com.espertech.esper.epl.expression.baseagg

Class ExprAggregateNodeBase

java.lang.Object

com.espertech.esper.epl.expression.core.ExprNodeBase

com.espertech.esper.epl.expression.baseagg.ExprAggregateNodeBase

All Implemented Interfaces:

ExprAggregateNode, ExprEvaluator, ExprForge, ExprNode, ExprNodeRenderable, ExprValidator, MetaDefItem, Serializable

Direct Known Subclasses:

ExprAggCountMinSketchNode, ExprAggMultiFunctionLinearAccessNode, ExprAggMultiFunctionSortedMinMaxByNode, ExprAvedevNode, ExprAvgNode, ExprCountEverNode, ExprCountNode, ExprFirstEverNode, ExprLastEverNode, ExprLeavingAggNode, ExprMedianNode, ExprMinMaxAggrNode, ExprNthAggNode, ExprPlugInAggMultiFunctionNode, ExprPlugInAggNode, ExprRateAggNode, ExprStddevNode, ExprSumNode

public abstract class ExprAggregateNodeBase
extends ExprNodeBase
implements ExprEvaluator, ExprAggregateNode, ExprForge

Base expression node that represents an aggregation function such as 'sum' or 'count'.

In terms of validation each concrete aggregation node must implement it's own validation.

In terms of evaluation this base class will ask the assigned AggregationResultFuture for the current state, using a column number assigned to the node.

Concrete subclasses must supply an aggregation state prototype node AggregationMethod that reflects each group's (there may be group-by critera) current aggregation state.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected AggregationResultFuture	aggregationResultFuture
protected int	column
protected boolean	isDistinct Indicator for whether the aggregation is distinct - i.e.
protected ExprAggregateLocalGroupByDesc	optionalAggregateLocalGroupByDesc
protected ExprNode	optionalFilter
protected ExprNode[]	positionalParams

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ExprAggregateNodeBase(boolean distinct) Ctor.

Method Summary

Modifier and Type	Method and Description
boolean	equalsNode(ExprNode node, boolean ignoreStreamPrefix) Return true if a expression node semantically equals the current node, or false if not.
protected abstract boolean	equalsNodeAggregateMethodOnly(ExprAggregateNode node) Return true if a expression aggregate node semantically equals the current node, or false if not.
Object	evaluate(EventBean[] events, boolean isNewData, ExprEvaluatorContext exprEvaluatorContext) Evaluate event tuple and return result.
CodegenExpression	evaluateCodegen(CodegenParamSetExprPremade params, CodegenContext context)
abstract String	getAggregationFunctionName() Returns the aggregation function name for representation in a generate expression string.
ExprForgeComplexityEnum	getComplexity()
Class	getEvaluationType()
ExprEvaluator	getExprEvaluator()
AggregationMethodFactory	getFactory() Returns the aggregation state factory for use in grouping aggregation states per group-by keys.
ExprForge	getForge()
ExprNode	getForgeRenderable()
ExprNode	getOptionalFilter()
ExprAggregateLocalGroupByDesc	getOptionalLocalGroupBy()
ExprNode[]	getPositionalParams()
ExprPrecedenceEnum	getPrecedence() Returns precedence.
boolean	isConstantResult() Returns true if the expression node's evaluation value doesn't depend on any events data, as must be determined at validation time, which is bottom-up and therefore reliably allows each node to determine constant value.
boolean	isDistinct() Returns true if the aggregation node is only aggregatig distinct values, or false if aggregating all values.
protected boolean	isExprTextWildcardWhenNoParams()
protected abstract boolean	isFilterExpressionAsLastParameter()
protected ExprValidationException	makeExceptionExpectedParamNum(int lower, int upper)
void	setAggregationResultFuture(AggregationResultFuture aggregationResultFuture, int column) Assigns to the node the future which can be queried for the current aggregation state at evaluation time.
void	toPrecedenceFreeEPL(StringWriter writer)
ExprNode	validate(ExprValidationContext validationContext)
protected abstract AggregationMethodFactory	validateAggregationChild(ExprValidationContext validationContext) Gives the aggregation node a chance to validate the sub-expression types.
void	validateFilter(ExprForge filterEvaluator)
protected Class	validateNumericChildAllowFilter(boolean hasFilter) For use by implementing classes, validates the aggregation node expecting a single numeric-type child node.
void	validatePositionals()

Methods inherited from class com.espertech.esper.epl.expression.core.ExprNodeBase

accept, accept, acceptChildnodes, addChildNode, addChildNodes, addChildNodeToFront, getChildNodes, replaceUnlistedChildNode, setChildNode, setChildNodes, toEPL

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.espertech.esper.epl.expression.core.ExprNode

accept, accept, acceptChildnodes, addChildNode, addChildNodes, getChildNodes, replaceUnlistedChildNode, setChildNode, setChildNodes

Methods inherited from interface com.espertech.esper.epl.expression.core.ExprNodeRenderable

toEPL

Field Detail

aggregationResultFuture

protected transient AggregationResultFuture aggregationResultFuture

column

protected int column

optionalAggregateLocalGroupByDesc

protected ExprAggregateLocalGroupByDesc optionalAggregateLocalGroupByDesc

optionalFilter

protected ExprNode optionalFilter

positionalParams

protected ExprNode[] positionalParams

isDistinct

protected boolean isDistinct

Indicator for whether the aggregation is distinct - i.e. only unique values are considered.

Constructor Detail

ExprAggregateNodeBase

protected ExprAggregateNodeBase(boolean distinct)

Ctor.

Parameters:

distinct - - sets the flag indicatating whether only unique values should be aggregated

Method Detail

getAggregationFunctionName

public abstract String getAggregationFunctionName()

Returns the aggregation function name for representation in a generate expression string.

