com.mckoi.database
Class DataTableFilter

java.lang.Object
  extended by com.mckoi.database.Table
      extended by com.mckoi.database.AbstractDataTable
          extended by 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