, allocating memory from 65 low addresses. When you want to build a symbol in the chunk you just 66 add chars above the current "high water mark" in the chunk. When you 67 have finished adding chars, because you got to the end of the symbol, 68 you know how long the chars are, and you can create a new object. 69 Mostly the chars will not burst over the highest address of the chunk, 70 because you would typically expect a chunk to be (say) 100 times as 71 long as an average object. 72 73 In case that isn't clear, when we have enough chars to make up 74 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 75 so we just point to it where it lies. No moving of chars is 76 needed and this is the second win: potentially long strings need 77 never be explicitly shuffled. Once an object is formed, it does not 78 change its address during its lifetime. 79 80 When the chars burst over a chunk boundary, we allocate a larger 81 chunk, and then copy the partly formed object from the end of the old 82 chunk to the beginning of the new larger chunk. We then carry on 83 accreting characters to the end of the object as we normally would. 84 85 A special macro is provided to add a single char at a time to a 86 growing object. This allows the use of register variables, which 87 break the ordinary 'growth' macro. 88 89 Summary: 90 We allocate large chunks. 91 We carve out one object at a time from the current chunk. 92 Once carved, an object never moves. 93 We are free to append data of any size to the currently 94 growing object. 95 Exactly one object is growing in an obstack at any one time. 96 You can run one obstack per control block. 97 You may have as many control blocks as you dare. 98 Because of the way we do it, you can `unwind' an obstack 99 back to a previous state. (You may remove objects much 100 as you would with a stack.) 101 */ 102 103 104 /* Don't do the contents of this file more than once. */ 105 106 #ifndef _OBSTACK_H 107 #define _OBSTACK_H 1 108 109 #ifdef __cplusplus 110 extern "C" { 111 #endif 112 113 /* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is 115 defined, as with GNU C, use that; that way we don't pollute the 116 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h> 117 and use ptrdiff_t. */ 118 119 #ifdef __PTRDIFF_TYPE__ 120 # define PTR_INT_TYPE __PTRDIFF_TYPE__ 121 #else 122 # include <stddef.h> 123 # define PTR_INT_TYPE ptrdiff_t 124 #endif 125 126 /* If B is the base of an object addressed by P, return the result of 127 aligning P to the next multiple of A + 1. B and P must be of type 128 char *. A + 1 must be a power of 2. */ 129 130 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A))) 131 132 /* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case 133 where pointers can be converted to integers, aligned as integers, 134 and converted back again. If PTR_INT_TYPE is narrower than a 135 pointer (e.g., the AS/400), play it safe and compute the alignment 136 relative to B. Otherwise, use the faster strategy of computing the 137 alignment relative to 0. */ 138 139 #define __PTR_ALIGN(B, P, A) \ 140 __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \ 141 P, A) 142 143 #include <string.h> 144 145 struct _obstack_chunk /* Lives at front of each chunk. */ 146 { 147 char *limit; /* 1 past end of this chunk */ 148 struct _obstack_chunk *prev; /* address of prior chunk or NULL */ 149 char contents[4]; /* objects begin here */ 150 }; 151 152 struct obstack /* control current object in current chunk */ 153 { 154 long chunk_size; /* preferred size to allocate chunks in */ 155 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */ 156 char *object_base; /* address of object we are building */ 157 char *next_free; /* where to add next char to current object */ 158 char *chunk_limit; /* address of char after current chunk */ 159 union 160 { 161 PTR_INT_TYPE tempint; 162 void *tempptr; 163 } temp; /* Temporary for some macros. */ 164 int alignment_mask; /* Mask of alignment for each object. */ 165 /* These prototypes vary based on `use_extra_arg', and we use 166 casts to the prototypeless function type in all assignments, 167 but having prototypes here quiets -Wstrict-prototypes. */ 168 struct _obstack_chunk *(*chunkfun) (void *, long); 169 void (*freefun) (void *, struct _obstack_chunk *); 170 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */ 171 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */ 172 unsigned maybe_empty_object:1;/* There is a possibility that the current 173 chunk contains a zero-length object. This 174 prevents freeing the chunk if we allocate 175 a bigger chunk to replace it. */ 176 unsigned alloc_failed:1; /* No longer used, as we now call the failed 177 handler on error, but retained for binary 178 compatibility. */ 179 }; 180 181 /* Declare the external functions we use; they are in obstack.c. */ 182 183 extern void _obstack_newchunk (struct obstack *, int); 184 extern int _obstack_begin (struct obstack *, int, int, 185 void *(*) (long), void (*) (void *)); 186 extern int _obstack_begin_1 (struct obstack *, int, int, 187 void *(*) (void *, long), 188 void (*) (void *, void *), void *); 189 extern int _obstack_memory_used (struct obstack *); 190 191 void obstack_free (struct obstack *__obstack, void *__block); 192 193 194 /* Error handler called when `obstack_chunk_alloc' failed to allocate 196 more memory. This can be set to a user defined function which 197 should either abort gracefully or use longjump - but shouldn't 198 return. The default action is to print a message and abort. */ 199 extern void (*obstack_alloc_failed_handler) (void); 200 201 /* Exit value used when `print_and_abort' is used. */ 202 extern int obstack_exit_failure; 203 204 /* Pointer to beginning of object being allocated or to be allocated next. 206 Note that this might not be the final address of the object 207 because a new chunk might be needed to hold the final size. */ 208 209 #define obstack_base(h) ((void *) (h)->object_base) 210 211 /* Size for allocating ordinary chunks. */ 212 213 #define obstack_chunk_size(h) ((h)->chunk_size) 214 215 /* Pointer to next byte not yet allocated in current chunk. */ 216 217 #define obstack_next_free(h) ((h)->next_free) 218 219 /* Mask specifying low bits that should be clear in address of an object. */ 220 221 #define obstack_alignment_mask(h) ((h)->alignment_mask) 222 223 /* To prevent prototype warnings provide complete argument list. */ 224 #define obstack_init(h) \ 225 _obstack_begin ((h), 0, 0, \ 226 (void *(*) (long)) obstack_chunk_alloc, \ 227 (void (*) (void *)) obstack_chunk_free) 228 229 #define obstack_begin(h, size) \ 230 _obstack_begin ((h), (size), 0, \ 231 (void *(*) (long)) obstack_chunk_alloc, \ 232 (void (*) (void *)) obstack_chunk_free) 233 234 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 235 _obstack_begin ((h), (size), (alignment), \ 236 (void *(*) (long)) (chunkfun), \ 237 (void (*) (void *)) (freefun)) 238 239 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 240 _obstack_begin_1 ((h), (size), (alignment), \ 241 (void *(*) (void *, long)) (chunkfun), \ 242 (void (*) (void *, void *)) (freefun), (arg)) 243 244 #define obstack_chunkfun(h, newchunkfun) \ 245 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 246 247 #define obstack_freefun(h, newfreefun) \ 248 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 249 250 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 251 252 #define obstack_blank_fast(h,n) ((h)->next_free += (n)) 253 254 #define obstack_memory_used(h) _obstack_memory_used (h) 255 256 #if defined __GNUC__ && defined __STDC__ && __STDC__ 258 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 259 does not implement __extension__. But that compiler doesn't define 260 __GNUC_MINOR__. */ 261 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 262 # define __extension__ 263 # endif 264 265 /* For GNU C, if not -traditional, 266 we can define these macros to compute all args only once 267 without using a global variable. 