libguile/weaks.c

   1 /*      Copyright (C) 1995,1996,1998, 2000 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.
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  40  * If you do not wish that, delete this exception notice.  */
  41
  42 /* Software engineering face-lift by Greg J. Badros, 11-Dec-1999,
  43    gjb@cs.washington.edu, http://www.cs.washington.edu/homes/gjb */
  44
  45 \f
  46 #include <stdio.h>
  47 #include "libguile/_scm.h"
  48 #include "libguile/vectors.h"
  49
  50 #include "libguile/validate.h"
  51 #include "libguile/weaks.h"
  52 \f
  53
  54
  55 /* {Weak Vectors}
  56  */
  57
  58
  59 SCM_DEFINE (scm_make_weak_vector, "make-weak-vector", 1, 1, 0,
  60            (SCM k, SCM fill),
  61             "Return a weak vector with @var{size} elements. If the optional\n"
  62             "argument @var{fill} is given, all entries in the vector will be set to\n"
  63             "@var{fill}. The default value for @var{fill} is the empty list.")
  64 #define FUNC_NAME s_scm_make_weak_vector
  65 {
  66   /* Dirk:FIXME:: We should probably rather use a double cell for weak vectors. */
  67   SCM v;
  68   v = scm_make_vector (scm_sum (k, SCM_MAKINUM (2)), fill);
  69   SCM_DEFER_INTS;
  70   SCM_SET_VECTOR_LENGTH (v, SCM_INUM (k), scm_tc7_wvect);
  71   SCM_SETVELTS(v, SCM_VELTS(v) + 2);
  72   SCM_VELTS(v)[-2] = SCM_EOL;
  73   SCM_UNPACK (SCM_VELTS (v)[-1]) = 0;
  74   SCM_ALLOW_INTS;
  75   return v;
  76 }
  77 #undef FUNC_NAME
  78
  79
  80 SCM_REGISTER_PROC(s_list_to_weak_vector, "list->weak-vector", 1, 0, 0, scm_weak_vector);
  81
  82 SCM_DEFINE (scm_weak_vector, "weak-vector", 0, 0, 1,
  83            (SCM l),
  84             "@deffnx primitive list->weak-vector l\n"
  85             "Construct a weak vector from a list: @code{weak-vector} uses the list of\n"
  86             "its arguments while @code{list->weak-vector} uses its only argument\n"
  87             "@var{l} (a list) to construct a weak vector the same way\n"
  88             "@code{vector->list} would.")
  89 #define FUNC_NAME s_scm_weak_vector
  90 {
  91   SCM res;
  92   register SCM *data;
  93   long i;
  94
  95   i = scm_ilength (l);
  96   SCM_ASSERT (i >= 0, l, SCM_ARG1, FUNC_NAME);
  97   res = scm_make_weak_vector (SCM_MAKINUM (i), SCM_UNSPECIFIED);
  98   data = SCM_VELTS (res);
  99   for (;
 100        i && SCM_CONSP (l);
 101        --i, l = SCM_CDR (l))
 102     *data++ = SCM_CAR (l);
 103   return res;
 104 }
 105 #undef FUNC_NAME
 106
 107
 108 SCM_DEFINE (scm_weak_vector_p, "weak-vector?", 1, 0, 0,
 109            (SCM x),
 110             "Return @var{#t} if @var{obj} is a weak vector. Note that all weak\n"
 111             "hashes are also weak vectors.")
