text: #pragma once
  
  #include <Poco/Timestamp.h>
  #include "IDictionarySource.h"
  #include <Core/Block.h>
  
  
  namespace DB
  {
  class Context;
  
  /// Allows loading dictionaries from a file with given format, does not support "random access"
  class FileDictionarySource final : public IDictionarySource
  {
  public:
      FileDictionarySource(const std::string & filename_, const std::string & format_, Block & sample_block_, const Context & context_);
  
      FileDictionarySource(const FileDictionarySource & other);
  
      BlockInputStreamPtr loadAll() override;
  
      BlockInputStreamPtr loadUpdatedAll() override
      {
          throw Exception{"Method loadUpdatedAll is unsupported for FileDictionarySource", ErrorCodes::NOT_IMPLEMENTED};
      }
  
      BlockInputStreamPtr loadIds(const std::vector<UInt64> & /*ids*/) override
      {
          throw Exception{"Method loadIds is unsupported for FileDictionarySource", ErrorCodes::NOT_IMPLEMENTED};
      }
  
      BlockInputStreamPtr loadKeys(const Columns & /*key_columns*/, const std::vector<size_t> & /*requested_rows*/) override
      {
          throw Exception{"Method loadKeys is unsupported for FileDictionarySource", ErrorCodes::NOT_IMPLEMENTED};
      }
  
      bool isModified() const override { return getLastModification() > last_modification; }
      bool supportsSelectiveLoad() const override { return false; }
  
      ///Not supported for FileDictionarySource
      bool hasUpdateField() const override { return false; }
  
      DictionarySourcePtr clone() const override { return std::make_unique<FileDictionarySource>(*this); }
  
      std::string toString() const override;
  
  private:
      Poco::Timestamp getLastModification() const;
  
      const std::string filename;
      const std::string format;
      Block sample_block;
      const Context & context;
      Poco::Timestamp last_modification;
  };
  
  }
  