libguile/hooks.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2003, 2006, 2008, 2009 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18
  19 \f
  20 #ifdef HAVE_CONFIG_H
  21 # include <config.h>
  22 #endif
  23
  24 #include <stdio.h>
  25 #include "libguile/_scm.h"
  26
  27 #include "libguile/eval.h"
  28 #include "libguile/ports.h"
  29 #include "libguile/procprop.h"
  30 #include "libguile/root.h"
  31 #include "libguile/smob.h"
  32 #include "libguile/strings.h"
  33
  34 #include "libguile/validate.h"
  35 #include "libguile/hooks.h"
  36
  37 \f
  38 /* C level hooks
  39  *
  40  * Currently, this implementation is separate from the Scheme level
  41  * hooks.  The possibility exists to implement the Scheme level hooks
  42  * using C level hooks.
  43  */
  44
  45 /* Hint for `scm_gc_malloc ()' and friends.  */
  46 static const char hook_entry_gc_hint[] = "hook entry";
  47
  48 void
  49 scm_c_hook_init (scm_t_c_hook *hook, void *hook_data, scm_t_c_hook_type type)
  50 {
  51   hook->first = 0;
  52   hook->type = type;
  53   hook->data = hook_data;
  54 }
  55
  56 void
  57 scm_c_hook_add (scm_t_c_hook *hook,
  58                 scm_t_c_hook_function func,
  59                 void *fn_data,
  60                 int appendp)
  61 {
  62   scm_t_c_hook_entry *entry;
  63   scm_t_c_hook_entry **loc = &hook->first;
  64
  65   entry = scm_gc_malloc (sizeof (scm_t_c_hook_entry), hook_entry_gc_hint);
  66   if (appendp)
  67     while (*loc)
  68       loc = &(*loc)->next;
  69   entry->next = *loc;
  70   entry->func = func;
  71   entry->data = fn_data;
  72   *loc = entry;
  73 }
  74
  75 void
  76 scm_c_hook_remove (scm_t_c_hook *hook,
  77                    scm_t_c_hook_function func,
  78                    void *fn_data)
  79 {
  80   scm_t_c_hook_entry **loc = &hook->first;
  81   while (*loc)
  82     {
  83       if ((*loc)->func == func && (*loc)->data == fn_data)
  84         {
  85           *loc = (*loc)->next;
  86           return;
  87         }
  88       loc = &(*loc)->next;
  89     }
  90   fprintf (stderr, "Attempt to remove non-existent hook function\n");
  91   abort ();
  92 }
  93
  94 void *
  95 scm_c_hook_run (scm_t_c_hook *hook, void *data)
  96 {
  97   scm_t_c_hook_entry *entry = hook->first;
  98   scm_t_c_hook_type type = hook->type;
  99   void *res = 0;
 100   while (entry)
 101     {
 102       res = (entry->func) (hook->data, entry->data, data);
 103       if (res)
 104         {
 105           if (type == SCM_C_HOOK_OR)
 106             break;
 107         }
 108       else
 109         {
 110           if (type == SCM_C_HOOK_AND)
 111             break;
 112         }
 113       entry = entry->next;
 114     }
 115   return res;
 116 }
 117
 118 \f
 119 /* Scheme level hooks
 120  *
 121  * A hook is basically a list of procedures to be called at well defined
 122  * points in time.
 123  *
 124  * Hook arity is not a full member of this type and therefore lacks an
 125  * accessor.  It exists to aid debugging and is not intended to be used in
 126  * programs.
 127  */
 128
 129 scm_t_bits scm_tc16_hook;
 130
 131
 132 static int
 133 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 134 {
 135   SCM ls, name;
 136   scm_puts ("#<hook ", port);
 137   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 138   scm_putc (' ', port);
 139   scm_uintprint (SCM_UNPACK (hook), 16, port);
 140   ls = SCM_HOOK_PROCEDURES (hook);
 141   while (SCM_NIMP (ls))
 142     {
 143       scm_putc (' ', port);
 144       name = scm_procedure_name (SCM_CAR (ls));
 145       if (scm_is_true (name))
 146         scm_iprin1 (name, port, pstate);
 147       else
 148         scm_putc ('?', port);
 149       ls = SCM_CDR (ls);
 150     }
 151   scm_putc ('>', port);
 152   return 1;
 153 }
 154
 155
 156 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 157             (SCM n_args),
 158             "Create a hook for storing procedure of arity @var{n_args}.\n"
 159             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 160             "object to be used with the other hook procedures.")
 161 #define FUNC_NAME s_scm_make_hook
 162 {
 163   unsigned int n;
 164
 165   if (SCM_UNBNDP (n_args))
 166     n = 0;
 167   else
 168     n = scm_to_unsigned_integer (n_args, 0, 16);
 169
 170   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 171 }
 172 #undef FUNC_NAME
 173
 174
 175 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 176             (SCM x),
 177             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 178 #define FUNC_NAME s_scm_hook_p
 179 {
 180   return scm_from_bool (SCM_HOOKP (x));
 181 }
 182 #undef FUNC_NAME
 183
 184
 185 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 186             (SCM hook),
 187             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 188             "otherwise.")
