/// <summary>
/// Returns the next reference.
/// </summary>
/// <returns>The next reference that meets the browse criteria.</returns>
public override IReference Next()
{
ComDaClientManager system = (ComDaClientManager)this.SystemContext.SystemHandle;
ComDaClient client = system.SelectClient((ServerSystemContext)SystemContext);
lock (DataLock)
{
IReference reference = null;
// enumerate pre-defined references.
// always call first to ensure any pushed-back references are returned first.
reference = base.Next();
if (reference != null)
{
return(reference);
}
// don't start browsing huge number of references when only internal references are requested.
if (InternalOnly)
{
return(null);
}
// fetch references from the server.
do
{
// fetch next reference.
reference = NextChild();
if (reference != null)
{
return(reference);
}
// go to the next stage.
NextStage();
}while (m_stage != Stage.Done);
// all done.
return(null);
}
}
/// <summary>
/// Returns the next child.
/// </summary>
private IReference NextChild()
{
ComDaClientManager system = (ComDaClientManager)this.SystemContext.SystemHandle;
ComDaClient client = system.SelectClient((ServerSystemContext)SystemContext);
// check if a specific browse name is requested.
if (QualifiedName.IsNull(base.BrowseName))
{
return(NextChild(m_stage));
}
// keep fetching references until a matching browse name if found.
NodeStateReference reference = null;
do
{
reference = NextChild(m_stage);
if (reference != null)
{
// need to let the caller look up the browse name.
if (reference.Target == null)
{
return(reference);
}
// check for browse name match.
if (reference.Target.BrowseName == base.BrowseName)
{
return(reference);
}
}
}while (reference != null);
// no match - need to go onto the next stage.
return(null);
}
/// <summary>
/// Initializes the next stage of browsing.
/// </summary>
private void NextStage()
{
ComDaClientManager system = (ComDaClientManager)this.SystemContext.SystemHandle;
ComDaClient client = system.SelectClient((ServerSystemContext)SystemContext);
// determine which stage is next based on the reference types requested.
for (Stage next = m_stage + 1; next <= Stage.Done; next++)
{
if (next == Stage.Children)
{
if (IsRequired(ReferenceTypeIds.Organizes, false))
{
m_stage = next;
break;
}
}
else if (next == Stage.Properties)
{
if (IsRequired(ReferenceTypeIds.HasProperty, false))
{
m_stage = next;
break;
}
}
else if (next == Stage.Parents)
{
if (IsRequired(ReferenceTypeIds.Organizes, true))
{
m_stage = next;
break;
}
}
else if (next == Stage.Done)
{
m_stage = next;
break;
}
}
m_position = 0;
// start enumerating branches.
if (m_stage == Stage.Children)
{
m_browser = client.CreateBrowser(m_itemId);
return;
}
// start enumerating properties.
if (m_stage == Stage.Properties)
{
m_properties = client.ReadAvailableProperties(m_itemId, true);
m_position = 0;
return;
}
// start enumerating parents.
if (m_stage == Stage.Parents)
{
m_parentId = client.FindElementParentId(m_itemId);
return;
}
// all done.
}
/// <summary>
/// Returns the next child.
/// </summary>
private NodeStateReference NextChild(Stage stage)
{
ComDaClientManager system = (ComDaClientManager)this.SystemContext.SystemHandle;
ComDaClient client = system.SelectClient((ServerSystemContext)SystemContext);
DaElement element = null;
if (stage == Stage.Children)
{
if (m_browser == null)
{
return(null);
}
element = m_browser.Next();
if (element == null)
{
return(null);
}
// construct the node.
NodeState node = ModelUtils.ConstructElement(SystemContext, element, m_namespaceIndex);
// return the reference.
return(new NodeStateReference(ReferenceTypeIds.Organizes, false, node));
}
if (stage == Stage.Properties)
{
if (m_properties == null)
{
return(null);
}
for (int ii = m_position; ii < m_properties.Length; ii++)
{
if (m_properties[ii].PropertyId <= PropertyIds.TimeZone)
{
continue;
}
m_position = ii + 1;
// construct the node.
NodeState node = ModelUtils.ConstructProperty(SystemContext, m_itemId, m_properties[ii], m_namespaceIndex);
// return the reference.
return(new NodeStateReference(ReferenceTypeIds.HasProperty, false, node));
}
// all done.
return(null);
}
if (stage == Stage.Parents)
{
if (m_parentId != null)
{
NodeId parentId = ModelUtils.ConstructIdForDaElement(m_parentId, -1, m_namespaceIndex);
m_parentId = null;
return(new NodeStateReference(ReferenceTypeIds.Organizes, true, parentId));
}
}
return(null);
}
