/// <summary>
/// Initializes a new instance of the <see cref="T:LexicographicalOrd`2"/> class.
/// </summary>
/// <param name="itemOrder">The order relation defined on the items of the list, must be effective.</param>
/// <exception cref="ArgumentNullException">If the given <paramref name="itemOrder"/> is not effective.</exception>
public LexicographicalOrd(IOrd <TA, TB> itemOrder)
{
if (itemOrder == null)
{
throw new ArgumentNullException("itemOrder");
}
Contract.EndContractBlock();
this.itemOrder = itemOrder;
}
/// <summary>
/// Compares the two effective items.
/// </summary>
/// <returns>The result of the comparsion of the two effective items.</returns>
/// <param name="a">The first item to compare.</param>
/// <param name="b">The second item to compare.</param>
protected override Ordering CompareEffective(IEnumerable <TA> a, IEnumerable <TB> b)
{
IEnumerator <TA> ea = a.GetEnumerator();
IEnumerator <TB> eb = b.GetEnumerator();
TA ca;
TB cb;
bool ma, mb;
Ordering res;
IOrd <TA, TB> itemOrder = this.itemOrder;
if (ea == null || eb == null)
{
return(Ordering.Unknown);
}
else
{
ma = ea.MoveNext();
mb = eb.MoveNext();
while (ma && mb)
{
ca = ea.Current;
cb = eb.Current;
res = itemOrder.Compare(ca, cb);
if ((res & Ordering.EQ) != 0x00)
{
return(res);
}
ma = ea.MoveNext();
mb = eb.MoveNext();
}
if (ma)
{
return(Ordering.GT);
}
else if (mb)
{
return(Ordering.LT);
}
return(Ordering.EQ);
}
}
