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', and we use 164 casts to the prototypeless function type in all assignments, 165 but having prototypes here quiets -Wstrict-prototypes. */ 166struct _obstack_chunk *(*chunkfun) (void*,long); 167void(*freefun) (void*,struct _obstack_chunk *); 168void*extra_arg;/* first arg for chunk alloc/dealloc funcs */ 169unsigned use_extra_arg:1;/* chunk alloc/dealloc funcs take extra arg */ 170unsigned 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. */ 174unsigned 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 181externvoid_obstack_newchunk(struct obstack *,int); 182externint_obstack_begin(struct obstack *,int,int, 183void*(*) (long),void(*) (void*)); 184externint_obstack_begin_1(struct obstack *,int,int, 185void*(*) (void*,long), 186void(*) (void*,void*),void*); 187externint_obstack_memory_used(struct obstack *); 188 189voidobstack_free(struct obstack *,void*); 190 191\f 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. */ 196externvoid(*obstack_alloc_failed_handler) (void); 197\f 198/* Pointer to beginning of object being allocated or to be allocated next. 199 Note that this might not be the final address of the object 200 because a new chunk might be needed to hold the final size. */ 201 202#define obstack_base(h) ((void *) (h)->object_base) 203 204/* Size for allocating ordinary chunks. */ 205 206#define obstack_chunk_size(h) ((h)->chunk_size) 207 208/* Pointer to next byte not yet allocated in current chunk. */ 209 210#define obstack_next_free(h) ((h)->next_free) 211 212/* Mask specifying low bits that should be clear in address of an object. */ 213 214#define obstack_alignment_mask(h) ((h)->alignment_mask) 215 216/* To prevent prototype warnings provide complete argument list. */ 217#define obstack_init(h) \ 218 _obstack_begin ((h), 0, 0, \ 219 (void *(*) (long)) obstack_chunk_alloc, \ 220 (void (*) (void *)) obstack_chunk_free) 221 222#define obstack_begin(h, size) \ 223 _obstack_begin ((h), (size), 0, \ 224 (void *(*) (long)) obstack_chunk_alloc, \ 225 (void (*) (void *)) obstack_chunk_free) 226 227#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 228 _obstack_begin ((h), (size), (alignment), \ 229 (void *(*) (long)) (chunkfun), \ 230 (void (*) (void *)) (freefun)) 231 232#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 233 _obstack_begin_1 ((h), (size), (alignment), \ 234 (void *(*) (void *, long)) (chunkfun), \ 235 (void (*) (void *, void *)) (freefun), (arg)) 236 237#define obstack_chunkfun(h, newchunkfun) \ 238 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 239 240#define obstack_freefun(h, newfreefun) \ 241 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 242 243#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 244 245#define obstack_blank_fast(h,n) ((h)->next_free += (n)) 246 247#define obstack_memory_used(h) _obstack_memory_used (h) 248\f 249#if defined __GNUC__ && defined __STDC__ && __STDC__ 250/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 251 does not implement __extension__. But that compiler doesn't define 252 __GNUC_MINOR__. */ 253# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 254# define __extension__ 255# endif 256 257/* For GNU C, if not -traditional, 258 we can define these macros to compute all args only once 259 without using a global variable. 260 Also, we can avoid using the `temp' slot, to make faster code. */ 261 262# define obstack_object_size(OBSTACK) \ 263 __extension__ \ 264 ({ struct obstack const *__o = (OBSTACK); \ 265 (unsigned) (__o->next_free - __o->object_base); }) 266 267# define obstack_room(OBSTACK) \ 268 __extension__ \ 269 ({ struct obstack const *__o = (OBSTACK); \ 270 (unsigned) (__o->chunk_limit - __o->next_free); }) 271 272# define obstack_make_room(OBSTACK,length) \ 273__extension__ \ 274({ struct obstack *__o = (OBSTACK); \ 275 int __len = (length); \ 276 if (__o->chunk_limit - __o->next_free < __len) \ 277 _obstack_newchunk (__o, __len); \ 