Returns:

aggregation function name

isFilterExpressionAsLastParameter

protected abstract boolean isFilterExpressionAsLastParameter()

equalsNodeAggregateMethodOnly

protected abstract boolean equalsNodeAggregateMethodOnly(ExprAggregateNode node)

Return true if a expression aggregate node semantically equals the current node, or false if not.

For use by the equalsNode implementation which compares the distinct flag.

Parameters:

node - to compare to

Returns:

true if semantically equal, or false if not equals

validateAggregationChild

protected abstract AggregationMethodFactory validateAggregationChild(ExprValidationContext validationContext)
                                                              throws ExprValidationException

Gives the aggregation node a chance to validate the sub-expression types.

Parameters:

validationContext - validation information

Returns:

aggregation function factory to use

Throws:

ExprValidationException - when expression validation failed

getPositionalParams

public ExprNode[] getPositionalParams()

Specified by:

getPositionalParams in interface ExprAggregateNode

getExprEvaluator

public ExprEvaluator getExprEvaluator()

Specified by:

getExprEvaluator in interface ExprForge

isConstantResult

public boolean isConstantResult()

Description copied from interface: ExprNode

Returns true if the expression node's evaluation value doesn't depend on any events data, as must be determined at validation time, which is bottom-up and therefore reliably allows each node to determine constant value.

Specified by:

isConstantResult in interface ExprNode

Returns:

true for constant evaluation value, false for non-constant evaluation value

getForgeRenderable

public ExprNode getForgeRenderable()

Specified by:

getForgeRenderable in interface ExprForge

validate

public ExprNode validate(ExprValidationContext validationContext)
                  throws ExprValidationException

Specified by:

validate in interface ExprValidator

Throws:

ExprValidationException

validatePositionals

public void validatePositionals()
                         throws ExprValidationException

Specified by:

validatePositionals in interface ExprAggregateNode

Throws:

ExprValidationException

getFactory

public AggregationMethodFactory getFactory()

Returns the aggregation state factory for use in grouping aggregation states per group-by keys.

Specified by:

getFactory in interface ExprAggregateNode

Returns:

prototype aggregation state as a factory for aggregation states per group-by key value

setAggregationResultFuture

public void setAggregationResultFuture(AggregationResultFuture aggregationResultFuture,
                                       int column)

Assigns to the node the future which can be queried for the current aggregation state at evaluation time.

Specified by:

setAggregationResultFuture in interface ExprAggregateNode

Parameters:

aggregationResultFuture - - future containing state

column - - column to hand to future for easy access

evaluate

public final Object evaluate(EventBean[] events,
                             boolean isNewData,
                             ExprEvaluatorContext exprEvaluatorContext)

Description copied from interface: ExprEvaluator

Evaluate event tuple and return result.

Specified by:

evaluate in interface ExprEvaluator

Parameters:

events - - event tuple

isNewData - - indicates whether we are dealing with new data (istream) or old data (rstream)

exprEvaluatorContext - context for expression evaluation

Returns:

evaluation result, a boolean value for OR/AND-type evalution nodes.

evaluateCodegen

public CodegenExpression evaluateCodegen(CodegenParamSetExprPremade params,
                                         CodegenContext context)

Specified by:

evaluateCodegen in interface ExprForge

getComplexity

public ExprForgeComplexityEnum getComplexity()

Specified by:

getComplexity in interface ExprForge

getEvaluationType

public Class getEvaluationType()

Specified by:

getEvaluationType in interface ExprForge

getForge

public ExprForge getForge()

Specified by:

getForge in interface ExprNode

isDistinct

public boolean isDistinct()

Returns true if the aggregation node is only aggregatig distinct values, or false if aggregating all values.

Specified by:

isDistinct in interface ExprAggregateNode

Returns:

true if 'distinct' keyword was given, false if not

equalsNode

public final boolean equalsNode(ExprNode node,
                                boolean ignoreStreamPrefix)

Description copied from interface: ExprNode

Return true if a expression node semantically equals the current node, or false if not.

Concrete implementations should compare the type and any additional information that impact the evaluation of a node.

Specified by:

equalsNode in interface ExprNode

Parameters:

node - to compare to

ignoreStreamPrefix - when the equals-comparison can ignore prefix of event properties

Returns:

true if semantically equal, or false if not equals

validateNumericChildAllowFilter

protected final Class validateNumericChildAllowFilter(boolean hasFilter)
                                               throws ExprValidationException

For use by implementing classes, validates the aggregation node expecting a single numeric-type child node.

Parameters:

hasFilter - for filter indication

Returns:

numeric type of single child

Throws:

ExprValidationException - if the validation failed

makeExceptionExpectedParamNum

protected ExprValidationException makeExceptionExpectedParamNum(int lower,
                                                                int upper)

toPrecedenceFreeEPL

public void toPrecedenceFreeEPL(StringWriter writer)

Specified by:

toPrecedenceFreeEPL in class ExprNodeBase

getPrecedence

public ExprPrecedenceEnum getPrecedence()

Description copied from interface: ExprNode

Returns precedence.

Specified by:

getPrecedence in interface ExprNode

Returns:

precedence

validateFilter

public void validateFilter(ExprForge filterEvaluator)
                    throws ExprValidationException

Throws:

ExprValidationException

getOptionalLocalGroupBy

public ExprAggregateLocalGroupByDesc getOptionalLocalGroupBy()

Specified by:

getOptionalLocalGroupBy in interface ExprAggregateNode

getOptionalFilter

public ExprNode getOptionalFilter()

isExprTextWildcardWhenNoParams

protected boolean isExprTextWildcardWhenNoParams()