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