/// <summary>
/// Return the list of constructor for a type that can be instantiated with the Registry,
/// i.e. whose parameters are registered or instantiable.
/// </summary>
IEnumerable <ConstructorInfo> FindConstructors(Type type, RequestCache cache)
{
if (FindSession == null)
{
FindSession = new Stack <Type>();
}
if (FindSession.Contains(type))
{
yield break;
}
FindSession.Push(type);
try
{
if (!CanBeInstantiated(type))
{
yield break;
}
var ctors = type.GetTypeInfo().DeclaredConstructors;
foreach (var c in ctors)
{
bool ok = true;
foreach (var p in c.GetParameters())
{
var impa = p.GetCustomAttribute <ImportAttribute>();
var t = (impa != null ? impa.ImportedType : null) ?? p.ParameterType;
var vault = FindRegistrations(t, cache).FirstOrDefault(x => x.Instance != null || x.Type != type);
if (vault != null)
{
continue;
}
if (p.HasDefaultValue)
{
continue;
}
if (CanCreate(p.ParameterType, cache))
{
continue;
}
ok = false;
break;
}
if (ok)
{
yield return(c);
}
}
}
finally
{
FindSession.Pop();
}
}
/// <summary>
/// Return the list of constructor for a type that can be instantiated with the Registry,
/// i.e. whose parameters are registered or instantiable.
/// </summary>
public static IEnumerable <ConstructorInfo> FindConstructors(ITypeTree <ServiceDefinition> services, ITypeTree <object> scope, Type type)
{
if (FindSession == null)
{
FindSession = new Stack <Type>();
}
if (FindSession.Contains(type) || !CanBeInstantiated(type))
{
return(Array.Empty <ConstructorInfo>());
}
FindSession.Push(type);
try
{
return
(from c in type.GetTypeInfo().DeclaredConstructors
let parameters = c.GetParameters()
where parameters.All(x => CanCreateParameter(x))
let N = parameters.Length
let difficulty = parameters.Select(x => IsKnownParameter(x) ? 0 : 1).Sum()
orderby difficulty ascending, N descending
select c
);
bool CanCreateParameter(ParameterInfo pi)
{
var impa = pi.GetCustomAttribute <ImportAttribute>();
var t = (impa != null ? impa.ImportedType : null) ?? pi.ParameterType;
if (t.IsValueType)
{
return(true);
}
var descendant = MergeKeys(services, scope, t).Where(x => x != type).FirstOrDefault();
if (descendant != null)
{
return(true);
}
if (pi.HasDefaultValue)
{
return(true);
}
if (CanCreate(services, scope, pi.ParameterType))
{
return(true);
}
return(false);
}
bool IsKnownParameter(ParameterInfo pi)
{
var impa = pi.GetCustomAttribute <ImportAttribute>();
var t = (impa != null ? impa.ImportedType : null) ?? pi.ParameterType;
var descendant = MergeKeys(services, scope, t).Where(x => x != type).FirstOrDefault();
if (descendant != null)
{
return(true);
}
return(false);
}
}
finally
{
FindSession.Pop();
}
}