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

Class FromExpression<T,R extends Stream<?>,C extends ConfiguredObject<?>>

java.lang.Object

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

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

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

Type Parameters:

T - Input parameter type

R - Return parameter type

C - ConfiguredObject descendant

All Implemented Interfaces:

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

public class FromExpression<T,R extends Stream<?>,C extends ConfiguredObject<?>>
extends ConstantExpression<T,R>

Contains information about domain queried and retrieves steams of entities from domain.

Field Summary

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

_metadata

Constructor Summary

Constructors

Constructor	Description
FromExpression(String domain, String alias)	Constructor stores domain properties

Method Summary

Modifier and Type	Method	Description
R	get()	Retrieves stream of data from domain
String	getAlias()	Returns domain alias
List<String>	getFieldNames()	Retrieves field names of a domain entity
<Y> List<ProjectionExpression<T,Y>>	getProjections(List<String> aliases, SelectExpression<T,R> selectExpression)	Retrieves accessor expressions for a domain entity
String	toString()

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

apply, of, of

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

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

Constructor Detail

FromExpression

public FromExpression(String domain,
                      String alias)

Constructor stores domain properties

Parameters:

domain - Domain name

alias - Domain alias

Method Detail

get

public R get()

Retrieves stream of data from domain

Specified by:

get in interface Supplier<T>

Overrides:

get in class ConstantExpression<T,R extends Stream<?>>

Returns:

Stream of data

getFieldNames

public List<String> getFieldNames()

Retrieves field names of a domain entity

Returns:

List of field names

getProjections

public <Y> List<ProjectionExpression<T,Y>> getProjections(List<String> aliases,
                                                                SelectExpression<T,R> selectExpression)

Retrieves accessor expressions for a domain entity

Type Parameters:

Y - Return parameter type

Parameters:

aliases - List of field names

selectExpression - SelectExpression instance

Returns:

List of projection expressions

getAlias

public String getAlias()

Returns domain alias

Specified by:

getAlias in interface ExpressionNode<T,R extends Stream<?>>

Overrides:

getAlias in class ConstantExpression<T,R extends Stream<?>>

Returns:

Domain alias

toString

public String toString()

Overrides:

toString in class ConstantExpression<T,R extends Stream<?>>