uk.ac.starlink.feather

Class StarColumnWriter

java.lang.Object

uk.ac.starlink.feather.StarColumnWriter

All Implemented Interfaces:

uk.ac.bristol.star.feather.FeatherColumnWriter

Direct Known Subclasses:

BooleanStarColumnWriter, NumberStarColumnWriter, VariableStarColumnWriter

public abstract class StarColumnWriter
extends Object
implements uk.ac.bristol.star.feather.FeatherColumnWriter

FeatherColumnWriter for use with StarTables.

Since:

26 Feb 2020

Author:

Mark Taylor

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	StarColumnWriter.DataStat Aggregates information about column output.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	StarColumnWriter(StarTable table, int icol, uk.ac.bristol.star.feather.FeatherType featherType, boolean isNullable) Constructor.

Method Summary

Modifier and Type	Method and Description
abstract ItemAccumulator	createItemAccumulator(StoragePolicy storage)
int	getColumnIndex() Returns the index of the input table column which is being written.
uk.ac.bristol.star.feather.FeatherType	getFeatherType() Returns the output data type code.
String	getName()
StarTable	getTable() Returns the table on which this writer is operating.
String	getUserMetadata()
boolean	isNullable() Indicates whether this writer may write a validity mask.
uk.ac.bristol.star.feather.ColStat	writeColumnBytes(OutputStream out)
abstract StarColumnWriter.DataStat	writeDataBytes(OutputStream out) Writes the bytes consituting the data stream for this column, excluding any optional validity mask.

Methods inherited from class java.lang.Object

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

Constructor Detail

StarColumnWriter

protected StarColumnWriter(StarTable table,
                           int icol,
                           uk.ac.bristol.star.feather.FeatherType featherType,
                           boolean isNullable)

Constructor. The isNullable parameter only needs to be given true if the writeData method cannot represent null values in its byte representation.

Parameters:

table - inupt table

icol - column index in input table

featherType - data type for output column

isNullable - true iff writeData cannot write in-band null values

Method Detail

writeDataBytes

public abstract StarColumnWriter.DataStat writeDataBytes(OutputStream out)
                                                  throws IOException

Writes the bytes consituting the data stream for this column, excluding any optional validity mask. Note the output does not need to be aligned on an 8-byte boundary.

Parameters:

out - destination stream

Returns:

information about what was actually written

Throws:

IOException

getTable

public StarTable getTable()

Returns the table on which this writer is operating.

Returns:

input table

getColumnIndex

public int getColumnIndex()

Returns the index of the input table column which is being written.

Returns:

input column index

getFeatherType

public uk.ac.bristol.star.feather.FeatherType getFeatherType()

Returns the output data type code.

Specified by:

getFeatherType in interface uk.ac.bristol.star.feather.FeatherColumnWriter

Returns:

feather output type

isNullable

public boolean isNullable()

Indicates whether this writer may write a validity mask.

Returns:

true iff output type supports masked null values

getName

public String getName()

Specified by:

getName in interface uk.ac.bristol.star.feather.FeatherColumnWriter

getUserMetadata

public String getUserMetadata()

Specified by:

getUserMetadata in interface uk.ac.bristol.star.feather.FeatherColumnWriter

writeColumnBytes

public uk.ac.bristol.star.feather.ColStat writeColumnBytes(OutputStream out)
                                                    throws IOException

Specified by:

writeColumnBytes in interface uk.ac.bristol.star.feather.FeatherColumnWriter

Throws:

IOException

createItemAccumulator

public abstract ItemAccumulator createItemAccumulator(StoragePolicy storage)