cmodule AModule {

  switchable S input = "STATICALAFLATTENLISTOFPAIRSLPAIRALLAOUTEMPTYLISTLLFORPAIRAPUNNULLLOUTADDPAOUTADDPBRETOUT";

  switchable S words = "ret ll ls static out list pair pairs flatten null of if else while for";

  S firstResult;

  transient BigInt totalCombinations;

  // basically immutable (we make a new copy for every step)

  // to allow evaluating states in parallel and in any order

  class GreedySplitIntoWordsCI_Multi implements IF0<Either<Iterable<GreedySplitIntoWordsCI_Multi>, LS>> {

    S s; // the input to be split

    TreeSet<S> wordsSet;

    Map<Int> longestMatchMap;

    int i = 0, last = 0;

    ReverseChain<S> out;

    *() {}

    *(S *s, Cl<S> words) {

      wordsSet = asCISet(words);

      longestMatchMap = new AutoMap<Int>(i -> dontPrint("longest match at " + i + ": ", lengthOfLongestPrefixInCISet(substring(s, i), wordsSet)));

    }

    Cl<S> wordsAtPosition(int i) {

      int longestMatch = longestMatchMap.get(i);

      ret mapNonNulls(countBackwardsTo1(longestMatch), matchLength -> {

        S word = substring(s, i, i+matchLength);

        ret contains(wordsSet, word) ? word : null;

      });

    }

    // either we return some choices or a final result

    Either<Iterable<GreedySplitIntoWordsCI_Multi>, LS> get() {

      if (i >= l(s)) ret done(); // done with input

      ret eitherA(listPlus(map(wordsAtPosition(i), wordMatched -> {

        GreedySplitIntoWordsCI_Multi clone = shallowClone(this, new GreedySplitIntoWordsCI_Multi);

        clone.flush();

        clone.i = clone.last = i+l(wordMatched);

        clone.out = revChainPlus(clone.out, substring(s, i, clone.i));

        ret clone;

      }), getVar(() -> {

        GreedySplitIntoWordsCI_Multi clone = shallowClone(this, new GreedySplitIntoWordsCI_Multi);

        clone.i++;

        ret clone;

      })));

    }

    Either<Iterable<GreedySplitIntoWordsCI_Multi>, LS> done() {

      flush();

      ret eitherB(asList(out));

    }

    S unflushed() { ret substring(s, last, i); }

    void flush {

      if (i <= last) ret;

      // modifying this object in spite of convention

      out = revChainPlus(out, unflushed());

      last = i;

    }

    toString { ret asList(out) + prependIfNempty("|", unflushed()) + ", " + i + "/" + l(s); }

    S sentence() { ret joinNemptiesWithSpace(listPlus(asList(out), unflushed())); }

  }

  GreedySplitIntoWordsCI_Multi root() {

    ret new GreedySplitIntoWordsCI_Multi(input, splitAtSpace(words));

  }

  visual northAndCenterWithMargins(

    jvstackWithSpacing(

      withLabel("Total combinations:", dm_label totalCombinations()),

      withLabel("Preferred result:", dm_label firstResult())),

    jDynamicEitherTree(root(),

      valueToText := (IF1<Either<GreedySplitIntoWordsCI_Multi, LS>, S>) x

        -> isEitherA(x) ? eitherAOpt(x).sentence() + "..." : joinWithSpace(eitherBOpt(x))));

  start-thread {

    dm_reloadOnFieldChange('words, 'input);

    time {

      print("First result: " + setField(firstResult := joinWithSpace(getFirstResultOfEitherTree(root()!))));

    }

    GreedySplitIntoWordsCI_Multi root = root();

    // We should subtract combinationsAtPosition(i-l(word)) for each word because I think it is counted twice

    setField(totalCombinations := combinationsForPositionalParser(

      l(input), i -> listPlus(lambdaMap l(root.wordsAtPosition(i)), 1), debug := true);

  }

}