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 27All the apparent functions defined here are macros. The idea 28is that you would use these pre-tested macros to solve a 29very specific set of problems, and they would run fast. 30Caution: no side-effects in arguments please!! They may be 31evaluated MANY times!! 32 33These macros operate a stack of objects. Each object starts life 34small, and may grow to maturity. (Consider building a word syllable 35by syllable.) An object can move while it is growing. Once it has 36been "finished" it never changes address again. So the "top of the 37stack" is typically an immature growing object, while the rest of the 38stack is of mature, fixed size and fixed address objects. 39 40These routines grab large chunks of memory, using a function you 41supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 42by calling `obstack_chunk_free'. You must define them and declare 43them before using any obstack macros. 44 45Each independent stack is represented by a `struct obstack'. 46Each of the obstack macros expects a pointer to such a structure 47as the first argument. 48 49One motivation for this package is the problem of growing char strings 50in 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 52would not like to put any arbitrary upper limit on the length of your 53symbols. 54 55In practice this often means you will build many short symbols and a 56few long symbols. At the time you are reading a symbol you don't know 57how long it is. One traditional method is to read a symbol into a 58buffer, realloc()ating the buffer every time you try to read a symbol 59that is longer than the buffer. This is beaut, but you still will 60want to copy the symbol from the buffer to a more permanent 61symbol-table entry say about half the time. 62 63With obstacks, you can work differently. Use one obstack for all symbol 64names. As you read a symbol, grow the name in the obstack gradually. 65When the name is complete, finalize it. Then, if the symbol exists already, 66free the newly read name. 67 68The way we do this is to take a large chunk, allocating memory from 69low addresses. When you want to build a symbol in the chunk you just 70add chars above the current "high water mark" in the chunk. When you 71have finished adding chars, because you got to the end of the symbol, 72you know how long the chars are, and you can create a new object. 73Mostly the chars will not burst over the highest address of the chunk, 74because you would typically expect a chunk to be (say) 100 times as 75long as an average object. 76 77In case that isn't clear, when we have enough chars to make up 78the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 79so we just point to it where it lies. No moving of chars is 80needed and this is the second win: potentially long strings need 81never be explicitly shuffled. Once an object is formed, it does not 82change its address during its lifetime. 83 84When the chars burst over a chunk boundary, we allocate a larger 85chunk, and then copy the partly formed object from the end of the old 86chunk to the beginning of the new larger chunk. We then carry on 87accreting characters to the end of the object as we normally would. 88 89A special macro is provided to add a single char at a time to a 90growing object. This allows the use of register variables, which 91break the ordinary 'growth' macro. 92 93Summary: 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 114extern "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 157struct _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 164struct 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 191extern void _obstack_newchunk (struct obstack *, int); 192extern void _obstack_free (struct obstack *, void *); 193extern int _obstack_begin (struct obstack *, int, int, 194 void *(*) (long), void (*) (void *)); 195extern int _obstack_begin_1 (struct obstack *, int, int, 196 void *(*) (void *, long), 197 void (*) (void *, void *), void *); 198extern int _obstack_memory_used (struct obstack *); 199 200/* Do the function-declarations after the structs 201 but before defining the macros. */ 202 203void