/// <summary>
/// Reorders a series of runs from logical to visual order, returning the left most run.
/// <see href="https://github.com/fribidi/linear-reorder/blob/f2f872257d4d8b8e137fcf831f254d6d4db79d3c/linear-reorder.c"/>
/// </summary>
/// <param name="run">The ordered bidi run.</param>
/// <returns>The <see cref="OrderedBidiRun"/>.</returns>
private static OrderedBidiRun LinearReOrder(OrderedBidiRun?run)
{
BidiRange?range = null;
while (run != null)
{
var next = run.Next;
while (range != null && range.Level > run.Level &&
range.Previous != null && range.Previous.Level >= run.Level)
{
range = BidiRange.MergeWithPrevious(range);
}
if (range != null && range.Level >= run.Level)
{
// Attach run to the range.
if ((run.Level & 1) != 0)
{
// Odd, range goes to the right of run.
run.Next = range.Left;
range.Left = run;
}
else
{
// Even, range goes to the left of run.
range.Right !.Next = run;
range.Right = run;
}
range.Level = run.Level;
}
else
{
var r = new BidiRange();
r.Left = r.Right = run;
r.Level = run.Level;
r.Previous = range;
range = r;
}
run = next;
}
while (range?.Previous != null)
{
range = BidiRange.MergeWithPrevious(range);
}
// Terminate.
range !.Right !.Next = null;
return(range.Left !);
}
public static BidiRange MergeWithPrevious(BidiRange range)
{
var previous = range.Previous;
BidiRange left;
BidiRange right;
if ((previous !.Level & 1) != 0)
{
// Odd, previous goes to the right of range.
left = range;
right = previous;
}