static ATerm unfold_rec(ATerm t) {
/* Completely unfolds t according to equivalence.
invariants:
- loop_detection contains "ancestors" of t
- t is end point of find
- solution contains correct results [t -> s]
returns NULL: loop detected
returns s: s is unfolding of t.
*/
ATerm s;
ATbool no_loop;
char unifiable=1;
if (ATisVariable(t)) return t;
if ((s=ATtableGet(solution,t))) return s;
ATindexedSetPut(loop_detection,t,&no_loop);
if (no_loop) {
Symbol sym = ATgetSymbol(t);
int i,n=ATgetArity(sym);
ATerm *args = (ATerm*)alloca(n*sizeof(ATerm));
for (i=0;i<n;i++)
if (!(args[i] = unfold_rec(find(ATgetArgument(t,i))))) {
unifiable=0;
break;
}
ATindexedSetRemove(loop_detection,t);
if (unifiable) {
s=(ATerm)ATmakeApplArray(sym,args);
ATtablePut(solution,t,s);
return s;
} }
/* here either !no_loop, or !unifiable holds */
return NULL;
}
void SG_UnMark(ATerm t)
{
ATindexedSetRemove(marks, (ATerm) t);
}
