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, write to the Free 18 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 Boston, MA 02110-1301, USA. */ 20 21/* Summary: 22 23All the apparent functions defined here are macros. The idea 24is that you would use these pre-tested macros to solve a 25very specific set of problems, and they would run fast. 26Caution: no side-effects in arguments please!! They may be 27evaluated MANY times!! 28 29These macros operate a stack of objects. Each object starts life 30small, and may grow to maturity. (Consider building a word syllable 31by syllable.) An object can move while it is growing. Once it has 32been "finished" it never changes address again. So the "top of the 33stack" is typically an immature growing object, while the rest of the 34stack is of mature, fixed size and fixed address objects. 35 36These routines grab large chunks of memory, using a function you 37supply, called `obstack_chunk_alloc'. On occasion, they free chunks, 38by calling `obstack_chunk_free'. You must define them and declare 39them before using any obstack macros. 40 41Each independent stack is represented by a `struct obstack'. 42Each of the obstack macros expects a pointer to such a structure 43as the first argument. 44 45One motivation for this package is the problem of growing char strings 46in symbol tables. Unless you are "fascist pig with a read-only mind" 47--Gosper's immortal quote from HAKMEM item 154, out of context--you 48would not like to put any arbitrary upper limit on the length of your 49symbols. 50 51In practice this often means you will build many short symbols and a 52few long symbols. At the time you are reading a symbol you don't know 53how long it is. One traditional method is to read a symbol into a 54buffer, realloc()ating the buffer every time you try to read a symbol 55that is longer than the buffer. This is beaut, but you still will 56want to copy the symbol from the buffer to a more permanent 57symbol-table entry say about half the time. 58 59With obstacks, you can work differently. Use one obstack for all symbol 60names. As you read a symbol, grow the name in the obstack gradually. 61When the name is complete, finalize it. Then, if the symbol exists already, 62free the newly read name. 63 64The way we do this is to take a large chunk, allocating memory from 65low addresses. When you want to build a symbol in the chunk you just 66add chars above the current "high water mark" in the chunk. When you 67have finished adding chars, because you got to the end of the symbol, 68you know how long the chars are, and you can create a new object. 69Mostly the chars will not burst over the highest address of the chunk, 70because you would typically expect a chunk to be (say) 100 times as 71long as an average object. 72 73In case that isn't clear, when we have enough chars to make up 74the object, THEY ARE ALREADY CONTIGUOUS IN THE CHUNK (guaranteed) 75so we just point to it where it lies. No moving of chars is 76needed and this is the second win: potentially long strings need 77never be explicitly shuffled. Once an object is formed, it does not 78change its address during its lifetime. 79 80When the chars burst over a chunk boundary, we allocate a larger 81chunk, and then copy the partly formed object from the end of the old 82chunk to the beginning of the new larger chunk. We then carry on 83accreting characters to the end of the object as we normally would. 84 85A special macro is provided to add a single char at a time to a 86growing object. This allows the use of register variables, which 87break the ordinary 'growth' macro. 88 89Summary: 90 We allocate large chunks. 91 We carve out one object at a time from the current chunk. 92 Once carved, an object never moves. 93 We are free to append data of any size to the currently 94 growing object. 95 Exactly one object is growing in an obstack at any one time. 96 You can run one obstack per control block. 97 You may have as many control blocks as you dare. 98 Because of the way we do it, you can `unwind' an obstack 99 back to a previous state. (You may remove objects much 100 as you would with a stack.) 