libguile/hooks.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001 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
  43 \f
  44
  45 #include <stdio.h>
  46 #include "libguile/_scm.h"
  47
  48 #include "libguile/eval.h"
  49 #include "libguile/ports.h"
  50 #include "libguile/procprop.h"
  51 #include "libguile/root.h"
  52 #include "libguile/smob.h"
  53 #include "libguile/strings.h"
  54
  55 #include "libguile/validate.h"
  56 #include "libguile/hooks.h"
  57
  58 \f
  59 /* C level hooks
  60  *
  61  * Currently, this implementation is separate from the Scheme level
  62  * hooks.  The possibility exists to implement the Scheme level hooks
  63  * using C level hooks.
  64  */
  65
  66 void
  67 scm_c_hook_init (scm_t_c_hook *hook, void *hook_data, scm_t_c_hook_type type)
  68 {
  69   hook->first = 0;
  70   hook->type = type;
  71   hook->data = hook_data;
  72 }
  73
  74 void
  75 scm_c_hook_add (scm_t_c_hook *hook,
  76                 scm_t_c_hook_function func,
  77                 void *func_data,
  78                 int appendp)
  79 {
  80   scm_t_c_hook_entry *entry = scm_malloc (sizeof (scm_t_c_hook_entry));
  81   scm_t_c_hook_entry **loc = &hook->first;
  82   if (appendp)
  83     while (*loc)
  84       *loc = (*loc)->next;
  85   entry->next = *loc;
  86   entry->func = func;
  87   entry->data = func_data;
  88   *loc = entry;
  89 }
  90
  91 void
  92 scm_c_hook_remove (scm_t_c_hook *hook,
  93                    scm_t_c_hook_function func,
  94                    void *func_data)
  95 {
  96   scm_t_c_hook_entry **loc = &hook->first;
  97   while (*loc)
  98     {
  99       if ((*loc)->func == func && (*loc)->data == func_data)
 100         {
 101           scm_t_c_hook_entry *entry = *loc;
 102           *loc = (*loc)->next;
 103           free (entry);
 104           return;
 105         }
 106       loc = &(*loc)->next;
 107     }
 108   fprintf (stderr, "Attempt to remove non-existent hook function\n");
 109   abort ();
 110 }
 111
 112 void *
 113 scm_c_hook_run (scm_t_c_hook *hook, void *data)
 114 {
 115   scm_t_c_hook_entry *entry = hook->first;
 116   scm_t_c_hook_type type = hook->type;
 117   void *res = 0;
 118   while (entry)
 119     {
 120       res = (entry->func) (hook->data, entry->data, data);
 121       if (res)
 122         {
 123           if (type == SCM_C_HOOK_OR)
 124             break;
 125         }
 126       else
 127         {
 128           if (type == SCM_C_HOOK_AND)
 129             break;
 130         }
 131       entry = entry->next;
 132     }
 133   return res;
 134 }
 135
 136 \f
 137 /* Scheme level hooks
 138  *
 139  * A hook is basically a list of procedures to be called at well defined
 140  * points in time.
 141  *
 142  * Hook arity is not a full member of this type and therefore lacks an
 143  * accessor.  It exists to aid debugging and is not intended to be used in
 144  * programs.
 145  */
 146
 147 scm_t_bits scm_tc16_hook;
 148
 149
 150 static int
 151 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 152 {
 153   SCM ls, name;
 154   scm_puts ("#<hook ", port);
 155   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 156   scm_putc (' ', port);
 157   scm_intprint (SCM_UNPACK (hook), 16, port);
 158   ls = SCM_HOOK_PROCEDURES (hook);
 159   while (SCM_NIMP (ls))
 160     {
 161       scm_putc (' ', port);
 162       name = scm_procedure_name (SCM_CAR (ls));
 163       if (!SCM_FALSEP (name))
 164         scm_iprin1 (name, port, pstate);
 165       else
 166         scm_putc ('?', port);
 167       ls = SCM_CDR (ls);
 168     }
 169   scm_putc ('>', port);
 170   return 1;
 171 }
 172
 173
 174 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 175             (SCM n_args),
 176             "Create a hook for storing procedure of arity @var{n_args}.\n"
 177             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 178             "object to be used with the other hook procedures.")
 179 #define FUNC_NAME s_scm_make_hook
 180 {
 181   int n;
 182
 183   if (SCM_UNBNDP (n_args))
 184     {
 185       n = 0;
 186     }
 187   else
 188     {
 189       SCM_VALIDATE_INUM_COPY (SCM_ARG1, n_args, n);
 190       if (n < 0 || n > 16)
 191         SCM_OUT_OF_RANGE (SCM_ARG1, n_args);
 192     }
 193
 194   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 195 }
 196 #undef FUNC_NAME
 197
 198
 199 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 200             (SCM x),
 201             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 202 #define FUNC_NAME s_scm_hook_p
 203 {
 204   return SCM_BOOL (SCM_HOOKP (x));
 205 }
 206 #undef FUNC_NAME
 207
 208
 209 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 210             (SCM hook),
 211             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 212             "otherwise.")
