ifclass LineCompCompressor
static LCLongerProds lcSimplifyToLongerProductions(LineCompCompressor comp) {
  ret lcSimplifyToLongerProductions(
    map(countIterator_exclusive(0, comp.nLiterals()), i -> comp.itemToString(i)),
    map(countIterator_exclusive(comp.nLiterals(), comp.nItems()), i -> comp.getPair(i)),
    comp.finalEncodings);
}
endif

static LCLongerProds lcSimplifyToLongerProductions(LS literals, L<IntPair> pairs, Map<S, L<Int>> files) {
  new LCLongerProds lc;
  lc.literals = literals;
  int nLiterals = l(literals);
  for i over pairs:
    lc.productions.put(nLiterals+i, intPairToList(pairs.get(i)));
  lc.files = mapValues cloneList(files);
  
  bool change;
  do {
    ping();
    change = false;
    new MultiSet<Int> counts;
    for (L<Int> l : concatLists(values(lc.productions), values(lc.files)))
      for (int i : l)
        if (i >= nLiterals)
          counts.add(i);
    for (int i : cloneList(counts.asSet()))
      if (counts.get(i) == 1) {
        set change;
        L<Int> unrolled = assertNotNull(lc.productions.get(i));
        print("Unrolling " + i + " => " + unrolled);
        lc.productions.remove(i);
        counts.remove(i);
        for (L<Int> l : concatLists(values(lc.productions), values(lc.files)))
          replaceSublist(l, ll(i), unrolled);
      }
  } while (change);
  ret lc;
}

Began life as a copy of #1028777