java.lang.Object
- uk.ac.starlink.table.AbstractStarTable
- - uk.ac.starlink.table.formats.StreamStarTable

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, StarTable

Direct Known Subclasses:

AsciiStarTable, CsvStarTable
```
public abstract class StreamStarTable
extends AbstractStarTable
```
Abstract superclass for tables which reads a stream of characters to obtain the row data and metadata. Since metadata is typically scarce in such tables, the strategy is to make one pass through the data attempting to work out column types etc at table initialisation time, and to make a further pass through for each required RowSequence, using the metadata obtained earlier.

Since:

21 Sep 2004

Author:

Mark Taylor (Starlink)

See Also:

RowEvaluator

Field Summary

Fields
Modifier and Type Field Description

protected static char END
Char representation of -1 (as returned end-of-stream read)

Constructor Summary

Constructors
Modifier Constructor Description

protected StreamStarTable()
Constructor.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`getColumnCount()`	Returns the number of columns in this table.
`ColumnInfo`	`getColumnInfo(int icol)`	Returns the object describing the data in a given column.
`protected java.io.PushbackInputStream`	`getInputStream()`	Convenience method which returns a buffered pushback stream based on this table's data source.
`long`	`getRowCount()`	Returns the number of rows in this table, if known.
`RowSequence`	`getRowSequence()`	Returns an object which can iterate over all the rows in the table sequentially.
`protected void`	`init(uk.ac.starlink.util.DataSource datsrc)`	Initialises the table from the input stream.
`protected abstract RowEvaluator.Metadata`	`obtainMetadata()`	Obtains column metadata for this table, probably by reading through the rows once and using a RowEvaluator.
`protected abstract java.util.List<java.lang.String>`	`readRow(java.io.PushbackInputStream in)`	Reads the next row of data from a given stream.

Methods inherited from class uk.ac.starlink.table.AbstractStarTable
checkedLongToInt, close, getCell, getColumnAuxDataInfos, getName, getParameters, getRow, getRowAccess, getRowSplittable, getURL, isRandom, setName, setParameters, setURL

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.StarTable
getParameterByName, setParameter

- Field Detail
  - END
```
protected static final char END
```
    Char representation of -1 (as returned end-of-stream read)
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - StreamStarTable
```
protected StreamStarTable()
```
    Constructor. This doesn't perform any processing; you must call init(uk.ac.starlink.util.DataSource) before doing anything with the constructed table. It is arranged this way so that the initialisation is able to call overridden methods in subclasses, which is a Bad thing to do from a constructor.
- Method Detail
  - init
```
protected void init(uk.ac.starlink.util.DataSource datsrc)
             throws TableFormatException,
                    java.io.IOException
```
    Initialises the table from the input stream. This method calls obtainMetadata(), which probably reads through some or all of the stream.
    
    Parameters:
    
    datsrc - data source from which the stream can be obtained
    
    Throws:
    
    TableFormatException
    
    java.io.IOException
  - getColumnCount
```
public int getColumnCount()
```
    Description copied from interface: StarTable
    
    Returns the number of columns in this table.
    
    Specified by:
    
    getColumnCount in interface StarTable
    
    Specified by:
    
    getColumnCount in class AbstractStarTable
    
    Returns:
    
    the number of columns
  - getRowCount
```
public long getRowCount()
```
    Description copied from interface: StarTable
    
    Returns the number of rows in this table, if known. If the number of rows cannot be (easily) determined, a value of -1 will be returned.
    
    Specified by:
    
    getRowCount in interface StarTable
    
    Specified by:
    
    getRowCount in class AbstractStarTable
    
    Returns:
    
    the number of rows, or -1
  - getColumnInfo
```
public ColumnInfo getColumnInfo(int icol)
```
    Description copied from interface: StarTable
    
    Returns the object describing the data in a given column.
    
    Specified by:
    
    getColumnInfo in interface StarTable
    
    Specified by:
    
    getColumnInfo in class AbstractStarTable
    
    Parameters:
    
    icol - the column for which header information is required
    
    Returns:
    
    a ValueInfo object for column icol
  - getRowSequence
```
public RowSequence getRowSequence()
                           throws java.io.IOException
```
    Description copied from interface: StarTable
    
    Returns an object which can iterate over all the rows in the table sequentially. Each such returned object is safe for use within a single thread, but not in general from multiple threads concurrently.
    
    Specified by:
    
    getRowSequence in interface StarTable
    
    Specified by:
    
    getRowSequence in class AbstractStarTable
    
    Returns:
    
    new RowSequence
    
    Throws:
    
    java.io.IOException - if there is an error providing access
  - getInputStream
```
protected java.io.PushbackInputStream getInputStream()
                                              throws java.io.IOException
```
    Convenience method which returns a buffered pushback stream based on this table's data source.
    
    Returns:
    
    input stream containing source data
    
    Throws:
    
    java.io.IOException
  - obtainMetadata
```
protected abstract RowEvaluator.Metadata obtainMetadata()
                                                 throws TableFormatException,
                                                        java.io.IOException
```
    Obtains column metadata for this table, probably by reading through the rows once and using a RowEvaluator.
    
    Returns:
    
    information about the table represented by the character stream
    
    Throws:
    
    TableFormatException - if the data doesn't represent this kind of table
    
    java.io.IOException - if I/O error is encountered
  - readRow
```
protected abstract java.util.List<java.lang.String> readRow(java.io.PushbackInputStream in)
                                                     throws TableFormatException,
                                                            java.io.IOException
```
    Reads the next row of data from a given stream. Ignorable rows are skipped; comments may be stashed away.
    
    Parameters:
    
    in - input stream
    
    Returns:
    
    list of Strings one for each cell in the row, or null for end of stream
    
    Throws:
    
    TableFormatException - if the data doesn't represent this kind of table
    
    java.io.IOException - if I/O error is encountered

Class StreamStarTable

Field Summary

Constructor Summary

Method Summary

Methods inherited from class uk.ac.starlink.table.AbstractStarTable

Methods inherited from class java.lang.Object

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

Field Detail

END

Constructor Detail

StreamStarTable

Method Detail

init

getColumnCount

getRowCount

getColumnInfo

getRowSequence

getInputStream

obtainMetadata

readRow