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_hookype_t 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_must_malloc (sizeof (scm_t_c_hook_entry),
  81                                              "C level hook entry");
  82   scm_t_c_hook_entry **loc = &hook->first;
  83   if (appendp)
  84     while (*loc)
  85       *loc = (*loc)->next;
  86   entry->next = *loc;
  87   entry->func = func;
  88   entry->data = func_data;
  89   *loc = entry;
  90 }
  91
  92 void
  93 scm_c_hook_remove (scm_t_c_hook *hook,
  94                    scm_t_c_hook_function func,
  95                    void *func_data)
  96 {
  97   scm_t_c_hook_entry **loc = &hook->first;
  98   while (*loc)
  99     {
 100       if ((*loc)->func == func && (*loc)->data == func_data)
 101         {
 102           scm_t_c_hook_entry *entry = *loc;
 103           *loc = (*loc)->next;
 104           scm_must_free (entry);
 105           return;
 106         }
 107       loc = &(*loc)->next;
 108     }
 109   fprintf (stderr, "Attempt to remove non-existent hook function\n");
 110   abort ();
 111 }
 112
 113 void *
 114 scm_c_hook_run (scm_t_c_hook *hook, void *data)
 115 {
 116   scm_t_c_hook_entry *entry = hook->first;
 117   scm_t_c_hookype_t type = hook->type;
 118   void *res = 0;
 119   while (entry)
 120     {
 121       res = (entry->func) (hook->data, entry->data, data);
 122       if (res)
 123         {
 124           if (type == SCM_C_HOOK_OR)
 125             break;
 126         }
 127       else
 128         {
 129           if (type == SCM_C_HOOK_AND)
 130             break;
 131         }
 132       entry = entry->next;
 133     }
 134   return res;
 135 }
 136
 137 \f
 138 /* Scheme level hooks
 139  *
 140  * A hook is basically a list of procedures to be called at well defined
 141  * points in time.
 142  *
 143  * Hook arity is not a full member of this type and therefore lacks an
 144  * accessor.  It exists to aid debugging and is not intended to be used in
 145  * programs.
 146  */
 147
 148 scm_t_bits scm_tc16_hook;
 149
 150
 151 static int
 152 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 153 {
 154   SCM ls, name;
 155   scm_puts ("#<hook ", port);
 156   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 157   scm_putc (' ', port);
 158   scm_intprint (SCM_UNPACK (hook), 16, port);
 159   ls = SCM_HOOK_PROCEDURES (hook);
 160   while (SCM_NIMP (ls))
 161     {
 162       scm_putc (' ', port);
 163       name = scm_procedure_name (SCM_CAR (ls));
 164       if (!SCM_FALSEP (name))
 165         scm_iprin1 (name, port, pstate);
 166       else
 167         scm_putc ('?', port);
 168       ls = SCM_CDR (ls);
 169     }
 170   scm_putc ('>', port);
 171   return 1;
 172 }
 173
 174
 175 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 176             (SCM n_args),
 177             "Create a hook for storing procedure of arity @var{n_args}.\n"
 178             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 179             "object to be used with the other hook procedures.")
 180 #define FUNC_NAME s_scm_make_hook
 181 {
 182   int n;
 183
 184   if (SCM_UNBNDP (n_args))
 185     {
 186       n = 0;
 187     }
 188   else
 189     {
 190       SCM_VALIDATE_INUM_COPY (SCM_ARG1, n_args, n);
 191       if (n < 0 || n > 16)
 192         SCM_OUT_OF_RANGE (SCM_ARG1, n_args);
 193     }
 194
 195   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 196 }
 197 #undef FUNC_NAME
 198
 199
 200 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 201             (SCM x),
 202             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 203 #define FUNC_NAME s_scm_hook_p
 204 {
 205   return SCM_BOOL (SCM_HOOKP (x));
 206 }
 207 #undef FUNC_NAME
 208
 209
 210 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 211             (SCM hook),
 212             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 213             "otherwise.")
 214 #define FUNC_NAME s_scm_hook_empty_p
 215 {
 216   SCM_VALIDATE_HOOK (1, hook);
 217   return SCM_BOOL (SCM_NULLP (SCM_HOOK_PROCEDURES (hook)));
 218 }
 219 #undef FUNC_NAME
 220
 221
 222 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 223             (SCM hook, SCM proc, SCM append_p),
 224             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 225             "procedure is added to the end if @var{append_p} is true,\n"
 226             "otherwise it is added to the front.  The return value of this\n"
 227             "procedure is not specified.")
