package com.github.mygreen.supercsv.cellprocessor.conversion;
   
   import java.util.Arrays;
   import java.util.Optional;
   import java.util.Set;
   import java.util.stream.Collectors;
   
   import org.supercsv.cellprocessor.ift.CellProcessor;
   import org.supercsv.cellprocessor.ift.StringCellProcessor;
  
  import com.github.mygreen.supercsv.annotation.conversion.CsvNullConvert;
  import com.github.mygreen.supercsv.builder.Configuration;
  import com.github.mygreen.supercsv.builder.FieldAccessor;
  import com.github.mygreen.supercsv.cellprocessor.ConversionProcessorFactory;
  import com.github.mygreen.supercsv.cellprocessor.format.TextFormatter;
  
  /**
   * アノテーション{@link CsvNullConvert}をハンドリングして、任意の値をnull変換するためのCellProcessor{@link NullConvert}を作成する。
   *
   * @since 2.0
   * @author T.TSUCHIE
   *
   */
  public class NullConvertFactory implements ConversionProcessorFactory<CsvNullConvert> {
      
      @Override
      public Optional<CellProcessor> create(final CsvNullConvert anno, final Optional<CellProcessor> next,
              final FieldAccessor field, final TextFormatter<?> formatter, final Configuration config) {
          
          final Set<String> tokens = Arrays.stream(anno.value())
                  .collect(Collectors.toSet());
          
          final NullConvertrsion/NullConvert.html#NullConvert">NullConvert processor = next.map(n -> new NullConvert(tokens, anno.ignoreCase(), (StringCellProcessor)n))
                  .orElseGet(() -> new NullConvert(tokens, anno.ignoreCase()));
          
          return Optional.of(processor);
      }
      
  }