libguile/hooks.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2003 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
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library 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 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  16  */
  17
  18
  19 \f
  20
  21 #include <stdio.h>
  22 #include "libguile/_scm.h"
  23
  24 #include "libguile/eval.h"
  25 #include "libguile/ports.h"
  26 #include "libguile/procprop.h"
  27 #include "libguile/root.h"
  28 #include "libguile/smob.h"
  29 #include "libguile/strings.h"
  30
  31 #include "libguile/validate.h"
  32 #include "libguile/hooks.h"
  33
  34 \f
  35 /* C level hooks
  36  *
  37  * Currently, this implementation is separate from the Scheme level
  38  * hooks.  The possibility exists to implement the Scheme level hooks
  39  * using C level hooks.
  40  */
  41
  42 void
  43 scm_c_hook_init (scm_t_c_hook *hook, void *hook_data, scm_t_c_hook_type type)
  44 {
  45   hook->first = 0;
  46   hook->type = type;
  47   hook->data = hook_data;
  48 }
  49
  50 void
  51 scm_c_hook_add (scm_t_c_hook *hook,
  52                 scm_t_c_hook_function func,
  53                 void *func_data,
  54                 int appendp)
  55 {
  56   scm_t_c_hook_entry *entry = scm_malloc (sizeof (scm_t_c_hook_entry));
  57   scm_t_c_hook_entry **loc = &hook->first;
  58   if (appendp)
  59     while (*loc)
  60       loc = &(*loc)->next;
  61   entry->next = *loc;
  62   entry->func = func;
  63   entry->data = func_data;
  64   *loc = entry;
  65 }
  66
  67 void
  68 scm_c_hook_remove (scm_t_c_hook *hook,
  69                    scm_t_c_hook_function func,
  70                    void *func_data)
  71 {
  72   scm_t_c_hook_entry **loc = &hook->first;
  73   while (*loc)
  74     {
  75       if ((*loc)->func == func && (*loc)->data == func_data)
  76         {
  77           scm_t_c_hook_entry *entry = *loc;
  78           *loc = (*loc)->next;
  79           free (entry);
  80           return;
  81         }
  82       loc = &(*loc)->next;
  83     }
  84   fprintf (stderr, "Attempt to remove non-existent hook function\n");
  85   abort ();
  86 }
  87
  88 void *
  89 scm_c_hook_run (scm_t_c_hook *hook, void *data)
  90 {
  91   scm_t_c_hook_entry *entry = hook->first;
  92   scm_t_c_hook_type type = hook->type;
  93   void *res = 0;
  94   while (entry)
  95     {
  96       res = (entry->func) (hook->data, entry->data, data);
  97       if (res)
  98         {
  99           if (type == SCM_C_HOOK_OR)
 100             break;
 101         }
 102       else
 103         {
 104           if (type == SCM_C_HOOK_AND)
 105             break;
 106         }
 107       entry = entry->next;
 108     }
 109   return res;
 110 }
 111
 112 \f
 113 /* Scheme level hooks
 114  *
 115  * A hook is basically a list of procedures to be called at well defined
 116  * points in time.
 117  *
 118  * Hook arity is not a full member of this type and therefore lacks an
 119  * accessor.  It exists to aid debugging and is not intended to be used in
 120  * programs.
 121  */
 122
 123 scm_t_bits scm_tc16_hook;
 124
 125
 126 static int
 127 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 128 {
 129   SCM ls, name;
 130   scm_puts ("#<hook ", port);
 131   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 132   scm_putc (' ', port);
 133   scm_intprint (SCM_UNPACK (hook), 16, port);
 134   ls = SCM_HOOK_PROCEDURES (hook);
 135   while (SCM_NIMP (ls))
 136     {
 137       scm_putc (' ', port);
 138       name = scm_procedure_name (SCM_CAR (ls));
 139       if (scm_is_true (name))
 140         scm_iprin1 (name, port, pstate);
 141       else
 142         scm_putc ('?', port);
 143       ls = SCM_CDR (ls);
 144     }
 145   scm_putc ('>', port);
 146   return 1;
 147 }
 148
 149
 150 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 151             (SCM n_args),
 152             "Create a hook for storing procedure of arity @var{n_args}.\n"
 153             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 154             "object to be used with the other hook procedures.")
 155 #define FUNC_NAME s_scm_make_hook
 156 {
 157   unsigned int n;
 158
 159   if (SCM_UNBNDP (n_args))
 160     n = 0;
 161   else
 162     n = scm_to_unsigned_integer (n_args, 0, 16);
 163
 164   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 165 }
 166 #undef FUNC_NAME
 167
 168
 169 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 170             (SCM x),
 171             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 172 #define FUNC_NAME s_scm_hook_p
 173 {
 174   return scm_from_bool (SCM_HOOKP (x));
 175 }
 176 #undef FUNC_NAME
 177
 178
 179 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 180             (SCM hook),
 181             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 182             "otherwise.")
