libguile/hooks.c

   1 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2003, 2006, 2008, 2009, 2011 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 /* Hint for `scm_gc_malloc ()' and friends.  */
  47 static const char hook_entry_gc_hint[] = "hook entry";
  48
  49 void
  50 scm_c_hook_init (scm_t_c_hook *hook, void *hook_data, scm_t_c_hook_type type)
  51 {
  52   hook->first = 0;
  53   hook->type = type;
  54   hook->data = hook_data;
  55 }
  56
  57 void
  58 scm_c_hook_add (scm_t_c_hook *hook,
  59                 scm_t_c_hook_function func,
  60                 void *fn_data,
  61                 int appendp)
  62 {
  63   scm_t_c_hook_entry *entry;
  64   scm_t_c_hook_entry **loc = &hook->first;
  65
  66   entry = scm_gc_malloc (sizeof (scm_t_c_hook_entry), hook_entry_gc_hint);
  67   if (appendp)
  68     while (*loc)
  69       loc = &(*loc)->next;
  70   entry->next = *loc;
  71   entry->func = func;
  72   entry->data = fn_data;
  73   *loc = entry;
  74 }
  75
  76 void
  77 scm_c_hook_remove (scm_t_c_hook *hook,
  78                    scm_t_c_hook_function func,
  79                    void *fn_data)
  80 {
  81   scm_t_c_hook_entry **loc = &hook->first;
  82   while (*loc)
  83     {
  84       if ((*loc)->func == func && (*loc)->data == fn_data)
  85         {
  86           *loc = (*loc)->next;
  87           return;
  88         }
  89       loc = &(*loc)->next;
  90     }
  91   fprintf (stderr, "Attempt to remove non-existent hook function\n");
  92   abort ();
  93 }
  94
  95 void *
  96 scm_c_hook_run (scm_t_c_hook *hook, void *data)
  97 {
  98   scm_t_c_hook_entry *entry = hook->first;
  99   scm_t_c_hook_type type = hook->type;
 100   void *res = 0;
 101   while (entry)
 102     {
 103       res = (entry->func) (hook->data, entry->data, data);
 104       if (res)
 105         {
 106           if (type == SCM_C_HOOK_OR)
 107             break;
 108         }
 109       else
 110         {
 111           if (type == SCM_C_HOOK_AND)
 112             break;
 113         }
 114       entry = entry->next;
 115     }
 116   return res;
 117 }
 118
 119 \f
 120 /* Scheme level hooks
 121  *
 122  * A hook is basically a list of procedures to be called at well defined
 123  * points in time.
 124  *
 125  * Hook arity is not a full member of this type and therefore lacks an
 126  * accessor.  It exists to aid debugging and is not intended to be used in
 127  * programs.
 128  */
 129
 130 scm_t_bits scm_tc16_hook;
 131
 132
 133 static int
 134 hook_print (SCM hook, SCM port, scm_print_state *pstate)
 135 {
 136   SCM ls, name;
 137   scm_puts_unlocked ("#<hook ", port);
 138   scm_intprint (SCM_HOOK_ARITY (hook), 10, port);
 139   scm_putc_unlocked (' ', port);
 140   scm_uintprint (SCM_UNPACK (hook), 16, port);
 141   ls = SCM_HOOK_PROCEDURES (hook);
 142   while (scm_is_pair (ls))
 143     {
 144       scm_putc_unlocked (' ', port);
 145       name = scm_procedure_name (SCM_CAR (ls));
 146       if (scm_is_true (name))
 147         scm_iprin1 (name, port, pstate);
 148       else
 149         scm_putc_unlocked ('?', port);
 150       ls = SCM_CDR (ls);
 151     }
 152   scm_putc_unlocked ('>', port);
 153   return 1;
 154 }
 155
 156
 157 SCM_DEFINE (scm_make_hook, "make-hook", 0, 1, 0,
 158             (SCM n_args),
 159             "Create a hook for storing procedure of arity @var{n_args}.\n"
 160             "@var{n_args} defaults to zero.  The returned value is a hook\n"
 161             "object to be used with the other hook procedures.")
