import ceylon.language { makeSpan=span, makeMeasure=measure } "A range of adjacent [[Enumerable]] values. Two values of an enumerable type are considered _adjacent_ if their [[offset|Enumerable.offset]] is of unit or zero magnitude. Thus, a `Range` is a list of values where for every integer `index` where both `index` and `index+1` fall within the indices of the range: range[index+1].offset(range[index]).magnitude <= 1 A range is always nonempty, containing at least one value. Thus, it is a [[Sequence]]. A sequence of adjacent values may be represented very efficiently in memory, either: - via its endpoints, `first..last`, or - via an endpoint and length, `first:size`. Furthermore, certain operations are much more efficient than for other lists, assuming that the enumerable type has efficient [[neighbour|Enumerable.neighbour]] and [[offset|Enumerable.offset]] functions. The functions [[ceylon.language::span]] and [[ceylon.language::measure]], and corresponding operators `..` and `:` are used to create new instances of `Range`." see (`function makeSpan`, `function makeMeasure`) shared sealed abstract class Range<Element>() of Span<Element> | Measure<Element> extends Object() satisfies [Element+] given Element satisfies Enumerable<Element> { "Determines if this range includes the given value." shared formal Boolean containsElement(Element element); "Determines if this range includes the given range." shared formal Boolean includesRange(Range<Element> range); "Returns a range of the same length and type as this range, with its endpoints shifted by the given number of elements, where: - a negative [[shift]] measures [[decrements|Ordinal.predecessor]], and - a positive `shift` measures [[increments|Ordinal.successor]]." shared formal Range<Element> shifted(Integer shift); "Determines if the range is increasing, that is, if successors occur after predecessors." shared formal Boolean increasing; "Determines if the range is decreasing, that is, if predecessors occur after successors." shared formal Boolean decreasing; "Returns the range itself, since a range cannot contain null elements." shared actual Range<Element> coalesced => this; }