1/* obstack.h - object stack macros 2 Copyright (C) 1988-1994,1996-1999,2003,2004,2005,2009 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, see 18 <http://www.gnu.org/licenses/>. */ 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\f 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/* Similar 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{ 145char*limit;/* 1 past end of this chunk */ 146struct _obstack_chunk *prev;/* address of prior chunk or NULL */ 147char contents[4];/* objects begin here */ 148}; 149 150struct obstack /* control current object in current chunk */ 151{ 152long chunk_size;/* preferred size to allocate chunks in */ 153struct _obstack_chunk *chunk;/* address of current struct obstack_chunk */ 154char*object_base;/* address of object we are building */ 155char*next_free;/* where to add next char to current object */ 156char*chunk_limit;/* address of char after current chunk */ 157union 158{ 159 PTR_INT_TYPE tempint; 160void*tempptr; 161} temp;/* Temporary for some macros. */ 162int alignment_mask;/* Mask of alignment for each object. */ 163/* These prototypes vary based on `use_extra_arg'. */ 164union{ 165void*(*plain) (long); 166struct _obstack_chunk *(*extra) (void*,long); 167} chunkfun; 168union{ 169void(*plain) (void*); 170void(*extra) (void*,struct _obstack_chunk *); 171} freefun; 172void*extra_arg;/* first arg for chunk alloc/dealloc funcs */ 173unsigned use_extra_arg:1;/* chunk alloc/dealloc funcs take extra arg */ 174unsigned maybe_empty_object:1;/* There is a possibility that the current 175 chunk contains a zero-length object. This 176 prevents freeing the chunk if we allocate 177 a bigger chunk to replace it. */ 178unsigned alloc_failed:1;/* No longer used, as we now call the failed 179 handler on error, but retained for binary 180 compatibility. */ 181}; 182 183/* Declare the external functions we use; they are in obstack.c. */ 184 185externvoid_obstack_newchunk(struct obstack *,int); 186externint_obstack_begin(struct obstack *,int,int, 187void*(*) (long),void(*) (void*)); 188externint_obstack_begin_1(struct obstack *,int,int, 189void*(*) (void*,long), 190void(*) (void*,void*),void*); 191externint_obstack_memory_used(struct obstack *); 192 193voidobstack_free(struct obstack *,void*); 194 195\f 196/* Error handler called when `obstack_chunk_alloc' failed to allocate 197 more memory. This can be set to a user defined function which 198 should either abort gracefully or use longjump - but shouldn't 199 return. The default action is to print a message and abort. */ 200externvoid(*obstack_alloc_failed_handler) (void); 201\f 202/* Pointer to beginning of object being allocated or to be allocated next. 203 Note that this might not be the final address of the object 204 because a new chunk might be needed to hold the final size. */ 205 206#define obstack_base(h) ((void *) (h)->object_base) 207 208/* Size for allocating ordinary chunks. */ 209 210#define obstack_chunk_size(h) ((h)->chunk_size) 211 212/* Pointer to next byte not yet allocated in current chunk. */ 213 214#define obstack_next_free(h) ((h)->next_free) 215 216/* Mask specifying low bits that should be clear in address of an object. */ 217 218#define obstack_alignment_mask(h) ((h)->alignment_mask) 219 220/* To prevent prototype warnings provide complete argument list. */ 221#define obstack_init(h) \ 222 _obstack_begin ((h), 0, 0, \ 223 (void *(*) (long)) obstack_chunk_alloc, \ 224 (void (*) (void *)) obstack_chunk_free) 225 226#define obstack_begin(h, size) \ 227 _obstack_begin ((h), (size), 0, \ 228 (void *(*) (long)) obstack_chunk_alloc, \ 229 (void (*) (void *)) obstack_chunk_free) 230 231#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 232 _obstack_begin ((h), (size), (alignment), \ 233 (void *(*) (long)) (chunkfun), \ 234 (void (*) (void *)) (freefun)) 235 236#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 237 _obstack_begin_1 ((h), (size), (alignment), \ 238 (void *(*) (void *, long)) (chunkfun), \ 239 (void (*) (void *, void *)) (freefun), (arg)) 240 241#define obstack_chunkfun(h, newchunkfun) \ 242 ((h)->chunkfun.extra = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 243 244#define obstack_freefun(h, newfreefun) \ 245 ((h)->freefun.extra = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 246 247#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 248 249#define obstack_blank_fast(h,n) ((h)->next_free += (n)) 250 251#define obstack_memory_used(h) _obstack_memory_used (h) 252\f 253#if defined __GNUC__ && defined __STDC__ && __STDC__ 254/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 255 does not implement __extension__. But that compiler doesn't define 256 __GNUC_MINOR__. */ 257# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 258# define __extension__ 259# endif 260 261/* For GNU C, if not -traditional, 262 we can define these macros to compute all args only once 263 without using a global variable. 