1 /* obstack.h - object stack macros 2 Copyright (C) 1988-1994,1996-1999,2003,2004,2005 3 Free Software Foundation, Inc. 4 This file is part of the GNU C Library. 5 6 This program is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 This program 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 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License along 17 with this program; if not, write to the Free Software Foundation, 18 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ 19 20 /* Summary: 21 22 All the apparent functions defined here are macros. The idea 23 is that you would use these pre-tested macros to solve a 24 very specific set of problems, and they would run fast. 25 Caution: no side-effects in arguments please!! They may be 26 evaluated MANY times!! 27 28 These macros operate a stack of objects. Each object starts life 29 small, and may grow to maturity. (Consider building a word syllable 30 by syllable.) An object can move while it is growing. Once it has 31 been "finished" it never changes address again. So the "top of the 32 stack" is typically an immature growing object, while the rest of the 33 stack is of mature, fixed size and fixed address objects. 34 35 These routines grab large chunks of memory, using a function you 36 supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 37 by calling `obstack_chunk_free'. You must define them and declare 38 them before using any obstack macros. 39 40 Each independent stack is represented by a `struct obstack'. 41 Each of the obstack macros expects a pointer to such a structure 42 as the first argument. 43 44 One motivation for this package is the problem of growing char strings 45 in symbol tables. Unless you are "fascist pig with a read-only mind" 46 --Gosper's immortal quote from HAKMEM item 154, out of context--you 47 would not like to put any arbitrary upper limit on the length of your 48 symbols. 49 50 In practice this often means you will build many short symbols and a 51 few long symbols. At the time you are reading a symbol you don't know 52 how long it is. One traditional method is to read a symbol into a 53 buffer, realloc()ating the buffer every time you try to read a symbol 54 that is longer than the buffer. This is beaut, but you still will 55 want to copy the symbol from the buffer to a more permanent 56 symbol-table entry say about half the time. 57 58 With obstacks, you can work differently. Use one obstack for all symbol 59 names. As you read a symbol, grow the name in the obstack gradually. 60 When the name is complete, finalize it. Then, if the symbol exists already, 61 free the newly read name. 62 63 The way we do this is to take a large chunk, allocating memory from 64 low addresses. When you want to build a symbol in the chunk you just 65 add chars above the current "high water mark" in the chunk. When you 66 have finished adding chars, because you got to the end of the symbol, 67 you know how long the chars are, and you can create a new object. 68 Mostly the chars will not burst over the highest address of the chunk, 69 because you would typically expect a chunk to be (say) 100 times as 70 long as an average object. 71 72 In case that isn't clear, when we have enough chars to make up 73 the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 74 so we just point to it where it lies. No moving of chars is 75 needed and this is the second win: potentially long strings need 76 never be explicitly shuffled. Once an object is formed, it does not 77 change its address during its lifetime. 78 79 When the chars burst over a chunk boundary, we allocate a larger 80 chunk, and then copy the partly formed object from the end of the old 81 chunk to the beginning of the new larger chunk. We then carry on 82 accreting characters to the end of the object as we normally would. 83 84 A special macro is provided to add a single char at a time to a 85 growing object. This allows the use of register variables, which 86 break the ordinary 'growth' macro. 87 88 Summary: 89 We allocate large chunks. 90 We carve out one object at a time from the current chunk. 91 Once carved, an object never moves. 92 We are free to append data of any size to the currently 93 growing object. 94 Exactly one object is growing in an obstack at any one time. 95 You can run one obstack per control block. 96 You may have as many control blocks as you dare. 97 Because of the way we do it, you can `unwind' an obstack 98 back to a previous state. (You may remove objects much 99 as you would with a stack.) 