 183 #define FUNC_NAME s_scm_hook_empty_p
 184 {
 185   SCM_VALIDATE_HOOK (1, hook);
 186   return scm_from_bool (SCM_NULLP (SCM_HOOK_PROCEDURES (hook)));
 187 }
 188 #undef FUNC_NAME
 189
 190
 191 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 192             (SCM hook, SCM proc, SCM append_p),
 193             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 194             "procedure is added to the end if @var{append_p} is true,\n"
 195             "otherwise it is added to the front.  The return value of this\n"
 196             "procedure is not specified.")
 197 #define FUNC_NAME s_scm_add_hook_x
 198 {
 199   SCM arity, rest;
 200   int n_args;
 201   SCM_VALIDATE_HOOK (1, hook);
 202   SCM_ASSERT (scm_is_true (arity = scm_i_procedure_arity (proc)),
 203               proc, SCM_ARG2, FUNC_NAME);
 204   n_args = SCM_HOOK_ARITY (hook);
 205   if (scm_to_int (SCM_CAR (arity)) > n_args
 206       || (scm_is_false (SCM_CADDR (arity))
 207           && (scm_to_int (SCM_CAR (arity)) + scm_to_int (SCM_CADR (arity))
 208               < n_args)))
 209     scm_wrong_type_arg (FUNC_NAME, 2, proc);
 210   rest = scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook));
 211   SCM_SET_HOOK_PROCEDURES (hook,
 212                            (!SCM_UNBNDP (append_p) && scm_is_true (append_p)
 213                             ? scm_append_x (scm_list_2 (rest, scm_list_1 (proc)))
 214                             : scm_cons (proc, rest)));
 215   return SCM_UNSPECIFIED;
 216 }
 217 #undef FUNC_NAME
 218
 219
 220 SCM_DEFINE (scm_remove_hook_x, "remove-hook!", 2, 0, 0,
 221             (SCM hook, SCM proc),
 222             "Remove the procedure @var{proc} from the hook @var{hook}.  The\n"
 223             "return value of this procedure is not specified.")
 224 #define FUNC_NAME s_scm_remove_hook_x
 225 {
 226   SCM_VALIDATE_HOOK (1, hook);
 227   SCM_SET_HOOK_PROCEDURES (hook,
 228                            scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook)));
 229   return SCM_UNSPECIFIED;
 230 }
 231 #undef FUNC_NAME
 232
 233
 234 SCM_DEFINE (scm_reset_hook_x, "reset-hook!", 1, 0, 0,
 235             (SCM hook),
 236             "Remove all procedures from the hook @var{hook}.  The return\n"
 237             "value of this procedure is not specified.")
 238 #define FUNC_NAME s_scm_reset_hook_x
 239 {
 240   SCM_VALIDATE_HOOK (1, hook);
 241   SCM_SET_HOOK_PROCEDURES (hook, SCM_EOL);
 242   return SCM_UNSPECIFIED;
 243 }
 244 #undef FUNC_NAME
 245
 246
 247 SCM_DEFINE (scm_run_hook, "run-hook", 1, 0, 1,
 248             (SCM hook, SCM args),
 249             "Apply all procedures from the hook @var{hook} to the arguments\n"
 250             "@var{args}.  The order of the procedure application is first to\n"
 251             "last.  The return value of this procedure is not specified.")
 252 #define FUNC_NAME s_scm_run_hook
 253 {
 254   SCM_VALIDATE_HOOK (1, hook);
 255   if (scm_ilength (args) != SCM_HOOK_ARITY (hook))
 256     SCM_MISC_ERROR ("Hook ~S requires ~A arguments",
 257                     scm_list_2 (hook, scm_from_int (SCM_HOOK_ARITY (hook))));
 258   scm_c_run_hook (hook, args);
 259   return SCM_UNSPECIFIED;
 260 }
 261 #undef FUNC_NAME
 262
 263
 264 void
 265 scm_c_run_hook (SCM hook, SCM args)
 266 {
 267   SCM procs = SCM_HOOK_PROCEDURES (hook);
 268   while (SCM_NIMP (procs))
 269     {
 270       scm_apply_0 (SCM_CAR (procs), args);
 271       procs = SCM_CDR (procs);
 272     }
 273 }
 274
 275
 276 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 277             (SCM hook),
 278             "Convert the procedure list of @var{hook} to a list.")
 279 #define FUNC_NAME s_scm_hook_to_list
 280 {
 281   SCM_VALIDATE_HOOK (1, hook);
 282   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 283 }
 284 #undef FUNC_NAME
 285
 286
 287 \f
 288
 289 void
 290 scm_init_hooks ()
 291 {
 292   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 293   scm_set_smob_mark (scm_tc16_hook, scm_markcdr);
 294   scm_set_smob_print (scm_tc16_hook, hook_print);
 295 #include "libguile/hooks.x"
 296 }
 297
 298 /*
 299   Local Variables:
 300   c-file-style: "gnu"
 301   End:
 302 */