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 22All the apparent functions defined here are macros. The idea 23is that you would use these pre-tested macros to solve a 24very specific set of problems, and they would run fast. 25Caution: no side-effects in arguments please!! They may be 26evaluated MANY times!! 27 28These macros operate a stack of objects. Each object starts life 29small, and may grow to maturity. (Consider building a word syllable 30by syllable.) An object can move while it is growing. Once it has 31been "finished" it never changes address again. So the "top of the 32stack" is typically an immature growing object, while the rest of the 33stack is of mature, fixed size and fixed address objects. 34 35These routines grab large chunks of memory, using a function you 36supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 37by calling `obstack_chunk_free'. You must define them and declare 38them before using any obstack macros. 39 40Each independent stack is represented by a `struct obstack'. 41Each of the obstack macros expects a pointer to such a structure 42as the first argument. 43 44One motivation for this package is the problem of growing char strings 45in 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 47would not like to put any arbitrary upper limit on the length of your 48symbols. 49 50In practice this often means you will build many short symbols and a 51few long symbols. At the time you are reading a symbol you don't know 52how long it is. One traditional method is to read a symbol into a 53buffer, realloc()ating the buffer every time you try to read a symbol 54that is longer than the buffer. This is beaut, but you still will 55want to copy the symbol from the buffer to a more permanent 56symbol-table entry say about half the time. 57 58With obstacks, you can work differently. Use one obstack for all symbol 59names. As you read a symbol, grow the name in the obstack gradually. 60When the name is complete, finalize it. Then, if the symbol exists already, 61free the newly read name. 62 63The way we do this is to take a large chunk, allocating memory from 64low addresses. When you want to build a symbol in the chunk you just 65add chars above the current "high water mark" in the chunk. When you 66have finished adding chars, because you got to the end of the symbol, 67you know how long the chars are, and you can create a new object. 68Mostly the chars will not burst over the highest address of the chunk, 69because you would typically expect a chunk to be (say) 100 times as 70long as an average object. 71 72In case that isn't clear, when we have enough chars to make up 73the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 74so we just point to it where it lies. No moving of chars is 75needed and this is the second win: potentially long strings need 76never be explicitly shuffled. Once an object is formed, it does not 77change its address during its lifetime. 78 79When the chars burst over a chunk boundary, we allocate a larger 80chunk, and then copy the partly formed object from the end of the old 81chunk to the beginning of the new larger chunk. We then carry on 82accreting characters to the end of the object as we normally would. 83 84A special macro is provided to add a single char at a time to a 85growing object. This allows the use of register variables, which 86break the ordinary 'growth' macro. 87 88Summary: 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 109extern "C" { 110#endif 111 112/* We need the type of a pointer subtraction. If __PTRDIFF_TYPE__ is 113 defined, as with GNU C, use that; that way we don't pollute the 114 namespace with <stddef.h>'s symbols. Otherwise, include <stddef.h> 115 and use ptrdiff_t. */ 116 117#ifdef __PTRDIFF_TYPE__ 118# define PTR_INT_TYPE __PTRDIFF_TYPE__ 119#else 120# include <stddef.h> 121# define PTR_INT_TYPE ptrdiff_t 122#endif 123 124/* If B is the base of an object addressed by P, return the result of 125 aligning P to the next multiple of A + 1. B and P must be of type 126 char *. A + 1 must be a power of 2. */ 127 128#define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A))) 129 130/* Similiar to _BPTR_ALIGN (B, P, A), except optimize the common case 131 where pointers can be converted to integers, aligned as integers, 132 and converted back again. If PTR_INT_TYPE is narrower than a 133 pointer (e.g., the AS/400), play it safe and compute the alignment 134 relative to B. Otherwise, use the faster strategy