 213 #define FUNC_NAME s_scm_hook_empty_p
 214 {
 215   SCM_VALIDATE_HOOK (1, hook);
 216   return SCM_BOOL (SCM_NULLP (SCM_HOOK_PROCEDURES (hook)));
 217 }
 218 #undef FUNC_NAME
 219
 220
 221 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 222             (SCM hook, SCM proc, SCM append_p),
 223             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 224             "procedure is added to the end if @var{append_p} is true,\n"
 225             "otherwise it is added to the front.  The return value of this\n"
 226             "procedure is not specified.")
 227 #define FUNC_NAME s_scm_add_hook_x
 228 {
 229   SCM arity, rest;
 230   int n_args;
 231   SCM_VALIDATE_HOOK (1, hook);
 232   SCM_ASSERT (!SCM_FALSEP (arity = scm_i_procedure_arity (proc)),
 233               proc, SCM_ARG2, FUNC_NAME);
 234   n_args = SCM_HOOK_ARITY (hook);
 235   if (SCM_INUM (SCM_CAR (arity)) > n_args
 236       || (SCM_FALSEP (SCM_CADDR (arity))
 237           && (SCM_INUM (SCM_CAR (arity)) + SCM_INUM (SCM_CADR (arity))
 238               < n_args)))
 239     scm_wrong_type_arg (FUNC_NAME, 2, proc);
 240   rest = scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook));
 241   SCM_SET_HOOK_PROCEDURES (hook,
 242                            (!SCM_UNBNDP (append_p) && !SCM_FALSEP (append_p)
 243                             ? scm_append_x (scm_list_2 (rest, scm_list_1 (proc)))
 244                             : scm_cons (proc, rest)));
 245   return SCM_UNSPECIFIED;
 246 }
 247 #undef FUNC_NAME
 248
 249
 250 SCM_DEFINE (scm_remove_hook_x, "remove-hook!", 2, 0, 0,
 251             (SCM hook, SCM proc),
 252             "Remove the procedure @var{proc} from the hook @var{hook}.  The\n"
 253             "return value of this procedure is not specified.")
 254 #define FUNC_NAME s_scm_remove_hook_x
 255 {
 256   SCM_VALIDATE_HOOK (1, hook);
 257   SCM_SET_HOOK_PROCEDURES (hook,
 258                            scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook)));
 259   return SCM_UNSPECIFIED;
 260 }
 261 #undef FUNC_NAME
 262
 263
 264 SCM_DEFINE (scm_reset_hook_x, "reset-hook!", 1, 0, 0,
 265             (SCM hook),
 266             "Remove all procedures from the hook @var{hook}.  The return\n"
 267             "value of this procedure is not specified.")
 268 #define FUNC_NAME s_scm_reset_hook_x
 269 {
 270   SCM_VALIDATE_HOOK (1, hook);
 271   SCM_SET_HOOK_PROCEDURES (hook, SCM_EOL);
 272   return SCM_UNSPECIFIED;
 273 }
 274 #undef FUNC_NAME
 275
 276
 277 SCM_DEFINE (scm_run_hook, "run-hook", 1, 0, 1,
 278             (SCM hook, SCM args),
 279             "Apply all procedures from the hook @var{hook} to the arguments\n"
 280             "@var{args}.  The order of the procedure application is first to\n"
 281             "last.  The return value of this procedure is not specified.")
 282 #define FUNC_NAME s_scm_run_hook
 283 {
 284   SCM_VALIDATE_HOOK (1, hook);
 285   if (scm_ilength (args) != SCM_HOOK_ARITY (hook))
 286     SCM_MISC_ERROR ("Hook ~S requires ~A arguments",
 287                     scm_list_2 (hook, SCM_MAKINUM (SCM_HOOK_ARITY (hook))));
 288   scm_c_run_hook (hook, args);
 289   return SCM_UNSPECIFIED;
 290 }
 291 #undef FUNC_NAME
 292
 293
 294 void
 295 scm_c_run_hook (SCM hook, SCM args)
 296 {
 297   SCM procs = SCM_HOOK_PROCEDURES (hook);
 298   while (SCM_NIMP (procs))
 299     {
 300       scm_apply_0 (SCM_CAR (procs), args);
 301       procs = SCM_CDR (procs);
 302     }
 303 }
 304
 305
 306 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 307             (SCM hook),
 308             "Convert the procedure list of @var{hook} to a list.")
 309 #define FUNC_NAME s_scm_hook_to_list
 310 {
 311   SCM_VALIDATE_HOOK (1, hook);
 312   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 313 }
 314 #undef FUNC_NAME
 315
 316
 317 \f
 318
 319 void
 320 scm_init_hooks ()
 321 {
 322   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 323   scm_set_smob_mark (scm_tc16_hook, scm_markcdr);
 324   scm_set_smob_print (scm_tc16_hook, hook_print);
 325 #include "libguile/hooks.x"
 326 }
 327
 328 /*
 329   Local Variables:
 330   c-file-style: "gnu"
 331   End:
 332 */