com.mckoi.database
Class DataTableFilter

java.lang.Object
  com.mckoi.database.Table
      com.mckoi.database.AbstractDataTable
          com.mckoi.database.DataTableFilter

All Implemented Interfaces:

RootTable, TableDataSource

public class DataTableFilter
extends AbstractDataTable

This object sits on top of a DataTable object filtering out certain types of calls. We could use this object to implement a ReferenceTable which can be used to declare a new table name with a DataTable type. We also use this object to implement a filter for column removals.

Author:

Tobias Downer

Field Summary

protected AbstractDataTable

parent The parent DataTable object.

Fields inherited from class com.mckoi.database.Table

DEBUG_QUERY

Constructor Summary

protected

DataTableFilter(AbstractDataTable table) The Constructor.

Method Summary

int	findFieldName(Variable v) Given a fully qualified variable field name, ie.
TObject	getCellContents(int column, int row) Returns an object that represents the information in the given cell in the table.
int	getColumnCount() Returns the number of columns in the table.
Database	getDatabase() Returns the Database context for this filtered table.
DataTableDef	getDataTableDef() Returns a DataTableDef object that defines the name of the table and the layout of the columns of the table.
Variable	getResolvedVariable(int column) Returns a fully qualified Variable object that represents the name of the column at the given index.
int	getRowCount() Returns the number of rows stored in the table.
boolean	hasRootsLocked() Returns true if the table has its row roots locked (via the lockRoot(int) method.
void	lockRoot(int lock_key) Locks the root table(s) of this table so that it is impossible to overwrite the underlying rows that may appear in this table.
RowEnumeration	rowEnumeration() Returns an Enumeration of the rows in this table.
void	unlockRoot(int lock_key) Unlocks the root tables so that the underlying rows may once again be used if they are not locked and have been removed.

Methods inherited from class com.mckoi.database.AbstractDataTable

getTableName, toString, typeEquals

Methods inherited from class com.mckoi.database.Table

all, allColumnMatchesValue, any, columnContainsCell, columnContainsValue, columnMatchesValue, columnMerge, compareCells, Debug, distinct, distinct, dumpTo, emptySelect, exhaustiveSelect, fastFindFieldName, getColumnDefAt, getColumnScheme, getFirstCellContent, getFirstCellContent, getLastCellContent, getLastCellContent, getSingleCellContent, getSingleCellContent, getSystem, getTableAccessState, getTTypeForColumn, getTTypeForColumn, join, orderByColumn, orderByColumn, orderByColumn, orderByColumns, orderedRowList, outside, printGraph, rangeSelect, selectAll, selectAll, selectFirst, selectLast, selectRange, selectRest, simpleJoin, simpleSelect, singleRowSelect, toMap, union

Methods inherited from class java.lang.Object

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

Field Detail

parent

protected AbstractDataTable parent

The parent DataTable object.

Constructor Detail

DataTableFilter

protected DataTableFilter(AbstractDataTable table)

The Constructor. A filter can only sit on top of a DataTable or DataTableFilter table. ISSUE: we could make an interface for this. This is a bit of a hack.

Method Detail

getDatabase

public Database getDatabase()

Returns the Database context for this filtered table.

Specified by:

getDatabase in class Table

getColumnCount

public int getColumnCount()

Returns the number of columns in the table.

Specified by:

getColumnCount in class Table

getRowCount

public final int getRowCount()

Returns the number of rows stored in the table.

Specified by:

getRowCount in interface TableDataSource

Specified by:

getRowCount in class Table

findFieldName

public int findFieldName(Variable v)

Given a fully qualified variable field name, ie. 'APP.CUSTOMER.CUSTOMERID' this will return the column number the field is at. Returns -1 if the field does not exist in the table.

Specified by:

findFieldName in class Table

getResolvedVariable

public Variable getResolvedVariable(int column)

Returns a fully qualified Variable object that represents the name of the column at the given index. For example, new Variable(new TableName("APP", "CUSTOMER"), "ID")

Specified by:

getResolvedVariable in class Table

getCellContents

public final TObject getCellContents(int column,
                                     int row)

Returns an object that represents the information in the given cell in the table. This will generally be an expensive algorithm, so calls to it should be kept to a minimum. Note that the offset between two rows is not necessarily 1.

Specified by:

getCellContents in interface TableDataSource

Specified by:

getCellContents in class Table

rowEnumeration

public final RowEnumeration rowEnumeration()

Returns an Enumeration of the rows in this table. The Enumeration is a fast way of retrieving consequtive rows in the table.

Specified by:

rowEnumeration in interface TableDataSource

Specified by:

rowEnumeration in class Table

getDataTableDef

public DataTableDef getDataTableDef()

Returns a DataTableDef object that defines the name of the table and the layout of the columns of the table. Note that for tables that are joined with other tables, the table name and schema for this object become mangled. For example, a table called 'PERSON' joined with a table called 'MUSIC' becomes a table called 'PERSON#MUSIC' in a null schema.

Specified by:

getDataTableDef in interface TableDataSource

Specified by:

getDataTableDef in class Table

lockRoot

public void lockRoot(int lock_key)

Locks the root table(s) of this table so that it is impossible to overwrite the underlying rows that may appear in this table. This is used when cells in the table need to be accessed 'outside' the lock. So we may have late access to cells in the table. 'lock_key' is a given key that will also unlock the root table(s). NOTE: This is nothing to do with the 'LockingMechanism' object.

Specified by:

lockRoot in class Table

unlockRoot

public void unlockRoot(int lock_key)

Unlocks the root tables so that the underlying rows may once again be used if they are not locked and have been removed. This should be called some time after the rows have been locked.

Specified by:

unlockRoot in class Table

hasRootsLocked

public boolean hasRootsLocked()

Returns true if the table has its row roots locked (via the lockRoot(int) method.

Specified by:

hasRootsLocked in class Table