// NewEngine takes facts which mix Java objects and sentence parts ("fragments")
// e.g. ll(obj1, Fragment("leads to"), obj2)
// short syntax: formatFrag("* leads to *", obj1, obj2)

// rules contain the same kind of construct on lhs and rhs with
// dollar variables (e.g. "$x", not as a Fragment)

sclass NewEngine implements Steppable {
  replace LogicRule with BasicLogicRule.

  transient new Map facts; // facts to trail
  transient AllOnAllWithOperation<LogicRule, O> rulesAndFacts = new(lambda2 applyLogicRuleToFact);

  new DeepZipTools tools;
  
  bool verbose = true, printNonMatches;
  
  public bool step() { ret rulesAndFacts.step(); }

  void addLogicRule(LogicRule rule) {
    rule = curryLHS_BasicLogicRule(rule);
    if (verbose) print("New rule: " + rule);
    rulesAndFacts.newA(rule);
  }

  void addFact(O fact) { addFact(fact, "external"); }
  
  void addFact(O fact, O trail) {
    if (trail == null) trail = "unknown";
    if (facts.put(fact, trail) != null) ret;
    if (verbose) print("New fact: " + fact);
    rulesAndFacts.newB(fact);
  }
  
  void addFormattedFact(S starPattern, O... args) {
    addFact(formatWithFragments(starPattern, args));
  }
   
  L factsInOrderOfDefinition() { ret rulesAndFacts.cloneBList(); }  
  
  void run {
    stepAll(this);
    print("done. " + nFacts(rulesAndFacts.bList) + ", " + nRules(rulesAndFacts.aList));
  }
  
  void think { run(); }

  void applyLogicRuleToFact(LogicRule rule, O fact) {
    new LogicRuleApplier ap;
    ap.rule = rule;
    ap.fact = fact;
    ap.verbose = verbose;
    ap.printNonMatches = printNonMatches;
    ap.addRewrittenRHS = lambda2 addRewrittenRHS;
    ap.tools = tools;
    ap.run();
  }

  void addRewrittenRHS(O o, O trail) {
    if (o cast LogicRule) {
      o.trail = trail;
      addLogicRule(o);
    } else if o is And(O a, O b) {
      addRewrittenRHS(a, o);
      addRewrittenRHS(b, o);
    } else if (o != null)
      addFact(o, trail);
  }
}

Began life as a copy of #1027758