of computing the 135 alignment relative to 0. */ 136 137#define __PTR_ALIGN(B, P, A) \ 138 __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \ 139 P, A) 140 141#include <string.h> 142 143struct _obstack_chunk /* Lives at front of each chunk. */ 144{ 145 char *limit; /* 1 past end of this chunk */ 146 struct _obstack_chunk *prev; /* address of prior chunk or NULL */ 147 char contents[4]; /* objects begin here */ 148}; 149 150struct obstack /* control current object in current chunk */ 151{ 152 long chunk_size; /* preferred size to allocate chunks in */ 153 struct _obstack_chunk *chunk; /* address of current struct obstack_chunk */ 154 char *object_base; /* address of object we are building */ 155 char *next_free; /* where to add next char to current object */ 156 char *chunk_limit; /* address of char after current chunk */ 157 union 158 { 159 PTR_INT_TYPE tempint; 160 void *tempptr; 161 } temp; /* Temporary for some macros. */ 162 int alignment_mask; /* Mask of alignment for each object. */ 163 /* These prototypes vary based on `use_extra_arg', and we use 164 casts to the prototypeless function type in all assignments, 165 but having prototypes here quiets -Wstrict-prototypes. */ 166 struct _obstack_chunk *(*chunkfun) (void *, long); 167 void (*freefun) (void *, struct _obstack_chunk *); 168 void *extra_arg; /* first arg for chunk alloc/dealloc funcs */ 169 unsigned use_extra_arg:1; /* chunk alloc/dealloc funcs take extra arg */ 170 unsigned maybe_empty_object:1;/* There is a possibility that the current 171 chunk contains a zero-length object. This 172 prevents freeing the chunk if we allocate 173 a bigger chunk to replace it. */ 174 unsigned alloc_failed:1; /* No longer used, as we now call the failed 175 handler on error, but retained for binary 176 compatibility. */ 177}; 178 179/* Declare the external functions we use; they are in obstack.c. */ 180 181extern void _obstack_newchunk (struct obstack *, int); 182extern int _obstack_begin (struct obstack *, int, int, 183 void *(*) (long), void (*) (void *)); 184extern int _obstack_begin_1 (struct obstack *, int, int, 185 void *(*) (void *, long), 186 void (*) (void *, void *), void *); 187extern int _obstack_memory_used (struct obstack *); 188 189void obstack_free (struct obstack *obstack, void *block); 190 191 192/* Error handler called when `obstack_chunk_alloc' failed to allocate 193 more memory. This can be set to a user defined function which 194 should either abort gracefully or use longjump - but shouldn't 195 return. The default action is to print a message and abort. */ 196extern void (*obstack_alloc_failed_handler) (void); 197 198/* Exit value used when `print_and_abort' is used. */ 199extern int obstack_exit_failure; 200 201/* Pointer to beginning of object being allocated or to be allocated next. 202 Note that this might not be the final address of the object 203 because a new chunk might be needed to hold the final size. */ 204 205#define obstack_base(h) ((void *) (h)->object_base) 206 207/* Size for allocating ordinary chunks. */ 208 209#define obstack_chunk_size(h) ((h)->chunk_size) 210 211/* Pointer to next byte not yet allocated in current chunk. */ 212 213#define obstack_next_free(h) ((h)->next_free) 214 215/* Mask specifying low bits that should be clear in address of an object. */ 216 217#define obstack_alignment_mask(h) ((h)->alignment_mask) 218 219/* To prevent prototype warnings provide complete argument list. */ 220#define obstack_init(h) \ 221 _obstack_begin ((h), 0, 0, \ 222 (void *(*) (long)) obstack_chunk_alloc, \ 223 (void (*) (void *)) obstack_chunk_free) 224 225#define obstack_begin(h, size) \ 226 _obstack_begin ((h), (size), 0, \ 227 (void *(*) (long)) obstack_chunk_alloc, \ 228 (void (*) (void *)) obstack_chunk_free) 229 230#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 231 _obstack_begin ((h), (size), (alignment), \ 232 (void *(*) (long)) (chunkfun), \ 233 (void (*) (void *)) (freefun)) 234 235#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 236 _obstack_begin_1 ((h), (size), (alignment), \ 237 (void *(*) (void *, long)) (chunkfun), \ 238 (void (*) (void *, void *)) (freefun), (arg)) 239 240#define obstack_chunkfun(h, newchunkfun) \ 241 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 242 243#define obstack_freefun(h, newfreefun) \ 244 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 245 246#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 247 248#define obstack_blank_fast(h,n) ((h)->next_free += (n)) 249 250#define obstack_memory_used(h) _obstack_memory_used (h) 251 252#if defined __GNUC__ && defined __STDC__ && __STDC__ 253/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 254 does not implement __extension__. But that compiler doesn't define 255 __GNUC_MINOR__. */ 256# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 257# define __extension__ 258# endif 259 260/* For GNU C, if not -traditional, 261 we can define these macros to compute all args only once 262 without using a global variable. 