libguile/dynwind.c

   1 /*      Copyright (C) 1995,1996 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program 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
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41 \f
  42
  43 #include <stdio.h>
  44 #include "_scm.h"
  45 #include "eval.h"
  46 #include "alist.h"
  47 #include "fluids.h"
  48
  49 #include "dynwind.h"
  50 \f
  51
  52 /* {Dynamic wind}
  53
  54    Things that can be on the wind list:
  55
  56    (enter-proc . leave-proc)     dynamic-wind
  57    (tag . jmpbuf)                catch
  58    (tag . lazy-catch)            lazy-catch
  59      tag is either a symbol or a boolean
  60
  61    ((fluid ...) . (value ...))   with-fluids
  62
  63 */
  64
  65
  66
  67 SCM_PROC(s_dynamic_wind, "dynamic-wind", 3, 0, 0, scm_dynamic_wind);
  68
  69 SCM
  70 scm_dynamic_wind (thunk1, thunk2, thunk3)
  71      SCM thunk1;
  72      SCM thunk2;
  73      SCM thunk3;
  74 {
  75   SCM ans;
  76   scm_apply (thunk1, SCM_EOL, SCM_EOL);
  77   scm_dynwinds = scm_acons (thunk1, thunk3, scm_dynwinds);
  78   ans = scm_apply (thunk2, SCM_EOL, SCM_EOL);
  79   scm_dynwinds = SCM_CDR (scm_dynwinds);
  80   scm_apply (thunk3, SCM_EOL, SCM_EOL);
  81   return ans;
  82 }
  83
  84
  85 void
  86 scm_dowinds (to, delta)
  87      SCM to;
  88      long delta;
  89 {
  90  tail:
  91   if (scm_dynwinds == to);
  92   else if (0 > delta)
  93     {
  94       SCM wind_elt;
  95       SCM wind_key;
  96
  97       scm_dowinds (SCM_CDR (to), 1 + delta);
  98       wind_elt = SCM_CAR (to);
  99 #if 0
 100       if (SCM_INUMP (wind_elt))
 101         {
 102           scm_cross_dynwind_binding_scope (wind_elt, 0);
 103         }
 104       else
 105 #endif
 106         {
 107           wind_key = SCM_CAR (wind_elt);
 108           if (!(SCM_NIMP (wind_key) && SCM_SYMBOLP (wind_key))
 109               && (wind_key != SCM_BOOL_F)
 110               && (wind_key != SCM_BOOL_T))
 111             {
 112               if (SCM_NIMP (wind_key) && SCM_CONSP (wind_key))
 113                 scm_swap_fluids (wind_key, SCM_CDR (wind_elt));
 114               else
 115                 scm_apply (wind_key, SCM_EOL, SCM_EOL);
 116             }
 117         }
 118       scm_dynwinds = to;
 119     }
 120   else
 121     {
 122       SCM from;
 123       SCM wind_elt;
 124       SCM wind_key;
 125
 126       from = SCM_CDR (SCM_CAR (scm_dynwinds));
 127       wind_elt = SCM_CAR (scm_dynwinds);
 128       scm_dynwinds = SCM_CDR (scm_dynwinds);
 129 #if 0
 130       if (SCM_INUMP (wind_elt))
 131         {
 132           scm_cross_dynwind_binding_scope (wind_elt, 0);
 133         }
 134       else
 135 #endif
 136         {
 137           wind_key = SCM_CAR (wind_elt);
 138           if (!(SCM_NIMP (wind_key) && SCM_SYMBOLP (wind_key))
 139               && (wind_key != SCM_BOOL_F)
 140               && (wind_key != SCM_BOOL_T))
 141             {
 142               if (SCM_NIMP (wind_key) && SCM_CONSP (wind_key))
 143                 scm_swap_fluids_reverse (wind_key, from);
 144               else
 145                 scm_apply (from, SCM_EOL, SCM_EOL);
 146             }
 147         }
 148       delta--;
 149       goto tail;                /* scm_dowinds(to, delta-1); */
 150     }
 151 }
 152
 153
 154
 155 void
 156 scm_init_dynwind ()
 157 {
 158 #include "dynwind.x"
 159 }