 189 #define FUNC_NAME s_scm_hook_empty_p
 190 {
 191   SCM_VALIDATE_HOOK (1, hook);
 192   return scm_from_bool (scm_is_null (SCM_HOOK_PROCEDURES (hook)));
 193 }
 194 #undef FUNC_NAME
 195
 196
 197 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 198             (SCM hook, SCM proc, SCM append_p),
 199             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 200             "procedure is added to the end if @var{append_p} is true,\n"
 201             "otherwise it is added to the front.  The return value of this\n"
 202             "procedure is not specified.")
 203 #define FUNC_NAME s_scm_add_hook_x
 204 {
 205   SCM arity, rest;
 206   int n_args;
 207   SCM_VALIDATE_HOOK (1, hook);
 208   SCM_ASSERT (scm_is_true (arity = scm_i_procedure_arity (proc)),
 209               proc, SCM_ARG2, FUNC_NAME);
 210   n_args = SCM_HOOK_ARITY (hook);
 211   if (scm_to_int (SCM_CAR (arity)) > n_args
 212       || (scm_is_false (SCM_CADDR (arity))
 213           && (scm_to_int (SCM_CAR (arity)) + scm_to_int (SCM_CADR (arity))
 214               < n_args)))
 215     scm_wrong_type_arg (FUNC_NAME, 2, proc);
 216   rest = scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook));
 217   SCM_SET_HOOK_PROCEDURES (hook,
 218                            (!SCM_UNBNDP (append_p) && scm_is_true (append_p)
 219                             ? scm_append_x (scm_list_2 (rest, scm_list_1 (proc)))
 220                             : scm_cons (proc, rest)));
 221   return SCM_UNSPECIFIED;
 222 }
 223 #undef FUNC_NAME
 224
 225
 226 SCM_DEFINE (scm_remove_hook_x, "remove-hook!", 2, 0, 0,
 227             (SCM hook, SCM proc),
 228             "Remove the procedure @var{proc} from the hook @var{hook}.  The\n"
 229             "return value of this procedure is not specified.")
 230 #define FUNC_NAME s_scm_remove_hook_x
 231 {
 232   SCM_VALIDATE_HOOK (1, hook);
 233   SCM_SET_HOOK_PROCEDURES (hook,
 234                            scm_delq_x (proc, SCM_HOOK_PROCEDURES (hook)));
 235   return SCM_UNSPECIFIED;
 236 }
 237 #undef FUNC_NAME
 238
 239
 240 SCM_DEFINE (scm_reset_hook_x, "reset-hook!", 1, 0, 0,
 241             (SCM hook),
 242             "Remove all procedures from the hook @var{hook}.  The return\n"
 243             "value of this procedure is not specified.")
 244 #define FUNC_NAME s_scm_reset_hook_x
 245 {
 246   SCM_VALIDATE_HOOK (1, hook);
 247   SCM_SET_HOOK_PROCEDURES (hook, SCM_EOL);
 248   return SCM_UNSPECIFIED;
 249 }
 250 #undef FUNC_NAME
 251
 252
 253 SCM_DEFINE (scm_run_hook, "run-hook", 1, 0, 1,
 254             (SCM hook, SCM args),
 255             "Apply all procedures from the hook @var{hook} to the arguments\n"
 256             "@var{args}.  The order of the procedure application is first to\n"
 257             "last.  The return value of this procedure is not specified.")
 258 #define FUNC_NAME s_scm_run_hook
 259 {
 260   SCM_VALIDATE_HOOK (1, hook);
 261   if (scm_ilength (args) != SCM_HOOK_ARITY (hook))
 262     SCM_MISC_ERROR ("Hook ~S requires ~A arguments",
 263                     scm_list_2 (hook, scm_from_int (SCM_HOOK_ARITY (hook))));
 264   scm_c_run_hook (hook, args);
 265   return SCM_UNSPECIFIED;
 266 }
 267 #undef FUNC_NAME
 268
 269
 270 void
 271 scm_c_run_hook (SCM hook, SCM args)
 272 {
 273   SCM procs = SCM_HOOK_PROCEDURES (hook);
 274   while (SCM_NIMP (procs))
 275     {
 276       scm_apply_0 (SCM_CAR (procs), args);
 277       procs = SCM_CDR (procs);
 278     }
 279 }
 280
 281
 282 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 283             (SCM hook),
 284             "Convert the procedure list of @var{hook} to a list.")
 285 #define FUNC_NAME s_scm_hook_to_list
 286 {
 287   SCM_VALIDATE_HOOK (1, hook);
 288   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 289 }
 290 #undef FUNC_NAME
 291
 292
 293 \f
 294
 295 void
 296 scm_init_hooks ()
 297 {
 298   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 299   scm_set_smob_print (scm_tc16_hook, hook_print);
 300 #include "libguile/hooks.x"
 301 }
 302
 303 /*
 304   Local Variables:
 305   c-file-style: "gnu"
 306   End:
 307 */