protected override void InternalFindNearest(IRow row)
{
IRow localRow = EnsurePartialKeyRow(row);
try
{
if (localRow != null)
{
BrowseTableItem item = GetTable(localRow, true, true);
_tables.Add(item);
EnterTableContext(item);
try
{
TopTable.MoveCrack();
}
finally
{
ExitTableContext(item);
}
}
else
{
_tables.Add(GetTable());
}
}
finally
{
if ((localRow != null) && !Object.ReferenceEquals(row, localRow))
{
localRow.Dispose();
}
}
}
// Must be called with the original stack
protected BrowseTableItem GetTable(IRow origin, bool forward, bool inclusive)
{
BrowseTableItem result = FindTable(origin, forward, inclusive);
if (result == null)
{
result = CreateTable(origin, forward, inclusive);
}
return(result);
}
protected override bool InternalFindKey(IRow row, bool forward)
{
IRow localRow = EnsureKeyRow(row);
try
{
bool tableCreated = false;
BrowseTableItem table = FindTable(localRow, forward, true);
if (table == null)
{
table = CreateTable(localRow, forward, true);
tableCreated = true;
}
try
{
EnterTableContext(table);
try
{
table.MoveCrack();
bool result = (table.UniqueKey != null) && (CompareKeys(localRow, table.UniqueKey) == 0);
if (result)
{
_tables.Add(table);
}
else
if (tableCreated)
{
table.Dispose();
}
return(result);
}
finally
{
ExitTableContext(table);
}
}
catch
{
if (tableCreated)
{
table.Dispose();
}
throw;
}
}
finally
{
if (!Object.ReferenceEquals(row, localRow))
{
localRow.Dispose();
}
}
}
// Must be called with the original stack
protected void SwapReader(IRow origin, bool forward, bool inclusive)
{
BrowseTableItem item = GetTable(origin, forward, inclusive);
_tables.Add(item);
EnterTableContext(TopTable);
try
{
TopTable.MoveCrack();
}
finally
{
ExitTableContext(TopTable);
}
}
protected void ExitTableContext(BrowseTableItem tableItem)
{
Program.Stack.Pop();
}
/*
* for each column in the order descending
* if the current order column is also in the origin
* [or]
* for each column in the origin less than the current order column
* [and] current origin column = current origin value
*
* [and]
* if the current order column is ascending xor the requested set is forward
* if the current order column includes nulls
* current order column is null or
* if requested set is inclusive and current order column is the last origin column
* current order column <= current origin value
* else
* current order column < current origin value
* else
* if requested set is inclusive and the current order column is the last origin column
* current order column >= current origin value
* else
* current order column > current origin value
*
* for each column in the order greater than the current order column
* if the current order column does not include nulls
* and current order column is not null
* else
* if the current order column does not include nulls
* [and] current order column is not null
*/
protected void EnterTableContext(BrowseTableItem tableItem)
{
Program.Stack.Push(tableItem.ContextVar);
}
protected override void InternalFirst()
{
BrowseTableItem item = GetTable(null, true, true);
_tables.Add(item);
}
