/// <summary>
/// returns all offset of all records in table of first key column
/// </summary>
/// <typeparam name="T">type of key column</typeparam>
/// <returns></returns>
internal IEnumerable <int> Rows <T>(DbColumn column = null)
where T : IComparable <T>
{
if (column == null)
{
yield break;
}
var treeReader = column.IndexTree <T>();
if (treeReader.Root == null)
{
//itemspage has only one page, no tree root
var page = column.IndexItems <T>().Pages.FirstOrDefault();
if (page != null)
{
foreach (var cvsOfs in page.Items.SelectMany(i => i.Value))
{
yield return(cvsOfs);
}
}
}
else
{
//In-Order return all values
foreach (var offs in
treeReader.DumpTreeNodesInOrder(treeReader.Root)
.SelectMany(pair => pair.Value))
{
yield return(offs);
}
}
}
/// <summary>
/// Fast indexed column coomparison by a constant value
/// </summary>
/// <typeparam name="T">type of column</typeparam>
/// <param name="key">table key</param>
/// <param name="column">comlumn to compare</param>
/// <param name="comparer">comparison operator</param>
/// <param name="value">constant value</param>
/// <returns></returns>
internal IEnumerable <KeyValuePair <T, List <int> > > CompareIndexedKeyWithKey <T>(
DbColumn key, DbColumn column, TokenType comparer, T value)
where T : IComparable <T>
{
var nodeTree = column.IndexTree <T>();
int offset = -1;
var collection = Enumerable.Empty <KeyValuePair <T, List <int> > >();
if (nodeTree.Root == null)
{
//go to .bin file directly, it's ONE page of items
collection = column.IndexItems <T>()
.FindByOper(DbGenerator.ItemsPageStart, value, comparer);
}
else
{
//this's for tree node page structure
switch (comparer)
{
case TokenType.Equal: // "="
//find page with key
var baseNode = nodeTree.FindKey(value) as PageIndexNodeBase <T>;
if (baseNode != null)
{
switch (baseNode.Type)
{
case MetaIndexType.Node:
//it's in a tree node page
var nodePage = baseNode as PageIndexNode <T>;
if (nodePage != null && nodePage.Values != null)
{
collection = new KeyValuePair <T, List <int> >[] {
new KeyValuePair <T, List <int> >(value, nodePage.Values)
};
}
break;
case MetaIndexType.Items:
//it's in a items page
offset = ((PageIndexItems <T>)baseNode).Offset;
DbKeyValues <T> item = column.IndexItems <T>().Find(offset, value);
if (item != null && item.Values != null)
{
collection = new KeyValuePair <T, List <int> >[] {
new KeyValuePair <T, List <int> >(value, item.Values)
};
}
break;
}
}
break;
case TokenType.Less: // "<"
collection = nodeTree.FindLessKey(value, TokenType.Less);
break;
case TokenType.LessOrEqual: // "<="
collection = nodeTree.FindLessKey(value, TokenType.LessOrEqual);
break;
case TokenType.Greater: // ">"
collection = nodeTree.FindGreaterKey(value, TokenType.Greater);
break;
case TokenType.GreaterOrEqual: //">="
collection = nodeTree.FindGreaterKey(value, TokenType.GreaterOrEqual);
break;
//throw new ArgumentException($"Operator: {Expression.Operator.Name} not implemented yet!");
}
}
foreach (var ofs in collection)
{
yield return(ofs);
}
}
