sclass NLLogicChecker_v2 {
  S input;
  new L<S> facts;
  StringMatcher matcher = new NLStringMatcher_noVars;
  new L<S> posted;
  new ThreadLocal<IfThen> checkingRule;
  
  sclass Matching {
    new LinkedHashMap<S> matches; // var -> match
    new L<Exp> output;
    bool verbose;
  }
  
  bool checkRule(IfThen rule, Matching m) {
    if (rule == null) false;
    temp tempSetThreadLocal(checkingRule, rule);
    if (!checkExpression(rule.in, m)) false;
    print("Rewriting output: " + sfu(rule.out));
    m.output.add(apply(rule.out, m));
    true;
  }
  
  Exp apply(Exp e, Matching m) {
    if (e == null) null;
    if (e cast And)
      ret And(apply(e.a, m), apply(e.b, m));
    if (e cast Func) {
      S s = nlLogic_text(e.arg);
      ret Func(e.name, Sentence(javaTok(matcher.apply(s, m.matches))));
    }
    ret e;
  }
  
  bool checkExpression(Exp e, Matching m) {
    if (e cast And)
      ret checkExpression(e.a, m) && checkExpression(e.b, m);
    if (e cast Func) {
      if (eq(e.name, "input")) {
        S pat = nlLogic_text(e.arg);
        bool result = matcher.match(pat, input, m.matches);
        if (m.verbose) print("matched " + sfu(e) + " with " + quote(input) + " & " + sfu(m.matches) + " => " + result);
        ret result;
      }
      else if (eq(e.name, "fact")) {
        S pat = nlLogic_text(e.arg);
        for (S fact : facts)
          if (matcher.match(pat, fact, m.matches))
            true;
      }
    }
    false;
  }
}