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
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  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
  43
  44 #include "libguile/_scm.h"
  45 #include "libguile/print.h"
  46 #include "libguile/smob.h"
  47 #include "libguile/dynwind.h"
  48 #include "libguile/fluids.h"
  49 #include "libguile/alist.h"
  50 #include "libguile/eval.h"
  51 #include "libguile/ports.h"
  52 #include "libguile/deprecation.h"
  53
  54 #define INITIAL_FLUIDS 10
  55 #include "libguile/validate.h"
  56
  57 static volatile long n_fluids;
  58 scm_t_bits scm_tc16_fluid;
  59
  60 SCM
  61 scm_make_initial_fluids ()
  62 {
  63   return scm_c_make_vector (INITIAL_FLUIDS, SCM_BOOL_F);
  64 }
  65
  66 static void
  67 grow_fluids (scm_root_state *root_state, int new_length)
  68 {
  69   SCM old_fluids, new_fluids;
  70   long old_length, i;
  71
  72   old_fluids = root_state->fluids;
  73   old_length = SCM_VECTOR_LENGTH (old_fluids);
  74   new_fluids = scm_c_make_vector (new_length, SCM_BOOL_F);
  75   i = 0;
  76   while (i < old_length)
  77     {
  78       SCM_VELTS(new_fluids)[i] = SCM_VELTS(old_fluids)[i];
  79       i++;
  80     }
  81   while (i < new_length)
  82     {
  83       SCM_VELTS(new_fluids)[i] = SCM_BOOL_F;
  84       i++;
  85     }
  86
  87   root_state->fluids = new_fluids;
  88 }
  89
  90 void
  91 scm_copy_fluids (scm_root_state *root_state)
  92 {
  93   grow_fluids (root_state, SCM_VECTOR_LENGTH (root_state->fluids));
  94 }
  95
  96 static int
  97 fluid_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED)
  98 {
  99   scm_puts ("#<fluid ", port);
 100   scm_intprint ((int) SCM_FLUID_NUM (exp), 10, port);
 101   scm_putc ('>', port);
 102   return 1;
 103 }
 104
 105 static long
 106 next_fluid_num ()
 107 {
 108   long n;
 109   SCM_CRITICAL_SECTION_START;
 110   n = n_fluids++;
 111   SCM_CRITICAL_SECTION_END;
 112   return n;
 113 }
 114
 115 SCM_DEFINE (scm_make_fluid, "make-fluid", 0, 0, 0,
 116             (),
 117             "Return a newly created fluid.\n"
 118             "Fluids are objects of a certain type (a smob) that can hold one SCM\n"
 119             "value per dynamic root.  That is, modifications to this value are\n"
 120             "only visible to code that executes within the same dynamic root as\n"
 121             "the modifying code.  When a new dynamic root is constructed, it\n"
 122             "inherits the values from its parent.  Because each thread executes\n"
 123             "in its own dynamic root, you can use fluids for thread local storage.")
 124 #define FUNC_NAME s_scm_make_fluid
 125 {
 126   long n;
 127
 128   n = next_fluid_num ();
 129   SCM_RETURN_NEWSMOB (scm_tc16_fluid, n);
 130 }
 131 #undef FUNC_NAME
 132
 133 SCM_DEFINE (scm_fluid_p, "fluid?", 1, 0, 0,
 134             (SCM obj),
 135             "Return @code{#t} iff @var{obj} is a fluid; otherwise, return\n"
 136             "@code{#f}.")
 137 #define FUNC_NAME s_scm_fluid_p
 138 {
 139   return SCM_BOOL(SCM_FLUIDP (obj));
 140 }
 141 #undef FUNC_NAME
 142
 143 SCM_DEFINE (scm_fluid_ref, "fluid-ref", 1, 0, 0,
 144             (SCM fluid),
 145             "Return the value associated with @var{fluid} in the current\n"
 146             "dynamic root.  If @var{fluid} has not been set, then return\n"
 147             "@code{#f}.")
 148 #define FUNC_NAME s_scm_fluid_ref
 149 {
 150   unsigned long int n;
 151
 152   SCM_VALIDATE_FLUID (1, fluid);
 153   n = SCM_FLUID_NUM (fluid);
 154
 155   if (SCM_VECTOR_LENGTH (scm_root->fluids) <= n)
 156     grow_fluids (scm_root, n+1);
 157   return SCM_VELTS (scm_root->fluids)[n];
 158 }
 159 #undef FUNC_NAME
 160
 161 SCM_DEFINE (scm_fluid_set_x, "fluid-set!", 2, 0, 0,
 162             (SCM fluid, SCM value),
 163             "Set the value associated with @var{fluid} in the current dynamic root.")
