From 931d54184d5b2cd03eab3d16f6b3b509679421f8 Mon Sep 17 00:00:00 2001
From: MikeGitb <MikeGitb@users.noreply.github.com>
Date: Tue, 6 Dec 2016 00:10:07 +0100
Subject: [PATCH] [algorithm] Add nth_element

---
 gsl/gsl_algorithm | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/gsl/gsl_algorithm b/gsl/gsl_algorithm
index fc5b101..b7cf753 100644
--- a/gsl/gsl_algorithm
+++ b/gsl/gsl_algorithm
@@ -45,7 +45,8 @@ void copy(span<SrcElementType, SrcExtent> src, span<DestElementType, DestExtent>
 {
     static_assert(std::is_assignable<decltype(*dest.data()), decltype(*src.data())>::value,
                   "Elements of source span can not be assigned to elements of destination span");
-    static_assert(SrcExtent == dynamic_extent || DestExtent == dynamic_extent || (SrcExtent <= DestExtent),
+    static_assert(SrcExtent == dynamic_extent || DestExtent == dynamic_extent ||
+                      (SrcExtent <= DestExtent),
                   "Source range is longer than target range");
 
     Expects(dest.size() >= src.size());
@@ -152,6 +153,21 @@ void stable_sort(span<SrcElementType, SrcExtent> rng, Compare comp)
     std::stable_sort(rng.data(), rng.data() + rng.size(), comp);
 }
 
+// nth_element
+template <class SrcElementType, std::ptrdiff_t SrcExtent>
+void nth_element(span<SrcElementType, SrcExtent> rng,
+	typename span<SrcElementType, SrcExtent>::index_type nth)
+{
+	std::nth_element(rng.data(), &rng[nth], rng.data() + rng.size());
+}
+
+template <class SrcElementType, std::ptrdiff_t SrcExtent, class Compare>
+void nth_element(span<SrcElementType, SrcExtent> rng,
+	typename span<SrcElementType, SrcExtent>::index_type nth, Compare comp)
+{
+	std::nth_element(rng.data(), &rng[nth], rng.data() + rng.size(), comp);
+}
+
 } // namespace gsl
 
 #ifdef _MSC_VER