From 421ae75fa94a05b71c03255af4ad597a60fc8ed9 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Fri, 8 Mar 2024 01:17:11 +0000
Subject: Rework stream support to work with any collection

---
 lib/stream_support.h                | 16 ++++------------
 test/test-static-stream_support.cpp | 21 +++++++++++++++------
 2 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/lib/stream_support.h b/lib/stream_support.h
index fa536f1..57d82a1 100644
--- a/lib/stream_support.h
+++ b/lib/stream_support.h
@@ -11,17 +11,16 @@
 template<typename S>
 concept stringlike = requires(const S & s) { s.substr(0); };
 template<typename T>
-concept spanable = std::is_constructible_v<std::span<const typename T::value_type>, T> && !stringlike<T>
-		&& !std::is_same_v<std::span<typename T::value_type>, T>;
+concept NonStringIterableCollection
+		= std::is_same_v<decltype(std::declval<T>().begin()), decltype(std::declval<T>().end())> && !stringlike<T>;
 
 namespace std {
-	template<typename T, std::size_t L>
 	std::ostream &
-	operator<<(std::ostream & s, const span<T, L> v)
+	operator<<(std::ostream & s, const NonStringIterableCollection auto & v)
 	{
 		s << '(';
 		for (const auto & i : v) {
-			if (&i != &v.front()) {
+			if (&i != &*v.begin()) {
 				s << ", ";
 			}
 			s << i;
@@ -43,13 +42,6 @@ namespace std {
 		return (s << std::span {&v[0], L});
 	}
 
-	template<spanable T>
-	std::ostream &
-	operator<<(std::ostream & s, const T & v)
-	{
-		return (s << std::span {v});
-	}
-
 	template<typename First, typename Second>
 	std::ostream &
 	operator<<(std::ostream & s, const std::pair<First, Second> & v)
diff --git a/test/test-static-stream_support.cpp b/test/test-static-stream_support.cpp
index 3002ccc..6bf9ea4 100644
--- a/test/test-static-stream_support.cpp
+++ b/test/test-static-stream_support.cpp
@@ -1,11 +1,20 @@
 #include "stream_support.h"
 
 #include <array>
+#include <map>
+#include <set>
 #include <vector>
 
-static_assert(spanable<std::vector<int>>);
-static_assert(spanable<std::vector<char>>);
-static_assert(spanable<std::array<int, 1>>);
-static_assert(spanable<std::array<char, 1>>);
-static_assert(!spanable<std::string>);
-static_assert(!spanable<std::string_view>);
+static_assert(NonStringIterableCollection<std::vector<int>>);
+static_assert(NonStringIterableCollection<std::set<int>>);
+static_assert(NonStringIterableCollection<std::map<int, int>>);
+static_assert(NonStringIterableCollection<std::vector<char>>);
+static_assert(NonStringIterableCollection<std::array<int, 1>>);
+static_assert(NonStringIterableCollection<std::array<char, 1>>);
+static_assert(!NonStringIterableCollection<std::string>);
+static_assert(!NonStringIterableCollection<std::string_view>);
+
+static_assert(requires(std::vector<int> i, std::ostream & o) { o << i; });
+static_assert(requires(std::array<int, 10> i, std::ostream & o) { o << i; });
+static_assert(requires(std::set<int> i, std::ostream & o) { o << i; });
+static_assert(requires(std::map<int, int> i, std::ostream & o) { o << i; });
-- 
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