// Looks up a member of given name and arity in a particular type.
private LookupResult MemberLookup(TypeSymbol type, string name, int arity, bool invoked)
{
LookupResult result;
switch (type.TypeKind)
{
case TypeKind.RefType:
return(MemberLookup(((RefTypeSymbol)type).ReferencedType, name, arity, invoked));
case TypeKind.TypeParameter:
result = MemberLookupInTypeParameter(type, name, arity, invoked); break;
case TypeKind.Interface:
result = MemberLookupInInterface(type, name, arity, invoked); break;
case TypeKind.Class:
case TypeKind.Struct:
case TypeKind.Enum:
case TypeKind.Delegate:
case TypeKind.ArrayType:
result = MemberLookupInClass(type, name, arity, invoked); break;
case TypeKind.Error:
case TypeKind.PointerType:
return(LookupResult.Empty);
case TypeKind.Unknown:
default:
Debug.Fail("Unknown type kind");
return(LookupResult.Empty);
}
// TODO: Diagnose ambiguity problems here, and conflicts between non-method and method? Or is that
// done in the caller?
return(result);
#if SLOW
// A member lookup is the process whereby the meaning of a name in the context of
// a type is determined. A member lookup can occur as part of evaluating a
// simple-name or a member-access in an expression. If the
// simple-name or member-access occurs as the simple-expression of an
// invocation-expression, the member is said to be invoked.
// If a member is a method or event, or if it is a constant, field or property
// of a delegate type, then the member is said to be invocable.
// Member lookup considers not only the name of a member but also the number of
// type parameters the member has and whether the member is accessible. For the
// purposes of member lookup, generic methods and nested generic types have the
// number of type parameters indicated in their respective declarations and all
// other members have zero type parameters.
// A member lookup of a name N with K type parameters in a type T is processed as follows:
// First, a set of accessible members named N is determined.
// If T is a type parameter, then the set is the union of the sets of accessible
// members named N in each of the types specified as a primary constraint or secondary
// constraint for T, along with the set of accessible members named N in object.
// Otherwise, the set consists of all accessible members named N in T,
// including inherited members and the accessible members named N in object. If T is
// a constructed type, the set of members is obtained by substituting type arguments
// as described in §10.3.2. Members that include an override modifier are excluded
// from the set.
var results = new HashSet <Symbol>();
var inaccessible = new HashSet <Symbol>();
var notInvocable = new HashSet <Symbol>();
var hidden1 = new HashSet <Symbol>();
var hidden2 = new HashSet <Symbol>();
var types = new HashSet <TypeSymbol>(type.TypeAndAllBaseTypes());
types.Add(System_Object);
foreach (TypeSymbol t in types)
{
results.UnionWith(
from s in t.GetMembers(name)
where !s.IsOverride
select s);
}
inaccessible.UnionWith(from s in results where !IsMemberAccessible(s) select s);
results.ExceptWith(inaccessible);
var badArity = new HashSet <Symbol>();
// Next, if K is zero, all nested types whose declarations include type parameters are removed.
// If K is not zero, all members with a different number of type parameters are removed.
// Note that when K is zero, methods having type parameters are not removed, since the
// type inference process might be able to infer the type arguments.
if (arity == 0)
{
badArity.UnionWith(from s in results where s.IsNestedType() && ((NamedTypeSymbol)s).Arity != 0 select s);
}
else
{
badArity.UnionWith(from s in results where s is NamedTypeSymbol && ((NamedTypeSymbol)s).Arity != arity select s);
badArity.UnionWith(from s in results where s is MethodSymbol && ((MethodSymbol)s).TypeParameters.Count != arity select s);
}
results.ExceptWith(badArity);
// Next, if the member is invoked, all non-invocable members are removed from the set.
if (invoked)
{
notInvocable.UnionWith(from s in results where !IsInvocable(s) select s);
}
results.ExceptWith(notInvocable);
// Next, members that are hidden by other members are removed from the set.
