uk.ac.starlink.table.formats

Class AbstractTextTableWriter

java.lang.Object

uk.ac.starlink.table.formats.DocumentedStreamStarTableWriter

uk.ac.starlink.table.formats.AbstractTextTableWriter

All Implemented Interfaces:

Documented, DocumentedIOHandler, StarTableWriter

Direct Known Subclasses:

AsciiTableWriter, IpacTableWriter, TextTableWriter

public abstract class AbstractTextTableWriter
extends DocumentedStreamStarTableWriter

A StarTableWriter which outputs text to a human-readable text file. Table parameters (per-table metadata) can optionally be output as well as the table data themselves.

Author:

Mark Taylor (Starlink)

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractTextTableWriter(String[] extensions, boolean writeParams) Constructor.

Method Summary

Modifier and Type	Method and Description
protected abstract String	formatValue(Object val, ValueInfo vinfo, int width) Formats a data value for output.
protected byte[]	getBytes(String str) Returns a byte array corresponding to a given string.
String	getFormatName() Returns "text";
int	getMaximumParameterLength() Returns the maximum length for the value of a parameter as passed to printParam(java.io.OutputStream, java.lang.String, java.lang.String, java.lang.Class<?>).
int	getMaxWidth() Returns the maximum width for any output column.
String	getMimeType() Returns a string suitable for use as the value of a MIME Content-Type header.
int	getMinNameWidth(ColumnInfo info) Returns the minimum width required to output the actual characters of the name for a given column.
int	getSampledRows() Returns the number of rows which will be sampled to work out the column width.
boolean	getWriteParameters() Finds out whether the output will include table parameters.
protected abstract void	printColumnHeads(OutputStream strm, int[] colwidths, ColumnInfo[] cinfos) Outputs headings for the table columns.
protected abstract void	printLine(OutputStream strm, int[] colwidths, String[] data) Outputs a line of table data.
protected abstract void	printParam(OutputStream strm, String name, String value, Class<?> clazz) Outputs a parameter and its value.
protected abstract void	printSeparator(OutputStream strm, int[] colwidths) Outputs a decorative separator line, of the sort you might find between the column headings and the table data.
void	setMaximumParameterLength(int maxParamLength) Sets the maximum length for the value of a parameter that will be output.
void	setMaxWidth(int maxWidth) Sets the maximum width in characters for any output column.
void	setSampledRows(int sampledRows) Sets the number of rows which will be sampled before output is commenced to work out the column widths.
void	setWriteParameters(boolean writeParams) Set whether the output should include table parameters.
void	writeStarTable(StarTable startab, OutputStream strm) Writes a StarTable object to a given output stream.

Methods inherited from class uk.ac.starlink.table.formats.DocumentedStreamStarTableWriter

getExtensions, looksLikeFile, writeStarTable

Methods inherited from class java.lang.Object

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

Methods inherited from interface uk.ac.starlink.table.formats.DocumentedIOHandler

docIncludesExample, matchesExtension, readText, toLink

Methods inherited from interface uk.ac.starlink.table.Documented

getXmlDescription

Constructor Detail

AbstractTextTableWriter

protected AbstractTextTableWriter(String[] extensions,
                                  boolean writeParams)

Constructor.

Parameters:

extensions - list of lower-cased filename extensions, excluding the '.' character

writeParams - whether parameters will be written by default

Method Detail

getFormatName

public String getFormatName()

Returns "text";

Returns:

"text"

getMimeType

public String getMimeType()

Description copied from interface: StarTableWriter

Returns a string suitable for use as the value of a MIME Content-Type header. If no suitable MIME type is available or known, one of "application/octet-stream" (for binary formats) or "text/plain" for ASCII ones) is recommended.

Returns:

MIME content type

writeStarTable

public void writeStarTable(StarTable startab,
                           OutputStream strm)
                    throws IOException

Description copied from interface: StarTableWriter

Writes a StarTable object to a given output stream. The implementation can assume that out is suitable for direct writing (for instance it should not normally wrap it in a BufferedOutputStream), and should not close it at the end of the call.

Not all table writers are capable of writing to a stream; an implementation may throw a TableFormatException to indicate that it cannot do so.

