libguile/fluids.c

   1 /* Copyright (C) 1996,1997,2000,2001 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, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE 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 the GUILE 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 the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, 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 them.
  37  *
  38  * If you write modifications of your own for GUILE, 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 /* 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
  46 #include "libguile/_scm.h"
  47 #include "libguile/print.h"
  48 #include "libguile/smob.h"
  49 #include "libguile/dynwind.h"
  50 #include "libguile/fluids.h"
  51 #include "libguile/alist.h"
  52 #include "libguile/eval.h"
  53 #include "libguile/ports.h"
  54 #include "libguile/deprecation.h"
  55
  56 #define INITIAL_FLUIDS 10
  57 #include "libguile/validate.h"
  58
  59 static volatile long n_fluids;
  60 scm_t_bits scm_tc16_fluid;
  61
  62 SCM
  63 scm_make_initial_fluids ()
  64 {
  65   return scm_c_make_vector (INITIAL_FLUIDS, SCM_BOOL_F);
  66 }
  67
  68 static void
  69 grow_fluids (scm_root_state *root_state, int new_length)
  70 {
  71   SCM old_fluids, new_fluids;
  72   long old_length, i;
  73
  74   old_fluids = root_state->fluids;
  75   old_length = SCM_VECTOR_LENGTH (old_fluids);
  76   new_fluids = scm_c_make_vector (new_length, SCM_BOOL_F);
  77   i = 0;
  78   while (i < old_length)
  79     {
  80       SCM_VELTS(new_fluids)[i] = SCM_VELTS(old_fluids)[i];
  81       i++;
  82     }
  83   while (i < new_length)
  84     {
  85       SCM_VELTS(new_fluids)[i] = SCM_BOOL_F;
  86       i++;
  87     }
  88
  89   root_state->fluids = new_fluids;
  90 }
  91
  92 void
  93 scm_copy_fluids (scm_root_state *root_state)
  94 {
  95   grow_fluids (root_state, SCM_VECTOR_LENGTH (root_state->fluids));
  96 }
  97
  98 static int
  99 fluid_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED)
 100 {
 101   scm_puts ("#<fluid ", port);
 102   scm_intprint ((int) SCM_FLUID_NUM (exp), 10, port);
 103   scm_putc ('>', port);
 104   return 1;
 105 }
 106
 107 static long
 108 next_fluid_num ()
 109 {
 110   long n;
 111   SCM_CRITICAL_SECTION_START;
 112   n = n_fluids++;
 113   SCM_CRITICAL_SECTION_END;
 114   return n;
 115 }
 116
 117 SCM_DEFINE (scm_make_fluid, "make-fluid", 0, 0, 0,
 118             (),
 119             "Return a newly created fluid.\n"
 120             "Fluids are objects of a certain type (a smob) that can hold one SCM\n"
 121             "value per dynamic root.  That is, modifications to this value are\n"
 122             "only visible to code that executes within the same dynamic root as\n"
 123             "the modifying code.  When a new dynamic root is constructed, it\n"
 124             "inherits the values from its parent.  Because each thread executes\n"
 125             "in its own dynamic root, you can use fluids for thread local storage.")
 126 #define FUNC_NAME s_scm_make_fluid
 127 {
 128   long n;
 129
 130   n = next_fluid_num ();
 131   SCM_RETURN_NEWSMOB (scm_tc16_fluid, n);
 132 }
 133 #undef FUNC_NAME
 134
 135 SCM_DEFINE (scm_fluid_p, "fluid?", 1, 0, 0,
 136             (SCM obj),
 137             "Return @code{#t} iff @var{obj} is a fluid; otherwise, return\n"
 138             "@code{#f}.")
 139 #define FUNC_NAME s_scm_fluid_p
 140 {
 141   return SCM_BOOL(SCM_FLUIDP (obj));
 142 }
 143 #undef FUNC_NAME
 144
 145 SCM_DEFINE (scm_fluid_ref, "fluid-ref", 1, 0, 0,
 146             (SCM fluid),
 147             "Return the value associated with @var{fluid} in the current\n"
 148             "dynamic root.  If @var{fluid} has not been set, then return\n"
 149             "@code{#f}.")
 150 #define FUNC_NAME s_scm_fluid_ref
 151 {
 152   unsigned long int n;
 153
 154   SCM_VALIDATE_FLUID (1, fluid);
 155   n = SCM_FLUID_NUM (fluid);
 156
 157   if (SCM_VECTOR_LENGTH (scm_root->fluids) <= n)
 158     grow_fluids (scm_root, n+1);
 159   return SCM_VELTS (scm_root->fluids)[n];
 160 }
 161 #undef FUNC_NAME
 162
 163 SCM_DEFINE (scm_fluid_set_x, "fluid-set!", 2, 0, 0,
 164             (SCM fluid, SCM value),
 165             "Set the value associated with @var{fluid} in the current dynamic root.")
