Method iff

basex-core/src/main/java/org/basex/query/QueryParser.java:1658–1684

Parses the "IfExpr" rule. @return query expression or null @throws QueryException query exception

()

   * @throws QueryException query exception
   */
  private Expr iff() throws QueryException {
    if(!wsConsumeWs(IF, IFPAR, "(")) return null;

    final LinkedList<InputInfo> infos = new LinkedList<>();
    infos.add(info());
    final ExprList list = new ExprList(3).add(ifCond());
    if(wsConsumeWs(THEN)) {
      list.add(check(single(), NOIF));
      if(wsConsumeWs(ELSE)) list.add(check(single(), NOIF));
    } else {
      list.add(enclosedExpr());
      while(wsConsume(ELSE)) {
        if(!wsConsume(IF)) {
          list.add(enclosedExpr());
          break;
        }
        infos.add(info());
        list.add(ifCond()).add(enclosedExpr());
      }
    }
    Expr expr = (list.size() & 1) == 0 ? Empty.VALUE : list.pop();
    while(!list.isEmpty()) {
      final Expr thn = list.pop(), cond = list.pop();
      expr = new If(infos.removeLast(), cond, thn, expr);
    }
    return expr;
  }

  /**
   * Parses the if condition.