LineReader.hpp

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 **/

#ifndef QUICKSTEP_CLI_LINE_READER_HPP_
#define QUICKSTEP_CLI_LINE_READER_HPP_

#include <string>

#include "utility/Macros.hpp"

namespace quickstep {

/** \addtogroup CLI
 *  @{
 */

/**
 * @brief An interface for reading user input from command lines.
 **/
class LineReader {
 public:
  /**
   * @brief Constructor.
   *
   * @param default_prompt The default command prompt.
   * @param continue_prompt The prompt given when a command extends over more
   *        than one line.
   **/
  LineReader(const std::string &default_prompt,
             const std::string &continue_prompt)
      : default_prompt_(default_prompt), continue_prompt_(continue_prompt) {
  }

  /**
   * @brief Virtual destructor.
   **/
  virtual ~LineReader() {
  }

  /**
   * @brief Obtain the next full SQL command from user input.
   *
   * @return The next user-inputted command.
   **/
  std::string getNextCommand();

 protected:
  /**
   * @brief Get the next newline-terminated line from input.
   *
   * @param continuing True if continuing a command from a previous line, false
   *        otherwise.
   * @return The next line of input.
   **/
  virtual std::string getLineInternal(const bool continuing) = 0;

  const std::string default_prompt_;
  const std::string continue_prompt_;
  std::string leftover_;

 private:
  enum LineState {
    kNormal,
    kSingleQuote,
    kSingleQuoteWithEscape,
    kDoubleQuote,
    kDoubleQuoteWithEscape,
    kComment,
    kCommand
  };

  bool getMoreInput(std::string *input_buffer, bool *continuing);

  DISALLOW_COPY_AND_ASSIGN(LineReader);
};

/** @} */

}  // namespace quickstep

#endif  // QUICKSTEP_CLI_LINE_READER_HPP_