private TypeExpression InternalPromotion(UnionType from, object arg)
{
if (from.IsFreshVariable() && this.methodAnalyzed != null)
{
// * A constraint is added to the method analyzed
PromotionConstraint constraint = new PromotionConstraint(from, this.to, this.op, this.location);
this.methodAnalyzed.AddConstraint(constraint);
return(this.to);
}
// * Static Behaviour: All the types in typeset must promote
// * Dynamic Behaviour: One of the types in typeset must promote
int aux = 0;
UnionType dynamicUnionType = new UnionType();
dynamicUnionType.IsDynamic = true;
foreach (TypeExpression subType in from.TypeSet)
{
if (from.IsDynamic)
{
// * Dynamic
if (subType.IsFreshVariable())
{
dynamicUnionType.AddType(subType);
}
else
{
aux = (int)subType.AcceptOperation(new PromotionLevelOperation(this.to), arg);
if (aux != -1)
{
return(this.to);
}
}
}
else // * !from.IsDynamic, so it is static
{
aux = (int)subType.AcceptOperation(new PromotionLevelOperation(this.to), arg);
if (aux == -1)
{
return((TypeExpression)ReportError(from));
}
}
}
if (dynamicUnionType.Count != 0) // * If the union type is dynamic and no type in the type set promotes, then we generate a constraint with one promotion grouping the fresh types in the type set
{
PromotionConstraint constraint = new PromotionConstraint(dynamicUnionType, this.to, this.op, this.location);
this.methodAnalyzed.AddConstraint(constraint);
return(this.to);
}
if (from.IsDynamic && aux == -1)
{
// * No promotion at all
return((TypeExpression)ReportError(from));
}
return(this.to);
}
public override object Exec(TypeVariable from, object arg)
{
if (from.Substitution != null)
{
DynVarOptions.Instance.AssignDynamism(from.Substitution, from.IsDynamic);
return(from.Substitution.AcceptOperation(this, arg));
}
if (methodAnalyzed != null)
{
// * A constraint is added to the method analyzed
PromotionConstraint constraint = new PromotionConstraint(from, this.to, this.location);
this.methodAnalyzed.AddConstraint(constraint);
return(constraint.ReturnType);
}
return(ReportError(from));
}