101*/ 102 103 104/* Don't do the contents of this file more than once. */ 105 106#ifndef _OBSTACK_H 107#define _OBSTACK_H 1 108 109#ifdef __cplusplus 110extern"C"{ 111#endif 112\f 113/* 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/* Similar 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 144struct _obstack_chunk /* Lives at front of each chunk. */ 145{ 146char*limit;/* 1 past end of this chunk */ 147struct _obstack_chunk *prev;/* address of prior chunk or NULL */ 148char contents[4];/* objects begin here */ 149}; 150 151struct obstack /* control current object in current chunk */ 152{ 153long chunk_size;/* preferred size to allocate chunks in */ 154struct _obstack_chunk *chunk;/* address of current struct obstack_chunk */ 155char*object_base;/* address of object we are building */ 156char*next_free;/* where to add next char to current object */ 157char*chunk_limit;/* address of char after current chunk */ 158union 159{ 160 PTR_INT_TYPE tempint; 161void*tempptr; 162} temp;/* Temporary for some macros. */ 163int 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. */ 167struct _obstack_chunk *(*chunkfun) (void*,long); 168void(*freefun) (void*,struct _obstack_chunk *); 169void*extra_arg;/* first arg for chunk alloc/dealloc funcs */ 170unsigned use_extra_arg:1;/* chunk alloc/dealloc funcs take extra arg */ 171unsigned 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. */ 175unsigned 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 182externvoid_obstack_newchunk(struct obstack *,int); 183externint_obstack_begin(struct obstack *,int,int, 184void*(*) (long),void(*) (void*)); 185externint_obstack_begin_1(struct obstack *,int,int, 186void*(*) (void*,long), 187void(*) (void*,void*),void*); 188externint_obstack_memory_used(struct obstack *); 189 190voidobstack_free(struct obstack *,void*); 191 192\f 193/* Error handler called when `obstack_chunk_alloc' failed to allocate 194 more memory. This can be set to a user defined function which 195 should either abort gracefully or use longjump - but shouldn't 196 return. The default action is to print a message and abort. */ 197externvoid(*obstack_alloc_failed_handler) (void); 198\f 199/* Pointer to beginning of object being allocated or to be allocated next. 200 Note that this might not be the final address of the object 201 because a new chunk might be needed to hold the final size. */ 202 203#define obstack_base(h) ((void *) (h)->object_base) 204 205/* Size for allocating ordinary chunks. */ 206 207#define obstack_chunk_size(h) ((h)->chunk_size) 208 209/* Pointer to next byte not yet allocated in current chunk. */ 210 211#define obstack_next_free(h) ((h)->next_free) 212 213/* Mask specifying low bits that should be clear in address of an object. */ 214 215#define obstack_alignment_mask(h) ((h)->alignment_mask) 216 217/* To prevent prototype warnings provide complete argument list. */ 218#define obstack_init(h) \ 219 _obstack_begin ((h), 0, 0, \ 220 (void *(*) (long)) obstack_chunk_alloc, \ 221 (void (*) (void *)) obstack_chunk_free) 222 223#define obstack_begin(h, size) \ 224 _obstack_begin ((h), (size), 0, \ 225 (void *(*) (long)) obstack_chunk_alloc, \ 226 (void (*) (void *)) obstack_chunk_free) 227 228#define obstack_specify_allocation(h, size, alignment, chunkfun, freefun) \ 229 _obstack_begin ((h), (size), (alignment), \ 230 (void *(*) (long)) (chunkfun), \ 231 (void (*) (void *)) (freefun)) 232 233#define obstack_specify_allocation_with_arg(h, size, alignment, chunkfun, freefun, arg) \ 234 _obstack_begin_1 ((h), (size), (alignment), \ 235 (void *(*) (void *, long)) (chunkfun), \ 236 (void (*) (void *, void *)) (freefun), (arg)) 237 238#define obstack_chunkfun(h, newchunkfun) \ 239 ((h) -> chunkfun = (struct _obstack_chunk *(*)(void *, long)) (newchunkfun)) 240 241#define obstack_freefun(h, newfreefun) \ 242 ((h) -> freefun = (void (*)(void *, struct _obstack_chunk *)) (newfreefun)) 243 244#define obstack_1grow_fast(h,achar) (*((h)->next_free)++ = (achar)) 245 246#define obstack_blank_fast(h,n) ((h)->next_free += (n)) 247 248#define obstack_memory_used(h) _obstack_memory_used (h) 249\f 250#if defined __GNUC__ && defined __STDC__ && __STDC__ 251/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and 252 does not implement __extension__. But that compiler doesn't define 253 __GNUC_MINOR__. */ 254# if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__) 255# define __extension__ 256# endif 257 258/* For GNU C, if not -traditional, 259 we can define these macros to compute all args only once 260 without using a global variable. 