/*
* @(#)FirstApplicableRuleAlg.java
*
* Copyright 2003-2005 Sun Microsystems, Inc. All Rights Reserved.
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package com.sun.xacml.combine;
import java.net.URI;
import java.util.Iterator;
import java.util.List;
import com.sun.xacml.EvaluationCtx;
import com.sun.xacml.Rule;
import com.sun.xacml.ctx.Result;
/**
* This is the standard First Applicable rule combining algorithm. It looks through the set of
* rules, finds the first one that applies, and returns that evaluation result.
*
* @since 1.0
* @author Seth Proctor
*/
public class FirstApplicableRuleAlg extends RuleCombiningAlgorithm {
/**
* The standard URN used to identify this algorithm
*/
public static final String algId = "urn:oasis:names:tc:xacml:1.0:rule-combining-algorithm:"
+ "first-applicable";
// a URI form of the identifier
private static final URI identifierURI = URI.create(algId);
/**
* Standard constructor.
*/
public FirstApplicableRuleAlg() {
super(identifierURI);
}
/**
* Applies the combining rule to the set of rules based on the evaluation context.
*
* @param context
* the context from the request
* @param parameters
* a (possibly empty) non-null <code>List</code> of <code>CombinerParameter<code>s
* @param ruleElements
* the rules to combine
*
* @return the result of running the combining algorithm
*/
public Result combine(EvaluationCtx context, List<CombinerParameter> parameters,
List<? extends CombinerElement> ruleElements) {
Iterator<? extends CombinerElement> it = ruleElements.iterator();
while (it.hasNext()) {
Rule rule = ((RuleCombinerElement) (it.next())).getRule();
Result result = rule.evaluate(context);
int value = result.getDecision();
// in the case of PERMIT, DENY, or INDETERMINATE, we always
// just return that result, so only on a rule that doesn't
// apply do we keep going...
if (value != Result.DECISION_NOT_APPLICABLE)
return result;
}
// if we got here, then none of the rules applied
return new Result(Result.DECISION_NOT_APPLICABLE, context.getResourceId().encode());
}
}