libguile/weaks.c

   1 /* Copyright (C) 1995,1996,1998,2000,2001 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of this library.
  20  *
  21  * The exception is that, if you link this library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking this library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by
  31  * Free Software Foundation as part of this library.  If you copy
  32  * code from other releases distributed under the terms of the GPL into a copy of
  33  * this library, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from such code.
  37  *
  38  * If you write modifications of your own for this library, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41
  42
  43 \f
  44
  45 #include "libguile/_scm.h"
  46 #include "libguile/vectors.h"
  47 #include "libguile/lang.h"
  48
  49 #include "libguile/validate.h"
  50 #include "libguile/weaks.h"
  51
  52 \f
  53
  54 /* {Weak Vectors}
  55  */
  56
  57
  58 /* Allocate memory for a weak vector on behalf of the caller.  The allocated
  59  * vector will be of the given weak vector subtype.  It will contain size
  60  * elements which are initialized with the 'fill' object, or, if 'fill' is
  61  * undefined, with an unspecified object.
  62  */
  63 static SCM
  64 allocate_weak_vector (scm_t_bits type, SCM size, SCM fill, const char* caller)
  65 #define FUNC_NAME caller
  66 {
  67   if (SCM_INUMP (size))
  68     {
  69       size_t c_size;
  70       SCM v;
  71
  72       SCM_ASSERT_RANGE (1, size, SCM_INUM (size) >= 0);
  73       c_size = SCM_INUM (size);
  74
  75       if (c_size > 0)
  76         {
  77           scm_t_bits *base;
  78           size_t j;
  79
  80           if (SCM_UNBNDP (fill))
  81             fill = SCM_UNSPECIFIED;
  82
  83           SCM_ASSERT_RANGE (1, size, c_size <= SCM_VECTOR_MAX_LENGTH);
  84           base = scm_gc_malloc (c_size * sizeof (scm_t_bits), "weak vector");
  85           for (j = 0; j != c_size; ++j)
  86             base[j] = SCM_UNPACK (fill);
  87           v = scm_double_cell (SCM_MAKE_VECTOR_TAG (c_size, scm_tc7_wvect),
  88                                (scm_t_bits) base,
  89                                type,
  90                                SCM_UNPACK (SCM_EOL));
  91           scm_remember_upto_here_1 (fill);
  92         }
  93       else
  94         {
  95           v = scm_double_cell (SCM_MAKE_VECTOR_TAG (0, scm_tc7_wvect),
  96                                (scm_t_bits) NULL,
  97                                type,
  98                                SCM_UNPACK (SCM_EOL));
  99         }
 100
 101       return v;
 102     }
 103   else if (SCM_BIGP (size))
 104     SCM_OUT_OF_RANGE (1, size);
 105   else
 106     SCM_WRONG_TYPE_ARG (1, size);
 107 }
 108 #undef FUNC_NAME
 109
 110
 111 SCM_DEFINE (scm_make_weak_vector, "make-weak-vector", 1, 1, 0,
 112             (SCM size, SCM fill),
 113             "Return a weak vector with @var{size} elements. If the optional\n"
 114             "argument @var{fill} is given, all entries in the vector will be\n"
 115             "set to @var{fill}. The default value for @var{fill} is the\n"
 116             "empty list.")
 117 #define FUNC_NAME s_scm_make_weak_vector
 118 {
 119   return allocate_weak_vector (0, size, fill, FUNC_NAME);
 120 }
 121 #undef FUNC_NAME
 122
 123
 124 SCM_REGISTER_PROC(s_list_to_weak_vector, "list->weak-vector", 1, 0, 0, scm_weak_vector);
 125
 126 SCM_DEFINE (scm_weak_vector, "weak-vector", 0, 0, 1,
 127            (SCM l),
 128             "@deffnx {Scheme Procedure} list->weak-vector l\n"
 129             "Construct a weak vector from a list: @code{weak-vector} uses\n"
 130             "the list of its arguments while @code{list->weak-vector} uses\n"
 131             "its only argument @var{l} (a list) to construct a weak vector\n"
 132             "the same way @code{list->vector} would.")
 133 #define FUNC_NAME s_scm_weak_vector
 134 {
 135   SCM res;
 136   SCM *data;
 137   long i;
 138
 139   /* Dirk:FIXME:: In case of multiple threads, the list might get corrupted
 140      while the vector is being created. */
 141   i = scm_ilength (l);
 142   SCM_ASSERT (i >= 0, l, SCM_ARG1, FUNC_NAME);
 143   res = scm_make_weak_vector (SCM_MAKINUM (i), SCM_UNSPECIFIED);
 144
 145   /*
 146     no alloc, so  this loop is safe.
