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1   /*
2    * ModeShape (http://www.modeshape.org)
3    * See the COPYRIGHT.txt file distributed with this work for information
4    * regarding copyright ownership.  Some portions may be licensed
5    * to Red Hat, Inc. under one or more contributor license agreements.
6    * See the AUTHORS.txt file in the distribution for a full listing of 
7    * individual contributors.
8    *
9    * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10   * is licensed to you under the terms of the GNU Lesser General Public License as
11   * published by the Free Software Foundation; either version 2.1 of
12   * the License, or (at your option) any later version.
13   * 
14   * ModeShape is distributed in the hope that it will be useful,
15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17   * Lesser General Public License for more details.
18   *
19   * You should have received a copy of the GNU Lesser General Public
20   * License along with this software; if not, write to the Free
21   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23   */
24  package org.modeshape.graph.query.optimize;
25  
26  import java.util.LinkedList;
27  import net.jcip.annotations.Immutable;
28  import org.modeshape.graph.query.QueryContext;
29  import org.modeshape.graph.query.plan.PlanNode;
30  
31  /**
32   * Interface that defines an {@link Optimizer} rule.
33   */
34  @Immutable
35  public interface OptimizerRule {
36  
37      /**
38       * Optimize the supplied plan using the supplied context, hints, and yet-to-be-run rules.
39       * 
40       * @param context the context in which the query is being optimized; never null
41       * @param plan the plan to be optimized; never null
42       * @param ruleStack the stack of rules that will be run after this rule; never null
43       * @return the optimized plan; never null
44       */
45      PlanNode execute( QueryContext context,
46                        PlanNode plan,
47                        LinkedList<OptimizerRule> ruleStack );
48  
49  }