From e4d8d35af51aab9b072242aef0f57d8ce70625ab Mon Sep 17 00:00:00 2001
From: "Elron A. Yellin" <elron@motu.com>
Date: Fri, 20 Nov 2015 17:50:02 -0500
Subject: [PATCH] add as_span overload for basic_string which doesn't have
 nonconst .data() like other contiguous containers

---
 include/span.h       | 8 ++++++++
 tests/span_tests.cpp | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/span.h b/include/span.h
index 74a5e11..2bf9d20 100644
--- a/include/span.h
+++ b/include/span.h
@@ -1568,6 +1568,14 @@ template <typename Cont>
 constexpr auto as_span(Cont &&arr) -> std::enable_if_t<!details::is_span<std::decay_t<Cont>>::value,
     span<std::remove_reference_t<decltype(arr.size(), *arr.data())>, dynamic_range>> = delete;
 
+// from basic_string which doesn't have nonconst .data() member like other contiguous containers
+template <typename CharT, typename Traits, typename Allocator>
+constexpr auto as_span(std::basic_string<CharT, Traits, Allocator> &str) -> span<CharT, dynamic_range>
+{
+    fail_fast_assert(str.size() < PTRDIFF_MAX);
+    return {&str[0], static_cast<std::ptrdiff_t>(str.size())};
+}
+
 template <typename ValueType, size_t Rank>
 class strided_span
 {
diff --git a/tests/span_tests.cpp b/tests/span_tests.cpp
index a78fe6e..e5078af 100644
--- a/tests/span_tests.cpp
+++ b/tests/span_tests.cpp
@@ -203,6 +203,15 @@ SUITE(span_tests)
 			overloaded_func(av3.as_span(dim<>(1), dim<3>(), dim<5>()), 't');
 		}
 
+		{
+			string str;
+			span<char> strspan = as_span(str);
+			(void)strspan;
+			const string cstr;
+			span<const char> cstrspan = as_span(cstr);
+			(void)cstrspan;
+		}
+
 		{
 			int a[3][4][5];
 			auto av = as_span(a);