/// <summary>
/// Creates a <see cref="ReadCondition" /> to read samples with the desired sample states, view states and instance states.
/// </summary>
/// <param name="sampleStates">The desired sample states mask.</param>
/// <param name="viewStates">The desired view states mask.</param>
/// <param name="instanceStates">The desired instance states mask.</param>
/// <returns>The newly created <see cref="ReadCondition" /> on success, otherwise <see langword="null"/>.</returns>
public ReadCondition CreateReadCondition(SampleStateMask sampleStates, ViewStateMask viewStates, InstanceStateMask instanceStates)
{
IntPtr native = UnsafeNativeMethods.CreateReadCondition(_native, sampleStates, viewStates, instanceStates);
ReadCondition readCondition = null;
if (native != IntPtr.Zero)
{
readCondition = new ReadCondition(native, this);
_conditions.Add(readCondition);
}
return(readCondition);
}
/// <summary>
/// Creates a <see cref="QueryCondition" /> with the desired sample states, view states and instance states.
/// </summary>
/// <remarks>
/// The returned <see cref="QueryCondition" /> will be attached and belong to the <see cref="DataReader" />.
/// </remarks>
/// <param name="sampleStates">The desired sample states mask.</param>
/// <param name="viewStates">The desired view states mask.</param>
/// <param name="instanceStates">The desired instance states mask.</param>
/// <param name="queryExpression">The query string, which must be a subset of the SQL query language.</param>
/// <param name="queryParameters">A sequence of strings which are the parameter values used in the SQL query string. The number of values in queryParameters must be equal or greater than the highest referenced n token in the queryExpression.</param>
/// <returns>The newly created <see cref="QueryCondition" /> on success, otherwise <see langword="null"/>.</returns>
public QueryCondition CreateQueryCondition(SampleStateMask sampleStates, ViewStateMask viewStates, InstanceStateMask instanceStates, string queryExpression, params string[] queryParameters)
{
IntPtr seq = IntPtr.Zero;
IList <string> parameters = queryParameters.ToList();
parameters.StringSequenceToPtr(ref seq, false);
IntPtr native = UnsafeNativeMethods.CreateQueryCondition(_native, sampleStates, viewStates, instanceStates, queryExpression, seq);
QueryCondition queryCondition = null;
if (native != IntPtr.Zero)
{
queryCondition = new QueryCondition(native, this);
_conditions.Add(queryCondition);
}
return(queryCondition);
}
/// <summary>
/// Allows the application to access the <see cref="DataReader" /> objects that contain samples with the specified sampleStates,
/// viewStates, and instanceStates.
/// </summary>
/// <remarks>
/// <para>If the <see cref="PresentationQosPolicy" /> of the <see cref="Subscriber" /> to which the <see cref="DataReader" /> belongs has the
/// <see cref="PresentationQosPolicy.AccessScope" /> set to <see cref="PresentationQosPolicyAccessScopeKind.GroupPresentationQos" />,
/// this operation should only be invoked inside a <see cref="BeginAccess" />/<see cref="EndAccess" /> block. Otherwise it will return the error
/// <see cref="ReturnCode.PreconditionNotMet" />.</para>
/// <para>Depending on the setting of the <see cref="PresentationQosPolicy" />, the returned collection of <see cref="DataReader" /> objects may
/// be a 'set' containing each <see cref="DataReader" /> at most once in no specified order, or a 'list' containing each <see cref="DataReader" /> one or more
/// times in a specific order.
/// <list type="number">
/// <item><description>If <see cref="PresentationQosPolicy.AccessScope" /> is <see cref="PresentationQosPolicyAccessScopeKind.InstancePresentationQos" /> or
/// <see cref="PresentationQosPolicyAccessScopeKind.TopicPresentationQos" /> the returned collection behaves as a 'set'.</description></item>
/// <item><description>If <see cref="PresentationQosPolicy.AccessScope" /> is <see cref="PresentationQosPolicyAccessScopeKind.GroupPresentationQos" /> and
/// <see cref="PresentationQosPolicy.OrderedAccess" /> is set to <see langword="true"/>, then the returned collection behaves as a 'list'.</description></item>
/// </list></para>
/// <para>This difference is due to the fact that, in the second situation it is required to access samples belonging to different <see cref="DataReader" />
/// objects in a particular order. In this case, the application should process each <see cref="DataReader" /> in the same order it appears in the
/// 'list' and Read or Take exactly one sample from each <see cref="DataReader" />.</para>
/// </remarks>
/// <param name="readers">The <see cref="DataReader" /> collection to be filled up.</param>
/// <param name="sampleStates">The returned <see cref="DataReader" /> in the collection must contain samples that have one of the sample states.</param>
/// <param name="viewStates">The returned <see cref="DataReader" /> in the collection must contain samples that have one of the view states.</param>
/// <param name="instanceStates">The returned <see cref="DataReader" /> in the collection must contain samples that have one of the instance states.</param>
/// <returns>The <see cref="ReturnCode" /> that indicates the operation result.</returns>
public ReturnCode GetDataReaders(IList <DataReader> readers, SampleStateMask sampleStates, ViewStateMask viewStates, InstanceStateMask instanceStates)
{
if (readers == null)
{
return(ReturnCode.BadParameter);
}
readers.Clear();
IntPtr ptr = IntPtr.Zero;
ReturnCode ret = UnsafeNativeMethods.GetDataReaders(_native, ref ptr, sampleStates, viewStates, instanceStates);
if (ret == ReturnCode.Ok && !ptr.Equals(IntPtr.Zero))
{
IList <IntPtr> lst = new List <IntPtr>();
MarshalHelper.PtrToSequence(ptr, ref lst);
if (lst != null)
{
foreach (IntPtr ptrReader in lst)
{
IntPtr ptrEnity = DataReader.NarrowBase(ptrReader);
var entity = EntityManager.Instance.Find(ptrEnity);
if (entity is DataReader dataReader)
{
readers.Add(dataReader);
}
else
{
readers.Add(new DataReader(ptrReader));
}
}
}
}
return(ret);
}
