org.apache.cassandra.cql3.selection

Class Selector.Factory

java.lang.Object

org.apache.cassandra.cql3.selection.Selector.Factory

Direct Known Subclasses:

SimpleSelector.SimpleSelectorFactory

Enclosing class:

Selector

public abstract static class Selector.Factory
extends java.lang.Object

A factory for Selector instances.

Constructor Summary

Constructors

Constructor and Description
Factory()

Method Summary

Modifier and Type	Method and Description
protected abstract void	addColumnMapping(SelectionColumnMapping mapping, ColumnSpecification resultsColumn) Record a mapping between the ColumnDefinitions that are used by the selector instances created by this factory and a column in the ResultSet.Metadata returned with a query.
void	addFunctionsTo(java.util.List<Function> functions)
protected abstract java.lang.String	getColumnName() Returns the name of the column corresponding to the output value of the selector instances created by this factory.
ColumnSpecification	getColumnSpecification(TableMetadata table) Returns the column specification corresponding to the output value of the selector instances created by this factory.
protected abstract AbstractType<?>	getReturnType() Returns the type of the values returned by the selector instances created by this factory.
boolean	isAggregateSelectorFactory() Checks if this factory creates selectors instances that creates aggregates.
boolean	isSimpleSelectorFactory() Checks if this factory creates Selectors that simply return a column value.
boolean	isSimpleSelectorFactoryFor(int index) Checks if this factory creates Selectors that simply return the specified column.
boolean	isTTLSelectorFactory() Checks if this factory creates TTL selectors instances.
boolean	isWritetimeSelectorFactory() Checks if this factory creates writetime selectors instances.
abstract Selector	newInstance(QueryOptions options) Creates a new Selector instance.

Methods inherited from class java.lang.Object

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

Constructor Detail

Factory

public Factory()

Method Detail

addFunctionsTo

public void addFunctionsTo(java.util.List<Function> functions)

getColumnSpecification

public ColumnSpecification getColumnSpecification(TableMetadata table)

Returns the column specification corresponding to the output value of the selector instances created by this factory.

Parameters:

table - the table meta data

Returns:

a column specification

newInstance

public abstract Selector newInstance(QueryOptions options)
                              throws InvalidRequestException

Creates a new Selector instance.

Parameters:

options - the options of the query for which the instance is created (some selector depends on the bound values in particular).

Returns:

a new Selector instance

Throws:

InvalidRequestException

isAggregateSelectorFactory

public boolean isAggregateSelectorFactory()

Checks if this factory creates selectors instances that creates aggregates.

Returns:

true if this factory creates selectors instances that creates aggregates, false otherwise

isWritetimeSelectorFactory

public boolean isWritetimeSelectorFactory()

Checks if this factory creates writetime selectors instances.

Returns:

true if this factory creates writetime selectors instances, false otherwise

isTTLSelectorFactory

public boolean isTTLSelectorFactory()

Checks if this factory creates TTL selectors instances.

Returns:

true if this factory creates TTL selectors instances, false otherwise

isSimpleSelectorFactory

public boolean isSimpleSelectorFactory()

Checks if this factory creates Selectors that simply return a column value.

Parameters:

index - the column index

Returns:

true if this factory creates Selectors that simply return a column value, false otherwise.

isSimpleSelectorFactoryFor

public boolean isSimpleSelectorFactoryFor(int index)

Checks if this factory creates Selectors that simply return the specified column.

Parameters:

index - the column index

Returns:

true if this factory creates Selectors that simply return the specified column, false otherwise.

getColumnName

protected abstract java.lang.String getColumnName()

Returns the name of the column corresponding to the output value of the selector instances created by this factory.

Returns:

a column name

getReturnType

protected abstract AbstractType<?> getReturnType()

Returns the type of the values returned by the selector instances created by this factory.

Returns:

the selector output type

addColumnMapping

protected abstract void addColumnMapping(SelectionColumnMapping mapping,
                                         ColumnSpecification resultsColumn)

Record a mapping between the ColumnDefinitions that are used by the selector instances created by this factory and a column in the ResultSet.Metadata returned with a query. In most cases, this is likely to be a 1:1 mapping, but some selector instances may utilise multiple columns (or none at all) to produce a value (i.e. functions).

Parameters:

mapping - the instance of the column mapping belonging to the current query's Selection

resultsColumn - the column in the ResultSet.Metadata to which the ColumnDefinitions used by the Selector are to be mapped