263 Also, we can avoid using the `temp' slot, to make faster code. */ 264 265# define obstack_object_size(OBSTACK) \ 266 __extension__ \ 267 ({ struct obstack const *__o = (OBSTACK); \ 268 (unsigned) (__o->next_free - __o->object_base); }) 269 270# define obstack_room(OBSTACK) \ 271 __extension__ \ 272 ({ struct obstack const *__o = (OBSTACK); \ 273 (unsigned) (__o->chunk_limit - __o->next_free); }) 274 275# define obstack_make_room(OBSTACK,length) \ 276__extension__ \ 277({ struct obstack *__o = (OBSTACK); \ 278 int __len = (length); \ 279 if (__o->chunk_limit - __o->next_free < __len) \ 280 _obstack_newchunk (__o, __len); \ 281 (void) 0; }) 282 283# define obstack_empty_p(OBSTACK) \ 284 __extension__ \ 285 ({ struct obstack const *__o = (OBSTACK); \ 286 (__o->chunk->prev == 0 \ 287 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 288 __o->chunk->contents, \ 289 __o->alignment_mask)); }) 290 291# define obstack_grow(OBSTACK,where,length) \ 292__extension__ \ 293({ struct obstack *__o = (OBSTACK); \ 294 int __len = (length); \ 295 if (__o->next_free + __len > __o->chunk_limit) \ 296 _obstack_newchunk (__o, __len); \ 297 memcpy (__o->next_free, where, __len); \ 298 __o->next_free += __len; \ 299 (void) 0; }) 300 301# define obstack_grow0(OBSTACK,where,length) \ 302__extension__ \ 303({ struct obstack *__o = (OBSTACK); \ 304 int __len = (length); \ 305 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 306 _obstack_newchunk (__o, __len + 1); \ 307 memcpy (__o->next_free, where, __len); \ 308 __o->next_free += __len; \ 309 *(__o->next_free)++ = 0; \ 310 (void) 0; }) 311 312# define obstack_1grow(OBSTACK,datum) \ 313__extension__ \ 314({ struct obstack *__o = (OBSTACK); \ 315 if (__o->next_free + 1 > __o->chunk_limit) \ 316 _obstack_newchunk (__o, 1); \ 317 obstack_1grow_fast (__o, datum); \ 318 (void) 0; }) 319 320/* These assume that the obstack alignment is good enough for pointers 321 or ints, and that the data added so far to the current object 322 shares that much alignment. */ 323 324# define obstack_ptr_grow(OBSTACK,datum) \ 325__extension__ \ 326({ struct obstack *__o = (OBSTACK); \ 327 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 328 _obstack_newchunk (__o, sizeof (void *)); \ 329 obstack_ptr_grow_fast (__o, datum); }) \ 330 331# define obstack_int_grow(OBSTACK,datum) \ 332__extension__ \ 333({ struct obstack *__o = (OBSTACK); \ 334 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 335 _obstack_newchunk (__o, sizeof (int)); \ 336 obstack_int_grow_fast (__o, datum); }) 337 338# define obstack_ptr_grow_fast(OBSTACK,aptr) \ 339__extension__ \ 340({ struct obstack *__o1 = (OBSTACK); \ 341 *(const void **) __o1->next_free = (aptr); \ 342 __o1->next_free += sizeof (const void *); \ 343 (void) 0; }) 344 345# define obstack_int_grow_fast(OBSTACK,aint) \ 346__extension__ \ 347({ struct obstack *__o1 = (OBSTACK); \ 348 *(int *) __o1->next_free = (aint); \ 349 __o1->next_free += sizeof (int); \ 350 (void) 0; }) 351 352# define obstack_blank(OBSTACK,length) \ 353__extension__ \ 354({ struct obstack *__o = (OBSTACK); \ 355 int __len = (length); \ 356 if (__o->chunk_limit - __o->next_free < __len) \ 357 _obstack_newchunk (__o, __len); \ 358 obstack_blank_fast (__o, __len); \ 359 (void) 0; }) 360 361# define obstack_alloc(OBSTACK,length) \ 362__extension__ \ 363({ struct obstack *__h = (OBSTACK); \ 364 obstack_blank (__h, (length)); \ 365 obstack_finish (__h); }) 366 367# define obstack_copy(OBSTACK,where,length) \ 368__extension__ \ 369({ struct obstack *__h = (OBSTACK); \ 370 obstack_grow (__h, (where), (length)); \ 371 obstack_finish (__h); }) 372 373# define obstack_copy0(OBSTACK,where,length) \ 374__extension__ \ 375({ struct obstack *__h = (OBSTACK); \ 376 obstack_grow0 (__h, (where), (length)); \ 377 obstack_finish (__h); }) 378 379/* The local variable is named __o1 to avoid a name conflict 380 when obstack_blank is called. */ 381# define obstack_finish(OBSTACK) \ 