com.espertech.esper.epl.join.exec.base

Class NestedIterationExecNode

java.lang.Object

com.espertech.esper.epl.join.exec.base.ExecNode

com.espertech.esper.epl.join.exec.base.NestedIterationExecNode

public class NestedIterationExecNode
extends ExecNode

Execution node that performs a nested iteration over all child nodes.

Each child node under this node typically represents a table lookup. The implementation 'hops' from the first child to the next recursively for each row returned by a child.

It passes a 'prototype' row (prefillPath) to each new child which contains the current partial event set.

Constructor Summary

Constructors

Constructor and Description
NestedIterationExecNode(int[] nestedStreams) Ctor.

Method Summary

Modifier and Type	Method and Description
void	addChildNode(ExecNode childNode) Add a child node.
void	print(IndentWriter writer) Output the execution strategy.
void	process(EventBean lookupEvent, EventBean[] prefillPath, Collection<EventBean[]> result, ExprEvaluatorContext exprEvaluatorContext) Process single event using the prefill events to compile lookup results.
protected void	recursiveNestedJoin(EventBean lookupEvent, int nestingOrderIndex, EventBean[] currentPath, Collection<EventBean[]> result, ExprEvaluatorContext exprEvaluatorContext) Recursive method to run through all child nodes and, for each result set tuple returned by a child node, execute the inner child of the child node until there are no inner child nodes.

Methods inherited from class com.espertech.esper.epl.join.exec.base.ExecNode

print

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

NestedIterationExecNode

public NestedIterationExecNode(int[] nestedStreams)

Ctor.

Parameters:

nestedStreams - - array of integers defining order of streams in nested join.

Method Detail

addChildNode

public void addChildNode(ExecNode childNode)

Add a child node.

Parameters:

childNode - to add

process

public void process(EventBean lookupEvent,
                    EventBean[] prefillPath,
                    Collection<EventBean[]> result,
                    ExprEvaluatorContext exprEvaluatorContext)

Description copied from class: ExecNode

Process single event using the prefill events to compile lookup results.

Specified by:

process in class ExecNode

Parameters:

lookupEvent - - event to look up for or query for

prefillPath - - set of events currently in the example tuple to serve as a prototype for result rows.

result - is the list of tuples to add a result row to

exprEvaluatorContext - context for expression evaluation

recursiveNestedJoin

protected void recursiveNestedJoin(EventBean lookupEvent,
                                   int nestingOrderIndex,
                                   EventBean[] currentPath,
                                   Collection<EventBean[]> result,
                                   ExprEvaluatorContext exprEvaluatorContext)

Recursive method to run through all child nodes and, for each result set tuple returned by a child node, execute the inner child of the child node until there are no inner child nodes.

Parameters:

lookupEvent - - current event to use for lookup by child node

nestingOrderIndex - - index within the child nodes indicating what nesting level we are at

currentPath - - prototype result row to use by child nodes for generating result rows

result - - result tuple rows to be populated

exprEvaluatorContext - context for expression evalauation

print

public void print(IndentWriter writer)

Description copied from class: ExecNode

Output the execution strategy.

Specified by:

print in class ExecNode

Parameters:

writer - to output to