uk.ac.starlink.ttools.jel

Class ColumnIdentifier

java.lang.Object

uk.ac.starlink.ttools.jel.ColumnIdentifier

public class ColumnIdentifier
extends Object

Can identify columns of a table using string identifiers. Permitted identifiers are (currently) column name (case insensitive), column index (1-based), ucd$* / utype$* style UCD/Utype specifiers (see JELRowReader) and where requested cases simple wildcarding expressions.

Since:

2 Mar 2005

Author:

Mark Taylor (Starlink)

Constructor Summary

Constructors

Constructor and Description
ColumnIdentifier(StarTable table) Constructor.

Method Summary

Modifier and Type	Method and Description
boolean[]	getColumnFlags(String colIdList) Returns an array of flags, the same length as the number of columns in the table, with an element set true for each column which is specified in colIdList.
int	getColumnIndex(String colid) Returns the index of a column given an identifying string.
int[]	getColumnIndices(String colidList) Returns an array of column indices from a <colid-list> string.
static Pattern	globToRegex(String glob, boolean caseSensitive) Turns a glob-type pattern into a regular expression Pattern.
boolean	isCaseSensitive() Determines whether case is significant in column names.
void	setCaseSensitive(boolean caseSensitive) Sets whether case is significant in column names.

Methods inherited from class java.lang.Object

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

Constructor Detail

ColumnIdentifier

public ColumnIdentifier(StarTable table)

Constructor.

Parameters:

table - table whose columns this identifier can identify

Method Detail

setCaseSensitive

public void setCaseSensitive(boolean caseSensitive)

Sets whether case is significant in column names. By default it is not.

Parameters:

caseSensitive - is matching case sensitive?

isCaseSensitive

public boolean isCaseSensitive()

Determines whether case is significant in column names. By default it is not.

Returns:

true iff matching is case sensitive

getColumnIndex

public int getColumnIndex(String colid)
                   throws IOException

Returns the index of a column given an identifying string. If the string can't be identified as a column of this object's table, an IOException is thrown.

Parameters:

colid - identifying string

Returns:

column index

Throws:

IOException - if colid does not name a column

getColumnIndices

public int[] getColumnIndices(String colidList)
                       throws IOException

Returns an array of column indices from a <colid-list> string. The string is split up into whitespace-separated tokens, each of which must be one of:

• identifier for an individual column
• glob-like pattern containing "*", matching zero or more columns
• column range of the form <col1>-<colN> (inclusive)

and each element must either be the identifier of an individual column or a non-trivial glob-like pattern which may match zero or more columns, or a column range.

Parameters:

colidList - string containing a representation of a list of columns

Returns:

array of column indices

Throws:

IOException - if colid doesn't look like a colid-list specifier

getColumnFlags

public boolean[] getColumnFlags(String colIdList)
                         throws IOException

Returns an array of flags, the same length as the number of columns in the table, with an element set true for each column which is specified in colIdList. This convenience function just works on the result of getColumnIndices(java.lang.String).

Parameters:

colIdList - string containing a representation of a list of columns

Returns:

array of column inclusion flags

Throws:

IOException - if colid doesn't look like a colid-list specifier

globToRegex

public static Pattern globToRegex(String glob,
                                  boolean caseSensitive)

Turns a glob-type pattern into a regular expression Pattern. Currently the only construction recognised is a "*" at one or more places in the string, which will match any sequence of characters. Note: If glob contains no wildcards, null will be returned.

Parameters:

glob - glob pattern

caseSensitive - whether matching should be case sensitive

Returns:

equivalent regular expression pattern, or null if glob is trivial