final BaseDescr descr,
final Pattern prefixPattern) {
final AccumulateDescr accumDescr = (AccumulateDescr) descr;
final PatternBuilder patternBuilder = (PatternBuilder) context.getDialect().getBuilder( PatternDescr.class );
final Pattern sourcePattern = (Pattern) patternBuilder.build( context,
accumDescr.getInputPattern() );
if ( sourcePattern == null ) {
return null;
}