/// <summary>
/// Gets the data type of the value.
/// </summary>
/// <param name="context">The evaluation context.</param>
/// <returns>The data type descriptor.</returns>
public IDataType GetType(EvaluationContext context)
{
return(EvaluationEngine.GetDataType(DataTypeValue));
}
/// <summary>
/// This method overrides the ApplyBase method in order to provide extra validations
/// required in the condition evaluation, for example the final return value should be a
/// boolean value.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The EvaluationValue with the results of the condition evaluation.</returns>
public override EvaluationValue Evaluate(EvaluationContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
context.Trace("Evaluating condition");
context.AddIndent();
try
{
// Iterate through the arguments, the IExpressionType is a mark interface
foreach (IExpression arg in ApplyDefinition.Arguments)
{
if (arg is ApplyElement)
{
context.Trace("Apply within condition.");
// There is a nested apply un this policy a new Apply will be created and also
// evaluated. It's return value will be used as the processed argument.
var childApply = new Apply((ApplyElement)arg);
// Evaluate the Apply
EvaluationValue retVal = childApply.Evaluate(context);
return(retVal);
}
else if (arg is FunctionElementReadWrite)
{
throw new NotImplementedException("FunctionElement"); //TODO:
}
else if (arg is VariableReferenceElement)
{
var variableRef = arg as VariableReferenceElement;
var variableDef = context.CurrentPolicy.VariableDefinition[variableRef.VariableId] as VariableDefinition;
Debug.Assert(variableDef != null, "variableDef != null");
if (!variableDef.IsEvaluated)
{
return(variableDef.Evaluate(context));
}
else
{
return(variableDef.Value);
}
}
else if (arg is AttributeValueElementReadWrite)
{
// The AttributeValue does not need to be processed
context.Trace("Attribute value {0}", arg.ToString());
var attributeValue = new AttributeValueElement(((AttributeValueElementReadWrite)arg).DataType, ((AttributeValueElementReadWrite)arg).Contents, ((AttributeValueElementReadWrite)arg).SchemaVersion);
return(new EvaluationValue(
attributeValue.GetTypedValue(attributeValue.GetType(context), 0),
attributeValue.GetType(context)));
}
else if (arg is AttributeDesignatorBase)
{
// Returning an empty bag, since the condition is not supposed to work with a bag
context.Trace("Processing attribute designator: {0}", arg.ToString());
var attrDes = (AttributeDesignatorBase)arg;
var bag = new BagValue(EvaluationEngine.GetDataType(attrDes.DataType));
return(new EvaluationValue(bag, bag.GetType(context)));
}
else if (arg is AttributeSelectorElement)
{
// Returning an empty bag, since the condition is not supposed to work with a bag
context.Trace("Attribute selector");
var attrSel = (AttributeSelectorElement)arg;
var bag = new BagValue(EvaluationEngine.GetDataType(attrSel.DataType));
return(new EvaluationValue(bag, bag.GetType(context)));
}
}
throw new NotSupportedException("internal error");
}
finally
{
context.TraceContextValues();
context.RemoveIndent();
}
}