// For every member S.M in the set, where S is the type in which the member M is declared,
// the following rules are applied:
foreach (var member in results)
{
var declaringType = member.ContainingType;
// If M is a constant, field, property, event, or enumeration member,
// then all members declared in a base type of S are removed from the set.
if (member is FieldSymbol || member is PropertySymbol /* UNDONE || member is EventSymbol */)
{
foreach (var baseType in declaringType.AllBaseTypeDefinitions())
{
hidden1.UnionWith(
from s in results
where s.ContainingType.OriginalDefinition == baseType
select s);
}
}
else if (member is NamedTypeSymbol)
{
// If M is a type declaration, then all non-types declared in a base type of S
// are removed from the set, and all type declarations with the same number of
// type parameters as M declared in a base type of S are removed from the set.
foreach (var baseType in declaringType.AllBaseTypeDefinitions())
{
hidden1.UnionWith(
from s in results
where s.ContainingType.OriginalDefinition == baseType
where !(s is NamedTypeSymbol) || ((NamedTypeSymbol)s).Arity == ((NamedTypeSymbol)member).Arity
select s);
}
}
else if (member is MethodSymbol)
{
// If M is a method, then all non-method members declared in a base type of S
// are removed from the set.
foreach (var baseType in declaringType.AllBaseTypeDefinitions())
{
hidden1.UnionWith(
from m in results
where m.ContainingType.OriginalDefinition == baseType && !(m is MethodSymbol)
select m);
}
}
}
results.ExceptWith(hidden1);
// Next, interface members that are hidden by class members are removed from the set.
// This step only has an effect if T is a type parameter and T has both an effective base
// class other than object and a non-empty effective interface set. For every
// member S.M in the set, where S is the type in which the member M is declared, the
// following rules are applied if S is a class declaration other than object:
foreach (var member in results)
{
var declaringType = member.ContainingType;
if (!declaringType.IsClassType() || declaringType == System_Object)
{
continue;
}
// If M is a constant, field, property, event, enumeration member, or type declaration,
// then all members declared in an interface declaration are removed from the set.
if (member is FieldSymbol || member is PropertySymbol /* UNDONE || member is EventSymbol */ || member is NamedTypeSymbol)
{
hidden2.UnionWith(
from m in results
where m.ContainingType.IsInterfaceType()
select m);
}
else if (member is MethodSymbol)
{
// If M is a method, then all non-method members declared in an interface declaration
// are removed from the set, and all methods with the same signature as M declared
// in an interface declaration are removed from the set.
hidden2.UnionWith(
from m in results
where m.ContainingType.IsInterfaceType() && (!(m is MethodSymbol) || HaveSameSignature((MethodSymbol)m, (MethodSymbol)member))
select m);
}
}
results.ExceptWith(hidden2);
hidden1.UnionWith(hidden2);
// Finally, having removed hidden members, the result of the lookup is determined:
// If the set consists of a single member that is not a method, then this member is the result of the lookup.
// Otherwise, if the set contains only methods, then this group of methods is the result of the lookup.
// Otherwise, the lookup is ambiguous, and a compile-time error occurs.
// For member lookups in types other than type parameters and interfaces, and member lookups in interfaces
// that are strictly single-inheritance (each interface in the inheritance chain has exactly zero or one direct
// base interface), the effect of the lookup rules is simply that derived members hide base members with the
// same name or signature. Such single-inheritance lookups are never ambiguous. The ambiguities that can possibly
// arise from member lookups in multiple-inheritance interfaces are described in §13.2.5.
// UNDONE: Make this match what the original compiler does.
if (results.Count == 0 ||
(results.Count > 1 && !results.All(m => m is MethodSymbol)))
{
if (inaccessible.Count != 0)
{
return(LookupResult.Inaccessible(inaccessible.First()));
}
else if (badArity.Count != 0)
{
return(LookupResult.WrongArity(badArity.First(), null));
}
else
{
return(LookupResult.Bad((DiagnosticInfo)null));
}
}
else
{
return(LookupResult.ForSymbols(results));
}
#endif
}