libguile/hooks.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2003, 2006, 2008 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public License
   5  * as published by the Free Software Foundation; either version 3 of
   6  * the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301 USA
  17  */
  18
  19
  20 \f
  21 #ifdef HAVE_CONFIG_H
  22 # include <config.h>
  23 #endif
  24
  25 #include <stdio.h>
  26 #include "libguile/_scm.h"
  27
  28 #include "libguile/eval.h"
  29 #include "libguile/ports.h"
  30 #include "libguile/procprop.h"
  31 #include "libguile/root.h"
  32 #include "libguile/smob.h"
  33 #include "libguile/strings.h"
  34
  35 #include "libguile/validate.h"
  36 #include "libguile/hooks.h"
  37
  38 \f
  39 /* C level hooks
  40  *
  41  * Currently, this implementation is separate from the Scheme level
  42  * hooks.  The possibility exists to implement the Scheme level hooks
  43  * using C level hooks.
  44  */
  45
  46 void
  47 scm_c_hook_init (scm_t_c_hook *hook, void *hook_data, scm_t_c_hook_type type)
  48 {
  49   hook->first = 0;
  50   hook->type = type;
  51   hook->data = hook_data;
  52 }
  53
  54 void
  55 scm_c_hook_add (scm_t_c_hook *hook,
  56                 scm_t_c_hook_function func,
  57                 void *fn_data,
  58                 int appendp)
  59 {
  60   scm_t_c_hook_entry *entry = scm_malloc (sizeof (scm_t_c_hook_entry));
  61   scm_t_c_hook_entry **loc = &hook->first;
  62   if (appendp)
  63     while (*loc)
  64       loc = &(*loc)->next;
  65   entry->next = *loc;
  66   entry->func = func;
  67   entry->data = fn_data;
  68   *loc = entry;
  69 }
  70
  71 void
  72 scm_c_hook_remove (scm_t_c_hook *hook,
  73                    scm_t_c_hook_function func,
  74                    void *fn_data)
  75 {
  76   scm_t_c_hook_entry **loc = &hook->first;
  77   while (*loc)
  78     {
  79       if ((*loc)->func == func && (*loc)->data == fn_data)
  80         {
  81           scm_t_c_hook_entry *entry = *loc;
  82           *loc = (*loc)->next;
  83           free (entry);
  84           return;
  85         }
  86       loc = &(*loc)->next;
  87     }
  88   fprintf (stderr, "Attempt to remove non-existent hook function\n");
  89   abort ();
  90 }
  91
  92 void *
  93 scm_c_hook_run (scm_t_c_hook *hook, void *data)
  94 {
  95   scm_t_c_hook_entry *entry = hook->first;
  96   scm_t_c_hook_type type = hook->type;
  97   void *res = 0;
  98   while (entry)
  99     {
 100       res = (entry->func) (hook->data, entry->data, data);
 101       if (res)
 102         {
 103           if (type == SCM_C_HOOK_OR)
 104             break;
 105         }
 106       else
 107         {
 108           if (type == SCM_C_HOOK_AND)
 109             break;
 110         }
 111       entry = entry->next;
 112     }
 113   return res;
 114 }
 115
 116 \f
 117 /* Scheme level hooks
 118  *
 119  * A hook is basically a list of procedures to be called at well defined
 120  * points in time.
 121  *
 122  * Hook arity is not a full member of this type and therefore lacks an
 123  * accessor.  It exists to aid debugging and is not intended to be used in
 124  * programs.
 125  */
 126
 127 scm_t_bits scm_tc16_hook;
 128
 129
 130 static int
 131 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 132 {
 133   SCM ls, name;
 134   scm_puts ("#<hook ", port);
 135   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 136   scm_putc (' ', port);
 137   scm_uintprint (SCM_UNPACK (hook), 16, port);
 138   ls = SCM_HOOK_PROCEDURES (hook);
 139   while (SCM_NIMP (ls))
 140     {
 141       scm_putc (' ', port);
 142       name = scm_procedure_name (SCM_CAR (ls));
 143       if (scm_is_true (name))
 144         scm_iprin1 (name, port, pstate);
 145       else
 146         scm_putc ('?', port);
 147       ls = SCM_CDR (ls);
 148     }
 149   scm_putc ('>', port);
 150   return 1;
 151 }
 152
 153
 154 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 155             (SCM n_args),
 156             "Create a hook for storing procedure of arity @var{n_args}.\n"
 157             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 158             "object to be used with the other hook procedures.")
 159 #define FUNC_NAME s_scm_make_hook
 160 {
 161   unsigned int n;
 162
 163   if (SCM_UNBNDP (n_args))
 164     n = 0;
 165   else
 166     n = scm_to_unsigned_integer (n_args, 0, 16);
 167
 168   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 169 }
 170 #undef FUNC_NAME
 171
 172
 173 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 174             (SCM x),
 175             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 176 #define FUNC_NAME s_scm_hook_p
 177 {
 178   return scm_from_bool (SCM_HOOKP (x));
 179 }
 180 #undef FUNC_NAME
 181
 182
 183 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 184             (SCM hook),
 185             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 186             "otherwise.")