382__extension__ \ 383({ struct obstack *__o1 = (OBSTACK); \ 384 void *__value = (void *) __o1->object_base; \ 385 if (__o1->next_free == __value) \ 386 __o1->maybe_empty_object = 1; \ 387 __o1->next_free \ 388 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 389 __o1->alignment_mask); \ 390 if (__o1->next_free - (char *)__o1->chunk \ 391 > __o1->chunk_limit - (char *)__o1->chunk) \ 392 __o1->next_free = __o1->chunk_limit; \ 393 __o1->object_base = __o1->next_free; \ 394 __value; }) 395 396# define obstack_free(OBSTACK, OBJ) \ 397__extension__ \ 398({ struct obstack *__o = (OBSTACK); \ 399 void *__obj = (OBJ); \ 400 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 401 __o->next_free = __o->object_base = (char *)__obj; \ 402 else (obstack_free) (__o, __obj); }) 403 404#else /* not __GNUC__ or not __STDC__ */ 405 406# define obstack_object_size(h) \ 407 (unsigned) ((h)->next_free - (h)->object_base) 408 409# define obstack_room(h) \ 410 (unsigned) ((h)->chunk_limit - (h)->next_free) 411 412# define obstack_empty_p(h) \ 413 ((h)->chunk->prev == 0 \ 414 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 415 (h)->chunk->contents, \ 416 (h)->alignment_mask)) 417 418/* Note that the call to _obstack_newchunk is enclosed in (..., 0) 419 so that we can avoid having void expressions 420 in the arms of the conditional expression. 421 Casting the third operand to void was tried before, 422 but some compilers won't accept it. */ 423 424# define obstack_make_room(h,length) \ 425( (h)->temp.tempint = (length), \ 426 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 427 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 428 429# define obstack_grow(h,where,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 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 434 (h)->next_free += (h)->temp.tempint) 435 436# define obstack_grow0(h,where,length) \ 437( (h)->temp.tempint = (length), \ 438 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 439 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 440 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 441 (h)->next_free += (h)->temp.tempint, \ 442 *((h)->next_free)++ = 0) 443 444# define obstack_1grow(h,datum) \ 445( (((h)->next_free + 1 > (h)->chunk_limit) \ 446 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 447 obstack_1grow_fast (h, datum)) 448 449# define obstack_ptr_grow(h,datum) \ 450( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 451 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 452 obstack_ptr_grow_fast (h, datum)) 453 454# define obstack_int_grow(h,datum) \ 455( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 456 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 457 obstack_int_grow_fast (h, datum)) 458 459# define obstack_ptr_grow_fast(h,aptr) \ 460 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 461 462# define obstack_int_grow_fast(h,aint) \ 463 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 464 465# define obstack_blank(h,length) \ 466( (h)->temp.tempint = (length), \ 467 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 468 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 469 obstack_blank_fast (h, (h)->temp.tempint)) 470 471# define obstack_alloc(h,length) \ 472 (obstack_blank ((h), (length)), obstack_finish ((h))) 473 474# define obstack_copy(h,where,length) \ 475 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 476 477# define obstack_copy0(h,where,length) \ 478 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 479 480# define obstack_finish(h) \ 481( ((h)->next_free == (h)->object_base \ 482 ? (((h)->maybe_empty_object = 1), 0) \ 483 : 0), \ 484 (h)->temp.tempptr = (h)->object_base, \ 485 (h)->next_free \ 486 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 487 (h)->alignment_mask), \ 488 (((h)->next_free - (char *) (h)->chunk \ 489 > (h)->chunk_limit - (char *) (h)->chunk) \ 490 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 491 (h)->object_base = (h)->next_free, \ 492 (h)->temp.tempptr) 493 494# define obstack_free(h,obj) \ 495( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 496 ((((h)->temp.tempint > 0 \ 497 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 498 ? (int) ((h)->next_free = (h)->object_base \ 499 = (h)->temp.tempint + (char *) (h)->chunk) \ 500 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0))) 501 502#endif /* not __GNUC__ or not __STDC__ */ 503 504#ifdef __cplusplus 505} /* C++ */ 506#endif 507 508#endif /* obstack.h */ 509