/// <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;
}
}