 228 #define FUNC_NAME s_scm_add_hook_x
 229 {
 230   SCM arity, rest;
 231   int n_args;
 232   SCM_VALIDATE_HOOK (1,hook);
 233   SCM_ASSERT (!SCM_FALSEP (arity = scm_i_procedure_arity (proc)),
 234               proc, SCM_ARG2, FUNC_NAME);
 235   n_args = SCM_HOOK_ARITY (hook);
 236   if (SCM_INUM (SCM_CAR (arity)) > n_args
 237       || (SCM_FALSEP (SCM_CADDR (arity))
 238           && (SCM_INUM (SCM_CAR (arity)) + SCM_INUM (SCM_CADR (arity))
 239               < n_args)))
 240     scm_wrong_type_arg (FUNC_NAME, 2, proc);
 241   rest = scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook));
 242   SCM_SET_HOOK_PROCEDURES (hook,
 243                            (!SCM_UNBNDP (append_p) && !SCM_FALSEP (append_p)
 244                             ? scm_append_x (scm_list_2 (rest, scm_list_1 (proc)))
 245                             : scm_cons (proc, rest)));
 246   return SCM_UNSPECIFIED;
 247 }
 248 #undef FUNC_NAME
 249
 250
 251 SCM_DEFINE (scm_remove_hook_x, "remove-hook!", 2, 0, 0,
 252             (SCM hook, SCM proc),
 253             "Remove the procedure @var{proc} from the hook @var{hook}.  The\n"
 254             "return value of this procedure is not specified.")
 255 #define FUNC_NAME s_scm_remove_hook_x
 256 {
 257   SCM_VALIDATE_HOOK (1, hook);
 258   SCM_SET_HOOK_PROCEDURES (hook,
 259                            scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook)));
 260   return SCM_UNSPECIFIED;
 261 }
 262 #undef FUNC_NAME
 263
 264
 265 SCM_DEFINE (scm_reset_hook_x, "reset-hook!", 1, 0, 0,
 266             (SCM hook),
 267             "Remove all procedures from the hook @var{hook}.  The return\n"
 268             "value of this procedure is not specified.")
 269 #define FUNC_NAME s_scm_reset_hook_x
 270 {
 271   SCM_VALIDATE_HOOK (1,hook);
 272   SCM_SET_HOOK_PROCEDURES (hook, SCM_EOL);
 273   return SCM_UNSPECIFIED;
 274 }
 275 #undef FUNC_NAME
 276
 277
 278 SCM_DEFINE (scm_run_hook, "run-hook", 1, 0, 1,
 279             (SCM hook, SCM args),
 280             "Apply all procedures from the hook @var{hook} to the arguments\n"
 281             "@var{args}.  The order of the procedure application is first to\n"
 282             "last.  The return value of this procedure is not specified.")
 283 #define FUNC_NAME s_scm_run_hook
 284 {
 285   SCM_VALIDATE_HOOK (1,hook);
 286   if (scm_ilength (args) != SCM_HOOK_ARITY (hook))
 287     SCM_MISC_ERROR ("Hook ~S requires ~A arguments",
 288                     scm_list_2 (hook, SCM_MAKINUM (SCM_HOOK_ARITY (hook))));
 289   scm_c_run_hook (hook, args);
 290   return SCM_UNSPECIFIED;
 291 }
 292 #undef FUNC_NAME
 293
 294
 295 void
 296 scm_c_run_hook (SCM hook, SCM args)
 297 {
 298   SCM procs = SCM_HOOK_PROCEDURES (hook);
 299   while (SCM_NIMP (procs))
 300     {
 301       scm_apply_0 (SCM_CAR (procs), args);
 302       procs = SCM_CDR (procs);
 303     }
 304 }
 305
 306
 307 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 308             (SCM hook),
 309             "Convert the procedure list of @var{hook} to a list.")
 310 #define FUNC_NAME s_scm_hook_to_list
 311 {
 312   SCM_VALIDATE_HOOK (1, hook);
 313   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 314 }
 315 #undef FUNC_NAME
 316
 317
 318 \f
 319
 320 void
 321 scm_init_hooks ()
 322 {
 323   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 324   scm_set_smob_mark (scm_tc16_hook, scm_markcdr);
 325   scm_set_smob_print (scm_tc16_hook, hook_print);
 326 #ifndef SCM_MAGIC_SNARFER
 327 #include "libguile/hooks.x"
 328 #endif
 329 }
 330
 331 /*
 332   Local Variables:
 333   c-file-style: "gnu"
 334   End:
 335 */