}
public BetaMemory createBetaMemory(final RuleBaseConfiguration config) {
BetaMemory memory;
if ( this.indexed ) {
final IndexableConstraint indexableConstraint = (IndexableConstraint) this.constraint;
final FieldIndex index = new FieldIndex( indexableConstraint.getFieldExtractor(),
indexableConstraint.getIndexingDeclaration(),
indexableConstraint.getIndexEvaluator() );
LeftTupleMemory tupleMemory;
if ( this.conf.isIndexLeftBetaMemory() ) {
tupleMemory = new LeftTupleIndexHashTable( new FieldIndex[]{index} );
} else {
tupleMemory = new LeftTupleList();