/// <summary>
/// Verify that the results are ordered accoring to the specified ordering.
/// </summary>
/// <param name="ordering">The ordering to verify by.</param>
/// <param name="elements">The elements on which to verify the ordering.</param>
/// <returns>A value indicating whether the collection is properly sorted.</returns>
public static bool IsOrdered(QueryOrdering ordering, IEnumerable <object> elements)
{
ExceptionUtilities.CheckArgumentNotNull(ordering, "ordering");
QueryScalarValue[][] sortedSelectorsTable = BuildSortedSelectorsTable(ordering, elements);
int totalRows = sortedSelectorsTable.GetLength(0);
for (int row = 0; row < totalRows - 1; row++)
{
if (!RowsAreOrdered(sortedSelectorsTable[row], sortedSelectorsTable[row + 1], ordering))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Builds a table of sorted orderby primitive values, where the rows by the size of result set, the columns by the number of orderby key selectors.
/// </summary>
/// <param name="ordering">query ordering of order by key selectors</param>
/// <param name="elements">Elements used to get the table values.</param>
/// <returns>the table of sorted orderby/thenby scalar values. </returns>
private static QueryScalarValue[][] BuildSortedSelectorsTable(QueryOrdering ordering, IEnumerable <object> elements)
{
int orderingSelectorsCount = ordering.Selectors.Count();
int selectorRowCount = elements.Count();
var orderingSelectorsTable = new QueryScalarValue[selectorRowCount][];
for (int i = 0; i < selectorRowCount; i++)
{
orderingSelectorsTable[i] = new QueryScalarValue[orderingSelectorsCount];
}
for (int row = 0; row < selectorRowCount; row++)
{
var currentRow = elements.ElementAt(row);
for (int col = 0; col < orderingSelectorsCount; col++)
{
var selector = ordering.Selectors.ElementAt(col);
orderingSelectorsTable[row][col] = selector(currentRow);
}
}
return(orderingSelectorsTable);
}
private static bool RowsAreOrdered(QueryScalarValue[] selectorsRow1, QueryScalarValue[] selectorsRow2, QueryOrdering ordering)
{
var verifyNextColumn = true;
var col = 0;
while (verifyNextColumn && col < selectorsRow1.Length)
{
verifyNextColumn = false;
var isDecending = ordering.AreDescending.ElementAt(col);
var compareResult = QueryScalarValue.Comparer.Compare(selectorsRow1[col], selectorsRow2[col]);
if (compareResult == 0)
{
verifyNextColumn = true;
}
if (isDecending)
{
if (compareResult < 0)
{
return(false);
}
}
else
{
if (compareResult > 0)
{
return(false);
}
}
col++;
}
return(true);
}
