// A naive suffix tree implementation
sclass IntSuffixTree {
  Node root;
  L<Int> fullText;
  int nodeCount;
  
  Comparator<IFirstChar> childComparator = (a, b) -> a.firstCharOrMinus1(this)-b.firstCharOrMinus1(this);
  new DummyNode dummyNode;
  int printEvery = 1000000;
  
  sinterface IFirstChar {
    int firstCharOrMinus1(IntSuffixTree tree);
  }
  
  sclass DummyNode implements IFirstChar {
    int firstChar;
    
    public int firstCharOrMinus1(IntSuffixTree tree) { ret firstChar; }
  }

  sclass Node implements IFirstChar {
    int from, to; // our range in fullText
    CompactTreeSet<IFirstChar> children;

    *() {}
    *(int *from, int *to) {}
    *(IntRange s) { from = s.start; to = s.end; }
    
    L<Int> text(IntSuffixTree tree) { ret subList(tree.fullText, from, to); }
    
    int lText() { ret to-from; }
    
    bool isTerminal(IntSuffixTree tree) { ret to == l(tree.fullText); }
    
    void addChild(IntSuffixTree tree, Node n) {
      if (children == null) children = makeEmptyChildrenSet(tree);
      children.add(n);
    }
    
    CompactTreeSet<IFirstChar> makeEmptyChildrenSet(IntSuffixTree tree) {
      ret new CompactTreeSet<>(tree.childComparator);
    }
        
    Cl<IFirstChar> children() {
      ret children;
    }
    
    public int firstCharOrMinus1(IntSuffixTree tree) {
      ret getOrMinus1(tree.fullText, from);
    }
    
    Node getChild(IntSuffixTree tree, int c) {
      if (children == null) null;
      tree.dummyNode.firstChar = c;
      ret (Node) children.find(tree.dummyNode);
    }
  }

  *() {}
  *(L<Int> fullText) {
    process(fullText);
  }
  
  void process(L<Int> fullText) {
    root = new Node(0, 0);
    ++nodeCount;
    for i over fullText: {
      ping();
      addSuffix(IntRange(i, l(fullText)));
      if (((i+1) % printEvery) == 0)
        print((i+1) + "/" + l(fullText ) + " suffixes added (" + nNodes(nodeCount) + ")");
    }
  }

  void addSuffix(IntRange s) {
    Node node = root;
    
    while (!empty(s)) {
      int _n = lCommonPrefix_lists_ext(fullText, node.from, fullText, s.start);
      s.start += _n;
      if (_n >= node.lText()) { // node text exhausted
        if (empty(s)) { // pattern also exhausted - done
          //print("Exhausted: " + node.from + "/" + node.to);
          // add a new termination node
          Node nNew = new Node(s);
          ++nodeCount;
          node.addChild(IntSuffixTree.this, nNew);
          ret;
        } else {
          Node n = node.getChild(IntSuffixTree.this, getOrMinus1(fullText, s.start));
          if (n == null) {
            n = new Node(s);
            ++nodeCount;
            node.addChild(IntSuffixTree.this, n);
            ret;
          } else
            node = n;
        }
      } else { // node text not exhausted
        // split node. first, move all the node's vitals to a new node nOld
        Node nOld = new Node(node.from+_n, node.to);
        ++nodeCount;
        nOld.children = node.children;
        node.children = null;
        node.to = node.from+_n;
        node.addChild(IntSuffixTree.this, nOld);

        // now add a new node
        Node nNew = new Node(s);
        ++nodeCount;
        node.addChild(IntSuffixTree.this, nNew);
        ret;
      }
    }
  }

  public L<Int> indicesOf(L<Int> pattern) {
    ret asList(indicesOf_iterator(pattern));
  }

  public ItIt<Int> indicesOf_iterator(L<Int> pattern) {
    ret mapI_notNull(allNodesUnder(scanDown(root, pattern)),
      nad -> nad.node.isTerminal(this) ? nad.position() : null);
  }
  
  srecord NodeAndDepth(Node node, int depth) {
    int position() {
      int position = node.from-depth;
      //print("from=" + node.from + ", to=" + node.to + ", depth=" + depth + ", position=" + position);
      ret position;
    }
    
    Cl<NodeAndDepth> children() {
      ret lmap wrapChild((Cl<Node>) (Cl) node.children());
    }
    
    NodeAndDepth wrapChild(Node n) {
      ret n == null ? null : new NodeAndDepth(n, depth+node.lText());
    }
    
    NodeAndDepth getChild(IntSuffixTree tree, int c) {
      ret wrapChild(node.getChild(tree, c));
    }
  }

  NodeAndDepth scanDown(Node node, L<Int> pattern) {
    int lPattern = l(pattern), iPattern = 0;
    NodeAndDepth nad = new(node, 0);
    while true {
      int n = lCommonPrefix_lists(nad.node.text(this), subList(pattern, iPattern));
      iPattern += n;
      if (iPattern >= lPattern) break; // pattern exhausted - done
      if (n < nad.node.lText()) null; // mismatch, exit
      NodeAndDepth child = nad.getChild(IntSuffixTree.this, or(get(pattern, iPattern), -1));
      if (child != null) continue with nad = child;
      null;
    }
    
    ret nad;
  }
  
  void printMe() {
    printNode("", "", new NodeAndDepth(root, 0));
  }
  
  void printNode(S indent, S pre, NodeAndDepth nad) {
    print(indent + pre + takeFirst(20, nad.node.text(this)) + (!nad.node.isTerminal(this) ? "" : " [" + nad.position() + "]"));
    fOr (NodeAndDepth n : nad.children()) {
      printNode(indent + "  ", takeFirst(1, n.node.text(this)) + " ", n);
    }
  }
  
  ItIt<NodeAndDepth> allNodes() {
    ret allNodesUnder(new NodeAndDepth(root, 0));
  }
  
  // includes the node itself
  ItIt<NodeAndDepth> allNodesUnder(NodeAndDepth nad) {
    new L<Iterator<NodeAndDepth>> stack;
    if (nad != null)
      stack.add(iteratorLL(nad));
    ret iteratorFromFunction_if0(() -> {
      while (nempty(stack)) {
        if (!last(stack).hasNext())
          popLast(stack);
        else {
          NodeAndDepth n = last(stack).next();
          stack.add((Iterator) iterator(n.children()));
          ret n;
        }
      }
      null;
    });
  }
}

Began life as a copy of #1029234