private static bool TryDecorateOpenGeneric(this IServiceCollection services, Type serviceType, Type decoratorType, [NotNullWhen(false)] out Exception?error)
{
var closedGenericServiceTypes = services
.Where(x => !x.ServiceType.IsGenericTypeDefinition)
.Where(x => HasSameTypeDefinition(x.ServiceType, serviceType))
.Select(x => x.ServiceType)
.Distinct()
.ToList();
if (closedGenericServiceTypes.Count == 0)
{
error = new MissingTypeRegistrationException(serviceType);
return(false);
}
foreach (var closedGenericServiceType in closedGenericServiceTypes)
{
var arguments = closedGenericServiceType.GenericTypeArguments;
var closedServiceType = serviceType.MakeGenericType(arguments);
var closedDecoratorType = decoratorType.MakeGenericType(arguments);
if (!services.TryDecorateDescriptors(closedServiceType, out error, x => x.Decorate(closedDecoratorType)))
{
return(false);
}
}
error = default;
return(true);
}
private static bool TryDecorateDescriptors(this IServiceCollection services, Type serviceType, [NotNullWhen(false)] out Exception?error, Func <ServiceDescriptor, ServiceDescriptor> decorator)
{
if (!services.TryGetDescriptors(serviceType, out var descriptors))
{
error = new MissingTypeRegistrationException(serviceType);
return(false);
}
foreach (var descriptor in descriptors)
{
var index = services.IndexOf(descriptor);
// To avoid reordering descriptors, in case a specific order is expected.
services[index] = decorator(descriptor);
}
error = default;
return(true);
}
/// <summary>
///
/// </summary>
/// <param name="services"></param>
/// <param name="serviceType"></param>
/// <param name="error"></param>
/// <param name="decorator"></param>
/// <returns></returns>
private static bool TryDecorateDescriptors(this IServiceCollection services, Type serviceType, [NotNullWhen(false)] out Exception?error, Func <ServiceDescriptor, ServiceDescriptor> decorator)
{
if (!services.TryGetDescriptors(serviceType, out var descriptors))
{
error = new MissingTypeRegistrationException(serviceType);
return(false);
}
foreach (var descriptor in descriptors)
{
var index = services.IndexOf(descriptor);
// 为了避免对描述符重新排序，在需要特定顺序的情况下.
services[index] = decorator(descriptor);
}
error = default;
return(true);
}