/// <summary>
/// Returns the first key-value pair in the dictionary. If the dictionary
/// is empty, this method throws an InvalidOperationException.
/// </summary>
internal static KeyValuePair <TK, TV> FirstKeyValuePair <TK, TV>(
BTree <TK, KeyValuePair <TK, TV> > underlying,
BoundRange <TK> range)
{
var lower = range.Lower;
var cursor = lower != null
? lower.IsInclusive
? underlying.LessThanOrEqual(lower.Value, underlying.RootCursor)
: underlying.LessThan(lower.Value, underlying.RootCursor)
: underlying.Begin();
if (cursor.IsEnd)
{
throw new InvalidOperationException();
}
return(cursor.Value);
}
public bool TryLessThanOrEqualTo(
TK value,
out TK result)
{
return(TryWithCursor(_underlying.LessThanOrEqual(value, _underlying.RootCursor), out result));
}