/// <summary>
/// Evaluate the specified expression, for the given element and model.
/// </summary>
/// <param name="expression">The expression to evaluate.</param>
/// <param name="context">The rendering context for the expression being evaluated.</param>
/// <param name="model">The ZPT model, providing the context for evaluation.</param>
public override ExpressionResult Evaluate(Expression expression, IRenderingContext context, ITalesModel model)
{
if(expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if(context == null)
{
throw new ArgumentNullException(nameof(context));
}
if(model == null)
{
throw new ArgumentNullException(nameof(model));
}
var trimmedContent = expression.Content.TrimStart();
var result = model.Evaluate(ExpressionCreator.Create(trimmedContent), context);
bool booleanResult = this.CoerceToBoolean(result);
return new ExpressionResult(!booleanResult);
}
