Constraint constraint = null;
if ( restriction instanceof AbstractCompositeRestriction ) {
constraint = new MultiRestrictionFieldConstraint( extractor,
restriction );
} else if ( restriction instanceof LiteralRestriction ) {
constraint = new LiteralConstraint( extractor,
(LiteralRestriction) restriction );
registerReadAccessor( context,
pattern.getObjectType(),
fieldName,
(LiteralConstraint) constraint );