lenode.java

一个完整的XACML工程,学习XACML技术的好例子!

/*
* Copyright (c) 2000-2005, University of Salford
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without 
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice, this 
* list of conditions and the following disclaimer.
* 
* Redistributions in binary form must reproduce the above copyright notice, 
* this list of conditions and the following disclaimer in the documentation 
* and/or other materials provided with the distribution. 
*
* Neither the name of the University of Salford nor the names of its 
* contributors may be used to endorse or promote products derived from this 
* software without specific prior written permission. 
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE 
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
* POSSIBILITY OF SUCH DAMAGE.
*/

package issrg.pba.rbac.xmlpolicy.ifstatement;

/**
 * This is the class for LE node of the IF-statement. Its functionality is
 * very much determined by OperationNode, which is
 * configured to deliver the following semantics:
 *
 * <p>This operation expects two and only two Terms of any type, and 
 * returns a 
 * value of type Types.BOOLEAN_TYPE.
 * The evaluation result is "true", if and only if there is an interpreter for
 * the required set of Terms, and it evaluates that the first Term is 
 * less than or equal to the second Term.
 *
 * <p>It is possible to register the interpreters for specific 
 * combinations of Terms. Use registerInterpreter method to do that. There is no 
 * default 
 * Interpreter. 
 *
 * @see #registerInterpreter
 *
 * @author A.Otenko
 */

public class LeNode extends OperationNode {
  public static final String LE_NODE = "LE";

  /**
   * Call this method to register this node with the XMLPolicyParser.
   */
  public static void register(){
    try{
      issrg.pba.rbac.xmlpolicy.XMLPolicyParser.registerXMLNode(LE_NODE, LeNode.class);
    }catch (NoSuchMethodException nsme){
      nsme.printStackTrace();
    }
  }

  /**
   * This method maintains a register of interpreters for specific combinations
   * of Terms. If no special interpreters are registered, the evaluation error
   * occurs. The semantics of the interpreters should make sure that the first
   * Term is less or equal to the second Term in the array passed to the
   * evaluate method of that Interpreter.
   *
   * @param i - the Interpreter instance that can evaluate inequality expression
   *   for some combination of Terms
   *
   * @see Interpreter#evaluate
   */
  public static void registerInterpreter(Interpreter i){
    OperationNode.registerInterpreterForNode(LE_NODE, i);
  }

  protected LeNode() {
  }

  /**
   * This constructor builds a LeNode given the XMLPolicyParser and the set of
   * attributes of this XML element. It expects that there are two and only two
   * child nodes.
   *
   * @param p - the XMLPolicyParser that builds this LeNode
   * @param attr - the attributes of this XML element
   */
  public LeNode(issrg.pba.rbac.xmlpolicy.XMLPolicyParser p, org.xml.sax.Attributes attrs){
    super(LE_NODE, attrs, 2, 2);
  }
}