From 6ba4d916a9a7e45d167b7af9a2e2ed9a4bf39840 Mon Sep 17 00:00:00 2001
From: Jessica James <jessica.aj@outlook.com>
Date: Tue, 9 Nov 2021 23:57:02 -0600
Subject: [PATCH] Added impl::member_from_range to workaround missing library
 support for basic_string_view(first,last)

---
 src/include/split.hpp       | 37 +++++++++++++++++++++++++------------
 src/include/type_traits.hpp | 28 ++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/src/include/split.hpp b/src/include/split.hpp
index 777acda..60b6e8b 100644
--- a/src/include/split.hpp
+++ b/src/include/split.hpp
@@ -20,6 +20,7 @@
 
 #include <string_view>
 #include <vector>
+#include "type_traits.hpp" // is_string_view; remove when compilers don't suck
 
 namespace jessilib {
 namespace impl {
@@ -45,6 +46,18 @@ constexpr auto split_container_helper_f() -> ContainerT<ArgsT...> {
 template<template<typename...> typename ContainerT, typename... ArgsT>
 using split_container_helper_t = decltype(split_container_helper_f<ContainerT, ArgsT...>());
 
+template<typename MemberT, typename ItrT, typename EndT, typename std::enable_if<is_basic_string_view<MemberT>::value>::type* = nullptr>
+MemberT member_from_range(ItrT in_itr, EndT in_end) {
+	// Workaround due to C++20 iterator constructor being inconsistently available
+	return { &*in_itr, static_cast<size_t>(in_end - in_itr) };
+}
+
+template<typename MemberT, typename ItrT, typename EndT, typename std::enable_if<!is_basic_string_view<MemberT>::value>::type* = nullptr>
+MemberT member_from_range(ItrT in_itr, EndT in_end) {
+	// Workaround due to C++20 iterator constructor being inconsistently available
+	return { in_itr, in_end };
+}
+
 } // namespace impl
 
 /**
@@ -66,18 +79,18 @@ constexpr auto split(const InputT& in_string, typename InputT::value_type in_del
 		return result;
 	}
 
-	auto begin = in_string.data();
-	auto end = in_string.data() + in_string.size();
+	auto begin = in_string.begin();
+	auto end = in_string.end();
 	for (auto itr = begin; itr != end; ++itr) {
 		if (*itr == in_delim) {
 			// Push token to result
-			result.emplace_back(begin, itr);
+			result.push_back(impl::member_from_range<MemberT>(begin, itr));
 			begin = itr + 1;
 		}
 	}
 
 	// Push final token to the end; may be empty
-	result.emplace_back(begin, end);
+	result.push_back(impl::member_from_range<MemberT>(begin, end));
 
 	return result;
 }
@@ -102,13 +115,13 @@ constexpr std::pair<ResultMemberT, ResultMemberT> split_once(const InStringT& in
 		return result;
 	}
 
-	auto begin = in_string.data();
-	auto end = in_string.data() + in_string.size();
+	auto begin = in_string.begin();
+	auto end = in_string.end();
 	for (auto itr = begin; itr != end; ++itr) {
 		if (*itr == in_delim) {
 			// in_delim found; split upon it
-			result.first = ResultMemberT{ begin, itr };
-			result.second = ResultMemberT{ itr + 1, end };
+			result.first = impl::member_from_range<ResultMemberT>(begin, itr);
+			result.second = impl::member_from_range<ResultMemberT>(itr + 1, end);
 			return result;
 		}
 	}
@@ -138,19 +151,19 @@ constexpr auto split_n(const InputT& in_string, typename InputT::value_type in_d
 		return result;
 	}
 
-	auto begin = in_string.data();
-	auto end = in_string.data() + in_string.size();
+	auto begin = in_string.begin();
+	auto end = in_string.end();
 	for (auto itr = begin; itr != end && in_limit != 0; ++itr) {
 		if (*itr == in_delim) {
 			// Push token to result
-			result.emplace_back(begin, itr);
+			result.push_back(impl::member_from_range<MemberT>(begin, itr));
 			begin = itr + 1;
 			--in_limit;
 		}
 	}
 
 	// Push final token to the end; may be empty
-	result.emplace_back(begin, end);
+	result.push_back(impl::member_from_range<MemberT>(begin, end));
 
 	return result;
 }
diff --git a/src/include/type_traits.hpp b/src/include/type_traits.hpp
index af6242f..85fd80d 100644
--- a/src/include/type_traits.hpp
+++ b/src/include/type_traits.hpp
@@ -27,6 +27,8 @@
 #include <unordered_set>
 #include <map>
 #include <unordered_map>
+#include <string>
+#include <string_view>
 
 namespace jessilib {
 
@@ -37,6 +39,32 @@ struct remove_cvref {
 	typedef std::remove_cv_t<std::remove_reference_t<T>> type;
 };
 
+/** is_basic_string */
+
+template<typename T>
+struct is_basic_string : std::false_type {};
+
+template<typename T>
+struct is_basic_string<std::basic_string<T>> {
+	using type = T;
+	static constexpr bool value{ true };
+	constexpr operator bool() const noexcept { return true; }
+	constexpr bool operator()() const noexcept { return true; }
+};
+
+/** is_basic_string_view */
+
+template<typename T>
+struct is_basic_string_view : std::false_type {};
+
+template<typename T>
+struct is_basic_string_view<std::basic_string_view<T>> {
+	using type = T;
+	static constexpr bool value{ true };
+	constexpr operator bool() const noexcept { return true; }
+	constexpr bool operator()() const noexcept { return true; }
+};
+
 /** is_vector */
 
 template<typename T>