 112 #define FUNC_NAME s_scm_weak_vector_p
 113 {
 114   return SCM_BOOL(SCM_WVECTP (x) && !SCM_IS_WHVEC (x));
 115 }
 116 #undef FUNC_NAME
 117
 118
 119
 120 \f
 121
 122
 123
 124 SCM_DEFINE (scm_make_weak_key_hash_table, "make-weak-key-hash-table", 1, 0, 0,
 125            (SCM k),
 126             "@deffnx primitive make-weak-value-hash-table size\n"
 127             "@deffnx primitive make-doubly-weak-hash-table size\n"
 128             "Return a weak hash table with @var{size} buckets. As with any hash\n"
 129             "table, choosing a good size for the table requires some caution.\n\n"
 130             "You can modify weak hash tables in exactly the same way you would modify\n"
 131             "regular hash tables. (@pxref{Hash Tables})")
 132 #define FUNC_NAME s_scm_make_weak_key_hash_table
 133 {
 134   SCM v;
 135   SCM_VALIDATE_INUM (1,k);
 136   v = scm_make_weak_vector (k, SCM_EOL);
 137   SCM_DEFER_INTS;
 138   SCM_UNPACK (SCM_VELTS (v)[-1]) = 1;
 139   SCM_ALLOW_INTS;
 140   return v;
 141 }
 142 #undef FUNC_NAME
 143
 144
 145 SCM_DEFINE (scm_make_weak_value_hash_table, "make-weak-value-hash-table", 1, 0, 0,
 146             (SCM k),
 147             "")
 148 #define FUNC_NAME s_scm_make_weak_value_hash_table
 149 {
 150   SCM v;
 151   SCM_VALIDATE_INUM (1,k);
 152   v = scm_make_weak_vector (k, SCM_EOL);
 153   SCM_DEFER_INTS;
 154   SCM_UNPACK (SCM_VELTS (v)[-1]) = 2;
 155   SCM_ALLOW_INTS;
 156   return v;
 157 }
 158 #undef FUNC_NAME
 159
 160
 161
 162 SCM_DEFINE (scm_make_doubly_weak_hash_table, "make-doubly-weak-hash-table", 1, 0, 0,
 163             (SCM k),
 164             "")
 165 #define FUNC_NAME s_scm_make_doubly_weak_hash_table
 166 {
 167   SCM v;
 168   SCM_VALIDATE_INUM (1,k);
 169   v = scm_make_weak_vector (k, SCM_EOL);
 170   SCM_DEFER_INTS;
 171   SCM_UNPACK (SCM_VELTS (v)[-1]) = 3;
 172   SCM_ALLOW_INTS;
 173   return v;
 174 }
 175 #undef FUNC_NAME
 176
 177 SCM_DEFINE (scm_weak_key_hash_table_p, "weak-key-hash-table?", 1, 0, 0,
 178            (SCM x),
 179             "@deffnx primitive weak-value-hash-table? obj\n"
 180             "@deffnx primitive doubly-weak-hash-table? obj\n"
 181             "Return @var{#t} if @var{obj} is the specified weak hash table. Note\n"
 182             "that a doubly weak hash table is neither a weak key nor a weak value\n"
 183             "hash table.")
 184 #define FUNC_NAME s_scm_weak_key_hash_table_p
 185 {
 186   return SCM_BOOL(SCM_WVECTP (x) && SCM_IS_WHVEC(x));
 187 }
 188 #undef FUNC_NAME
 189
 190
 191 SCM_DEFINE (scm_weak_value_hash_table_p, "weak-value-hash-table?", 1, 0, 0,
 192             (SCM x),
 193             "")
 194 #define FUNC_NAME s_scm_weak_value_hash_table_p
 195 {
 196   return SCM_BOOL(SCM_WVECTP (x) && SCM_IS_WHVEC_V(x));
 197 }
 198 #undef FUNC_NAME
 199
 200
 201 SCM_DEFINE (scm_doubly_weak_hash_table_p, "doubly-weak-hash-table?", 1, 0, 0,
 202             (SCM x),
 203             "")
 204 #define FUNC_NAME s_scm_doubly_weak_hash_table_p
 205 {
 206   return SCM_BOOL(SCM_WVECTP (x) && SCM_IS_WHVEC_B (x));
 207 }
 208 #undef FUNC_NAME
 209
 210 static void *
 211 scm_weak_vector_gc_init (void *dummy1, void *dummy2, void *dummy3)
 212 {
 213   scm_weak_vectors = SCM_EOL;
 214
 215   return 0;
 216 }
 217
 218 static void *
 219 scm_mark_weak_vector_spines (void *dummy1, void *dummy2, void *dummy3)
 220 {
 221   SCM w;
 222
