code: package it.unibz.inf.ontop.model.term.functionsymbol.db.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.type.DBTermType;
  
  import java.util.function.Function;
  
  public class NonSimplifiableTypedNullFunctionSymbol extends AbstractTypedDBFunctionSymbol {
  
      /**
       * May differ from the target type (e.g. INTEGER for SERIAL)
       */
      private final DBTermType castingType;
  
      protected NonSimplifiableTypedNullFunctionSymbol(DBTermType targetType) {
          super("NULL-" + targetType, ImmutableList.of(), targetType);
          castingType = targetType;
      }
  
      protected NonSimplifiableTypedNullFunctionSymbol(DBTermType targetType, DBTermType castingType) {
          super("NULL-" + castingType, ImmutableList.of(), targetType);
          this.castingType = castingType;
      }
  
      @Override
      public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() {
          return true;
      }
  
      @Override
      public boolean canBePostProcessed(ImmutableList<? extends ImmutableTerm> arguments) {
          return false;
      }
  
  
      @Override
      public String getNativeDBString(ImmutableList<? extends ImmutableTerm> terms,
                                      Function<ImmutableTerm, String> termConverter, TermFactory termFactory) {
          return termConverter.apply(
                  termFactory.getDBCastFunctionalTerm(castingType, termFactory.getNullConstant()));
      }
  }
  