// Logic thread for "for any * holds *"

static class LThread2 {
  IEngine engine;
  new L<Lisp> statements;

  new SNLMatches m; // current variable assignments
  int opIdx;
  new L<Lisp> output;
  L<S> log;
  new L<Iterator<Boolean>> iterators;
  new L<Integer> states;
  
  *(Lisp code) {
    this(null, code);
  }
  
  *(IEngine *engine, Lisp code) {
    assertTrue(snlMatch2("for < any < For < holds < Holds", code, m));
    addIterator(getIterator("For"));
  }
  
  void addIterator(Iterator<Boolean> it) {
    if (it != null) {
      iterators.add(it);
  }
  
  // returns false if done
  boolean step() {
    while true {
      if (empty(iterators)) ret false;
    
      Iterator<Boolean it = last(iterators);
      if (it.next())
        ret true;
      
      popLast(iterators);
    }
  }
  
  Iterator<Boolean> getIterator(S var) {
    Lisp term = snlApply(m.get(var), m);
    new SNLMatches m2;
    if (!snlMatch2("X < in < Y", m2))
      ret null;
    final L<Lisp> list = snlParseList(Y);
    int state = -1;
    
    ret new Iterator<Boolean>() {
      int i = 0;
      
      public boolean hasNext() {
        ret i < l(list);
      ]
      
      public Boolean next() {
        m.set(m2.str("X"), list.get(i++));
        ret true;
      }
      
      public void remove() {}
    };
  }
  
  void say(Lisp b) {
    output.add(snlApply(b, m.map));
  }
}

Began life as a copy of #1002752