Package org.apache.qpid.server.query.engine.parsing.query

Class HavingExpression<T,R>

java.lang.Object

org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode<T,R>

org.apache.qpid.server.query.engine.parsing.query.HavingExpression<T,R>

Type Parameters:

T - Input parameter type

R - Return parameter type

All Implemented Interfaces:

Function<T,R>, Predicate<T>, Expression<T,R>, ExpressionNode<T,R>

public class HavingExpression<T,R>
extends AbstractExpressionNode<T,R>
implements Predicate<T>

Contains expression for evaluation of having clause predicate

Field Summary

Fields inherited from class org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode

_metadata

Constructor Summary

Constructors

Constructor	Description
HavingExpression(SelectExpression<T,R> selectExpression, ExpressionNode<T,R> expression)	Constructor initializes children expression list

Method Summary

Modifier and Type	Method	Description
R	apply(T value)	Evaluates an object against having clause
<A> void	applyAggregation(SelectExpression<T,R> selectExpression, List<T> items)	Prepares boolean mask in form of a map having same structure as actual aggregation result, but containing boolean values instead of actual values.
void	filter(Map<String,R> result)	Filters aggregation result in accordance with the having predicate
boolean	test(T value)	Evaluates an object against having clause

Methods inherited from class org.apache.qpid.server.query.engine.parsing.expression.AbstractExpressionNode

containsAggregation, ctx, evaluateChild, getAggregations, getAlias, getChild, getChildren, getParent, isAccessor, isInstantlyEvaluable, setAlias, setParent, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.qpid.server.query.engine.parsing.expression.Expression

andThen

Methods inherited from interface java.util.function.Function

andThen, compose

Methods inherited from interface java.util.function.Predicate

and, negate, or

Constructor Detail

HavingExpression

public HavingExpression(SelectExpression<T,R> selectExpression,
                        ExpressionNode<T,R> expression)

Constructor initializes children expression list

Parameters:

selectExpression - Select expression

expression - Having expression

Method Detail

apply

public R apply(T value)

Evaluates an object against having clause

Specified by:

apply in interface Expression<T,R>

Specified by:

apply in interface Function<T,R>

Parameters:

value - Object to handle

Returns:

Evaluation result

test

public boolean test(T value)

Evaluates an object against having clause

Specified by:

test in interface Predicate<T>

Parameters:

value - Object to handle

Returns:

Evaluation result

applyAggregation

public <A> void applyAggregation(SelectExpression<T,R> selectExpression,
                                 List<T> items)

Prepares boolean mask in form of a map having same structure as actual aggregation result, but containing boolean values instead of actual values. Later this boolean mask is applied to the aggregation result to filter it in accordance with the having predicate.

Type Parameters:

A - Collector accumulation type

Parameters:

selectExpression - Select expression

items - List of objects to be aggregated

filter

public void filter(Map<String,R> result)

Filters aggregation result in accordance with the having predicate

Parameters:

result - Map with aggregation result