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/*!
 * Copyright (c) 2015 by Contributors
 * \file json.h
 * \brief Lightweight JSON Reader/Writer that read save into C++ data structs.
 *  This includes STL composites and structures.
 */
#ifndef DMLC_JSON_H_
#define DMLC_JSON_H_

// This code requires C++11 to compile
#include <vector>
#include <iostream>
#include <cctype>
#include <string>
#include <algorithm>
#include <map>
#include <list>
#include <utility>

#include "./base.h"
#include "./logging.h"
#include "./type_traits.h"

#if DMLC_USE_CXX11
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#if DMLC_STRICT_CXX11
#if DMLC_ENABLE_RTTI
#include "./any.h"
#endif  // DMLC_ENABLE_RTTI
#endif  // DMLC_STRICT_CXX11
#endif  // DMLC_USE_CXX11

namespace dmlc {
/*!
 * \brief Lightweight JSON Reader to read any STL compositions and structs.
 *  The user need to know the schema of the
 *
 */
class JSONReader {
 public:
  /*!
   * \brief Constructor.
   * \param is the input stream.
   */
  explicit JSONReader(std::istream *is)
      : is_(is),
        line_count_r_(0),
        line_count_n_(0) {}
  /*!
   * \brief Parse next JSON string.
   * \param out_str the output string.
   * \throw dmlc::Error when next token is not string
   */
  inline void ReadString(std::string *out_str);
  /*!
   * \brief Read Number.
   * \param out_value output value;
   * \throw dmlc::Error when next token is not number of ValueType.
   * \tparam ValueType type of the number
   */
  template<typename ValueType>
  inline void ReadNumber(ValueType *out_value);
  /*!
   * \brief Begin parsing an object.
   * \code
   *  std::string key;
   *  // value can be any type that is json serializable.
   *  std::string value;
   *  reader->BeginObject();
   *  while (reader->NextObjectItem(&key)) {
   *    // do somthing to key value
   *    reader->Read(&value);
   *  }
   * \endcode
   */
  inline void BeginObject();
  /*!
   * \brief Begin parsing an array.
   * \code
   *  // value can be any type that is json serializable.
   *  std::string value;
   *  reader->BeginArray();
   *  while (reader->NextObjectArrayItem(&value)) {
   *    // do somthing to value
   *  }
   * \endcode
   */
  inline void BeginArray();
  /*!
   * \brief Try to move to next object item.
   *  If this call is successful, user can proceed to call
   *  reader->Read to read in the value.
   * \param out_key the key to the next object.
   * \return true if the read is successful, false if we are at end of the object.
   */
  inline bool NextObjectItem(std::string *out_key);
  /*!
   * \brief Try to read the next element in the array.
   *  If this call is successful, user can proceed to call
   *  reader->Read to read in the value.
   * \return true if the read is successful, false if we are at end of the array.
   */
  inline bool NextArrayItem();
  /*!
   * \brief Read next ValueType.
   * \param out_value any STL or json readable type to be read
   * \throw dmlc::Error when the read of ValueType is not successful.
   * \tparam ValueType the data type to be read.
   */
  template<typename ValueType>
  inline void Read(ValueType *out_value);

  /*! \return current line count */
  inline std::string line_info() const {
    char temp[64];
    std::ostringstream os;
    os << " Line " << std::max(line_count_r_, line_count_n_);
    is_->getline(temp, 64);
    os << ", around ^`" << temp << "`";
    return os.str();
  }

 private:
  /*! \brief internal reader stream */
  std::istream *is_;
  /*! \brief "\\r" counter */
  size_t line_count_r_;
  /*! \brief "\\n" counter */
  size_t line_count_n_;
  /*!
   * \brief record how many element processed in
   *  current array/object scope.
   */
  std::vector<size_t> scope_counter_;
  /*!
   * \brief Read next nonspace character.
   * \return the next nonspace character.
   */
  inline int NextNonSpace();
  /*!
   * \brief Read just before next nonspace but not read that.
   * \return the next nonspace character.
   */
  inline int PeekNextNonSpace();
};

/*!
 * \brief Lightweight json to write any STL compositions.
 */
class JSONWriter {
 public:
  /*!
   * \brief Constructor.
   * \param os the output stream.
   */
  explicit JSONWriter(std::ostream *os)
      : os_(os) {}
  /*!
   * \brief Write a string that do not contain escape characters.
   * \param s the string to be written.
   */
  inline void WriteNoEscape(const std::string &s);
  /*!
   * \brief Write a string that can contain escape characters.
   * \param s the string to be written.
   */
  inline void WriteString(const std::string &s);