private bool TryResolve(Type type, string key, ResolutionContext context, out BoundActivation resolved)
{
Debug.Assert(_lock.IsReadLockHeld);
var regKey = new RegistrationKey(type, key);
if (context.WouldCreateCycle(regKey))
{
resolved = null;
return(false);
}
using (context.Activating(regKey))
{
// fast path: the type has a provider registered
if (_registrations.TryGetValue(regKey, out var reg))
{
resolved = new BoundActivation(reg);
return(true);
}
// there's nothing registered for the type - see if we can form an implicit
// registration based on its constructors and what is registered.
ConstructorInfo[] ctors = type.GetConstructors()
.OrderByDescending(ci => ci.GetParameters().Length)
.ToArray();
for (int i = 0; i < ctors.Length; i++)
{
ConstructorInfo ctor = ctors[i];
ParameterInfo[] pis = ctor.GetParameters();
BoundActivation[] parameters = new BoundActivation[pis.Length];
bool allBound = true;
for (int p = 0;
allBound && p < pis.Length;
p++)
{
string bindingKey = null;
BoundActivation paramProvider;
var bindingKeyAttr = pis[p].GetCustomAttribute <BindingKeyAttribute>();
if (!(bindingKeyAttr is null))
{
bindingKey = bindingKeyAttr.Key;
}
if (TryResolve(pis[p].ParameterType, bindingKey, context, out paramProvider))
{
// exact match with the binding key in this or parent.
parameters[p] = paramProvider;
}
else if (!(bindingKeyAttr is null) &&
bindingKeyAttr.FallbackToDefaultBinding &&
TryResolve(pis[p].ParameterType, null, context, out paramProvider))
{
// exact match with the fallback key in this or parent.
parameters[p] = paramProvider;
}
private static bool ContainsCycle(BoundActivation a, Stack <Type> types)
{
if (types.Contains(a.Type))
{
return(true);
}
types.Push(a.Type);
if (!(a._parameters is null))
{
for (int i = 0; i < a._parameters.Length; i++)
{
if (ContainsCycle(a._parameters[i], types))
{
return(true);
}
}
}
types.Pop();
return(false);
}