 164 #define FUNC_NAME s_scm_fluid_set_x
 165 {
 166   unsigned long int n;
 167
 168   SCM_VALIDATE_FLUID (1, fluid);
 169   n = SCM_FLUID_NUM (fluid);
 170
 171   if (SCM_VECTOR_LENGTH (scm_root->fluids) <= n)
 172     grow_fluids (scm_root, n+1);
 173   SCM_VELTS (scm_root->fluids)[n] = value;
 174   return SCM_UNSPECIFIED;
 175 }
 176 #undef FUNC_NAME
 177
 178 void
 179 scm_swap_fluids (SCM fluids, SCM vals)
 180 {
 181   while (!SCM_NULLP (fluids))
 182     {
 183       SCM fl = SCM_CAR (fluids);
 184       SCM old_val = scm_fluid_ref (fl);
 185       scm_fluid_set_x (fl, SCM_CAR (vals));
 186       SCM_SETCAR (vals, old_val);
 187       fluids = SCM_CDR (fluids);
 188       vals = SCM_CDR (vals);
 189     }
 190 }
 191
 192 /* Swap the fluid values in reverse order.  This is important when the
 193 same fluid appears multiple times in the fluids list. */
 194
 195 void
 196 scm_swap_fluids_reverse (SCM fluids, SCM vals)
 197 {
 198   if (!SCM_NULLP (fluids))
 199     {
 200       SCM fl, old_val;
 201
 202       scm_swap_fluids_reverse (SCM_CDR (fluids), SCM_CDR (vals));
 203       fl = SCM_CAR (fluids);
 204       old_val = scm_fluid_ref (fl);
 205       scm_fluid_set_x (fl, SCM_CAR (vals));
 206       SCM_SETCAR (vals, old_val);
 207     }
 208 }
 209
 210
 211 static SCM
 212 apply_thunk (void *thunk)
 213 {
 214   return scm_call_0 (SCM_PACK (thunk));
 215 }
 216
 217 SCM_DEFINE (scm_with_fluids, "with-fluids*", 3, 0, 0,
 218             (SCM fluids, SCM values, SCM thunk),
 219             "Set @var{fluids} to @var{values} temporary, and call @var{thunk}.\n"
 220             "@var{fluids} must be a list of fluids and @var{values} must be the same\n"
 221             "number of their values to be applied.  Each substitution is done\n"
 222             "one after another.  @var{thunk} must be a procedure with no argument.")
 223 #define FUNC_NAME s_scm_with_fluids
 224 {
 225   return scm_c_with_fluids (fluids, values, apply_thunk, (void *) SCM_UNPACK (thunk));
 226 }
 227 #undef FUNC_NAME
 228
 229 SCM
 230 scm_c_with_fluids (SCM fluids, SCM values, SCM (*cproc) (), void *cdata)
 231 #define FUNC_NAME "scm_c_with_fluids"
 232 {
 233   SCM ans;
 234   long flen, vlen;
 235
 236   SCM_VALIDATE_LIST_COPYLEN (1, fluids, flen);
 237   SCM_VALIDATE_LIST_COPYLEN (2, values, vlen);
 238   if (flen != vlen)
 239     scm_out_of_range (s_scm_with_fluids, values);
 240
 241   scm_swap_fluids (fluids, values);
 242   scm_dynwinds = scm_acons (fluids, values, scm_dynwinds);
 243   ans = cproc (cdata);
 244   scm_dynwinds = SCM_CDR (scm_dynwinds);
 245   scm_swap_fluids_reverse (fluids, values);
 246   return ans;
 247 }
 248 #undef FUNC_NAME
 249
 250 SCM
 251 scm_c_with_fluid (SCM fluid, SCM value, SCM (*cproc) (), void *cdata)
 252 #define FUNC_NAME "scm_c_with_fluid"
 253 {
 254   return scm_c_with_fluids (scm_list_1 (fluid), scm_list_1 (value),
 255                             cproc, cdata);
 256 }
 257 #undef FUNC_NAME
 258
 259 void
 260 scm_init_fluids ()
 261 {
 262   scm_tc16_fluid = scm_make_smob_type ("fluid", 0);
 263   scm_set_smob_print (scm_tc16_fluid, fluid_print);
 264 #ifndef SCM_MAGIC_SNARFER
 265 #include "libguile/fluids.x"
 266 #endif
 267 }
 268
 269 /*
 270   Local Variables:
 271   c-file-style: "gnu"
 272   End:
 273 */