/// <summary>
/// Prints the list of character and label ranges.
/// </summary>
/// <param name="characters">The collection of characters; or <see langword="null"/>.</param>
/// <param name="labels">The collection of labels; or <see langword="null"/>.</param>
/// <returns>A list of terms.</returns>
private IListTerm PrintCharacterRangesAndLabels(IEnumerable<CodePoint> characters, IEnumerable<LabelRef> labels)
{
#region Contract
Contract.Ensures(Contract.Result<IListTerm>() != null);
#endregion
// Put all characters and labels in one set (that tracks ranges).
var set = new OrderedRangedSet<int>();
if (characters != null)
{
var codePoints = characters as CodePoint[] ?? characters.ToArray();
set.AddAll(codePoints.Where(c => !c.IsEof).Select(c => unchecked((int)c.Value)));
// If the range contains the 16-bit Eof, add the 8-bit Eof.
if (codePoints.Any(c => c.IsEof))
set.Add(256);
}
if (labels != null)
set.AddAll(labels.Select(l => l.Index + SpoofaxParseTableFormat.LabelBase));
// Turn each range into a term.
List<ITerm> result = new List<ITerm>();
foreach(var range in set.GetRanges())
{
if (range.IsEmpty)
// ReSharper disable once RedundantJumpStatement
continue;
else if (range.Start == range.End - 1)
result.Add(factory.Int(range.Start));
else
result.Add(factory.Cons("range", factory.Int(range.Start), factory.Int(range.End - 1)));
}
return factory.List(result);
}