278 (void) 0; }) 279 280# define obstack_empty_p(OBSTACK) \ 281 __extension__ \ 282 ({ struct obstack const *__o = (OBSTACK); \ 283 (__o->chunk->prev == 0 \ 284 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 285 __o->chunk->contents, \ 286 __o->alignment_mask)); }) 287 288# define obstack_grow(OBSTACK,where,length) \ 289__extension__ \ 290({ struct obstack *__o = (OBSTACK); \ 291 int __len = (length); \ 292 if (__o->next_free + __len > __o->chunk_limit) \ 293 _obstack_newchunk (__o, __len); \ 294 memcpy (__o->next_free, where, __len); \ 295 __o->next_free += __len; \ 296 (void) 0; }) 297 298# define obstack_grow0(OBSTACK,where,length) \ 299__extension__ \ 300({ struct obstack *__o = (OBSTACK); \ 301 int __len = (length); \ 302 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 303 _obstack_newchunk (__o, __len + 1); \ 304 memcpy (__o->next_free, where, __len); \ 305 __o->next_free += __len; \ 306 *(__o->next_free)++ = 0; \ 307 (void) 0; }) 308 309# define obstack_1grow(OBSTACK,datum) \ 310__extension__ \ 311({ struct obstack *__o = (OBSTACK); \ 312 if (__o->next_free + 1 > __o->chunk_limit) \ 313 _obstack_newchunk (__o, 1); \ 314 obstack_1grow_fast (__o, datum); \ 315 (void) 0; }) 316 317/* These assume that the obstack alignment is good enough for pointers 318 or ints, and that the data added so far to the current object 319 shares that much alignment. */ 320 321# define obstack_ptr_grow(OBSTACK,datum) \ 322__extension__ \ 323({ struct obstack *__o = (OBSTACK); \ 324 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 325 _obstack_newchunk (__o, sizeof (void *)); \ 326 obstack_ptr_grow_fast (__o, datum); }) \ 327 328# define obstack_int_grow(OBSTACK,datum) \ 329__extension__ \ 330({ struct obstack *__o = (OBSTACK); \ 331 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 332 _obstack_newchunk (__o, sizeof (int)); \ 333 obstack_int_grow_fast (__o, datum); }) 334 335# define obstack_ptr_grow_fast(OBSTACK,aptr) \ 336__extension__ \ 337({ struct obstack *__o1 = (OBSTACK); \ 338 *(const void **) __o1->next_free = (aptr); \ 339 __o1->next_free += sizeof (const void *); \ 340 (void) 0; }) 341 342# define obstack_int_grow_fast(OBSTACK,aint) \ 343__extension__ \ 344({ struct obstack *__o1 = (OBSTACK); \ 345 *(int *) __o1->next_free = (aint); \ 346 __o1->next_free += sizeof (int); \ 347 (void) 0; }) 348 349# define obstack_blank(OBSTACK,length) \ 350__extension__ \ 351({ struct obstack *__o = (OBSTACK); \ 352 int __len = (length); \ 353 if (__o->chunk_limit - __o->next_free < __len) \ 354 _obstack_newchunk (__o, __len); \ 355 obstack_blank_fast (__o, __len); \ 356 (void) 0; }) 357 358# define obstack_alloc(OBSTACK,length) \ 359__extension__ \ 360({ struct obstack *__h = (OBSTACK); \ 361 obstack_blank (__h, (length)); \ 362 obstack_finish (__h); }) 363 364# define obstack_copy(OBSTACK,where,length) \ 365__extension__ \ 366({ struct obstack *__h = (OBSTACK); \ 367 obstack_grow (__h, (where), (length)); \ 368 obstack_finish (__h); }) 369 370# define obstack_copy0(OBSTACK,where,length) \ 371__extension__ \ 372({ struct obstack *__h = (OBSTACK); \ 373 obstack_grow0 (__h, (where), (length)); \ 374 obstack_finish (__h); }) 375 376/* The local variable is named __o1 to avoid a name conflict 377 when obstack_blank is called. */ 378# define obstack_finish(OBSTACK) \ 379__extension__ \ 380({ struct obstack *__o1 = (OBSTACK); \ 381 void *__value = (void *) __o1->object_base; \ 382 if (__o1->next_free == __value) \ 383 __o1->maybe_empty_object = 1; \ 384 __o1->next_free \ 385 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 386 __o1->alignment_mask); \ 387 if (__o1->next_free - (char *)__o1->chunk \ 388 > __o1->chunk_limit - (char *)__o1->chunk) \ 389 __o1->next_free = __o1->chunk_limit; \ 390 __o1->object_base = __o1->next_free; \ 391 __value; }) 392 393# define obstack_free(OBSTACK, OBJ) \ 394__extension__ \ 395({ struct obstack *__o = (OBSTACK); \ 396 void *__obj = (OBJ); \ 397 