package be.ugent.rgnosis.teiid.udf;
import org.teiid.CommandContext;
import org.teiid.UserDefinedAggregate;


public class GroupConcat implements UserDefinedAggregate<String> {
	
	private boolean first = true;
	private boolean isNull = true;
	private StringBuffer buffer = new StringBuffer();
	
	public void addInput(String val, char separator) {
	  if (!first) {
	   buffer.append(separator);
	  }
	  buffer.append(val);
	  first = false;
	  isNull = false;
	 }

	@Override
	public String getResult(CommandContext arg0) {
		 if (isNull) {
		   return null;
		  }
		  return buffer.toString();
	}

	@Override
	public void reset() {
		first = true;
		isNull = true;
		buffer = new StringBuffer();
	}

}