// executes things like "hasWord($x) => ..."

sclass AI_ExecuteSimpleForWhere implements Steppable {

  // filled by user (necessary)

  ForWhere fw;

  DeepZipTools tools;

  // handle output

  swappable void addLogicRule(BasicLogicRule rule) {}

  // iterate values for function

  swappable Iterable elementsForFunction(S functionName) { null; }

  // internal variables

  O var;

  S functionName;

  Iterator elements;

  *() {}

  *(DeepZipTools *tools, IVF1<BasicLogicRule> *addLogicRule,

    IF1<S, Iterable> *elementsForFunction, ForWhere *fw) {}

  public bool step() {

    if (elements == null) {

      Pair p = forWhereParseSimpleFunctionCall(fw, tools);

      if (p == null) false;

      functionName = (S) p.b;

      var = p.a;

      elements = iterator(elementsForFunction(functionName));

    }

    if (!elements.hasNext()) false;

    addLogicRule((BasicLogicRule) tools.replaceVars(fw.body, litmap(var, elements.next())));

    true;

  }

}