Package org.apache.druid.query.rowsandcols.concrete

Class FrameRowsAndColumns

java.lang.Object

org.apache.druid.query.rowsandcols.concrete.FrameRowsAndColumns

All Implemented Interfaces:

RowsAndColumns

public class FrameRowsAndColumns
extends Object
implements RowsAndColumns

Constructor Summary

Constructors

Constructor	Description
FrameRowsAndColumns(Frame frame, RowSignature signature)

Method Summary

Modifier and Type	Method	Description
<T> T	as(Class<T> clazz)	Asks the RowsAndColumns to return itself as a concrete implementation of a specific interface.
Column	findColumn(String name)	Finds a column by name.
Collection<String>	getColumnNames()	The set of column names available from the RowsAndColumns
int	numRows()	The number of rows in the RowsAndColumns object

Methods inherited from class java.lang.Object

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

Constructor Detail

FrameRowsAndColumns

public FrameRowsAndColumns(Frame frame,
                           RowSignature signature)

Method Detail

getColumnNames

public Collection<String> getColumnNames()

Description copied from interface: RowsAndColumns

The set of column names available from the RowsAndColumns

Specified by:

getColumnNames in interface RowsAndColumns

Returns:

The set of column names available from the RowsAndColumns

numRows

public int numRows()

Description copied from interface: RowsAndColumns

The number of rows in the RowsAndColumns object

Specified by:

numRows in interface RowsAndColumns

Returns:

the integer number of rows

findColumn

@Nullable
public Column findColumn(String name)

Description copied from interface: RowsAndColumns

Finds a column by name. null is returned if the column is not found. The RowsAndColumns object should not attempt to default not-found columns to pretend as if they exist, instead the user of the RowsAndColumns object should decide the correct semantic interpretation of a column that does not exist. It is expected that most locations will choose to believe that the column does exist and is always null, but there are often optimizations that can effect this same assumption without doing a lot of extra work if the calling code knows that it does not exist.

Specified by:

findColumn in interface RowsAndColumns

Parameters:

name - the name of the column to find

Returns:

the Column, if found. null if not found.

as

@Nullable
public <T> T as(Class<T> clazz)

Description copied from interface: RowsAndColumns

Asks the RowsAndColumns to return itself as a concrete implementation of a specific interface. The interface asked for will tend to be a semantically-meaningful interface. This method allows the calling code to interrogate the RowsAndColumns object about whether it can offer a meaningful optimization of the semantic interface. If a RowsAndColumns cannot do anything specifically optimal for the interface requested, it should return null instead of trying to come up with its own default implementation.

Specified by:

as in interface RowsAndColumns

Type Parameters:

T - The interface that the calling code wants a concrete implementation of

Parameters:

clazz - A class object representing the interface that the calling code wants a concrete implementation of

Returns:

A concrete implementation of the interface, or null if there is no meaningful optimization to be had through a local implementation of the interface.