/// <summary>
/// Constructor used for the top-level search
/// </summary>
/// <param name="type"></param>
/// <param name="owner"></param>
public TargetTypeSelectorParams(Type type, TargetTypeSelector owner)
: this(type)
{
RootTargets = owner?.RootTargets;
// variance always starts off enabled.
EnableVariance = true;
bool enableContravariance = true;
this._forceContravariance = GetInternalContravarianceOverride(Type);
if (this._forceContravariance == null)
{
if (RootTargets != null)
{
enableContravariance = RootTargets.GetOption(
Type, Options.EnableContravariance.Default);
}
}
else
{
enableContravariance = this._forceContravariance.Value;
}
if (enableContravariance)
{
Contravariance = Contravariance.BasesAndInterfaces;
}
else
{
Contravariance = Contravariance.None;
}
}
public TargetTypeSelectorParams(Type type,
Type typeParameter = null,
TargetTypeSelectorParams parent = null,
Contravariance?contravariantSearchType = null)
: this(type)
{
Parent = parent;
RootTargets = parent?.RootTargets;
TypeParameter = typeParameter;
// We enable variance if we have no parent
// Or if we have a variant type parameter and
// the parent hasn't disabled variance.
EnableVariance = parent == null ||
(TypeParameterIsVariant && Parent.EnableVariance);
if (EnableVariance)
{
bool enableContravariance;
if (ForceContravariance == null)
{
// start off always enabled
enableContravariance = true;
var overridenContravariance = GetInternalContravarianceOverride(Type);
if (overridenContravariance != null)
{
// once it's forced, all child searches will avoid testing the EnableContravariance option
this._forceContravariance = overridenContravariance;
enableContravariance = overridenContravariance.Value;
}
else if (RootTargets != null)
{
enableContravariance = RootTargets.GetOption(
Type, Options.EnableContravariance.Default);
}
}
else
{
enableContravariance = ForceContravariance.Value;
}
if (contravariantSearchType != null)
{
Contravariance = contravariantSearchType.Value;
}
else
{
if (!enableContravariance)
{
Contravariance = Contravariance.None;
}
else
{
// if the parent has its contravariance search set to None, we inherit that
// and move on.
if (Parent?.Contravariance == Contravariance.None)
{
Contravariance = Contravariance.None;
}
else
{
var numContras = TypeParameterChain.Count(t => t.IsContravariantTypeParameter());
if (numContras <= 1 || (numContras % 2) == 1)
{
Contravariance = Contravariance.BasesAndInterfaces;
}
else
{
Contravariance = Contravariance.Derived;
}
}
}
}
}
}