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* list.c (scm_reverse): Report an error if given a circular list
instead of filling memory. * list.c (scm_reverse_x): Check args.
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1 changed files with 36 additions and 27 deletions
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@ -259,42 +259,51 @@ scm_last_pair(sx)
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/* reversing lists */
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SCM_PROC (s_reverse, "reverse", 1, 0, 0, scm_reverse);
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SCM
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scm_reverse(lst)
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SCM lst;
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scm_reverse (SCM ls)
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{
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SCM res = SCM_EOL;
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SCM p = lst;
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for(;SCM_NIMP(p);p = SCM_CDR(p)) {
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SCM_ASSERT(SCM_CONSP(p), lst, SCM_ARG1, s_reverse);
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res = scm_cons(SCM_CAR(p), res);
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}
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SCM_ASSERT(SCM_NULLP(p), lst, SCM_ARG1, s_reverse);
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return res;
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SCM res = SCM_EOL;
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SCM p = ls, t = ls;
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while (SCM_NIMP (p))
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{
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SCM_ASSERT (SCM_CONSP (p), ls, SCM_ARG1, s_reverse);
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res = scm_cons (SCM_CAR (p), res);
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p = SCM_CDR (p);
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if (SCM_IMP (p))
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break;
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SCM_ASSERT (SCM_CONSP (p), ls, SCM_ARG1, s_reverse);
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res = scm_cons (SCM_CAR (p), res);
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p = SCM_CDR (p);
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t = SCM_CDR (t);
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if (t == p)
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scm_misc_error (s_reverse, "Circular structure: %S", SCM_LIST1 (ls));
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}
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SCM_ASSERT (SCM_NULLP (p), ls, SCM_ARG1, s_reverse);
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return res;
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}
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SCM_PROC (s_reverse_x, "reverse!", 1, 1, 0, scm_reverse_x);
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SCM
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scm_reverse_x (lst, newtail)
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SCM lst;
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SCM newtail;
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scm_reverse_x (ls, new_tail)
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SCM ls;
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SCM new_tail;
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{
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SCM old_tail;
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if (newtail == SCM_UNDEFINED)
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newtail = SCM_EOL;
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SCM_ASSERT (scm_ilength (ls) >= 0, ls, SCM_ARG1, s_reverse_x);
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if (SCM_UNBNDP (new_tail))
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new_tail = SCM_EOL;
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else
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SCM_ASSERT (scm_ilength (new_tail) >= 0, new_tail, SCM_ARG2, s_reverse_x);
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loop:
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if (!(SCM_NIMP (lst) && SCM_CONSP (lst)))
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return lst;
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old_tail = SCM_CDR (lst);
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SCM_SETCDR (lst, newtail);
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if (SCM_NULLP (old_tail))
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return lst;
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newtail = lst;
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lst = old_tail;
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goto loop;
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while (SCM_NIMP (ls))
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{
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old_tail = SCM_CDR (ls);
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SCM_SETCDR (ls, new_tail);
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new_tail = ls;
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ls = old_tail;
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}
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return new_tail;
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}
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