Add reference handler

[bryankenote]

Based on #10. Will open once that is merged.

[bryankenote]

This could be rewritten using the query syntax if that is preferred. I originally used the method syntax because it was easier to debug.

Suggested change

	public static IEnumerable<ServicePart> GetReferencedServicePartsAtPosition(this ServiceInfo service, Position requestPosition)
	{
	var members = service.GetDescendants().OfType<ServiceMemberInfo>().ToList().AsReadOnly();
	// memberNameAtCursor will be null if the cursor is not on a member name.
	var memberNameAtCursor = members
	.Select(member =>
	{
	var part = member.GetPart(ServicePartKind.Name);
	var name = member.Name;
	return (part, name);
	})
	.Where(x => x.part != null && requestPosition >= x.part.Position && requestPosition < x.part.EndPosition)
	.Select(x => x.name)
	.FirstOrDefault();
	var fields = service.GetDescendants().OfType<ServiceFieldInfo>().ToList().AsReadOnly();
	// fieldTypeNameAtCursor will be null if the cursor is not on a field type name.
	var fieldTypeNameAtCursor = fields
	.Select(field =>
	{
	var part = field.GetPart(ServicePartKind.TypeName);
	var typeName = service.GetFieldTypeName(field);
	return (part, typeName);
	})
	.Where(x => x.part != null && requestPosition >= x.part.Position && requestPosition < x.part.EndPosition)
	.Select(x => x.typeName)
	.FirstOrDefault();
	return fields
	.Select(field =>
	{
	var part = field.GetPart(ServicePartKind.TypeName);
	var typeName = service.GetFieldTypeName(field);
	var type = service.GetFieldType(field);
	var memberTypeName = type?.GetMemberTypeName();
	return (part, memberTypeName, typeName);
	})
	.Where(x => x.part != null && ((memberNameAtCursor != null && x.memberTypeName == memberNameAtCursor) || x.typeName == fieldTypeNameAtCursor))
	.Select(x => x.part);
	}
	public static IEnumerable<ServicePart> GetReferencedServicePartsAtPosition(this ServiceInfo service, Position requestPosition)
	{
	// memberNameAtCursor will be null if the cursor is not on a member name.
	var memberNameAtCursor = (
	from member in service.GetDescendants().OfType<ServiceMemberInfo>()
	let part = member.GetPart(ServicePartKind.Name)
	let memberName = member.Name
	where part != null && requestPosition >= part.Position && requestPosition < part.EndPosition
	select memberName).FirstOrDefault();
	var fields = service.GetDescendants().OfType<ServiceFieldInfo>().ToList().AsReadOnly();
	// fieldTypeNameAtCursor will be null if the cursor is not on a member name.
	var fieldTypeNameAtCursor = (
	from field in fields
	let part = field.GetPart(ServicePartKind.TypeName)
	let typeName = service.GetFieldTypeName(field)
	where part != null && requestPosition >= part.Position && requestPosition < part.EndPosition
	select typeName).FirstOrDefault();
	return
	from field in fields
	let part = field.GetPart(ServicePartKind.TypeName)
	let typeName = service.GetFieldTypeName(field)
	let type = service.GetFieldType(field)
	let memberTypeName = type?.GetMemberTypeName()
	where part != null && ((memberNameAtCursor != null && memberTypeName == memberNameAtCursor) || typeName == fieldTypeNameAtCursor)
	select part;
	}

[ddunkin]

That does read better, especially if you move the where part != null to immediately after let part = lines, but I don't feel strongly about it.