100 */ 101 102 103 /* Don't do the contents of this file more than once. */ 104 105 #ifndef _OBSTACK_H 106 #define _OBSTACK_H 1 107 108 #ifdef __cplusplus 109 extern "C" { 110 #endif 111 112 /* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is 114 defined, as with GNU C, use that; that way we don't pollute the 115 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h> 116 and use ptrdiff_t. */ 117 118 #ifdef __PTRDIFF_TYPE__ 119 # define PTR_INT_TYPE __PTRDIFF_TYPE__ 120 #else 121 # include <stddef.h> 122 # define PTR_INT_TYPE ptrdiff_t 123 #endif 124 125 /* If B is the base of an object addressed by P, return the result of 126 aligning P to the next multiple of A + 1. B and P must be of type 127 char *. A + 1 must be a power of 2. */ 128 129 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A))) 130 131 /* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case 132 where pointers can be converted to integers, aligned as integers, 133 and converted back again. If PTR_INT_TYPE is narrower than a 134 pointer (e.g., the AS/400), play it safe and compute the alignment 135 relative to B. Otherwise, use the faster strategy of computing the 136 alignment relative to 0. */ 137 138 #define __PTR_ALIGN(B, P, A) \ 139 __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \ 140 P, A) 141 142 #include <string.h> 143 144 struct _obstack_chunk /* Lives at front of each chunk. */ 145 { 146 char *limit; /* 1 past end of this chunk */ 147 struct _obstack_chunk *prev; /* address of prior chunk or NULL */ 148 char contents[4]; /* objects begin here */ 149 }; 150 151 struct obstack /* control current object in current chunk */ 152 { 153 long chunk_size; /* preferred size to allocate chunks in */ 154 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */ 155 char *object_base; /* address of object we are building */ 156 char *next_free; /* where to add next char to current object */ 157 char *chunk_limit; /* address of char after current chunk */ 158 union 159 { 160 PTR_INT_TYPE tempint; 161 void *tempptr; 162 } temp; /* Temporary for some macros. */ 163 int alignment_mask; /* Mask of alignment for each object. */ 164 /* These prototypes vary based on `use_extra_arg', and we use 165 casts to the prototypeless function type in all assignments, 166 but having prototypes here quiets -Wstrict-prototypes. */ 167 struct _obstack_chunk *(*chunkfun) (void *, long); 168 void (*freefun) (void *, struct _obstack_chunk *); 169 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */ 170 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */ 171 unsigned maybe_empty_object:1;/* There is a possibility that the current 172 chunk contains a zero-length object. This 173 prevents freeing the chunk if we allocate 174 a bigger chunk to replace it. */ 175 unsigned alloc_failed:1; /* No longer used, as we now call the failed 176 handler on error, but retained for binary 177 compatibility. */ 178 }; 179 180 /* Declare the external functions we use; they are in obstack.c. */ 181 182 extern void _obstack_newchunk (struct obstack *, int); 183 extern int _obstack_begin (struct obstack *, int, int, 184 void *(*) (long), void (*) (void *)); 185 extern int _obstack_begin_1 (struct obstack *, int, int, 186 void *(*) (void *, long), 187 void (*) (void *, void *), void *); 188 extern int _obstack_memory_used (struct obstack *); 189 190 void obstack_free (struct obstack *obstack, void *block); 191 192 193 /* Error handler called when `obstack_chunk_alloc' failed to allocate 195 more memory. This can be set to a user defined function which 196 should either abort gracefully or use longjump - but shouldn't 197 return. The default action is to print a message and abort. */ 198 extern void (*obstack_alloc_failed_handler) (void); 199 200 /* Exit value used when `print_and_abort' is used. */ 201 extern int obstack_exit_failure; 202 203 /* Pointer to beginning of object being allocated or to be allocated next. 205 Note that this might not be the final address of the object 206 because a new chunk might be needed to hold the final size. */ 207 208 #define obstack_base(h) ((void *) (h)->object_base) 209 210 /* Size for allocating ordinary chunks. */ 211 212 #define obstack_chunk_size(h) ((h)->chunk_size) 213 214 /* Pointer to next byte not yet allocated in current chunk. */ 215 216 #define obstack_next_free(h) ((h)->next_free) 217 218 /* Mask specifying low bits that should be clear in address of an object. */ 219 220 #define obstack_alignment_mask(h) ((h)->alignment_mask) 221 222 /* To prevent prototype warnings provide complete argument list. */ 223 #define obstack_init(h) \ 224 _obstack_begin ((h), 0, 0, \ 225 (void *(*) (long)) obstack_chunk_alloc, \ 226 (void (*) (void *)) obstack_chunk_free) 227 228 #define obstack_begin(h, size) \ 229 _obstack_begin ((h), (size), 0, \ 230 (void *(*) (long)) obstack_chunk_alloc, \ 231 (void (*) (void *)) obstack_chunk_free) 232 233 #define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 234 _obstack_begin ((h), (size), (alignment), \ 235 (void *(*) (long)) (chunkfun), \ 236 (void (*) (void *)) (freefun)) 237 238 #define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 