FirstUniqueByPropertyView (Esper API Documentation)

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com.espertech.esper.view.std
Class FirstUniqueByPropertyView

java.lang.Object
  com.espertech.esper.view.ViewSupport
      com.espertech.esper.view.std.FirstUniqueByPropertyView

All Implemented Interfaces:: CloneableView, DataWindowView, EventCollection, GroupableView, View, Viewable, ViewDataVisitable, java.lang.Iterable<EventBean>

public class FirstUniqueByPropertyView
extends ViewSupport
implements CloneableView, DataWindowView
extends ViewSupport
implements CloneableView, DataWindowView

This view retains the first event for each multi-key of distinct property values.

The view does not post a remove stream unless explicitly deleted from.

The view swallows any insert stream events that provide no new distinct set of property values.

Field Summary
`protected AgentInstanceViewFactoryChainContext`	`agentInstanceViewFactoryContext`
`protected java.util.Map<java.lang.Object,EventBean>`	`firstEvents`
`protected ExprEvaluator[]`	`uniqueCriteriaEval`

Fields inherited from class com.espertech.esper.view.ViewSupport
`EMPTY_VIEW_ARRAY, parent`

Constructor Summary
`FirstUniqueByPropertyView(FirstUniqueByPropertyViewFactory viewFactory, AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)` Constructor.

Method Summary
`View`	`cloneView()` Duplicates the view.
`EventType`	`getEventType()` Provides metadata information about the type of object the event collection contains.
`ExprNode[]`	`getUniqueCriteria()` Returns the expressions supplying the unique value to keep the most recent record for.
`protected java.lang.Object`	`getUniqueKey(EventBean theEvent)`
`ViewFactory`	`getViewFactory()`
`void`	`internalHandleAdded(java.lang.Object key, EventBean newEvent)`
`void`	`internalHandleRemoved(java.lang.Object key, EventBean lastValue)`
`boolean`	`isEmpty()` Returns true if empty.
`java.util.Iterator<EventBean>`	`iterator()` Allows iteration through all elements in this event collection.
`java.lang.String`	`toString()`
`void`	`update(EventBean[] newData, EventBean[] oldData)` Notify that data has been added or removed from the Viewable parent.
`void`	`visitView(ViewDataVisitor viewDataVisitor)`

Methods inherited from class com.espertech.esper.view.ViewSupport
`addView, addView, dumpChildViews, dumpUpdateParams, dumpUpdateParams, findDescendent, findViewIndex, getParent, getViews, hasViews, removeAllViews, removeView, removeView, setParent, updateChildren, updateChildren`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Methods inherited from interface com.espertech.esper.view.View
`getParent, setParent`

Methods inherited from interface com.espertech.esper.view.Viewable
`addView, getViews, hasViews, removeAllViews, removeView`

Field Detail

uniqueCriteriaEval

protected final ExprEvaluator[] uniqueCriteriaEval

firstEvents

protected final java.util.Map<java.lang.Object,EventBean> firstEvents

agentInstanceViewFactoryContext

protected final AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext

Constructor Detail

FirstUniqueByPropertyView

public FirstUniqueByPropertyView(FirstUniqueByPropertyViewFactory viewFactory,
                                 AgentInstanceViewFactoryChainContext agentInstanceViewFactoryContext)

Constructor.

Method Detail

cloneView

public View cloneView()

Description copied from interface: CloneableView

Duplicates the view.

Expected to return a same view in initialized state for grouping.

Specified by:: cloneView in interface CloneableView

getUniqueCriteria

public final ExprNode[] getUniqueCriteria()

Returns the expressions supplying the unique value to keep the most recent record for.

Returns:: expressions for unique value

getEventType

public final EventType getEventType()

Description copied from interface: EventCollection

Provides metadata information about the type of object the event collection contains.

Specified by:: getEventType in interface EventCollection

Returns:: metadata for the objects in the collection

update

public final void update(EventBean[] newData,
                         EventBean[] oldData)

Description copied from interface: View

Notify that data has been added or removed from the Viewable parent. The last object in the newData array of objects would be the newest object added to the parent view. The first object of the oldData array of objects would be the oldest object removed from the parent view. If the call to update contains new (inserted) data, then the first argument will be a non-empty list and the second will be empty. Similarly, if the call is a notification of deleted data, then the first argument will be empty and the second will be non-empty. Either the newData or oldData will be non-null. This method won't be called with both arguments being null, but either one could be null. The same is true for zero-length arrays. Either newData or oldData will be non-empty. If both are non-empty, then the update is a modification notification. When update() is called on a view by the parent object, the data in newData will be in the collection of the parent, and its data structures will be arranged to reflect that. The data in oldData will not be in the parent's data structures, and any access to the parent will indicate that that data is no longer there.

Specified by:: update in interface View

Parameters:: newData - is the new data that has been added to the parent view; oldData - is the old data that has been removed from the parent view

internalHandleRemoved

public void internalHandleRemoved(java.lang.Object key,
                                  EventBean lastValue)

internalHandleAdded

public void internalHandleAdded(java.lang.Object key,
                                EventBean newEvent)

iterator

public final java.util.Iterator<EventBean> iterator()