264 Also, we can avoid using the `temp' slot, to make faster code. */ 265 266# define obstack_object_size(OBSTACK) \ 267 __extension__ \ 268 ({ struct obstack const *__o = (OBSTACK); \ 269 (unsigned) (__o->next_free - __o->object_base); }) 270 271# define obstack_room(OBSTACK) \ 272 __extension__ \ 273 ({ struct obstack const *__o = (OBSTACK); \ 274 (unsigned) (__o->chunk_limit - __o->next_free); }) 275 276# define obstack_make_room(OBSTACK,length) \ 277__extension__ \ 278({ struct obstack *__o = (OBSTACK); \ 279 int __len = (length); \ 280 if (__o->chunk_limit - __o->next_free < __len) \ 281 _obstack_newchunk (__o, __len); \ 282 (void) 0; }) 283 284# define obstack_empty_p(OBSTACK) \ 285 __extension__ \ 286 ({ struct obstack const *__o = (OBSTACK); \ 287 (__o->chunk->prev == 0 \ 288 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 289 __o->chunk->contents, \ 290 __o->alignment_mask)); }) 291 292# define obstack_grow(OBSTACK,where,length) \ 293__extension__ \ 294({ struct obstack *__o = (OBSTACK); \ 295 int __len = (length); \ 296 if (__o->next_free + __len > __o->chunk_limit) \ 297 _obstack_newchunk (__o, __len); \ 298 memcpy (__o->next_free, where, __len); \ 299 __o->next_free += __len; \ 300 (void) 0; }) 301 302# define obstack_grow0(OBSTACK,where,length) \ 303__extension__ \ 304({ struct obstack *__o = (OBSTACK); \ 305 int __len = (length); \ 306 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 307 _obstack_newchunk (__o, __len + 1); \ 308 memcpy (__o->next_free, where, __len); \ 309 __o->next_free += __len; \ 310 *(__o->next_free)++ = 0; \ 311 (void) 0; }) 312 313# define obstack_1grow(OBSTACK,datum) \ 314__extension__ \ 315({ struct obstack *__o = (OBSTACK); \ 316 if (__o->next_free + 1 > __o->chunk_limit) \ 317 _obstack_newchunk (__o, 1); \ 318 obstack_1grow_fast (__o, datum); \ 319 (void) 0; }) 320 321/* These assume that the obstack alignment is good enough for pointers 322 or ints, and that the data added so far to the current object 323 shares that much alignment. */ 324 325# define obstack_ptr_grow(OBSTACK,datum) \ 326__extension__ \ 327({ struct obstack *__o = (OBSTACK); \ 328 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 329 _obstack_newchunk (__o, sizeof (void *)); \ 330 obstack_ptr_grow_fast (__o, datum); }) \ 331 332# define obstack_int_grow(OBSTACK,datum) \ 333__extension__ \ 334({ struct obstack *__o = (OBSTACK); \ 335 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 336 _obstack_newchunk (__o, sizeof (int)); \ 337 obstack_int_grow_fast (__o, datum); }) 338 339# define obstack_ptr_grow_fast(OBSTACK,aptr) \ 340__extension__ \ 341({ struct obstack *__o1 = (OBSTACK); \ 342 *(const void **) __o1->next_free = (aptr); \ 343 __o1->next_free += sizeof (const void *); \ 344 (void) 0; }) 345 346# define obstack_int_grow_fast(OBSTACK,aint) \ 347__extension__ \ 348({ struct obstack *__o1 = (OBSTACK); \ 349 *(int *) __o1->next_free = (aint); \ 350 __o1->next_free += sizeof (int); \ 351 (void) 0; }) 352 353# define obstack_blank(OBSTACK,length) \ 354__extension__ \ 355({ struct obstack *__o = (OBSTACK); \ 356 int __len = (length); \ 357 if (__o->chunk_limit - __o->next_free < __len) \ 358 _obstack_newchunk (__o, __len); \ 359 obstack_blank_fast (__o, __len); \ 360 (void) 0; }) 361 362# define obstack_alloc(OBSTACK,length) \ 363__extension__ \ 364({ struct obstack *__h = (OBSTACK); \ 365 obstack_blank (__h, (length)); \ 366 obstack_finish (__h); }) 367 368# define obstack_copy(OBSTACK,where,length) \ 369__extension__ \ 370({ struct obstack *__h = (OBSTACK); \ 371 obstack_grow (__h, (where), (length)); \ 372 obstack_finish (__h); }) 373 374# define obstack_copy0(OBSTACK,where,length) \ 375__extension__ \ 376({ struct obstack *__h = (OBSTACK); \ 377 obstack_grow0 (__h, (where), (length)); \ 378 obstack_finish (__h); }) 379 380/* The local variable is named __o1 to avoid a name conflict 381 when obstack_blank is called. */ 382# define obstack_finish(OBSTACK) \ 383__extension__ \ 384({ struct