/// <summary>
/// Handles instantiation of Request-scoped components.
/// </summary>
/// <param name="component"></param>
/// <returns></returns>
internal static object InstanceRequestScoped(Type component)
{
// Check if type is an alias
if (Container.Aliases.ContainsKey(component))
{
component = Container.Aliases[component];
}
// Locate the autowiring constructor, if present
var constructor = LocateAutowiredConstructor(component);
// Missing constructor: Create default instance and return
if (constructor is null)
{
var instance = SnowActivator.CreateInstance(component);
if (instance == null)
{
throw new NoSuitableConstructorFound(component.FullName);
}
ReadyInstance(component, instance);
return(instance);
}
// Found constructor: Locate and inject dependencies
var parameters = constructor.GetParameters();
var paramObjects = new List <object>();
foreach (var parameter in parameters)
{
// Parameter must be a component
if (parameter.ParameterType.CustomAttributes.Any(ca => typeof(ComponentAttribute).IsAssignableFrom(ca.AttributeType)))
{
// At this point, all dependencies have been registered
// during the initial launch pass.
paramObjects.Add(Container.Retrieve(parameter.ParameterType));
}
else
{
throw new AutowiringConstructorException($@"Parameter {parameter.ParameterType} is not a component.
All parameters in an Autowired Constructor must be components.");
}
}
// Invoke constructor and register component
var newInstance = constructor.Invoke(paramObjects.ToArray());
ReadyInstance(component, newInstance);
return(newInstance);
}
private static void InstanceComponent(Type component)
{
// Check if type is an alias
if (Container.Aliases.ContainsKey(component))
{
component = Container.Aliases[component];
}
// The component may have been initialized by the
// autowiring constructor on one of the previous components.
if (Container.Dependencies.Keys.Contains(component))
{
return;
}
// Locate the autowiring constructor, if present
var constructor = LocateAutowiredConstructor(component);
// Missing constructor: Create default instance and store
if (constructor is null)
{
var instance = SnowActivator.CreateInstance(component);
if (instance == null)
{
throw new NoSuitableConstructorFound(component.FullName);
}
Container.Register(component, instance);
// Look for type aliases
var defAliases = component.CustomAttributes.Where(ca => typeof(TypeAliasAttribute).IsAssignableFrom(ca.AttributeType))
.SelectMany(ca => ca.ConstructorArguments)
.Select(ca => ca.Value)
.Cast <Type>();
foreach (var alias in defAliases)
{
// The component must be assignable to alias type
if (!alias.IsAssignableFrom(component))
{
throw new InvalidTypeAliasException($"{component} cannot have {alias} as a Type Alias.");
}
Container.Register(alias, instance);
Container.Aliases.Add(alias, component);
}
return;
}
// Found constructor: Locate and inject dependencies
var parameters = constructor.GetParameters();
var paramObjects = new List <object>();
foreach (var parameter in parameters)
{
var parameterType = parameter.ParameterType;
// Check if parameter is an alias
if (Container.Aliases.ContainsKey(parameterType))
{
parameterType = Container.Aliases[parameterType];
}
// Parameter must be a component
if (parameterType.CustomAttributes.Any(ca => typeof(ComponentAttribute).IsAssignableFrom(ca.AttributeType)))
{
// Check if the type is already instanced
if (!Container.Dependencies.Keys.Contains(parameterType))
{
// Instance the type before injecting it
InstanceComponent(parameterType);
}
paramObjects.Add(Container.Retrieve(parameterType));
}
else
{
throw new AutowiringConstructorException($@"Parameter {parameterType} is not a component.
All parameters in an Autowired Constructor must be components.");
}
}
// Invoke constructor and register component
var newInstance = constructor.Invoke(paramObjects.ToArray());
Container.Register(component, newInstance);
// Look for type aliases
var aliases = component.CustomAttributes.Where(ca => typeof(TypeAliasAttribute).IsAssignableFrom(ca.AttributeType));
}