239 _obstack_begin_1 ((h), (size), (alignment), \ 240 (void *(*) (void *, long)) (chunkfun), \ 241 (void (*) (void *, void *)) (freefun), (arg)) 242 243 #define obstack_chunkfun(h, newchunkfun) \ 244 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 245 246 #define obstack_freefun(h, newfreefun) \ 247 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 248 249 #define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 250 251 #define obstack_blank_fast(h,n) ((h)->next_free += (n)) 252 253 #define obstack_memory_used(h) _obstack_memory_used (h) 254 255 #if defined __GNUC__ && defined __STDC__ && __STDC__ 257 /* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 258 does not implement __extension__. But that compiler doesn't define 259 __GNUC_MINOR__. */ 260 # if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 261 # define __extension__ 262 # endif 263 264 /* For GNU C, if not -traditional, 265 we can define these macros to compute all args only once 266 without using a global variable. 267 Also, we can avoid using the `temp' slot, to make faster code. */ 268 269 # define obstack_object_size(OBSTACK) \ 270 __extension__ \ 271 ({ struct obstack const *__o = (OBSTACK); \ 272 (unsigned) (__o->next_free - __o->object_base); }) 273 274 # define obstack_room(OBSTACK) \ 275 __extension__ \ 276 ({ struct obstack const *__o = (OBSTACK); \ 277 (unsigned) (__o->chunk_limit - __o->next_free); }) 278 279 # define obstack_make_room(OBSTACK,length) \ 280 __extension__ \ 281 ({ struct obstack *__o = (OBSTACK); \ 282 int __len = (length); \ 283 if (__o->chunk_limit - __o->next_free < __len) \ 284 _obstack_newchunk (__o, __len); \ 285 (void) 0; }) 286 287 # define obstack_empty_p(OBSTACK) \ 288 __extension__ \ 289 ({ struct obstack const *__o = (OBSTACK); \ 290 (__o->chunk->prev == 0 \ 291 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 292 __o->chunk->contents, \ 293 __o->alignment_mask)); }) 294 295 # define obstack_grow(OBSTACK,where,length) \ 296 __extension__ \ 297 ({ struct obstack *__o = (OBSTACK); \ 298 int __len = (length); \ 299 if (__o->next_free + __len > __o->chunk_limit) \ 300 _obstack_newchunk (__o, __len); \ 301 memcpy (__o->next_free, where, __len); \ 302 __o->next_free += __len; \ 303 (void) 0; }) 304 305 # define obstack_grow0(OBSTACK,where,length) \ 306 __extension__ \ 307 ({ struct obstack *__o = (OBSTACK); \ 308 int __len = (length); \ 309 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 310 _obstack_newchunk (__o, __len + 1); \ 311 memcpy (__o->next_free, where, __len); \ 312 __o->next_free += __len; \ 313 *(__o->next_free)++ = 0; \ 314 (void) 0; }) 315 316 # define obstack_1grow(OBSTACK,datum) \ 317 __extension__ \ 318 ({ struct obstack *__o = (OBSTACK); \ 319 if (__o->next_free + 1 > __o->chunk_limit) \ 320 _obstack_newchunk (__o, 1); \ 321 obstack_1grow_fast (__o, datum); \ 322 (void) 0; }) 323 324 /* These assume that the obstack alignment is good enough for pointers 325 or ints, and that the data added so far to the current object 326 shares that much alignment. */ 327 328 # define obstack_ptr_grow(OBSTACK,datum) \ 329 __extension__ \ 330 ({ struct obstack *__o = (OBSTACK); \ 331 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 332 _obstack_newchunk (__o, sizeof (void *)); \ 333 obstack_ptr_grow_fast (__o, datum); }) \ 334 335 # define obstack_int_grow(OBSTACK,datum) \ 336 __extension__ \ 337 ({ struct obstack *__o = (OBSTACK); \ 338 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 339 _obstack_newchunk (__o, sizeof (int)); \ 340 obstack_int_grow_fast (__o, datum); }) 341 342 # define obstack_ptr_grow_fast(OBSTACK,aptr) \ 343 __extension__ \ 344 ({ struct obstack *__o1 = (OBSTACK); \ 345 *(const void **) __o1->next_free = (aptr); \ 346 __o1->next_free += sizeof (const void *); \ 347 (void) 0; }) 348 349 # define obstack_int_grow_fast(OBSTACK,aint) \ 350 __extension__ \ 351 ({ struct obstack *__o1 = (OBSTACK); \ 352 *(int *) __o1->next_free = (aint); \ 353 __o1->next_free += sizeof (int); \ 354 (void) 0; }) 355 356 # define obstack_blank(OBSTACK,length) \ 357 __extension__ \ 358 ({ struct obstack *__o = (OBSTACK); \ 359 int __len = (length); \ 360 if (__o->chunk_limit - __o->next_free < __len) \ 361 _obstack_newchunk (__o, __len); \ 362 obstack_blank_fast (__o, __len); \ 363 (void) 0; }) 364 365 # define obstack_alloc(OBSTACK,length) \ 366 __extension__ \ 367 ({ struct obstack *__h = (OBSTACK); \ 368 obstack_blank (__h, (length)); \ 369 obstack_finish (__h); }) 370 371 # define obstack_copy(OBSTACK,where,length) \ 372 __extension__ \ 373 ({ struct obstack *__h = (OBSTACK); \ 374 obstack_grow (__h, (where), (length)); \ 375 obstack_finish (__h); }) 376 377 # define obstack_copy0(OBSTACK,where,length) \ 378 __extension__ \ 379 ({ struct obstack *__h = (OBSTACK); \ 380 obstack_grow0 (__h, (where), (length)); \ 381 obstack_finish (__h); }) 382 383 /* The local variable is named __o1 to avoid a name conflict 384 when obstack_blank is called. */ 385 # define obstack_finish(OBSTACK) \ 386 __extension__ \ 387 ({ struct obstack *__o1 = (OBSTACK); \ 388 void *__value = (void *) __o1->object_base; \ 389 if (__o1->next_free == __value) \ 390 __o1->maybe_empty_object = 1; \ 391 __o1->next_free \ 392 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 393 __o1->alignment_mask); \ 394 if (__o1->next_free - (char *)__o1->chunk \ 395 > __o1->chunk_limit - (char *)__o1->chunk) \ 396 __o1->next_free = __o1->chunk_limit; \ 397 __o1->object_base = __o1->next_free; \ 398 __value; }) 399 400 # define obstack_free(OBSTACK, OBJ) \ 401 __extension__ \ 402 ({ struct obstack *__o = (OBSTACK); \ 403 void *__obj = (OBJ); \ 404 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 405 __o->next_free = __o->object_base = (char *)__obj; \ 406 else (obstack_free) (__o, __obj); }) 407 408 #else /* not __GNUC__ or not __STDC__ */ 410 411 # define obstack_object_size(h) \ 412 (unsigned) ((h)->next_free - (h)->object_base) 413 414 # define obstack_room(h) \ 415 (unsigned) ((h)->chunk_limit - (h)->next_free) 416 417 # define obstack_empty_p(h) \ 418 ((h)->chunk->prev == 0 \ 419 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 420 (h)->chunk->contents, \ 421 (h)->alignment_mask)) 422 423 /* Note that the call to _obstack_newchunk is enclosed in (..., 0) 424 so that we can avoid having void expressions 425 in the arms of the conditional expression. 426 Casting the third operand to void was tried before, 427 but some compilers won't accept it. */ 428 429 # define obstack_make_room(h,length) \ 430 ( (h)->temp.tempint = (length), \ 431 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 432 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 433 434 # define obstack_grow(h,where,length) \ 435 ( (h)->temp.tempint = (length), \ 436 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 437 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 438 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 439 (h)->next_free += (h)->temp.tempint) 440 441 # define obstack_grow0(h,where,length) \ 442 ( (h)->temp.tempint = (length), \ 443 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 444 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 445 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 446 (h)->next_free += (h)->temp.tempint, \ 447 *((h)->next_free)++ = 0) 448 449 # define obstack_1grow(h,datum) \ 450 ( (((h)->next_free + 1 > (h)->chunk_limit) \ 451 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 452 obstack_1grow_fast (h, datum)) 453 454 # define obstack_ptr_grow(h,datum) \ 455 ( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 456 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 457 obstack_ptr_grow_fast (h, datum)) 458 459 # define obstack_int_grow(h,datum) \ 460 ( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 461 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 462 obstack_int_grow_fast (h, datum)) 463 464 # define obstack_ptr_grow_fast(h,aptr) \ 465 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 466 467 # define obstack_int_grow_fast(h,aint) \ 468 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 469 470 # define obstack_blank(h,length) \ 471 ( (h)->temp.tempint = (length), \ 472 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 473 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 474 obstack_blank_fast (h, (h)->temp.tempint)) 475 476 # define obstack_alloc(h,length) \ 477 (obstack_blank ((h), (length)), obstack_finish ((h))) 478 479 # define obstack_copy(h,where,length) \ 480 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 481 482 # define obstack_copy0(h,where,length) \ 483 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 484 485 # define obstack_finish(h) \ 486 ( ((h)->next_free == (h)->object_base \ 487 ? (((h)->maybe_empty_object = 1), 0) \ 488 : 0), \ 489 (h)->temp.tempptr = (h)->object_base, \ 490 (h)->next_free \ 491 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 492 (h)->alignment_mask), \ 493 (((h)->next_free - (char *) (h)->chunk \ 494 > (h)->chunk_limit - (char *) (h)->chunk) \ 495 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 496 (h)->object_base = (h)->next_free, \ 497 (h)->temp.tempptr) 498 499 # define obstack_free(h,obj) \ 500 ( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 501 ((((h)->temp.tempint > 0 \ 502 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 503 ? (int) ((h)->next_free = (h)->object_base \ 504 = (h)->temp.tempint + (char *) (h)->chunk) \ 505 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0))) 506 507 #endif /* not __GNUC__ or not __STDC__ */ 508 509 #ifdef __cplusplus 510 } /* C++ */ 511 #endif 512 513 #endif /* obstack.h */ 514
