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guile/libguile/dynwind.c

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/* Copyright (C) 1995,1996 Free Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
* As a special exception, the Free Software Foundation gives permission
* for additional uses of the text contained in its release of GUILE.
*
* The exception is that, if you link the GUILE library with other files
* to produce an executable, this does not by itself cause the
* resulting executable to be covered by the GNU General Public License.
* Your use of that executable is in no way restricted on account of
* linking the GUILE library code into it.
*
* This exception does not however invalidate any other reasons why
* the executable file might be covered by the GNU General Public License.
*
* This exception applies only to the code released by the
* Free Software Foundation under the name GUILE. If you copy
* code from other Free Software Foundation releases into a copy of
* GUILE, as the General Public License permits, the exception does
* not apply to the code that you add in this way. To avoid misleading
* anyone as to the status of such modified files, you must delete
* this exception notice from them.
*
* If you write modifications of your own for GUILE, it is your choice
* whether to permit this exception to apply to your modifications.
* If you do not wish that, delete this exception notice.
*/
#include <stdio.h>
#include "_scm.h"
/* {Dynamic wind}
*/
SCM_PROC(s_dynamic_wind, "dynamic-wind", 3, 0, 0, scm_dynamic_wind);
#ifdef __STDC__
SCM
scm_dynamic_wind (SCM thunk1, SCM thunk2, SCM thunk3)
#else
SCM
scm_dynamic_wind (thunk1, thunk2, thunk3)
SCM thunk1;
SCM thunk2;
SCM thunk3;
#endif
{
SCM ans;
scm_apply (thunk1, SCM_EOL, SCM_EOL);
scm_dynwinds = scm_acons (thunk1, thunk3, scm_dynwinds);
ans = scm_apply (thunk2, SCM_EOL, SCM_EOL);
scm_dynwinds = SCM_CDR (scm_dynwinds);
scm_apply (thunk3, SCM_EOL, SCM_EOL);
return ans;
}
#ifdef __STDC__
void
scm_dowinds (SCM to, long delta)
#else
void
scm_dowinds (to, delta)
SCM to;
long delta;
#endif
{
tail:
if (scm_dynwinds == to);
else if (0 > delta)
{
SCM wind_elt;
SCM wind_key;
scm_dowinds (SCM_CDR (to), 1 + delta);
wind_elt = SCM_CAR (to);
#if 0
if (SCM_INUMP (wind_elt))
{
scm_cross_dynwind_binding_scope (wind_elt, 0);
}
else
#endif
{
wind_key = SCM_CAR (wind_elt);
if ( !(SCM_NIMP (wind_key) && SCM_SYMBOLP (wind_key))
&& (wind_key != SCM_BOOL_F)
&& (wind_key != SCM_BOOL_T))
scm_apply (wind_key, SCM_EOL, SCM_EOL);
}
scm_dynwinds = to;
}
else
{
SCM from;
SCM wind_elt;
SCM wind_key;
from = SCM_CDR (SCM_CAR (scm_dynwinds));
wind_elt = SCM_CAR (scm_dynwinds);
scm_dynwinds = SCM_CDR (scm_dynwinds);
#if 0
if (SCM_INUMP (wind_elt))
{
scm_cross_dynwind_binding_scope (wind_elt, 0);
}
else
#endif
{
wind_key = SCM_CAR (wind_elt);
if ( !(SCM_NIMP (wind_key) && SCM_SYMBOLP (wind_key))
&& (wind_key != SCM_BOOL_F)
&& (wind_key != SCM_BOOL_T))
scm_apply (from, SCM_EOL, SCM_EOL);
}
delta--;
goto tail; /* scm_dowinds(to, delta-1); */
}
}
#ifdef __STDC__
void
scm_init_dynwind (void)
#else
void
scm_init_dynwind ()
#endif
{
#include "dynwind.x"
}