 147   */
 148   data = SCM_WRITABLE_VELTS (res);
 149   while (!SCM_NULL_OR_NIL_P (l))
 150     {
 151       *data++ = SCM_CAR (l);
 152       l = SCM_CDR (l);
 153     }
 154
 155   return res;
 156 }
 157 #undef FUNC_NAME
 158
 159
 160 SCM_DEFINE (scm_weak_vector_p, "weak-vector?", 1, 0, 0,
 161             (SCM obj),
 162             "Return @code{#t} if @var{obj} is a weak vector. Note that all\n"
 163             "weak hashes are also weak vectors.")
 164 #define FUNC_NAME s_scm_weak_vector_p
 165 {
 166   return SCM_BOOL (SCM_WVECTP (obj) && !SCM_IS_WHVEC (obj));
 167 }
 168 #undef FUNC_NAME
 169
 170 \f
 171
 172 SCM_DEFINE (scm_make_weak_key_hash_table, "make-weak-key-hash-table", 1, 0, 0,
 173             (SCM size),
 174             "@deffnx {Scheme Procedure} make-weak-value-hash-table size\n"
 175             "@deffnx {Scheme Procedure} make-doubly-weak-hash-table size\n"
 176             "Return a weak hash table with @var{size} buckets. As with any\n"
 177             "hash table, choosing a good size for the table requires some\n"
 178             "caution.\n"
 179             "\n"
 180             "You can modify weak hash tables in exactly the same way you\n"
 181             "would modify regular hash tables. (@pxref{Hash Tables})")
 182 #define FUNC_NAME s_scm_make_weak_key_hash_table
 183 {
 184   return allocate_weak_vector (1, size, SCM_EOL, FUNC_NAME);
 185 }
 186 #undef FUNC_NAME
 187
 188
 189 SCM_DEFINE (scm_make_weak_value_hash_table, "make-weak-value-hash-table", 1, 0, 0,
 190             (SCM size),
 191             "Return a hash table with weak values with @var{size} buckets.\n"
 192             "(@pxref{Hash Tables})")
 193 #define FUNC_NAME s_scm_make_weak_value_hash_table
 194 {
 195   return allocate_weak_vector (2, size, SCM_EOL, FUNC_NAME);
 196 }
 197 #undef FUNC_NAME
 198
 199
 200 SCM_DEFINE (scm_make_doubly_weak_hash_table, "make-doubly-weak-hash-table", 1, 0, 0,
 201             (SCM size),
 202             "Return a hash table with weak keys and values with @var{size}\n"
 203             "buckets.  (@pxref{Hash Tables})")
 204 #define FUNC_NAME s_scm_make_doubly_weak_hash_table
 205 {
 206   return allocate_weak_vector (3, size, SCM_EOL, FUNC_NAME);
 207 }
 208 #undef FUNC_NAME
 209
 210
 211 SCM_DEFINE (scm_weak_key_hash_table_p, "weak-key-hash-table?", 1, 0, 0,
 212            (SCM obj),
 213             "@deffnx {Scheme Procedure} weak-value-hash-table? obj\n"
 214             "@deffnx {Scheme Procedure} doubly-weak-hash-table? obj\n"
 215             "Return @code{#t} if @var{obj} is the specified weak hash\n"
 216             "table. Note that a doubly weak hash table is neither a weak key\n"
 217             "nor a weak value hash table.")
 218 #define FUNC_NAME s_scm_weak_key_hash_table_p
 219 {
 220   return SCM_BOOL (SCM_WVECTP (obj) && SCM_IS_WHVEC (obj));
 221 }
 222 #undef FUNC_NAME
 223
 224
 225 SCM_DEFINE (scm_weak_value_hash_table_p, "weak-value-hash-table?", 1, 0, 0,
 226             (SCM obj),
 227             "Return @code{#t} if @var{obj} is a weak value hash table.")
 228 #define FUNC_NAME s_scm_weak_value_hash_table_p
 229 {
 230   return SCM_BOOL (SCM_WVECTP (obj) && SCM_IS_WHVEC_V (obj));
 231 }
 232 #undef FUNC_NAME
 233
 234
 235 SCM_DEFINE (scm_doubly_weak_hash_table_p, "doubly-weak-hash-table?", 1, 0, 0,
 236             (SCM obj),
 237             "Return @code{#t} if @var{obj} is a doubly weak hash table.")
