public  void addFilter(Filter filter) 
{
	    
		this.chainedFilters.add( filter );
}

 public BitSet bits(IndexReader reader) throws IOException 
{
		if (chainedFilters.size() == 0) throw new AssertionFailure("Chainedfilter has no filters to chain for");
		//we need to copy the first BitSet because BitSet is modified by .logicalOp
		Filter filter = chainedFilters.get( 0 );
		BitSet result = (BitSet) filter.bits( reader ).clone();
		for (int index = 1 ; index <  chainedFilters.size() ; index++) {
			result.and( chainedFilters.get( index ).bits( reader ) );
		}
		return result;
}

 public String toString() 
{
		StringBuilder sb = new StringBuilder("ChainedFilter [");
		for (Filter filter : chainedFilters) {
			sb.append( "\n  ").append( filter.toString() );
		}
		return sb.append("\n]" ).toString();
}