 166 #define FUNC_NAME s_scm_fluid_set_x
 167 {
 168   unsigned long int n;
 169
 170   SCM_VALIDATE_FLUID (1, fluid);
 171   n = SCM_FLUID_NUM (fluid);
 172
 173   if (SCM_VECTOR_LENGTH (scm_root->fluids) <= n)
 174     grow_fluids (scm_root, n+1);
 175   SCM_VELTS (scm_root->fluids)[n] = value;
 176   return SCM_UNSPECIFIED;
 177 }
 178 #undef FUNC_NAME
 179
 180 void
 181 scm_swap_fluids (SCM fluids, SCM vals)
 182 {
 183   while (!SCM_NULLP (fluids))
 184     {
 185       SCM fl = SCM_CAR (fluids);
 186       SCM old_val = scm_fluid_ref (fl);
 187       scm_fluid_set_x (fl, SCM_CAR (vals));
 188       SCM_SETCAR (vals, old_val);
 189       fluids = SCM_CDR (fluids);
 190       vals = SCM_CDR (vals);
 191     }
 192 }
 193
 194 /* Swap the fluid values in reverse order.  This is important when the
 195 same fluid appears multiple times in the fluids list. */
 196
 197 void
 198 scm_swap_fluids_reverse (SCM fluids, SCM vals)
 199 {
 200   if (!SCM_NULLP (fluids))
 201     {
 202       SCM fl, old_val;
 203
 204       scm_swap_fluids_reverse (SCM_CDR (fluids), SCM_CDR (vals));
 205       fl = SCM_CAR (fluids);
 206       old_val = scm_fluid_ref (fl);
 207       scm_fluid_set_x (fl, SCM_CAR (vals));
 208       SCM_SETCAR (vals, old_val);
 209     }
 210 }
 211
 212
 213 static SCM
 214 apply_thunk (void *thunk)
 215 {
 216   return scm_call_0 (SCM_PACK (thunk));
 217 }
 218
 219 SCM_DEFINE (scm_with_fluids, "with-fluids*", 3, 0, 0,
 220             (SCM fluids, SCM values, SCM thunk),
 221             "Set @var{fluids} to @var{values} temporary, and call @var{thunk}.\n"
 222             "@var{fluids} must be a list of fluids and @var{values} must be the same\n"
 223             "number of their values to be applied.  Each substitution is done\n"
 224             "one after another.  @var{thunk} must be a procedure with no argument.")
 225 #define FUNC_NAME s_scm_with_fluids
 226 {
 227   return scm_c_with_fluids (fluids, values, apply_thunk, (void *) SCM_UNPACK (thunk));
 228 }
 229 #undef FUNC_NAME
 230
 231 SCM
 232 scm_c_with_fluids (SCM fluids, SCM values, SCM (*cproc) (), void *cdata)
 233 #define FUNC_NAME "scm_c_with_fluids"
 234 {
 235   SCM ans;
 236   long flen, vlen;
 237
 238   SCM_VALIDATE_LIST_COPYLEN (1, fluids, flen);
 239   SCM_VALIDATE_LIST_COPYLEN (2, values, vlen);
 240   if (flen != vlen)
 241     scm_out_of_range (s_scm_with_fluids, values);
 242
 243   scm_swap_fluids (fluids, values);
 244   scm_dynwinds = scm_acons (fluids, values, scm_dynwinds);
 245   ans = cproc (cdata);
 246   scm_dynwinds = SCM_CDR (scm_dynwinds);
 247   scm_swap_fluids_reverse (fluids, values);
 248   return ans;
 249 }
 250 #undef FUNC_NAME
 251
 252 SCM
 253 scm_c_with_fluid (SCM fluid, SCM value, SCM (*cproc) (), void *cdata)
 254 #define FUNC_NAME "scm_c_with_fluid"
 255 {
 256   return scm_c_with_fluids (scm_list_1 (fluid), scm_list_1 (value),
 257                             cproc, cdata);
 258 }
 259 #undef FUNC_NAME
 260
 261 void
 262 scm_init_fluids ()
 263 {
 264   scm_tc16_fluid = scm_make_smob_type ("fluid", 0);
 265   scm_set_smob_print (scm_tc16_fluid, fluid_print);
 266 #ifndef SCM_MAGIC_SNARFER
 267 #include "libguile/fluids.x"
 268 #endif
 269 }
 270
 271 #if SCM_DEBUG_DEPRECATED == 0
 272
 273 SCM
 274 scm_internal_with_fluids (SCM fluids, SCM values, SCM (*cproc) (), void *cdata)
 275 {
 276   scm_c_issue_deprecation_warning ("`scm_internal_with_fluids' is deprecated. "
 277                                    "Use `scm_c_with_fluids' instead.");
 278
 279   return scm_c_with_fluids (fluids, values, cproc, cdata);
 280 }
 281
 282 #endif
 283
 284 /*
 285   Local Variables:
 286   c-file-style: "gnu"
 287   End:
 288 */