/// <summary>Transform Delete-Insert case.</summary>
/// <param name="o1">An operation to be transformed.</param>
/// <param name="o2">Operation with respect to which perform the transformation.</param>
/// <returns>Transformed operation.</returns>
private static IOperation TransformDeleteInsert(IOperation o1, IOperation o2)
{
if (o1.Index < o2.Index)
{
// Tdi(Del[3], Ins[4, "b"]) -> Del[3]
return(o1);
}
// Tdi(Del[3], Ins[1, "b"]) -> Del[4]
return(OperationFactory.CreateOperation(o1.ClientId, o1.OperationType, o1.Index + 1, o1.Value, o1.Timestamp));
}
/// <summary>Transform Insert-Delete case.</summary>
/// <param name="o1">An operation to be transformed.</param>
/// <param name="o2">Operation with respect to which perform the transformation.</param>
/// <returns>Transformed operation.</returns>
private static IOperation TransformInsertDelete(IOperation o1, IOperation o2)
{
if (o1.Index <= o2.Index)
{
// Tid(Ins[3, "a"], Del[4]) -> Ins[3, "a"]
return(o1);
}
// Tid(Ins[3, "a"], Del[1]) -> Ins[2, "a"]
return(OperationFactory.CreateOperation(o1.ClientId, o1.OperationType, o1.Index - 1, o1.Value, o1.Timestamp));
}
/// <summary>Transform Insert-Insert case.</summary>
/// <param name="o1">An operation to be transformed.</param>
/// <param name="o2">Operation with respect to which perform the transformation.</param>
/// <returns>Transformed operation.</returns>
private static IOperation TransformInsertInsert(IOperation o1, IOperation o2)
{
// Original OT algorithm considers Timstamp to determine which operation has higher priority.
// Here the value comparison is used to support sorted data set.
if (o1.Index < o2.Index || (o1.Index == o2.Index && o1.Value.Value <= o2.Value.Value))
{
// Tii(Ins[3, "a"], Ins[4, "b"]) -> Ins[3, "a"]
return(o1);
}
// Tii(Ins[3, "a"], Ins[1, "b"]) -> Ins[4, "a"]
return(OperationFactory.CreateOperation(o1.ClientId, o1.OperationType, o1.Index + 1, o1.Value, o1.Timestamp));
}
/// <summary>Transform Delete-Delete case.</summary>
/// <param name="o1">An operation to be transformed.</param>
/// <param name="o2">Operation with respect to which perform the transformation.</param>
/// <returns>Transformed operation. NULL if operations are identical and operation execution is not needed.</returns>
private static IOperation TransformDeleteDelete(IOperation o1, IOperation o2)
{
if (o1.Index < o2.Index)
{
// Tdd(Del[3], Del[4]) -> Del[3]
return(o1);
}
if (o1.Index > o2.Index)
{
// Tdd(Del[3], Del[1]) -> Del[2]
return(OperationFactory.CreateOperation(o1.ClientId, o1.OperationType, o1.Index - 1, o1.Value, o1.Timestamp));
}
// breaking deletion (identity operation), meaning operations are equivalent Tdd(Del[3], Del[3]) -> I
return(null);
}