/// <summary>
/// Creates an <see cref="Argument{T}"/> for validating an argument value.
/// </summary>
/// <typeparam name="TPrevious">The previous argument type.</typeparam>
/// <typeparam name="T">The argument type.</typeparam>
/// <param name="argument">A wrapper object containing the previous argument value.</param>
/// <param name="parameter">The parameter.</param>
/// <returns>A wrapper object containing the actual argument value.</returns>
/// <exception cref="ArgumentNullException"><paramref name="parameter"/> is null.</exception>
/// <exception cref="ArgumentException"><paramref name="parameter"/> does not select a parameter.</exception>
public static IArgument <TPrevious> That <TPrevious, T>(this IValidatedArgument <T> argument, Expression <Func <TPrevious> > parameter)
{
if (parameter == null)
{
throw new ArgumentNullException(ParameterNames.Parameter);
}
var memberExpression = parameter.Body as MemberExpression;
if (memberExpression == null)
{
throw new ArgumentException(Messages.MustSelectParameter, ParameterNames.Parameter);
}
var constantExpression = memberExpression.Expression as ConstantExpression;
if (constantExpression == null)
{
throw new ArgumentException(Messages.MustSelectParameter, ParameterNames.Parameter);
}
var parameterName = memberExpression.Member.Name;
var type = constantExpression.Value.GetType();
var field = type.GetField(parameterName);
var value = (TPrevious)field.GetValue(constantExpression.Value);
return(new Argument <TPrevious>(value, parameterName));
}
public static IArgument <TPrevious> That <TPrevious, T>(this IValidatedArgument <T> argument, TPrevious value, string parameterName)
{
return(new Argument <TPrevious>(value, parameterName));
}