268 Also, we can avoid using the `temp' slot, to make faster code. */ 269 270 # define obstack_object_size(OBSTACK) \ 271 __extension__ \ 272 ({ struct obstack const *__o = (OBSTACK); \ 273 (unsigned) (__o->next_free - __o->object_base); }) 274 275 # define obstack_room(OBSTACK) \ 276 __extension__ \ 277 ({ struct obstack const *__o = (OBSTACK); \ 278 (unsigned) (__o->chunk_limit - __o->next_free); }) 279 280 # define obstack_make_room(OBSTACK,length) \ 281 __extension__ \ 282 ({ struct obstack *__o = (OBSTACK); \ 283 int __len = (length); \ 284 if (__o->chunk_limit - __o->next_free < __len) \ 285 _obstack_newchunk (__o, __len); \ 286 (void) 0; }) 287 288 # define obstack_empty_p(OBSTACK) \ 289 __extension__ \ 290 ({ struct obstack const *__o = (OBSTACK); \ 291 (__o->chunk->prev == 0 \ 292 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 293 __o->chunk->contents, \ 294 __o->alignment_mask)); }) 295 296 # define obstack_grow(OBSTACK,where,length) \ 297 __extension__ \ 298 ({ struct obstack *__o = (OBSTACK); \ 299 int __len = (length); \ 300 if (__o->next_free + __len > __o->chunk_limit) \ 301 _obstack_newchunk (__o, __len); \ 302 memcpy (__o->next_free, where, __len); \ 303 __o->next_free += __len; \ 304 (void) 0; }) 305 306 # define obstack_grow0(OBSTACK,where,length) \ 307 __extension__ \ 308 ({ struct obstack *__o = (OBSTACK); \ 309 int __len = (length); \ 310 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 311 _obstack_newchunk (__o, __len + 1); \ 312 memcpy (__o->next_free, where, __len); \ 313 __o->next_free += __len; \ 314 *(__o->next_free)++ = 0; \ 315 (void) 0; }) 316 317 # define obstack_1grow(OBSTACK,datum) \ 318 __extension__ \ 319 ({ struct obstack *__o = (OBSTACK); \ 320 if (__o->next_free + 1 > __o->chunk_limit) \ 321 _obstack_newchunk (__o, 1); \ 322 obstack_1grow_fast (__o, datum); \ 323 (void) 0; }) 324 325 /* These assume that the obstack alignment is good enough for pointers 326 or ints, and that the data added so far to the current object 327 shares that much alignment. */ 328 329 # define obstack_ptr_grow(OBSTACK,datum) \ 330 __extension__ \ 331 ({ struct obstack *__o = (OBSTACK); \ 332 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 333 _obstack_newchunk (__o, sizeof (void *)); \ 334 obstack_ptr_grow_fast (__o, datum); }) \ 335 336 # define obstack_int_grow(OBSTACK,datum) \ 337 __extension__ \ 338 ({ struct obstack *__o = (OBSTACK); \ 339 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 340 _obstack_newchunk (__o, sizeof (int)); \ 341 obstack_int_grow_fast (__o, datum); }) 342 343 # define obstack_ptr_grow_fast(OBSTACK,aptr) \ 344 __extension__ \ 345 ({ struct obstack *__o1 = (OBSTACK); \ 346 *(const void **) __o1->next_free = (aptr); \ 347 __o1->next_free += sizeof (const void *); \ 348 (void) 0; }) 349 350 # define obstack_int_grow_fast(OBSTACK,aint) \ 351 __extension__ \ 352 ({ struct obstack *__o1 = (OBSTACK); \ 353 *(int *) __o1->next_free = (aint); \ 354 __o1->next_free += sizeof (int); \ 355 (void) 0; }) 356 357 # define obstack_blank(OBSTACK,length) \ 358 __extension__ \ 359 ({ struct obstack *__o = (OBSTACK); \ 360 int __len = (length); \ 361 if (__o->chunk_limit - __o->next_free < __len) \ 362 _obstack_newchunk (__o, __len); \ 363 obstack_blank_fast (__o, __len); \ 364 (void) 0; }) 365 366 # define obstack_alloc(OBSTACK,length) \ 367 __extension__ \ 368 ({ struct obstack *__h = (OBSTACK); \ 369 obstack_blank (__h, (length)); \ 370 obstack_finish (__h); }) 371 372 # define obstack_copy(OBSTACK,where,length) \ 373 __extension__ \ 374 ({ struct obstack *__h = (OBSTACK); \ 375 obstack_grow (__h, (where), (length)); \ 376 obstack_finish (__h); }) 377 378 # define obstack_copy0(OBSTACK,where,length) \ 379 __extension__ \ 380 ({ struct obstack *__h = (OBSTACK); \ 381 obstack_grow0 (__h, (where), (length)); \ 382 obstack_finish (__h); }) 383 384 /* The local variable is named __o1 to avoid a name conflict 385 when obstack_blank is called. */ 386 # define obstack_finish(OBSTACK) \ 387 __extension__ \ 388 ({ struct obstack *__o1 = (OBSTACK); \ 389 void *__value = (void *) __o1->object_base; \ 390 if (__o1->next_free == __value) \ 391 __o1->maybe_empty_object = 1; \ 392 __o1->next_free \ 393 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 394 __o1->alignment_mask); \ 395 if (__o1->next_free - (char *)__o1->chunk \ 396 > __o1->chunk_limit - (char *)__o1->chunk) \ 397 __o1->next_free = __o1->chunk_limit; \ 398 __o1->object_base = __o1->next_free; \ 399 __value; }) 400 401 # define obstack_free(OBSTACK, OBJ) \ 402 __extension__ \ 403 ({ struct obstack *__o = (OBSTACK); \ 404 void *__obj = (OBJ); \ 405 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 406 __o->next_free = __o->object_base = (char *)__obj; \ 407 else (obstack_free) (__o, __obj); }) 408 409 #else /* not __GNUC__ or not __STDC__ */ 411 412 # define obstack_object_size(h) \ 413 (unsigned) ((h)->next_free - (h)->object_base) 414 415 # define obstack_room(h) \ 416 (unsigned) ((h)->chunk_limit - (h)->next_free) 417 418 # define obstack_empty_p(h) \ 419 ((h)->chunk->prev == 0 \ 420 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 421 (h)->chunk->contents, \ 422 (h)->alignment_mask)) 423 424 /* Note that the call to _obstack_newchunk is enclosed in (..., 0) 425 so that we can avoid having void expressions 426 in the arms of the conditional expression. 427 Casting the third operand to void was tried before, 428 but some compilers won't accept it. */ 429 430 # define obstack_make_room(h,length) \ 431 ( (h)->temp.tempint = (length), \ 432 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 433 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 434 435 # define obstack_grow(h,where,length) \ 436 ( (h)->temp.tempint = (length), \ 437 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 438 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 439 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 440 (h)->next_free += (h)->temp.tempint) 441 442 # define obstack_grow0(h,where,length) \ 443 ( (h)->temp.tempint = (length), \ 444 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 445 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 446 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 447 (h)->next_free += (h)->temp.tempint, \ 448 *((h)->next_free)++ = 0) 449 450 # define obstack_1grow(h,datum) \ 451 ( (((h)->next_free + 1 > (h)->chunk_limit) \ 452 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 453 obstack_1grow_fast (h, datum)) 454 455 # define obstack_ptr_grow(h,datum) \ 456 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 457 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 458 obstack_ptr_grow_fast (h, datum)) 459 460 # define obstack_int_grow(h,datum) \ 461 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 462 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 463 obstack_int_grow_fast (h, datum)) 464 465 # define obstack_ptr_grow_fast(h,aptr) \ 466 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 467 468 # define obstack_int_grow_fast(h,aint) \ 469 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 470 471 # define obstack_blank(h,length) \ 472 ( (h)->temp.tempint = (length), \ 473 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 474 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 475 obstack_blank_fast (h, (h)->temp.tempint)) 476 477 # define obstack_alloc(h,length) \ 478 (obstack_blank ((h), (length)), obstack_finish ((h))) 479 480 # define obstack_copy(h,where,length) \ 481 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 482 483 # define obstack_copy0(h,where,length) \ 484 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 485 486 # define obstack_finish(h) \ 487 ( ((h)->next_free == (h)->object_base \ 488 ? (((h)->maybe_empty_object = 1), 0) \ 489 : 0), \ 490 (h)->temp.tempptr = (h)->object_base, \ 491 (h)->next_free \ 492 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 493 (h)->alignment_mask), \ 494 (((h)->next_free - (char *) (h)->chunk \ 495 > (h)->chunk_limit - (char *) (h)->chunk) \ 496 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 497 (h)->object_base = (h)->next_free, \ 498 (h)->temp.tempptr) 499 500 # define obstack_free(h,obj) \ 501 ( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 502 ((((h)->temp.tempint > 0 \ 503 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 504 ? (((h)->next_free = (h)->object_base \ 505 = (h)->temp.tempint + (char *) (h)->chunk), 0) \ 506 : ((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0))) 507 508 #endif /* not __GNUC__ or not __STDC__ */ 509 510 #ifdef __cplusplus 511 } /* C++ */ 512 #endif 513 514 #endif /* obstack.h */ 515
