sclass GazelleTree {

  L<GazelleTree> children;

  GazelleTree parent;

  double weight = 1, totalWeight;

  S line, lineType;

  S prediction, judgement;

  RuleEngine2_MatchedRule mr;

  bool isSplitNode;

  long created = now();

  transient GazelleEvalContext ctx;

  *() {}

  *(S *line) {}

  *(GazelleEvalContext *ctx, S *line) {}

  // e.g. for rendering tree

  toString {

    ret (isSplitNode ? "[split] " : "") + line + appendSquareBracketed(joinWithComma(listPlusNempties(renderQualityElements(), ruleID())));

  }

  LS renderQualityElements() {

    new LS l;

    addIfNempty(l, prediction);

    if (mr != null) {

      l.add(mr.qualitySum() + " / " + formatDouble(mr.relativeQuality(), 2));

      if (mr.moreConditions())

        l.add("unsatisfied");

    }

    ret l;

  }

  // includes this node

  LS history() {

    new LS l;

    GazelleTree e = this;

    while (e != null) {

      l.add(e.line);

      e = e.parent;

    }

    ret reversed(l);

  }

  void add(GazelleTree child) {

    if (children == null) children = new L;

    child.parent = this;

    child.setContext(ctx);

    children.add(child);

  }

  void setContext(GazelleEvalContext ctx) {

    this.ctx = ctx;

    pcallFAll(ctx.onNewNode, this);

    _add(ctx.linesSet, line);

  }

  RuleEngine2.Rule rule() {

    ret mr == null ? null : mr.rule;

  }

  S ruleID() { ret rule() == null ? null : rule().globalID; }

  SS varMap() {

    ret mr == null ? null : mr.map;

  }

  void flush() {

    if (mr != null) {

      mr.flush();

      line = mr.outText();

    }

  }

  Collection<S> ruleComments() {

    RuleEngine2.Rule rule = rule();

    ret rule == null ? null : rule.comments;

  }

}