public IVarTuple this[int?fromIncluded, int?toExcluded]
{
get
{
int begin = fromIncluded.HasValue ? TupleHelpers.MapIndexBounded(fromIncluded.Value, m_count) : 0;
int end = toExcluded.HasValue ? TupleHelpers.MapIndexBounded(toExcluded.Value, m_count) : m_count;
if (end <= begin)
{
return(STuple.Empty);
}
int p = this.Head.Count;
if (begin >= p)
{ // all selected items are in the tail
return(this.Tail[begin - p, end - p]);
}
if (end <= p)
{ // all selected items are in the head
return(this.Head[begin, end]);
}
// selected items are both in head and tail
return(new JoinedTuple(this.Head[begin, null], this.Tail[null, end - p]));
}
}
public IVarTuple this[int?fromIncluded, int?toExcluded]
{
get
{
int begin = fromIncluded.HasValue ? TupleHelpers.MapIndexBounded(fromIncluded.Value, m_count) : 0;
int end = toExcluded.HasValue ? TupleHelpers.MapIndexBounded(toExcluded.Value, m_count) : m_count;
int len = end - begin;
if (len <= 0)
{
return(STuple.Empty);
}
if (begin == 0 && len == m_count)
{
return(this);
}
Contract.Assert(m_offset + begin >= m_offset);
Contract.Assert(len >= 0 && len <= m_count);
return(new ListTuple(m_items, m_offset + begin, len));
}
}
public IVarTuple this[int?fromIncluded, int?toExcluded]
{
get
{
int count = m_items.Length;
int begin = fromIncluded.HasValue ? TupleHelpers.MapIndexBounded(fromIncluded.Value, count) : 0;
int end = toExcluded.HasValue ? TupleHelpers.MapIndexBounded(toExcluded.Value, count) : count;
int len = end - begin;
if (len <= 0)
{
return(STuple.Empty);
}
if (begin == 0 && len == count)
{
return(this);
}
Contract.Debug.Assert(begin >= 0);
Contract.Debug.Assert((uint)len <= count);
return(new ListTuple <T>(m_items.Slice(begin, len)));
}
}
