content: /* 
   * Kodkod -- Copyright (c) 2005-present, Emina Torlak
   * Pardinus -- Copyright (c) 2013-present, Nuno Macedo, INESC TEC
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  package kodkod.engine.fol2sat;
  
  import java.util.Collections;
  import java.util.LinkedHashSet;
  import java.util.Set;
  
  import kodkod.ast.Node;
  import kodkod.ast.Relation;
  import kodkod.ast.visitor.AbstractCollector;
  
  /**
   * Collects relations in a given Node. 
   * 
   * @see FreeVariableCollector
   * 
   * @author Emina Torlak
   */
  public class RelationCollector extends AbstractCollector<Relation> {
  	
  	/**
  	 * Constructs a new collector using the given structural information.
  	 * The given set is required to contain the syntactically shared subtrees of the
  	 * node for which we are computing caching information.
  	 */
  	public RelationCollector(Set<Node> cached) {
  		super(cached);
  	}
  	
  	/**
  	 * @see kodkod.ast.visitor.AbstractCollector#newSet()
  	 */
  	@Override
  	protected Set<Relation> newSet() {
  		return new LinkedHashSet<Relation>(2);
  	}
  		
  	/**
  	 * Returns the singleton set containing the given variable.
  	 * @return {variable}
  	 */
  	@Override
  	public Set<Relation> visit(Relation variable) {
  		return cache(variable, Collections.singleton(variable));
  	}
  	
  }