text: #pragma once
  
  #include <Core/Block.h>
  #include <Processors/Formats/IRowInputFormat.h>
  #include <Formats/FormatSettings.h>
  #include <Common/HashTable/HashMap.h>
  
  
  namespace DB
  {
  
  class ReadBuffer;
  
  
  /** Stream for reading data in TSKV format.
    * TSKV is a very inefficient data format.
    * Similar to TSV, but each field is written as key=value.
    * Fields can be listed in any order (including, in different lines there may be different order),
    *  and some fields may be missing.
    * An equal sign can be escaped in the field name.
    * Also, as an additional element there may be a useless tskv fragment - it needs to be ignored.
    */
  class TSKVRowInputFormat : public IRowInputFormat
  {
  public:
      TSKVRowInputFormat(ReadBuffer & in_, Block header_, Params params_, const FormatSettings & format_settings_);
  
      String getName() const override { return "TSKVRowInputFormat"; }
  
      bool readRow(MutableColumns & columns, RowReadExtension &) override;
      bool allowSyncAfterError() const override { return true; }
      void syncAfterError() override;
  
  private:
      const FormatSettings format_settings;
  
      /// Buffer for the read from the stream the field name. Used when you have to copy it.
      String name_buf;
  
      /// Hash table matching `field name -> position in the block`. NOTE You can use perfect hash map.
      using NameMap = HashMap<StringRef, size_t, StringRefHash>;
      NameMap name_map;
  
      /// Set of columns for which the values were read. The rest will be filled with default values.
      std::vector<UInt8> read_columns;
      /// Set of columns which already met in row. Exception is thrown if there are more than one column with the same name.
      std::vector<UInt8> seen_columns;
      /// These sets may be different, because if null_as_default=1 read_columns[i] will be false and seen_columns[i] will be true
      /// for row like ..., non-nullable column name=\N, ...
  };
  
  }
  