// Constructor. Use static Create method to create instances.
private MergedNamespaceSymbol(NamespaceExtent extent, NamespaceSymbol containingNamespace, ImmutableArray <NamespaceSymbol> namespacesToMerge, string nameOpt)
{
_extent = extent;
_namespacesToMerge = namespacesToMerge;
_containingNamespace = containingNamespace;
_cachedLookup = new CachingDictionary <string, Symbol>(SlowGetChildrenOfName, SlowGetChildNames, EqualityComparer <string> .Default);
_nameOpt = nameOpt;
#if DEBUG
// We shouldn't merged namespaces that are already merged.
foreach (NamespaceSymbol ns in namespacesToMerge)
{
Debug.Assert(ns.ConstituentNamespaces.Length == 1);
}
#endif
}
/// <summary>
/// Create a possibly merged namespace symbol. If only a single namespace is passed it, it
/// is just returned directly. If two or more namespaces are passed in, then a new merged
/// namespace is created with the given extent and container.
/// </summary>
/// <param name="extent">The namespace extent to use, IF a merged namespace is created.</param>
/// <param name="containingNamespace">The containing namespace to used, IF a merged
/// namespace is created.</param>
/// <param name="namespacesToMerge">One or more namespaces to merged. If just one, then it
/// is returned. The merged namespace symbol may hold onto the array.</param>
/// <param name="nameOpt">An optional name to give the resulting namespace.</param>
/// <returns>A namespace symbol representing the merged namespace.</returns>
internal static NamespaceSymbol Create(
NamespaceExtent extent,
NamespaceSymbol containingNamespace,
ImmutableArray <NamespaceSymbol> namespacesToMerge,
string nameOpt = null)
{
// Currently, if we are just merging 1 namespace, we just return the namespace itself.
// This is by far the most efficient, because it means that we don't create merged
// namespaces (which have a fair amount of memory overhead) unless there is actual
// merging going on. However, it means that the child namespace of a Compilation extent
// namespace may be a Module extent namespace, and the containing of that module extent
// namespace will be another module extent namespace. This is basically no different
// than type members of namespaces, so it shouldn't be TOO unexpected.
// EDMAURER if the caller is supplying a name, then produce the merged namespace with
// the new name even if only a single namespace was provided. This behavior was introduced
// to support nice extern alias error reporting.
Debug.Assert(namespacesToMerge.Length != 0);
return((namespacesToMerge.Length == 1 && nameOpt == null)
? namespacesToMerge[0]
: new MergedNamespaceSymbol(extent, containingNamespace, namespacesToMerge, nameOpt));
}