content: /*
   * Copyright 2022 paxos.cn.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package cn.paxos.mysql;
  
  import cn.paxos.mysql.engine.QueryResultColumn;
  
  import java.util.List;
  
  /**
   * Response writer.
   *
   * A normal result must call a writeColumns() before all invoking of writeRow() and call finish() finally
   */
  public interface ResultSetWriter {
  
      /**
       * Write columns.
       * It must be called before any invoking of writeRow()
       *
       * @param columns columns
       */
      void writeColumns(List<QueryResultColumn> columns);
  
      /**
       * Write a row.
       * finish() must be called after writing all rows
       *
       * @param row row of cells ordered by columns
       */
      void writeRow(List<String> row);
  
      /**
       * Finish the response
       */
      void finish();
  }
  