261 Also, we can avoid using the `temp' slot, to make faster code. */ 262 263# define obstack_object_size(OBSTACK) \ 264 __extension__ \ 265 ({ struct obstack const *__o = (OBSTACK); \ 266 (unsigned) (__o->next_free - __o->object_base); }) 267 268# define obstack_room(OBSTACK) \ 269 __extension__ \ 270 ({ struct obstack const *__o = (OBSTACK); \ 271 (unsigned) (__o->chunk_limit - __o->next_free); }) 272 273# define obstack_make_room(OBSTACK,length) \ 274__extension__ \ 275({ struct obstack *__o = (OBSTACK); \ 276 int __len = (length); \ 277 if (__o->chunk_limit - __o->next_free < __len) \ 278 _obstack_newchunk (__o, __len); \ 279 (void) 0; }) 280 281# define obstack_empty_p(OBSTACK) \ 282 __extension__ \ 283 ({ struct obstack const *__o = (OBSTACK); \ 284 (__o->chunk->prev == 0 \ 285 && __o->next_free == __PTR_ALIGN ((char *) __o->chunk, \ 286 __o->chunk->contents, \ 287 __o->alignment_mask)); }) 288 289# define obstack_grow(OBSTACK,where,length) \ 290__extension__ \ 291({ struct obstack *__o = (OBSTACK); \ 292 int __len = (length); \ 293 if (__o->next_free + __len > __o->chunk_limit) \ 294 _obstack_newchunk (__o, __len); \ 295 memcpy (__o->next_free, where, __len); \ 296 __o->next_free += __len; \ 297 (void) 0; }) 298 299# define obstack_grow0(OBSTACK,where,length) \ 300__extension__ \ 301({ struct obstack *__o = (OBSTACK); \ 302 int __len = (length); \ 303 if (__o->next_free + __len + 1 > __o->chunk_limit) \ 304 _obstack_newchunk (__o, __len + 1); \ 305 memcpy (__o->next_free, where, __len); \ 306 __o->next_free += __len; \ 307 *(__o->next_free)++ = 0; \ 308 (void) 0; }) 309 310# define obstack_1grow(OBSTACK,datum) \ 311__extension__ \ 312({ struct obstack *__o = (OBSTACK); \ 313 if (__o->next_free + 1 > __o->chunk_limit) \ 314 _obstack_newchunk (__o, 1); \ 315 obstack_1grow_fast (__o, datum); \ 316 (void) 0; }) 317 318/* These assume that the obstack alignment is good enough for pointers 319 or ints, and that the data added so far to the current object 320 shares that much alignment. */ 321 322# define obstack_ptr_grow(OBSTACK,datum) \ 323__extension__ \ 324({ struct obstack *__o = (OBSTACK); \ 325 if (__o->next_free + sizeof (void *) > __o->chunk_limit) \ 326 _obstack_newchunk (__o, sizeof (void *)); \ 327 obstack_ptr_grow_fast (__o, datum); }) \ 328 329# define obstack_int_grow(OBSTACK,datum) \ 330__extension__ \ 331({ struct obstack *__o = (OBSTACK); \ 332 if (__o->next_free + sizeof (int) > __o->chunk_limit) \ 333 _obstack_newchunk (__o, sizeof (int)); \ 334 obstack_int_grow_fast (__o, datum); }) 335 336# define obstack_ptr_grow_fast(OBSTACK,aptr) \ 337__extension__ \ 338({ struct obstack *__o1 = (OBSTACK); \ 339 *(const void **) __o1->next_free = (aptr); \ 340 __o1->next_free += sizeof (const void *); \ 341 (void) 0; }) 342 343# define obstack_int_grow_fast(OBSTACK,aint) \ 344__extension__ \ 345({ struct obstack *__o1 = (OBSTACK); \ 346 *(int *) __o1->next_free = (aint); \ 347 __o1->next_free += sizeof (int); \ 348 (void) 0; }) 349 350# define obstack_blank(OBSTACK,length) \ 351__extension__ \ 352({ struct obstack *__o = (OBSTACK); \ 353 int __len = (length); \ 354 if (__o->chunk_limit - __o->next_free < __len) \ 355 _obstack_newchunk (__o, __len); \ 356 obstack_blank_fast (__o, __len); \ 357 (void) 0; }) 358 359# define obstack_alloc(OBSTACK,length) \ 360__extension__ \ 361({ struct obstack *__h = (OBSTACK); \ 362 obstack_blank (__h, (length)); \ 363 obstack_finish (__h); }) 364 365# define obstack_copy(OBSTACK,where,length) \ 366__extension__ \ 367({ struct obstack *__h = (OBSTACK); \ 368 obstack_grow (__h, (where), (length)); \ 369 obstack_finish (__h); }) 370 371# define obstack_copy0(OBSTACK,where,length) \ 372__extension__ \ 373({ struct obstack *__h = (OBSTACK); \ 374 obstack_grow0 (__h, (where), (length)); \ 375 obstack_finish (__h); }) 376 377/* The local variable is named __o1 to avoid a name conflict 378 when obstack_blank is called. */ 379# define obstack_finish(OBSTACK) \ 380__extension__ \ 381({ struct obstack *__o1 = (OBSTACK); \ 382 void *__value = (void *) __o1->object_base; \ 383 if (__o1->next_free == __value) \ 384 __o1->maybe_empty_object = 1; \ 385 __o1->next_free \ 386 = __PTR_ALIGN (__o1->object_base, __o1->next_free, \ 387 __o1->alignment_mask); \ 388 if (__o1->next_free - (char *)__o1->chunk \ 389 > __o1->chunk_limit - (char *)__o1->chunk) \ 390 __o1->next_free = __o1->chunk_limit; \ 391 __o1->object_base = __o1->next_free; \ 392 __value; }) 393 394# define obstack_free(OBSTACK, OBJ) \ 395__extension__ \ 396({ struct obstack *__o = (OBSTACK); \ 397 void *__obj = (OBJ); \ 398 if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit) \ 399 __o->next_free = __o->object_base = (char *)__obj; \ 400 else (obstack_free) (__o, __obj); }) 401\f 402#else/* not __GNUC__ or not __STDC__ */ 403 404# define obstack_object_size(h) \ 405 (unsigned) ((h)->next_free - (h)->object_base) 406 407# define obstack_room(h) \ 408 (unsigned) ((h)->chunk_limit - (h)->next_free) 409 410# define obstack_empty_p(h) \ 411 ((h)->chunk->prev == 0 \ 412 && (h)->next_free == __PTR_ALIGN ((char *) (h)->chunk, \ 413 (h)->chunk->contents, \ 414 (h)->alignment_mask)) 415 416/* Note that the call to _obstack_newchunk is enclosed in (..., 0) 417 so that we can avoid having void expressions 418 in the arms of the conditional expression. 419 Casting the third operand to void was tried before, 420 but some compilers won't accept it. */ 421 422# define obstack_make_room(h,length) \ 423( (h)->temp.tempint = (length), \ 424 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 425 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0)) 426 427# define obstack_grow(h,where,length) \ 428( (h)->temp.tempint = (length), \ 429 (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit) \ 430 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 431 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 432 (h)->next_free += (h)->temp.tempint) 433 434# define obstack_grow0(h,where,length) \ 435( (h)->temp.tempint = (length), \ 436 (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit) \ 437 ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0), \ 438 memcpy ((h)->next_free, where, (h)->temp.tempint), \ 439 (h)->next_free += (h)->temp.tempint, \ 440 *((h)->next_free)++ = 0) 441 442# define obstack_1grow(h,datum) \ 443( (((h)->next_free + 1 > (h)->chunk_limit) \ 444 ? (_obstack_newchunk ((h), 1), 0) : 0), \ 445 obstack_1grow_fast (h, datum)) 446 447# define obstack_ptr_grow(h,datum) \ 448( (((h)->next_free + sizeof (char *) > (h)->chunk_limit) \ 449 ? (_obstack_newchunk ((h), sizeof (char *)), 0) : 0), \ 450 obstack_ptr_grow_fast (h, datum)) 451 452# define obstack_int_grow(h,datum) \ 453( (((h)->next_free + sizeof (int) > (h)->chunk_limit) \ 454 ? (_obstack_newchunk ((h), sizeof (int)), 0) : 0), \ 455 obstack_int_grow_fast (h, datum)) 456 457# define obstack_ptr_grow_fast(h,aptr) \ 458 (((const void **) ((h)->next_free += sizeof (void *)))[-1] = (aptr)) 459 460# define obstack_int_grow_fast(h,aint) \ 461 (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint)) 462 463# define obstack_blank(h,length) \ 464( (h)->temp.tempint = (length), \ 465 (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint) \ 466 ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0), \ 467 obstack_blank_fast (h, (h)->temp.tempint)) 468 469# define obstack_alloc(h,length) \ 470 (obstack_blank ((h), (length)), obstack_finish ((h))) 471 472# define obstack_copy(h,where,length) \ 473 (obstack_grow ((h), (where), (length)), obstack_finish ((h))) 474 475# define obstack_copy0(h,where,length) \ 476 (obstack_grow0 ((h), (where), (length)), obstack_finish ((h))) 477 478# define obstack_finish(h) \ 479( ((h)->next_free == (h)->object_base \ 480 ? (((h)->maybe_empty_object = 1), 0) \ 481 : 0), \ 482 (h)->temp.tempptr = (h)->object_base, \ 483 (h)->next_free \ 484 = __PTR_ALIGN ((h)->object_base, (h)->next_free, \ 485 (h)->alignment_mask), \ 486 (((h)->next_free - (char *) (h)->chunk \ 487 > (h)->chunk_limit - (char *) (h)->chunk) \ 488 ? ((h)->next_free = (h)->chunk_limit) : 0), \ 489 (h)->object_base = (h)->next_free, \ 490 (h)->temp.tempptr) 491 492# define obstack_free(h,obj) \ 493( (h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk, \ 494 ((((h)->temp.tempint > 0 \ 495 && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk)) \ 496 ? (int) ((h)->next_free = (h)->object_base \ 497 = (h)->temp.tempint + (char *) (h)->chunk) \ 498 : (((obstack_free) ((h), (h)->temp.tempint + (char *) (h)->chunk), 0), 0))) 499 500#endif/* not __GNUC__ or not __STDC__ */ 501 502#ifdef __cplusplus 503}/* C++ */ 504#endif 505 506#endif/* obstack.h */