 223   for (w = scm_weak_vectors; !SCM_NULLP (w); w = SCM_WVECT_GC_CHAIN (w))
 224     {
 225       if (SCM_IS_WHVEC_ANY (w))
 226         {
 227           SCM *ptr;
 228           SCM obj;
 229           int j;
 230           int n;
 231
 232           obj = w;
 233           ptr = SCM_VELTS (w);
 234           n = SCM_VECTOR_LENGTH (w);
 235           for (j = 0; j < n; ++j)
 236             {
 237               SCM alist;
 238
 239               alist = ptr[j];
 240               while (   SCM_CONSP (alist)
 241                      && !SCM_GCMARKP (alist)
 242                      && SCM_CONSP  (SCM_CAR (alist)))
 243                 {
 244                   SCM_SETGCMARK (alist);
 245                   SCM_SETGCMARK (SCM_CAR (alist));
 246                   alist = SCM_GCCDR (alist);
 247                 }
 248             }
 249         }
 250     }
 251
 252   return 0;
 253 }
 254
 255 static void *
 256 scm_scan_weak_vectors (void *dummy1, void *dummy2, void *dummy3)
 257 {
 258   SCM *ptr, w;
 259   for (w = scm_weak_vectors; !SCM_NULLP (w); w = SCM_WVECT_GC_CHAIN (w))
 260     {
 261       if (!SCM_IS_WHVEC_ANY (w))
 262         {
 263           register long j, n;
 264
 265           ptr = SCM_VELTS (w);
 266           n = SCM_VECTOR_LENGTH (w);
 267           for (j = 0; j < n; ++j)
 268             if (SCM_FREE_CELL_P (ptr[j]))
 269               ptr[j] = SCM_BOOL_F;
 270         }
 271       else /* if (SCM_IS_WHVEC_ANY (scm_weak_vectors[i])) */
 272         {
 273           SCM obj = w;
 274           register long n = SCM_VECTOR_LENGTH (w);
 275           register long j;
 276
 277           ptr = SCM_VELTS (w);
 278
 279           for (j = 0; j < n; ++j)
 280             {
 281               SCM * fixup;
 282               SCM alist;
 283               int weak_keys;
 284               int weak_values;
 285
 286               weak_keys = SCM_IS_WHVEC (obj) || SCM_IS_WHVEC_B (obj);
 287               weak_values = SCM_IS_WHVEC_V (obj) || SCM_IS_WHVEC_B (obj);
 288
 289               fixup = ptr + j;
 290               alist = *fixup;
 291
 292               while (   SCM_CONSP (alist)
 293                         && SCM_CONSP (SCM_CAR (alist)))
 294                 {
 295                   SCM key;
 296                   SCM value;
 297
 298                   key = SCM_CAAR (alist);
 299                   value = SCM_CDAR (alist);
 300                   if (   (weak_keys && SCM_FREE_CELL_P (key))
 301                          || (weak_values && SCM_FREE_CELL_P (value)))
 302                     {
 303                       *fixup = SCM_CDR (alist);
 304                     }
 305                   else
 306                     fixup = SCM_CDRLOC (alist);
 307                   alist = SCM_CDR (alist);
 308                 }
 309             }
 310         }
 311     }
 312
 313   return 0;
 314 }
 315
 316
 317 \f
 318
 319
 320 void
 321 scm_weaks_prehistory ()
 322 {
 323   scm_c_hook_add (&scm_before_mark_c_hook, scm_weak_vector_gc_init, 0, 0);
 324   scm_c_hook_add (&scm_before_sweep_c_hook, scm_mark_weak_vector_spines, 0, 0);
 325   scm_c_hook_add (&scm_after_sweep_c_hook, scm_scan_weak_vectors, 0, 0);
 326 }
 327
 328 void
 329 scm_init_weaks ()
 330 {
 331 #ifndef SCM_MAGIC_SNARFER
 332 #include "libguile/weaks.x"
 333 #endif
 334 }
 335
 336
 337 /*
 338   Local Variables:
 339   c-file-style: "gnu"
 340   End:
 341 */