obstack *__o1 = (OBSTACK); \ 385 void *__value = (void *) __o1->object_base; \ 386 if (__o1->next_free == __value) \ 387 __o1->maybe_empty_object = 1; \ 388 __o1->next_free \ 389 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 390 __o1->alignment_mask); \ 391 if (__o1->next_free - (char *)__o1->chunk \ 392 > __o1->chunk_limit - (char *)__o1->chunk) \ 393 __o1->next_free = __o1->chunk_limit; \ 394 __o1->object_base = __o1->next_free; \ 395 __value; }) 396 397# define obstack_free(OBSTACK, OBJ) \ 398__extension__ \ 399({ struct obstack *__o = (OBSTACK); \ 400 void *__obj = (OBJ); \ 401 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 402 __o->next_free = __o->object_base = (char *)__obj; \ 403 else (obstack_free) (__o, __obj); }) 404\f 405#else/* not __GNUC__ or not __STDC__ */ 406 407# define obstack_object_size(h) \ 408 (unsigned) ((h)->next_free - (h)->object_base) 409 410# define obstack_room(h) \ 411 (unsigned) ((h)->chunk_limit - (h)->next_free) 412 413# define obstack_empty_p(h) \ 414 ((h)->chunk->prev == 0 \ 415 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 416 (h)->chunk->contents, \ 417 (h)->alignment_mask)) 418 419/* Note that the call to _obstack_newchunk is enclosed in (..., 0) 420 so that we can avoid having void expressions 421 in the arms of the conditional expression. 422 Casting the third operand to void was tried before, 423 but some compilers won't accept it. */ 424 425# define obstack_make_room(h,length) \ 426( (h)->temp.tempint = (length), \ 427 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 428 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 429 430# define obstack_grow(h,where,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 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 435 (h)->next_free += (h)->temp.tempint) 436 437# define obstack_grow0(h,where,length) \ 438( (h)->temp.tempint = (length), \ 439 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 440 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 441 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 442 (h)->next_free += (h)->temp.tempint, \ 443 *((h)->next_free)++ = 0) 444 445# define obstack_1grow(h,datum) \ 446( (((h)->next_free + 1 > (h)->chunk_limit) \ 447 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 448 obstack_1grow_fast (h, datum)) 449 450# define obstack_ptr_grow(h,datum) \ 451( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 452 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 453 obstack_ptr_grow_fast (h, datum)) 454 455# define obstack_int_grow(h,datum) \ 456( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 457 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 458 obstack_int_grow_fast (h, datum)) 459 460# define obstack_ptr_grow_fast(h,aptr) \ 461 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 462 463# define obstack_int_grow_fast(h,aint) \ 464 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 465 466# define obstack_blank(h,length) \ 467( (h)->temp.tempint = (length), \ 468 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 469 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 470 obstack_blank_fast (h, (h)->temp.tempint)) 471 472# define obstack_alloc(h,length) \ 473 (obstack_blank ((h), (length)), obstack_finish ((h))) 474 475# define obstack_copy(h,where,length) \ 476 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 477 478# define obstack_copy0(h,where,length) \ 479 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 480 481# define obstack_finish(h) \ 482( ((h)->next_free == (h)->object_base \ 483 ? (((h)->maybe_empty_object = 1), 0) \ 484 : 0), \ 485 (h)->temp.tempptr = (h)->object_base, \ 486 (h)->next_free \ 487 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 488 (h)->alignment_mask), \ 489 (((h)->next_free - (char *) (h)->chunk \ 490 > (h)->chunk_limit - (char *) (h)->chunk) \ 491 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 492 (h)->object_base = (h)->next_free, \ 493 (h)->temp.tempptr) 494 495# define obstack_free(h,obj) \ 496( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 497 ((((h)->temp.tempint > 0 \ 498 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 499 ? (ptrdiff_t) ((h)->next_free = (h)->object_base \ 500 = (h)->temp.tempint + (char *) (h)->chunk) \ 501 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0))) 502 503#endif/* not __GNUC__ or not __STDC__ */ 504 505#ifdef __cplusplus 506}/* C++ */ 507#endif 508 509#endif/* obstack.h */