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

Class ProjectionExpression<T,R>

java.lang.Object

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

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

Type Parameters:

T - Input parameter type

R - Return parameter type

All Implemented Interfaces:

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

public class ProjectionExpression<T,R>
extends AbstractExpressionNode<T,R>

Contains information about a single item in a SELECT clause

Field Summary

Fields

Modifier and Type	Field	Description
protected int	_ordinal	Ordinal value

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

_metadata

Constructor Summary

Constructors

Constructor	Description
ProjectionExpression(String alias, ExpressionNode<T,R> expression, int ordinal)	Constructor stores properties

Method Summary

Modifier and Type	Method	Description
R	apply(T object)	Evaluated an object against the expression
R	applyAggregation(SelectExpression<T,R> selectExpression, List<T> items)	Evaluates a collection of objects against an aggregation expression
String	getAlias()	Returns expression alias
Expression<T,R>	getExpression()	Returns wrapped expression
boolean	isOrdinal()
void	setAlias(String alias)	Setter for alias
String	toString()

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

containsAggregation, ctx, evaluateChild, getAggregations, getChild, getChildren, getParent, isAccessor, isInstantlyEvaluable, setParent

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

Field Detail

_ordinal

protected final int _ordinal

Ordinal value

Constructor Detail

ProjectionExpression

public ProjectionExpression(String alias,
                            ExpressionNode<T,R> expression,
                            int ordinal)

Constructor stores properties

Parameters:

alias - Item alias

expression - Item expression

ordinal - Ordinal value

Method Detail

apply

public R apply(T object)

Evaluated an object against the expression

Parameters:

object - Object to handle

Returns:

Evaluation result

applyAggregation

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

Evaluates a collection of objects against an aggregation expression

Parameters:

selectExpression - Select expression

items - Collection of objects

Returns:

Aggregation result

getExpression

public Expression<T,R> getExpression()

Returns wrapped expression

Returns:

Expression instance

setAlias

public void setAlias(String alias)

Description copied from class: AbstractExpressionNode

Setter for alias

Specified by:

setAlias in interface ExpressionNode<T,R>

Overrides:

setAlias in class AbstractExpressionNode<T,R>

Parameters:

alias - Expression alias

getAlias

public String getAlias()

Description copied from class: AbstractExpressionNode

Returns expression alias

Specified by:

getAlias in interface ExpressionNode<T,R>

Overrides:

getAlias in class AbstractExpressionNode<T,R>

Returns:

Expression alias

isOrdinal

public boolean isOrdinal()

toString

public String toString()

Overrides:

toString in class AbstractExpressionNode<T,R>