code: package it.unibz.inf.ontop.model.term.functionsymbol.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.iq.node.VariableNullability;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.type.RDFDatatype;
  import it.unibz.inf.ontop.model.type.TermTypeInference;
  import it.unibz.inf.ontop.model.vocabulary.SPARQL;
  
  import java.util.Optional;
  import java.util.UUID;
  
  /**
   * Non-deterministic
   *
   * TODO: explain the use of the UUID
   *
   */
  public class RandSPARQLFunctionSymbolImpl extends SPARQLFunctionSymbolImpl {
  
      private final UUID uuid;
      private final RDFDatatype xsdDoubleType;
  
      protected RandSPARQLFunctionSymbolImpl(UUID uuid, RDFDatatype xsdDoubleType) {
          super("SP_RAND" + uuid, SPARQL.RAND, ImmutableList.of());
          this.uuid = uuid;
          this.xsdDoubleType = xsdDoubleType;
      }
  
      @Override
      protected boolean tolerateNulls() {
          return false;
      }
  
      /**
       * Non-deterministic therefore non-injective
       */
      @Override
      public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() {
          return false;
      }
  
      @Override
      public Optional<TermTypeInference> inferType(ImmutableList<? extends ImmutableTerm> terms) {
          return Optional.of(TermTypeInference.declareTermType(xsdDoubleType));
      }
  
      @Override
      public boolean canBePostProcessed(ImmutableList<? extends ImmutableTerm> arguments) {
          return false;
      }
  
      @Override
      protected ImmutableTerm buildTermAfterEvaluation(ImmutableList<ImmutableTerm> newTerms, TermFactory termFactory,
                                                       VariableNullability variableNullability) {
  
          return termFactory.getRDFFunctionalTerm(
                  termFactory.getConversion2RDFLexical(termFactory.getDBRand(uuid), xsdDoubleType),
                  termFactory.getRDFTermTypeConstant(xsdDoubleType));
      }
  }
  