code: package it.unibz.inf.ontop.dbschema;
  
  /*
   * #%L
   * ontop-obdalib-core
   * %%
   * Copyright (C) 2009 - 2014 Free University of Bozen-Bolzano
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  
  /**
   * Database identifier used for possibly qualified column names
   * <p>
   * Relation can be empty (null)
   * 
   * @author Roman Kontchakov
   *
   */
  
  
  public class QualifiedAttributeID {
  
  	private final QuotedID attribute;
  	private final RelationID relation;
  	
  	public QualifiedAttributeID(RelationID relation, QuotedID attribute) {
  		this.relation = relation;
  		this.attribute = attribute;
  	}
  	
  	public QuotedID getAttribute() {
  		return attribute;
  	}
  	
  	public RelationID getRelation() {
  		return relation;
  	}
  
  	public String getSQLRendering() {
  		return ((relation == null) ? "" : (relation.getSQLRendering() + ".")) + attribute.getSQLRendering();
  	}
  	
  	@Override 
  	public boolean equals(Object obj) {
  		if (this == obj)
  			return true;
  		
  		if (obj instanceof QualifiedAttributeID) {
  			QualifiedAttributeID other = (QualifiedAttributeID)obj;
  			return (this.attribute.equals(other.attribute) && 
  					((this.relation == other.relation) || 
  							((this.relation != null) && this.relation.equals(other.relation))));
  		}
  		return false;
  	}
  	
  	@Override
  	public int hashCode() {
  		return attribute.hashCode();
  	}
  	
  	@Override
  	public String toString() {
  		return getSQLRendering();
  	}
  }
  