Parameters:

startab - the table to write

strm - the output stream to which startab should be written

Throws:

TableFormatException - if this table cannot be written to a stream

IOException - if there is some I/O error

setMaximumParameterLength

@ConfigMethod(property="maxParam",
              doc="<p>Maximum width in characters of an output table parameter. Parameters with values longer than this will be truncated.</p>")
public void setMaximumParameterLength(int maxParamLength)

Sets the maximum length for the value of a parameter that will be output.

Parameters:

maxParamLength - maximum printable parameter length

getMaximumParameterLength

public int getMaximumParameterLength()

Returns the maximum length for the value of a parameter as passed to printParam(java.io.OutputStream, java.lang.String, java.lang.String, java.lang.Class<?>). The default implementation currently returns 160.

Returns:

maximum length for output string parameters

setWriteParameters

@ConfigMethod(property="params",
              doc="<p>Whether to output table parameters as well as row data.</p>")
public void setWriteParameters(boolean writeParams)

Set whether the output should include table parameters. If so they are written as name:value pairs one per line before the start of the table proper.

Parameters:

writeParams - true iff you want table parameters to be output as well as the table data

getWriteParameters

public boolean getWriteParameters()

Finds out whether the output will include table parameters.

Returns:

true iff the table parameters will be output as well as the table data

setMaxWidth

@ConfigMethod(property="maxCell",
              doc="<p>Maximum width in characters of an output table cell. Cells longer than this will be truncated.</p>")
public void setMaxWidth(int maxWidth)

Sets the maximum width in characters for any output column. Values longer than this may be truncated.

Parameters:

maxWidth - maximum column value width in characters

getMaxWidth

public int getMaxWidth()

Returns the maximum width for any output column. Values longer than this may be truncated.

Returns:

maximum permitted column width in characters

getMinNameWidth

public int getMinNameWidth(ColumnInfo info)

Returns the minimum width required to output the actual characters of the name for a given column. Padding applied subsequently by this object's printColumnHeads(java.io.OutputStream, int[], uk.ac.starlink.table.ColumnInfo[]) method does not need to be included.

Parameters:

info - column metadata

Returns:

minimum number of characters required for column title

setSampledRows

@ConfigMethod(property="sampledRows",
              doc="<p>The number of rows examined on a first pass of the table to determine the width of each column. Only a representative number of rows needs to be examined, but if a formatted cell value after this limit is wider than the cells up to it, then such later wide cells may get truncated. If the value is &lt;=0, all rows are examined in the first pass; this is the default, but it can be configured to some other value if that takes too long.</p>")
public void setSampledRows(int sampledRows)

Sets the number of rows which will be sampled before output is commenced to work out the column widths.

Parameters:

sampledRows - number of rows to be sampled

getSampledRows

public int getSampledRows()

Returns the number of rows which will be sampled to work out the column width.

Returns:

number of rows scanned

formatValue

protected abstract String formatValue(Object val,
                                      ValueInfo vinfo,
                                      int width)

Formats a data value for output.

Parameters:

val - the value

vinfo - the metadata object describing val's type

width - maximum preferred width into which the value should be formatted

Returns:

formatted string meaning value, preferably no longer than width characters

printSeparator

protected abstract void printSeparator(OutputStream strm,
                                       int[] colwidths)
                                throws IOException

Outputs a decorative separator line, of the sort you might find between the column headings and the table data.

Parameters:

strm - stream to write into

colwidths - column widths in characters

Throws:

IOException

printColumnHeads

protected abstract void printColumnHeads(OutputStream strm,
                                         int[] colwidths,
                                         ColumnInfo[] cinfos)
                                  throws IOException

Outputs headings for the table columns.

Parameters:

strm - stream to write into

colwidths - column widths in characters

cinfos - array of column headings

Throws:

IOException

printLine

protected abstract void printLine(OutputStream strm,
                                  int[] colwidths,
                                  String[] data)
                           throws IOException

Outputs a line of table data.

Parameters:

strm - stream to write into

colwidths - column widths in characters

data - array of strings to be output, one per column

Throws:

IOException

printParam

protected abstract void printParam(OutputStream strm,
                                   String name,
                                   String value,
                                   Class<?> clazz)
                            throws IOException

Outputs a parameter and its value.

Parameters:

strm - stream to write into

name - parameter name

value - formatted parameter value

clazz - type of value

Throws:

IOException

getBytes

protected byte[] getBytes(String str)

Returns a byte array corresponding to a given string.

Parameters:

str - string to decode