 162 #define FUNC_NAME s_scm_make_hook
 163 {
 164   unsigned int n;
 165
 166   if (SCM_UNBNDP (n_args))
 167     n = 0;
 168   else
 169     n = scm_to_unsigned_integer (n_args, 0, 16);
 170
 171   SCM_RETURN_NEWSMOB (scm_tc16_hook + (n << 16), SCM_UNPACK (SCM_EOL));
 172 }
 173 #undef FUNC_NAME
 174
 175
 176 SCM_DEFINE (scm_hook_p, "hook?", 1, 0, 0,
 177             (SCM x),
 178             "Return @code{#t} if @var{x} is a hook, @code{#f} otherwise.")
 179 #define FUNC_NAME s_scm_hook_p
 180 {
 181   return scm_from_bool (SCM_HOOKP (x));
 182 }
 183 #undef FUNC_NAME
 184
 185
 186 SCM_DEFINE (scm_hook_empty_p, "hook-empty?", 1, 0, 0,
 187             (SCM hook),
 188             "Return @code{#t} if @var{hook} is an empty hook, @code{#f}\n"
 189             "otherwise.")
 190 #define FUNC_NAME s_scm_hook_empty_p
 191 {
 192   SCM_VALIDATE_HOOK (1, hook);
 193   return scm_from_bool (scm_is_null (SCM_HOOK_PROCEDURES (hook)));
 194 }
 195 #undef FUNC_NAME
 196
 197
 198 SCM_DEFINE (scm_add_hook_x, "add-hook!", 2, 1, 0,
 199             (SCM hook, SCM proc, SCM append_p),
 200             "Add the procedure @var{proc} to the hook @var{hook}. The\n"
 201             "procedure is added to the end if @var{append_p} is true,\n"
 202             "otherwise it is added to the front.  The return value of this\n"
 203             "procedure is not specified.")
 204 #define FUNC_NAME s_scm_add_hook_x
 205 {
 206   SCM rest;
 207   int n_args, p_req, p_opt, p_rest;
 208   SCM_VALIDATE_HOOK (1, hook);
 209   SCM_ASSERT (scm_i_procedure_arity (proc, &p_req, &p_opt, &p_rest),
 210               proc, SCM_ARG2, FUNC_NAME);
 211   n_args = SCM_HOOK_ARITY (hook);
 212   if (p_req > n_args || (!p_rest && p_req + p_opt < 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_is_pair (procs))
 273     {
 274       scm_apply_0 (SCM_CAR (procs), args);
 275       procs = SCM_CDR (procs);
 276     }
 277 }
 278
 279 void
 280 scm_c_run_hookn (SCM hook, SCM *argv, size_t nargs)
 281 {
 282   SCM procs = SCM_HOOK_PROCEDURES (hook);
 283   while (scm_is_pair (procs))
 284     {
 285       scm_call_n (SCM_CAR (procs), argv, nargs);
 286       procs = SCM_CDR (procs);
 287     }
 288 }
 289
 290
 291 SCM_DEFINE (scm_hook_to_list, "hook->list", 1, 0, 0,
 292             (SCM hook),
 293             "Convert the procedure list of @var{hook} to a list.")
 294 #define FUNC_NAME s_scm_hook_to_list
 295 {
 296   SCM_VALIDATE_HOOK (1, hook);
 297   return scm_list_copy (SCM_HOOK_PROCEDURES (hook));
 298 }
 299 #undef FUNC_NAME
 300
 301
 302 \f
 303
 304 void
 305 scm_init_hooks ()
 306 {
 307   scm_tc16_hook = scm_make_smob_type ("hook", 0);
 308   scm_set_smob_print (scm_tc16_hook, hook_print);
 309 #include "libguile/hooks.x"
 310 }
 311
 312 /*
 313   Local Variables:
 314   c-file-style: "gnu"
 315   End:
 316 */