sclass AI_ThoughtSpace implements AI_PostHandler, AI_CacheChecker {
  int limit; // 0 = no limit
  new TripleIndex index;

  *() {}
  *(int *limit) {}
  
  // existence of triple has already been checked
  public S postTriple(T3<S> t) {
    if (limitReached()) fail("Thought space limit reached");
    TripleWeb w = tripleWeb(t);
    index.addTriple(w);
    ret w.globalID();
  }
  
  void addWeb(Web web) {
    postTriple(webToTriple(web));
  }
  
  public bool hasTriple(S a, S b, S c) {
    L<Web> webs = ai_withoutInvalidWebs(nodesToWebs(shortestList3(
      index.get(a),
      index.get(b),
      index.get(c))));
    ret webs_search_noVar_bool(webFromTriples(a, b, c), webs);
  }
  
  bool limitReached() {
    ret limit > 0 && size() >= limit;
  }
  
  L<WebNode> indexedNodes_rawLookup(S s) {
    ret index.get(ai_shortenForIndex(s));
  }
  
  int numWebs() { ret l(websByID); }
  int size() { ret numWebs(); }
}