/// <summary>
/// Wrap the specified value provider in a value provider that utilises a more-derived context type.
/// </summary>
/// <typeparam name="TDerivedContext">
/// The more-derived type used by the new provider as a context for each request.
/// </typeparam>
/// <returns>
/// The outer (converting) value provider.
/// </returns>
public IValueProvider <TDerivedContext, TValue> ContextTo <TDerivedContext>()
where TDerivedContext : TContext
{
// Can't close over members of structs.
IValueProvider <TContext, TValue> valueProvider = ValueProvider;
return(ValueProvider <TDerivedContext> .FromSelector(
context => valueProvider.Get(context)
));
}
/// <summary>
/// Wrap the value provider in a value provider that converts its value to a string.
/// </summary>
/// <returns>
/// The outer (converting) value provider.
/// </returns>
/// <remarks>
/// If the underlying value is <c>null</c> then the converted string value will be <c>null</c>, too.
/// </remarks>
public IValueProvider <TContext, string> ValueToString()
{
// Special-case conversion to save on allocations.
if (typeof(TValue) == typeof(string))
{
return((IValueProvider <TContext, string>)ValueProvider);
}
// Can't close over members of structs.
IValueProvider <TContext, TValue> valueProvider = ValueProvider;
return(ValueProvider <TContext> .FromSelector(
context =>
{
TValue value = valueProvider.Get(context);
return value != null ? value.ToString() : null;
}
));
}