 238 #define FUNC_NAME s_scm_doubly_weak_hash_table_p
 239 {
 240   return SCM_BOOL (SCM_WVECTP (obj) && SCM_IS_WHVEC_B (obj));
 241 }
 242 #undef FUNC_NAME
 243
 244
 245 static void *
 246 scm_weak_vector_gc_init (void *dummy1 SCM_UNUSED,
 247                          void *dummy2 SCM_UNUSED,
 248                          void *dummy3 SCM_UNUSED)
 249 {
 250   scm_weak_vectors = SCM_EOL;
 251
 252   return 0;
 253 }
 254
 255
 256 static void *
 257 scm_mark_weak_vector_spines (void *dummy1 SCM_UNUSED,
 258                              void *dummy2 SCM_UNUSED,
 259                              void *dummy3 SCM_UNUSED)
 260 {
 261   SCM w;
 262
 263   for (w = scm_weak_vectors; !SCM_NULLP (w); w = SCM_WVECT_GC_CHAIN (w))
 264     {
 265       if (SCM_IS_WHVEC_ANY (w))
 266         {
 267           SCM const *ptr;
 268           SCM obj;
 269           long j;
 270           long n;
 271
 272           obj = w;
 273           ptr = SCM_VELTS (w);
 274           n = SCM_VECTOR_LENGTH (w);
 275           for (j = 0; j < n; ++j)
 276             {
 277               SCM alist;
 278
 279               alist = ptr[j];
 280               while (   SCM_CONSP (alist)
 281                      && !SCM_GC_MARK_P (alist)
 282                      && SCM_CONSP  (SCM_CAR (alist)))
 283                 {
 284                   SCM_SET_GC_MARK (alist);
 285                   SCM_SET_GC_MARK (SCM_CAR (alist));
 286                   alist = SCM_CDR (alist);
 287                 }
 288             }
 289         }
 290     }
 291
 292   return 0;
 293 }
 294
 295 #define UNMARKED_CELL_P(x) (SCM_NIMP(x) && !SCM_GC_MARK_P (x))
 296
 297 static void *
 298 scm_scan_weak_vectors (void *dummy1 SCM_UNUSED,
 299                        void *dummy2 SCM_UNUSED,
 300                        void *dummy3 SCM_UNUSED)
 301 {
 302   SCM *ptr, w;
 303   for (w = scm_weak_vectors; !SCM_NULLP (w); w = SCM_WVECT_GC_CHAIN (w))
 304     {
 305       if (!SCM_IS_WHVEC_ANY (w))
 306         {
 307           register long j, n;
 308
 309           ptr = SCM_GC_WRITABLE_VELTS (w);
 310           n = SCM_VECTOR_LENGTH (w);
 311           for (j = 0; j < n; ++j)
 312             if (UNMARKED_CELL_P (ptr[j]))
 313               ptr[j] = SCM_BOOL_F;
 314         }
 315       else /* if (SCM_IS_WHVEC_ANY (scm_weak_vectors[i])) */
 316         {
 317           SCM obj = w;
 318           register long n = SCM_VECTOR_LENGTH (w);
 319           register long j;
 320           int weak_keys = SCM_IS_WHVEC (obj) || SCM_IS_WHVEC_B (obj);
 321           int weak_values = SCM_IS_WHVEC_V (obj) || SCM_IS_WHVEC_B (obj);
 322
 323           ptr = SCM_GC_WRITABLE_VELTS (w);
 324
 325           for (j = 0; j < n; ++j)
 326             {
 327               SCM * fixup;
 328               SCM alist;
 329
 330               fixup = ptr + j;
 331               alist = *fixup;
 332
 333               while (SCM_CONSP (alist)
 334                      && SCM_CONSP (SCM_CAR (alist)))
 335                 {
 336                   SCM key;
 337                   SCM value;
 338
 339                   key = SCM_CAAR (alist);
 340                   value = SCM_CDAR (alist);
 341                   if (   (weak_keys && UNMARKED_CELL_P (key))
 342                          || (weak_values && UNMARKED_CELL_P (value)))
 343                     {
 344                       *fixup = SCM_CDR (alist);
 345                     }
 346                   else
 347                     fixup = SCM_CDRLOC (alist);
 348                   alist = SCM_CDR (alist);
 349                 }
 350             }
 351         }
 352     }
 353
 354   return 0;
 355 }
 356
 357 \f
 358
 359 void
 360 scm_weaks_prehistory ()
 361 {
 362   scm_c_hook_add (&scm_before_mark_c_hook, scm_weak_vector_gc_init, 0, 0);
 363   scm_c_hook_add (&scm_before_sweep_c_hook, scm_mark_weak_vector_spines, 0, 0);
 364   scm_c_hook_add (&scm_after_sweep_c_hook, scm_scan_weak_vectors, 0, 0);
 365 }
 366
 367
 368 void
 369 scm_init_weaks ()
 370 {
 371 #include "libguile/weaks.x"
 372 }
 373
 374
 375 /*
 376   Local Variables:
 377   c-file-style: "gnu"
 378   End:
 379 */