/// <summary>
/// Evaluates the policy.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The decission result for this policy.</returns>
public Decision Evaluate(EvaluationContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
context.Trace("Evaluating policy: {0}", _policy.Description);
context.AddIndent();
context.CurrentPolicy = this;
try
{
// Evaluate the variables
if (this._policy.SchemaVersion == XacmlVersion.Version20)
{
if (_variables == null)
{
context.Trace("Evaluating variables...");
_variables = new Hashtable();
foreach (pol.VariableDefinitionElement variableDef in _policy.VariableDefinitions.Values)
{
VariableDefinition variable = new VariableDefinition(variableDef);
_variables.Add(variableDef.Id, variable);
}
}
}
// Matches the target.
TargetEvaluationValue targetEvaluationValue = Match(context);
// If the target matches.
if (targetEvaluationValue == TargetEvaluationValue.Match)
{
context.Trace("Rule combination algorithm: {0}", _policy.RuleCombiningAlgorithm);
// Evaluate all rules and apply rule combination
inf.IRuleCombiningAlgorithm rca = EvaluationEngine.CreateRuleCombiningAlgorithm(_policy.RuleCombiningAlgorithm);
_evaluationValue = rca.Evaluate(context, _rules);
}
else if (targetEvaluationValue == TargetEvaluationValue.NoMatch)
{
_evaluationValue = Decision.NotApplicable;
}
else if (targetEvaluationValue == TargetEvaluationValue.Indeterminate)
{
_evaluationValue = Decision.Indeterminate;
}
context.Trace("Policy: {0}", _evaluationValue);
// Copy all the obligations.
_obligations = new pol.ObligationCollection();
if (_evaluationValue != Decision.Indeterminate &&
_evaluationValue != Decision.NotApplicable &&
_policy.Obligations != null && _policy.Obligations.Count != 0)
{
foreach (pol.ObligationElement obl in _policy.Obligations)
{
if ((obl.FulfillOn == pol.Effect.Deny && _evaluationValue == Decision.Deny) ||
(obl.FulfillOn == pol.Effect.Permit && _evaluationValue == Decision.Permit))
{
context.Trace("Adding obligation: {0} ", obl.ObligationId);
_obligations.Add(obl);
}
}
}
return(_evaluationValue);
}
finally
{
context.RemoveIndent();
context.CurrentPolicy = null;
}
}