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/*
Copyright (C) 1994 M. Hagiya, W. Schelter, T. Yuasa
Copyright (C) 2024 Camm Maguire
This file is part of GNU Common Lisp, herein referred to as GCL
GCL is free software; you can redistribute it and/or modify it under
the terms of the GNU LIBRARY GENERAL PUBLIC LICENSE as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
GCL 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with GCL; see the file COPYING. If not, write to the Free Software
Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
conditional.c
conditionals
*/
#include "include.h"
object sLotherwise;
static void
FFN(Fif)(object form)
{
object *top = vs_top;
if (endp(form) || endp(MMcdr(form)))
FEtoo_few_argumentsF(form);
if (!endp(MMcddr(form)) && !endp(MMcdddr(form)))
FEtoo_many_argumentsF(form);
eval(MMcar(form));
if (vs_base[0] == Cnil)
if (endp(MMcddr(form))) {
vs_top = vs_base = top;
vs_push(Cnil);
} else {
vs_top = top;
eval(MMcaddr(form));
}
else {
vs_top = top;
eval(MMcadr(form));
}
}
static void
FFN(Fcond)(object args)
{
object *top = vs_top;
object clause;
object conseq;
while (!endp(args)) {
clause = MMcar(args);
if (!consp(clause))
FEerror("~S is an illegal COND clause.",1,clause);
eval(MMcar(clause));
if (vs_base[0] != Cnil) {
conseq = MMcdr(clause);
if (endp(conseq)) {
vs_top = vs_base+1;
return;
}
while (!endp(conseq)) {
vs_top = top;
eval(MMcar(conseq));
conseq = MMcdr(conseq);
}
return;
}
vs_top = top;
args = MMcdr(args);
}
vs_base = vs_top = top;
vs_push(Cnil);
}
static void
FFN(Fcase)(object arg)
{
object *top = vs_top;
object clause;
object key;
object conseq;
if (endp(arg))
FEtoo_few_argumentsF(arg);
eval(MMcar(arg));
vs_top = top;
vs_push(vs_base[0]);
arg = MMcdr(arg);
while (!endp(arg)) {
clause = MMcar(arg);
if (!consp(clause))
FEerror("~S is an illegal CASE clause.",1,clause);
key = MMcar(clause);
conseq = MMcdr(clause);
if (consp(key))
do {
if (eql(MMcar(key),top[0]))
goto FOUND;
key = MMcdr(key);
} while (!endp(key));
else if (key == Cnil)
;
else if (key == Ct || key == sLotherwise || eql(key,top[0]))
goto FOUND;
arg = MMcdr(arg);
}
vs_base = vs_top = top;
vs_push(Cnil);
return;
FOUND:
if (endp(conseq)) {
vs_base = vs_top = top;
vs_push(Cnil);
} else
do {
vs_top = top;
eval(MMcar(conseq));
conseq = MMcdr(conseq);
} while (!endp(conseq));
return;
}
static void
FFN(Fwhen)(object form)
{
object *top = vs_top;
if (endp(form))
FEtoo_few_argumentsF(form);
eval(MMcar(form));
if (vs_base[0] == Cnil) {
vs_base = vs_top = top;
vs_push(Cnil);
} else {
form = MMcdr(form);
if (endp(form)) {
vs_base = vs_top = top;
vs_push(Cnil);
} else
do {
vs_top = top;
eval(MMcar(form));
form = MMcdr(form);
} while (!endp(form));
}
}
static void
FFN(Funless)(object form)
{
object *top = vs_top;
if (endp(form))
FEtoo_few_argumentsF(form);
eval(MMcar(form));
if (vs_base[0] == Cnil) {
vs_top = top;
form = MMcdr(form);
if (endp(form)) {
vs_base = vs_top = top;
vs_push(Cnil);
} else
do {
vs_top = top;
eval(MMcar(form));
form = MMcdr(form);
} while (!endp(form));
} else {
vs_base = vs_top = top;
vs_push(Cnil);
}
}
void
gcl_init_conditional(void)
{
make_special_form("IF",Fif);
make_special_form("COND",Fcond);
make_special_form("CASE",Fcase);
make_special_form("WHEN",Fwhen);
make_special_form("UNLESS",Funless);
sLotherwise = make_ordinary("OTHERWISE");
enter_mark_origin(&sLotherwise);
}
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