From ff7d20f167ff463b1c40ced831f904e9e14bd062 Mon Sep 17 00:00:00 2001 From: Nathan Sashihara <21227491+n8sh@users.noreply.github.com> Date: Tue, 8 Jan 2019 20:19:53 -0500 Subject: [PATCH] retro supports slicing if source range supports slicing --- source/tanya/algorithm/iteration.d | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/source/tanya/algorithm/iteration.d b/source/tanya/algorithm/iteration.d index bfd1f13..8281ae1 100644 --- a/source/tanya/algorithm/iteration.d +++ b/source/tanya/algorithm/iteration.d @@ -514,6 +514,22 @@ private struct Retro(Range) } } + static if (hasLength!Range && hasSlicing!Range) + { + alias opDollar = length; + + auto opSlice(size_t i, size_t j) + in + { + assert(i <= j); + assert(j <= length); + } + do + { + return typeof(this)(this.source[$-j .. $-i]); + } + } + static if (hasAssignableElements!Range) { @property void front(ref ElementType!Range value) @@ -609,6 +625,10 @@ if (isBidirectionalRange!Range) actual.popBack(); assert(actual.back == 2); assert(actual[1] == 2); + + // Check slicing. + auto slice = retro(given[])[1 .. $]; + assert(slice.length == 2 && slice.front == 2 && slice.back == 1); } // Elements can be assigned