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java.lang.Objectnet.esper.view.ViewServiceHelper
public class ViewServiceHelper
Utility methods to deal with chains of views, and for merge/group-by views.
Constructor Summary | |
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ViewServiceHelper()
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Method Summary | |
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protected static void |
addMergeViews(List<ViewSpec> specifications)
Add merge views for any views in the chain requiring a merge (group view). |
protected static List<View> |
instantiateChain(List<View> existingParentViews,
Viewable parentViewable,
List<ViewSpec> specifications,
ViewServiceContext context)
Instantiate a chain of views. |
protected static Pair<Viewable,List<View>> |
matchExistingViews(Viewable rootViewable,
Map<View,ViewSpec> specificationRepository,
List<ViewSpec> specifications)
Match the views under the stream to the list of view specications passed in. |
protected static List<View> |
removeChainLeafView(Viewable parentViewable,
Viewable viewToRemove)
Removes a view from a parent view returning the orphaned parent views in a list. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public ViewServiceHelper()
Method Detail |
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protected static void addMergeViews(List<ViewSpec> specifications)
specifications
- is a list of view definitions defining the chain of views.protected static List<View> instantiateChain(List<View> existingParentViews, Viewable parentViewable, List<ViewSpec> specifications, ViewServiceContext context) throws ViewProcessingException
existingParentViews
- - parent viewsparentViewable
- - parent view to add the chain tospecifications
- - view specification, one for each chain elementcontext
- - dependent services
ViewProcessingException
- is throw to indicate an error instantiating the chainprotected static List<View> removeChainLeafView(Viewable parentViewable, Viewable viewToRemove)
parentViewable
- - parent to remove view fromviewToRemove
- - view to remove
protected static Pair<Viewable,List<View>> matchExistingViews(Viewable rootViewable, Map<View,ViewSpec> specificationRepository, List<ViewSpec> specifications)
rootViewable
- is the top rootViewable event stream to which all views are attached as child viewsspecificationRepository
- is a map of view and specification that enables view specification comparisonspecifications
- is the non-empty list of specifications describing the new chain of views to create.
This parameter is changed by this method, ie. specifications are removed if they match existing views.
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