/// <summary>
/// Adds a new type expression.
/// </summary>
/// <param name="type">WriteType expression to add.</param>
/// <returns>If the type has been added</returns>
public bool AddType(TypeExpression type)
{
bool added = true;
IntersectionType intersection = TypeExpression.As <IntersectionType>(type);
if (intersection != null)
{
foreach (TypeExpression t in intersection.typeSet)
{
added = added && this.AddType(t);
}
this.ValidTypeExpression = false;
return(added);
}
Predicate <TypeExpression> predicate = delegate(TypeExpression te2) {
return((bool)te2.AcceptOperation(new EquivalentOperation(type), null));
};
if (this.typeSet.Find(predicate) == null)
{
this.typeSet.Add(type);
this.ValidTypeExpression = false;
return(true);
}
return(false);
}
/// <summary>
/// This method unifies two type expressions (this and te)
/// </summary>
/// <param name="te">The expression to be unfied with this</param>
/// <param name="unification">Indicates if the kind of unification (equivalent, incremental or override).</param>
/// <param name="previouslyUnified">To detect infinite loops. The previously unified pairs of type expressions.</param>
/// <returns>If the unification was successful</returns>
public override bool Unify(TypeExpression te, SortOfUnification unification, IList <Pair <TypeExpression, TypeExpression> > previouslyUnified)
{
InterfaceType it = TypeExpression.As <InterfaceType>(te);
if (it != null)
{
bool success = (bool)this.AcceptOperation(new EquivalentOperation(it), null);
// * Clears the type expression cache
this.ValidTypeExpression = false;
te.ValidTypeExpression = false;
return(success);
}
if (te is TypeVariable && unification != SortOfUnification.Incremental)
{
// * No incremental unification is commutative
return(te.Unify(this, unification, previouslyUnified));
}
return(false);
}
/// <summary>
/// Returns true if the union type contains method types and this methods returns differents types. (At least, one valut type).
/// </summary>
/// <returns>True if the union type contains method types and this methods returns differents types. Otherwise, false.</returns>
public bool ContainsDifferentReturns()
{
TypeExpression current = null;
TypeExpression aux = null;
for (int i = 0; i < this.typeSet.Count; i++)
{
if (this.typeSet[i] is TypeVariable)
{
return(true);
}
MethodType mt = null;
if ((mt = TypeExpression.As <MethodType>(this.typeSet[i])) != null)
{
current = mt.Return;
if (aux != null && aux != current) // This comparation searches differents value types.
{
return(true);
}
aux = current;
}
}
return(false);
}
/// <summary>
/// Tells if a type expression is a type or a type variable
/// unified to a type
/// </summary>
/// <typeparam name="T">A concrete type expression</typeparam>
/// <param name="type">The general type expression</param>
/// <returns>If the type is the expected one</returns>
public static bool Is <T>(TypeExpression type) where T : TypeExpression
{
return(TypeExpression.As <T>(type) != null);
}
// WriteType inference
#region overloadResolution()
/// <summary>
/// A public method for being used as a global overload resolution process
/// </summary>
/// <param name="arguments">The ordered types of actual parameters</param>
/// <param name="fileName"></param>
/// <param name="line"></param>
/// <param name="column"></param>
/// <returns>The actual method called (a union type if more than one is suitable)</returns>
public TypeExpression overloadResolution(TypeExpression[] arguments, Location location)
{
int aux;
int min = -1, index = -1, minNumFreeVariables = Int32.MaxValue;
// * We create a dictionary of <index,promotionValue> to remember the promotion values (they could have
// repeated values because of type variables)
Dictionary <int, int> promotionValues = new Dictionary <int, int>();
if (this.typeSet.Count == 0)
{
System.Diagnostics.Debug.Assert(false, "There should be no empty intersection types.");
return(null);
}
for (int i = 0; i < this.typeSet.Count; i++)
{
MethodType mt = TypeExpression.As <MethodType>(this.typeSet[i]);
if (mt == null)
{
ErrorManager.Instance.NotifyError(new OperationNotAllowedError("()", mt.FullName, location));
}
aux = mt.Promotion(arguments, location);
if (aux != -1)
{
if ((min >= aux) || (min == -1))
{
min = aux;
index = i;
promotionValues[index] = min;
}
}
}
// * No method is suitable
if (index == -1)
{
ErrorManager.Instance.NotifyError(new UnknownMemberError(location));
return(null);
}
index = -1;
// * Gets the min number of free variables
foreach (KeyValuePair <int, int> pair in promotionValues)
{
if (pair.Value == min)
{
aux = ((MethodType)this.typeSet[pair.Key]).GetNumberFreeVariables();
if (aux < minNumFreeVariables)
{
minNumFreeVariables = aux;
}
}
}
// * Assigns a union of all the best methods
TypeExpression bestMethods = null;
foreach (KeyValuePair <int, int> pair in promotionValues)
{
if (pair.Value == min && ((MethodType)this.typeSet[pair.Key]).GetNumberFreeVariables() == minNumFreeVariables)
{
bestMethods = UnionType.collect(bestMethods, this.typeSet[pair.Key]);
}
}
// * We've got'em
return(bestMethods);
}
