private static IEnumerable <Pair <IList <ITypeParameter>, ISubstitution> > EnumeratePossibleTStateCandidates(
[NotNull] IList <ITypeParameter> typeParameters, [NotNull] IList <ITypeParameter> candidateTypeParameters)
{
var typeParametersCount = typeParameters.Count;
var delta = candidateTypeParameters.Count - typeParametersCount;
if (delta <= 0)
{
yield break;
}
ISubstitution headSubstitution = EmptySubstitution.INSTANCE;
var candidateTypes = candidateTypeParameters.ToIList(TypeFactory.CreateType);
var stateTypeParameters = new List <ITypeParameter>();
var tailTypeParameters = new List <ITypeParameter>();
var tailTypeArguments = new List <IType>();
for (var headIndex = 0; headIndex <= typeParametersCount; headIndex++)
{
tailTypeParameters.Clear();
tailTypeArguments.Clear();
for (var tailIndex = headIndex; tailIndex < typeParametersCount; tailIndex++)
{
tailTypeParameters.Add(typeParameters[tailIndex]);
tailTypeArguments.Add(candidateTypes[tailIndex + delta]);
}
stateTypeParameters.Clear();
for (var stateIndex = 0; stateIndex < delta; stateIndex++)
{
stateTypeParameters.Add(candidateTypeParameters[headIndex + stateIndex]);
}
yield return(Pair.Of <IList <ITypeParameter>, ISubstitution>(
stateTypeParameters, headSubstitution.Extend(tailTypeParameters, tailTypeArguments)));
if (headIndex == typeParametersCount)
{
yield break;
}
headSubstitution = headSubstitution.Extend(typeParameters[headIndex], candidateTypes[headIndex]);
}
}