 187 #define FUNC_NAME s_scm_hook_empty_p
 188 {
 189   SCM_VALIDATE_HOOK (1, hook);
 190   return scm_from_bool (scm_is_null (SCM_HOOK_PROCEDURES (hook)));
 191 }
 192 #undef FUNC_NAME
 193
 194
 195 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 196             (SCM hook, SCM proc, SCM append_p),
 197             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 198             "procedure is added to the end if @var{append_p} is true,\n"
 199             "otherwise it is added to the front.  The return value of this\n"
 200             "procedure is not specified.")
 201 #define FUNC_NAME s_scm_add_hook_x
 202 {
 203   SCM arity, rest;
 204   int n_args;
 205   SCM_VALIDATE_HOOK (1, hook);
 206   SCM_ASSERT (scm_is_true (arity = scm_i_procedure_arity (proc)),
 207               proc, SCM_ARG2, FUNC_NAME);
 208   n_args = SCM_HOOK_ARITY (hook);
 209   if (scm_to_int (SCM_CAR (arity)) > n_args
 210       || (scm_is_false (SCM_CADDR (arity))
 211           && (scm_to_int (SCM_CAR (arity)) + scm_to_int (SCM_CADR (arity))
 212               < n_args)))
 213     scm_wrong_type_arg (FUNC_NAME, 2, proc);
 214   rest = scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook));
 215   SCM_SET_HOOK_PROCEDURES (hook,
 216                            (!SCM_UNBNDP (append_p) && scm_is_true (append_p)
 217                             ? scm_append_x (scm_list_2 (rest, scm_list_1 (proc)))
 218                             : scm_cons (proc, rest)));
 219   return SCM_UNSPECIFIED;
 220 }
 221 #undef FUNC_NAME
 222
 223
 224 SCM_DEFINE (scm_remove_hook_x, "remove-hook!", 2, 0, 0,
 225             (SCM hook, SCM proc),
 226             "Remove the procedure @var{proc} from the hook @var{hook}.  The\n"
 227             "return value of this procedure is not specified.")
 228 #define FUNC_NAME s_scm_remove_hook_x
 229 {
 230   SCM_VALIDATE_HOOK (1, hook);
 231   SCM_SET_HOOK_PROCEDURES (hook,
 232                            scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook)));
 233   return SCM_UNSPECIFIED;
 234 }
 235 #undef FUNC_NAME
 236
 237
 238 SCM_DEFINE (scm_reset_hook_x, "reset-hook!", 1, 0, 0,
 239             (SCM hook),
 240             "Remove all procedures from the hook @var{hook}.  The return\n"
 241             "value of this procedure is not specified.")
 242 #define FUNC_NAME s_scm_reset_hook_x
 243 {
 244   SCM_VALIDATE_HOOK (1, hook);
 245   SCM_SET_HOOK_PROCEDURES (hook, SCM_EOL);
 246   return SCM_UNSPECIFIED;
 247 }
 248 #undef FUNC_NAME
 249
 250
 251 SCM_DEFINE (scm_run_hook, "run-hook", 1, 0, 1,
 252             (SCM hook, SCM args),
 253             "Apply all procedures from the hook @var{hook} to the arguments\n"
 254             "@var{args}.  The order of the procedure application is first to\n"
 255             "last.  The return value of this procedure is not specified.")
 256 #define FUNC_NAME s_scm_run_hook
 257 {
 258   SCM_VALIDATE_HOOK (1, hook);
 259   if (scm_ilength (args) != SCM_HOOK_ARITY (hook))
 260     SCM_MISC_ERROR ("Hook ~S requires ~A arguments",
 261                     scm_list_2 (hook, scm_from_int (SCM_HOOK_ARITY (hook))));
 262   scm_c_run_hook (hook, args);
 263   return SCM_UNSPECIFIED;
 264 }
 265 #undef FUNC_NAME
 266
 267
 268 void
 269 scm_c_run_hook (SCM hook, SCM args)
 270 {
 271   SCM procs = SCM_HOOK_PROCEDURES (hook);
 272   while (SCM_NIMP (procs))
 273     {
 274       scm_apply_0 (SCM_CAR (procs), args);
 275       procs = SCM_CDR (procs);
 276     }
 277 }
 278
 279
 280 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 281             (SCM hook),
 282             "Convert the procedure list of @var{hook} to a list.")
 283 #define FUNC_NAME s_scm_hook_to_list
 284 {
 285   SCM_VALIDATE_HOOK (1, hook);
 286   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 287 }
 288 #undef FUNC_NAME
 289
 290
 291 \f
 292
 293 void
 294 scm_init_hooks ()
 295 {
 296   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 297   scm_set_smob_mark (scm_tc16_hook, scm_markcdr);
 298   scm_set_smob_print (scm_tc16_hook, hook_print);
 299 #include "libguile/hooks.x"
 300 }
 301
 302 /*
 303   Local Variables:
 304   c-file-style: "gnu"
 305   End:
 306 */