/// <summary>
/// Reads a reference to a spatial feature, using that reference to obtain the
/// corresponding feature. If the feature cannot be found, the reference will be cached as
/// a forward reference (on completion of deserialization, you then call <see cref="ApplyForwardRefs"/>
/// to process the cache).
/// </summary>
/// <typeparam name="T">The type of spatial feature expected by the caller</typeparam>
/// <param name="referenceFrom">The object that is making the reference</param>
/// <param name="field">A tag associated with the value</param>
/// <returns>
/// The feature that was read (null if not found, or the reference was undefined). May
/// actually have a type that is derived from the supplied type.
/// </returns>
/// <remarks>This does not create a brand new feature. Rather, it uses a reference
/// to try to obtain a feature that should have already been created.
/// </remarks>
internal T ReadFeatureRef <T>(IFeatureRef referenceFrom, DataField field) where T : Feature
{
InternalIdValue id = m_Reader.ReadInternalId(field.ToString());
if (id.IsEmpty)
{
return(default(T));
}
T result = MapModel.Find <T>(id);
if (result == null)
{
var fwRef = new ForwardFeatureRef(referenceFrom, field, id);
m_ForwardRefs.Add(fwRef);
}
return(result);
}
/// <summary>
/// Initializes a new instance of the <see cref="ForwardFeatureRef"/> class.
/// </summary>
/// <param name="referenceFrom">The object that makes the forward-reference (not null).</param>
/// <param name="field">The ID of the persistent field.</param>
/// <param name="parentLineId">The internal ID that has been persisted for the field (relating to a feature
/// that has not been created yet).</param>
/// <param name="splitBeforeId">The ID of the line section prior to the split (null if no split)</param>
/// <param name="splitAfterId">The ID of the line section after the the split (null if no split)</param>
/// <exception cref="ArgumentNullException">If <paramref name="referenceFrom"/> is not defined.</exception>
internal ForwardSplit(ForwardFeatureRef lineRef, string splitBeforeId, string splitAfterId)
{
m_LineRef = lineRef;
m_SplitBeforeId = splitBeforeId;
m_SplitAfterId = splitAfterId;
}
internal void AddForwardSplit(ForwardFeatureRef lineRef, string idBefore, string idAfter)
{
var fwSplit = new ForwardSplit(lineRef, idBefore, idAfter);
m_ForwardSplits.Add(fwSplit);
}
/// <summary>
/// Initializes a new instance of the <see cref="ForwardFeatureRef"/> class.
/// </summary>
/// <param name="referenceFrom">The object that makes the forward-reference (not null).</param>
/// <param name="field">The ID of the persistent field.</param>
/// <param name="parentLineId">The internal ID that has been persisted for the field (relating to a feature
/// that has not been created yet).</param>
/// <param name="splitBeforeId">The ID of the line section prior to the split (null if no split)</param>
/// <param name="splitAfterId">The ID of the line section after the the split (null if no split)</param>
/// <exception cref="ArgumentNullException">If <paramref name="referenceFrom"/> is not defined.</exception>
internal ForwardSplit(ForwardFeatureRef lineRef, string splitBeforeId, string splitAfterId)
{
m_LineRef = lineRef;
m_SplitBeforeId = splitBeforeId;
m_SplitAfterId = splitAfterId;
}
