/// <summary>
/// Gets the sequence exposed by the given expression.
/// </summary>
/// <returns>The sequence.</returns>
/// <param name="expression">Expression.</param>
/// <param name="model">Model.</param>
/// <param name="context">The rendering context.</param>
private IEnumerable GetSequence(string expression, IModel model, IRenderingContext context)
{
ExpressionResult result;
IEnumerable output;
try
{
result = model.Evaluate(expression, context);
}
catch(Exception ex)
{
string message = String.Format(ExceptionMessages.ExpressionEvaluationException,
ZptConstants.Tal.Namespace,
ZptConstants.Tal.DefineAttribute,
expression,
context.Element.Name);
throw new ModelEvaluationException(message, ex) {
ExpressionText = expression,
ElementName = context.Element.Name,
};
}
if(result.CancelsAction)
{
output = null;
}
else
{
try
{
output = result.GetValue<IEnumerable>();
}
catch(InvalidCastException ex)
{
string message = String.Format(ExceptionMessages.TalRepeatExpressionMustEvaluateToIEnumerable,
typeof(IEnumerable).FullName,
expression,
context.Element.Name);
throw new ModelEvaluationException(message, ex) {
ExpressionText = expression,
ElementName = context.Element.Name,
};
}
}
return output;
}
