import std.algorithm.comparison : equal; import std.range : cycle, take; // Here we create an infinitive cyclic sequence from [1, 2] // (i.e. get here [1, 2, 1, 2, 1, 2 and so on]) then // take 5 elements of this sequence (so we have [1, 2, 1, 2, 1]) // and compare them with the expected values for equality. assert(cycle([1, 2]).take(5).equal([ 1, 2, 1, 2, 1 ]));
Repeats the given forward range ad infinitum. If the original range is infinite (fact that would make Cycle the identity application), Cycle detects that and aliases itself to the range type itself. That works for non-forward ranges too. If the original range has random access, Cycle offers random access and also offers a constructor taking an initial position index. Cycle works with static arrays in addition to ranges, mostly for performance reasons.
Note: The input range must not be empty.
Tip: This is a great way to implement simple circular buffers.