obstack_init (struct obstack *obstack); 204 205void * obstack_alloc (struct obstack *obstack, int size); 206 207void * obstack_copy (struct obstack *obstack, void *address, int size); 208void * obstack_copy0 (struct obstack *obstack, void *address, int size); 209 210void obstack_free (struct obstack *obstack, void *block); 211 212void obstack_blank (struct obstack *obstack, int size); 213 214void obstack_grow (struct obstack *obstack, void *data, int size); 215void obstack_grow0 (struct obstack *obstack, void *data, int size); 216 217void obstack_1grow (struct obstack *obstack, int data_char); 218void obstack_ptr_grow (struct obstack *obstack, void *data); 219void obstack_int_grow (struct obstack *obstack, int data); 220 221void * obstack_finish (struct obstack *obstack); 222 223int obstack_object_size (struct obstack *obstack); 224 225int obstack_room (struct obstack *obstack); 226void obstack_make_room (struct obstack *obstack, int size); 227void obstack_1grow_fast (struct obstack *obstack, int data_char); 228void obstack_ptr_grow_fast (struct obstack *obstack, void *data); 229void obstack_int_grow_fast (struct obstack *obstack, int data); 230void obstack_blank_fast (struct obstack *obstack, int size); 231 232void * obstack_base (struct obstack *obstack); 233void * obstack_next_free (struct obstack *obstack); 234int obstack_alignment_mask (struct obstack *obstack); 235int obstack_chunk_size (struct obstack *obstack); 236int obstack_memory_used (struct obstack *obstack); 237 238/* Error handler called when `obstack_chunk_alloc' failed to allocate 239 more memory. This can be set to a user defined function. The 240 default action is to print a message and abort. */ 241extern void (*obstack_alloc_failed_handler) (void); 242 243/* Exit value used when `print_and_abort' is used. */ 244extern int obstack_exit_failure; 245 246/* Pointer to beginning of object being allocated or to be allocated next. 247 Note that this might not be the final address of the object 248 because a new chunk might be needed to hold the final size. */ 249 250#define obstack_base(h) ((h)->object_base) 251 252/* Size for allocating ordinary chunks. */ 253 254#define obstack_chunk_size(h) ((h)->chunk_size) 255 256/* Pointer to next byte not yet allocated in current chunk. */ 257 258#define obstack_next_free(h) ((h)->next_free) 259 260/* Mask specifying low bits that should be clear in address of an object. */ 261 262#define obstack_alignment_mask(h) ((h)->alignment_mask) 263 264/* To prevent prototype warnings provide complete argument list in 265 standard C version. */ 266# define obstack_init(h) \ 267 _obstack_begin ((h), 0, 0, \ 268 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 269 270# define obstack_begin(h, size) \ 271 _obstack_begin ((h), (size), 0, \ 272 (void *(*) (long)) obstack_chunk_alloc, (void (*) (void *)) obstack_chunk_free) 273 274# define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 275 _obstack_begin ((h), (size), (alignment), \ 276 (void *(*) (long)) (chunkfun), (void (*) (void *)) (freefun)) 277 278# define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 279 _obstack_begin_1 ((h), (size), (alignment), \ 280 (void *(*) (void *, long)) (chunkfun), \ 281 (void (*) (void *, void *)) (freefun), (arg)) 282 283# define obstack_chunkfun(h, newchunkfun) \ 284 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 285 286# define obstack_freefun(h, newfreefun) \ 287 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 288 289#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 290 291#define obstack_blank_fast(h,n) ((h)->next_free += (n)) 292 293#define obstack_memory_used(h) _obstack_memory_used (h) 294 295#if defined __GNUC__ && defined __STDC__ && __STDC__ 296/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 297 does not implement __extension__. But that compiler doesn't define 298 __GNUC_MINOR__. */ 299# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 300# define __extension__ 301# endif 302 303/* For GNU C, if not -traditional, 304 we can define these macros to compute all args only once 305 without using a global variable. 