// 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);

  }

}