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 398 __o->next_free = __o->object_base = (char *)__obj; \ 399 else (obstack_free) (__o, __obj); }) 400\f 401#else/* not __GNUC__ or not __STDC__ */ 402 403# define obstack_object_size(h) \ 404 (unsigned) ((h)->next_free - (h)->object_base) 405 406# define obstack_room(h) \ 407 (unsigned) ((h)->chunk_limit - (h)->next_free) 408 409# define obstack_empty_p(h) \ 410 ((h)->chunk->prev == 0 \ 411 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 412 (h)->chunk->contents, \ 413 (h)->alignment_mask)) 414 415/* Note that the call to _obstack_newchunk is enclosed in (..., 0) 416 so that we can avoid having void expressions 417 in the arms of the conditional expression. 418 Casting the third operand to void was tried before, 419 but some compilers won't accept it. */ 420 421# define obstack_make_room(h,length) \ 422( (h)->temp.tempint = (length), \ 423 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 424 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 425 426# define obstack_grow(h,where,length) \ 427( (h)->temp.tempint = (length), \ 428 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 429 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 430 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 431 (h)->next_free += (h)->temp.tempint) 432 433# define obstack_grow0(h,where,length) \ 434( (h)->temp.tempint = (length), \ 435 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 436 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 437 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 438 (h)->next_free += (h)->temp.tempint, \ 439 *((h)->next_free)++ = 0) 440 441# define obstack_1grow(h,datum) \ 442( (((h)->next_free + 1 > (h)->chunk_limit) \ 443 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 444 obstack_1grow_fast (h, datum)) 445 446# define obstack_ptr_grow(h,datum) \ 447( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 448 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 449 obstack_ptr_grow_fast (h, datum)) 450 451# define obstack_int_grow(h,datum) \ 452( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 453 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 454 obstack_int_grow_fast (h, datum)) 455 456# define obstack_ptr_grow_fast(h,aptr) \ 457 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 458 459# define obstack_int_grow_fast(h,aint) \ 460 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 461 462# define obstack_blank(h,length) \ 463( (h)->temp.tempint = (length), \ 464 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 465 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 466 obstack_blank_fast (h, (h)->temp.tempint)) 467 468# define obstack_alloc(h,length) \ 469 (obstack_blank ((h), (length)), obstack_finish ((h))) 470 471# define obstack_copy(h,where,length) \ 472 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 473 474# define obstack_copy0(h,where,length) \ 475 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 476 477# define obstack_finish(h) \ 478( ((h)->next_free == (h)->object_base \ 479 ? (((h)->maybe_empty_object = 1), 0) \ 480 : 0), \ 481 (h)->temp.tempptr = (h)->object_base, \ 482 (h)->next_free \ 483 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 484 (h)->alignment_mask), \ 485 (((h)->next_free - (char *) (h)->chunk \ 486 > (h)->chunk_limit - (char *) (h)->chunk) \ 487 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 488 (h)->object_base = (h)->next_free, \ 489 (h)->temp.tempptr) 490 491# define obstack_free(h,obj) \ 492( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 493 ((((h)->temp.tempint > 0 \ 494 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 495 ? (int) ((h)->next_free = (h)->object_base \ 496 = (h)->temp.tempint + (char *) (h)->chunk) \ 497 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0))) 498 499#endif/* not __GNUC__ or not __STDC__ */ 500 501#ifdef __cplusplus 502}/* C++ */ 503#endif 504 505#endif/* obstack.h */