@Override
 public StorageResults fetch(Expression userQuery) {
   Expression expression = userQuery.normalize();
   Matcher matcher = expression.accept(new MatcherCreator());
   List<DataRecord> matchRecords = new LinkedList<DataRecord>();
   for (DataRecord dataRecord : storage) {
     if (matcher.match(dataRecord)) {
       matchRecords.add(dataRecord);
     }
   }
   List<DataRecord> filteredRecords = expression.accept(new Filter(matchRecords));
   return new InMemoryStorageResults(filteredRecords);
 }
  /**
   * INTERNAL: For CR#2456 if this is part of an objExp.equal(objExp), do not need to add additional
   * expressions to normalizer both times, and the foreign key join replaces the equal expression.
   */
  public Expression normalize(ExpressionNormalizer normalizer, Vector foreignKeyJoinPointer) {
    if (hasBeenNormalized()) {
      return this;
    }
    super.normalize(normalizer);

    setHasBeenNormalized(true);
    if ((getMapping() != null) && getMapping().isDirectToXMLTypeMapping()) {
      normalizer.getStatement().setRequiresAliases(true);
    }

    // Check if any joins need to be added.
    if (isAttribute()) {
      return this;
    }

    // If the mapping is 'ref' or 'structure', no join needed.
    if ((getMapping() != null)
        && (getMapping().isReferenceMapping() || getMapping().isStructureMapping())) {
      normalizer.getStatement().setRequiresAliases(true);
      return this;
    }

    // Compute if a distinct is required during normalization.
    if (shouldQueryToManyRelationship()
        && (!normalizer.getStatement().isDistinctComputed())
        && (!normalizer.getStatement().isAggregateSelect())) {
      normalizer.getStatement().useDistinct();
    }

    // Turn off DISTINCT if nestedTableMapping is used (not supported by Oracle 8.1.5).
    if ((getMapping() != null) && getMapping().isNestedTableMapping()) {
      // There are two types of nested tables, one used by clients, one used by mappings, do nothing
      // in the mapping case.
      if (!shouldQueryToManyRelationship()) {
        return this;
      }
      normalizer.getStatement().dontUseDistinct();
    }

    Expression mappingExpression = mappingCriteria();
    if (mappingExpression != null) {
      mappingExpression = mappingExpression.normalize(normalizer);
    }
    if (mappingExpression != null) {
      // If the join was an outer join we must not add the join criteria to the where clause,
      // if the platform prints the join in the from clause.
      if (shouldUseOuterJoin() && (getSession().getPlatform().isInformixOuterJoin())) {
        normalizer.getStatement().getOuterJoinExpressions().addElement(this);
        normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(mappingExpression);
        normalizer.addAdditionalExpression(mappingExpression.and(additionalExpressionCriteria()));
        return this;
      } else if ((shouldUseOuterJoin() || isUsingOuterJoinForMultitableInheritance())
          && (!getSession().getPlatform().shouldPrintOuterJoinInWhereClause())) {
        if (shouldUseOuterJoin()) {
          normalizer.getStatement().getOuterJoinExpressions().addElement(this);
          normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(mappingExpression);
          normalizer
              .getStatement()
              .getOuterJoinedAdditionalJoinCriteria()
              .addElement(additionalExpressionCriteriaMap());
          normalizer.getStatement().getDescriptorsForMultitableInheritanceOnly().add(null);
          return this;
        } else {
          if (isUsingOuterJoinForMultitableInheritance()) {
            normalizer.getStatement().getOuterJoinExpressions().addElement(null);
            normalizer.getStatement().getOuterJoinedMappingCriteria().addElement(null);
            normalizer
                .getStatement()
                .getOuterJoinedAdditionalJoinCriteria()
                .addElement(additionalExpressionCriteriaMap());
            normalizer
                .getStatement()
                .getDescriptorsForMultitableInheritanceOnly()
                .add(getMapping().getReferenceDescriptor());
            // fall through to the main case
          }
        }
      }

      // This must be added even if outer. Actually it should be converted to use a right outer
      // join, but that gets complex
      // so we do not support this current which is a limitation in some cases.
      if (foreignKeyJoinPointer != null) {
        // If this expression is right side of an objExp.equal(objExp), one
        // need not add additionalExpressionCriteria twice.
        // Also the join will replace the original objExp.equal(objExp).
        // For CR#2456.
        foreignKeyJoinPointer.add(mappingExpression);
      } else {
        normalizer.addAdditionalExpression(mappingExpression.and(additionalExpressionCriteria()));
      }
    }

    // For bug 2900974 special code for DirectCollectionMappings moved to printSQL.
    return this;
  }