code: package it.unibz.inf.ontop.model.term.functionsymbol.db.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.iq.node.VariableNullability;
  import it.unibz.inf.ontop.model.term.DBConstant;
  import it.unibz.inf.ontop.model.term.ImmutableExpression;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.type.DBTermType;
  
  public abstract class AbstractDBIsStringEmptyFunctionSymbol extends DBBooleanFunctionSymbolImpl {
  
      protected AbstractDBIsStringEmptyFunctionSymbol(DBTermType dbBooleanType, DBTermType rootDBType) {
          super("IS_STR_EMPTY", ImmutableList.of(rootDBType), dbBooleanType);
      }
  
      @Override
      public boolean blocksNegation() {
          return true;
      }
  
      @Override
      public ImmutableExpression negate(ImmutableList<? extends ImmutableTerm> subTerms, TermFactory termFactory) {
          throw new UnsupportedOperationException();
      }
  
      @Override
      public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() {
          return false;
      }
  
      @Override
      public boolean canBePostProcessed(ImmutableList<? extends ImmutableTerm> arguments) {
          return true;
      }
  
      @Override
      protected ImmutableTerm buildTermAfterEvaluation(ImmutableList<ImmutableTerm> newTerms,
                                                       TermFactory termFactory, VariableNullability variableNullability) {
          ImmutableTerm newTerm = newTerms.get(0);
          if (newTerm instanceof DBConstant)
              return termFactory.getDBBooleanConstant(((DBConstant) newTerm).getValue().isEmpty());
  
          return super.buildTermAfterEvaluation(newTerms, termFactory, variableNullability);
      }
  
      @Override
      protected boolean tolerateNulls() {
          return false;
      }
  }
  