private IEnumerable<int> Range(int start, int end)
{
//// Description:
////
//// A range-expression creates an unconstrained 1-dimensional array whose elements are the values of
//// the int sequence specified by the range bounds. The values designated by the operands are converted
//// to int, if necessary (§6.4).
//// The operand designating the lower value after conversion is the lower
//// bound, while the operand designating the higher value after conversion is the upper bound.
if (start < end)
{
return Extensions.Enumerable._.Generate(start, i => i + 1, end).ToArray();
}
//// Both bounds may be the same, in which case, the resulting array has length 1.
if (start == end) return new[] { start };
//// If the left operand designates the lower bound, the sequence is in ascending order. If the left
//// operand designates the upper bound, the sequence is in descending order.
if (end < start)
{
return Extensions.Enumerable._.Generate(start, i => i - 1, end).ToArray();
}
//// [Note: Conceptually, this operator is a shortcut for the corresponding binary comma operator
//// sequence. For example, the range 5..8 can also be generated using 5,6,7,8. However, if an ascending
//// or descending sequence is needed without having an array, an implementation may avoid generating an
//// actual array. For example, in foreach ($i in 1..5) { … }, no array need be created. end note]
////
//// A range-expression can be used to specify an array slice (§9.9).
throw new Exception("unreachable");
}