306 Also, we can avoid using the `temp' slot, to make faster code. */ 307 308# define obstack_object_size(OBSTACK) \ 309 __extension__ \ 310 ({ struct obstack *__o = (OBSTACK); \ 311 (unsigned) (__o->next_free - __o->object_base); }) 312 313# define obstack_room(OBSTACK) \ 314 __extension__ \ 315 ({ struct obstack *__o = (OBSTACK); \ 316 (unsigned) (__o->chunk_limit - __o->next_free); }) 317 318# define obstack_make_room(OBSTACK,length) \ 319__extension__ \ 320({ struct obstack *__o = (OBSTACK); \ 321 int __len = (length); \ 322 if (__o->chunk_limit - __o->next_free < __len) \ 323 _obstack_newchunk (__o, __len); \ 324 (void) 0; }) 325 326# define obstack_empty_p(OBSTACK) \ 327 __extension__ \ 328 ({ struct obstack *__o = (OBSTACK); \ 329 (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); }) 330 331# define obstack_grow(OBSTACK,where,length) \ 332__extension__ \ 333({ struct obstack *__o = (OBSTACK); \ 334 int __len = (length); \ 335 if (__o->next_free + __len > __o->chunk_limit) \ 336 _obstack_newchunk (__o, __len); \ 337 _obstack_memcpy (__o->next_free, (where), __len); \ 338 __o->next_free += __len; \ 339 (void) 0; }) 340 341# define obstack_grow0(OBSTACK,where,length) \ 342__extension__ \ 343({ struct obstack *__o = (OBSTACK); \ 344 int __len = (length); \ 345 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 346 _obstack_newchunk (__o, __len + 1); \ 347 _obstack_memcpy (__o->next_free, (where), __len); \ 348 __o->next_free += __len; \ 349 *(__o->next_free)++ = 0; \ 350 (void) 0; }) 351 352# define obstack_1grow(OBSTACK,datum) \ 353__extension__ \ 354({ struct obstack *__o = (OBSTACK); \ 355 if (__o->next_free + 1 > __o->chunk_limit) \ 356 _obstack_newchunk (__o, 1); \ 357 obstack_1grow_fast (__o, datum); \ 358 (void) 0; }) 359 360/* These assume that the obstack alignment is good enough for pointers or ints, 361 and that the data added so far to the current object 362 shares that much alignment. */ 363 364# define obstack_ptr_grow(OBSTACK,datum) \ 365__extension__ \ 366({ struct obstack *__o = (OBSTACK); \ 367 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 368 _obstack_newchunk (__o, sizeof (void *)); \ 369 obstack_ptr_grow_fast (__o, datum); }) 370 371# define obstack_int_grow(OBSTACK,datum) \ 372__extension__ \ 373({ struct obstack *__o = (OBSTACK); \ 374 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 375 _obstack_newchunk (__o, sizeof (int)); \ 376 obstack_int_grow_fast (__o, datum); }) 377 378# define obstack_ptr_grow_fast(OBSTACK,aptr) \ 379__extension__ \ 380({ struct obstack *__o1 = (OBSTACK); \ 381 *(const void **) __o1->next_free = (aptr); \ 382 __o1->next_free += sizeof (const void *); \ 383 (void) 0; }) 384 385# define obstack_int_grow_fast(OBSTACK,aint) \ 386__extension__ \ 387({ struct obstack *__o1 = (OBSTACK); \ 388 *(int *) __o1->next_free = (aint); \ 389 __o1->next_free += sizeof (int); \ 390 (void) 0; }) 391 392# define obstack_blank(OBSTACK,length) \ 393__extension__ \ 394({ struct obstack *__o = (OBSTACK); \ 395 int __len = (length); \ 396 if (__o->chunk_limit - __o->next_free < __len) \ 397 _obstack_newchunk (__o, __len); \ 398 obstack_blank_fast (__o, __len); \ 399 (void) 0; }) 400 401# define obstack_alloc(OBSTACK,length) \ 402__extension__ \ 403({ struct obstack *__h = (OBSTACK); \ 404 obstack_blank (__h, (length)); \ 405 obstack_finish (__h); }) 406 407# define obstack_copy(OBSTACK,where,length) \ 408__extension__ \ 409({ struct obstack *__h = (OBSTACK); \ 410 obstack_grow (__h, (where), (length)); \ 411 obstack_finish (__h); }) 412 413# define obstack_copy0(OBSTACK,where,length) \ 414__extension__ \ 415({ struct obstack *__h = (OBSTACK); \ 416 obstack_grow0 (__h, (where), (length)); \ 417 obstack_finish (__h); }) 418 419/* The local variable is named __o1 to avoid a name conflict 420 when obstack_blank is called. */ 421# define obstack_finish(OBSTACK) \ 422__extension__ \ 423({ struct obstack *__o1 = (OBSTACK); \ 424 void *value; \ 425 value = (void *) __o1->object_base; \ 426 if (__o1->next_free == value) \ 427 __o1->maybe_empty_object = 1; \ 428 __o1->next_free \ 429 = __INT_TO_PTR ((__PTR_TO_INT (__o1->next_free)+__o1->alignment_mask)\ 430 & ~ (__o1->alignment_mask)); \ 431 if (__o1->next_free - (char *)__o1->chunk \ 432 > __o1->chunk_limit - (char *)__o1->chunk) \ 433 __o1->next_free = __o1->chunk_limit; \ 434 __o1->object_base = __o1->next_free; \ 435 value; }) 436 437# define obstack_free(OBSTACK, OBJ) \ 438__extension__ \ 439({ struct obstack *__o = (OBSTACK); \ 440 void *__obj = (void *) (OBJ); \ 441 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 442 __o->next_free = __o->object_base = (char *) __obj; \ 443 else (obstack_free) (__o, __obj); }) 444 445#else /* not __GNUC__ or not __STDC__ */ 446 447# define obstack_object_size(h) \ 448 (unsigned) ((h)->next_free - (h)->object_base) 449 450# define obstack_room(h) \ 451 (unsigned) ((h)->chunk_limit - (h)->next_free) 452 453# define obstack_empty_p(h) \ 454 ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0) 455 456/* Note that the call to _obstack_newchunk is enclosed in (..., 0) 457 so that we can avoid having void expressions 458 in the arms of the conditional expression. 459 Casting the third operand to void was tried before, 460 but some compilers won't accept it. */ 461 462# define obstack_make_room(h,length) \ 463( (h)->temp = (length), \ 464 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 465 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0)) 466 467# define obstack_grow(h,where,length) \ 468( (h)->temp = (length), \ 469 (((h)->next_free + (h)->temp > (h)->chunk_limit) \ 470 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 471 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 472 (h)->next_free += (h)->temp) 473 474# define obstack_grow0(h,where,length) \ 475( (h)->temp = (length), \ 476 (((h)->next_free + (h)->temp + 1 > (h)->chunk_limit) \ 477 ? (_obstack_newchunk ((h), (h)->temp + 1), 0) : 0), \ 478 _obstack_memcpy ((h)->next_free, (where), (h)->temp), \ 479 (h)->next_free += (h)->temp, \ 480 *((h)->next_free)++ = 0) 481 482# define obstack_1grow(h,datum) \ 483( (((h)->next_free + 1 > (h)->chunk_limit) \ 484 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 485 obstack_1grow_fast (h, datum)) 486 487# define obstack_ptr_grow(h,datum) \ 488( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 489 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 490 obstack_ptr_grow_fast (h, datum)) 491 492# define obstack_int_grow(h,datum) \ 493( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 494 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 495 obstack_int_grow_fast (h, datum)) 496 497# define obstack_ptr_grow_fast(h,aptr) \ 498 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 499 500# define obstack_int_grow_fast(h,aint) \ 501 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aptr)) 502 503# define obstack_blank(h,length) \ 504( (h)->temp = (length), \ 505 (((h)->chunk_limit - (h)->next_free < (h)->temp) \ 506 ? (_obstack_newchunk ((h), (h)->temp), 0) : 0), \ 507 obstack_blank_fast (h, (h)->temp)) 508 509# define obstack_alloc(h,length) \ 510 (obstack_blank ((h), (length)), obstack_finish ((h))) 511 512# define obstack_copy(h,where,length) \ 513 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 514 515# define obstack_copy0(h,where,length) \ 516 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 517 518# define obstack_finish(h) \ 519( ((h)->next_free == (h)->object_base \ 520 ? (((h)->maybe_empty_object = 1), 0) \ 521 : 0), \ 522 (h)->temp = __PTR_TO_INT ((h)->object_base), \ 523 (h)->next_free \ 524 = __INT_TO_PTR ((__PTR_TO_INT ((h)->next_free)+(h)->alignment_mask) \ 525 & ~ ((h)->alignment_mask)), \ 526 (((h)->next_free - (char *) (h)->chunk \ 527 > (h)->chunk_limit - (char *) (h)->chunk) \ 528 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 529 (h)->object_base = (h)->next_free, \ 530 (void *) __INT_TO_PTR ((h)->temp)) 531 532# define obstack_free(h,obj) \ 533( (h)->temp = (char *) (obj) - (char *) (h)->chunk, \ 534 (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\ 535 ? (((h)->next_free = (h)->object_base \ 536 = (h)->temp + (char *) (h)->chunk), 0) \ 537 : ((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0))) 538 539#endif /* not __GNUC__ or not __STDC__ */ 540 541#ifdef __cplusplus 542} /* C++ */ 543#endif 544 545#endif /* obstack.h */ 546