From dc6a08d10af1d45604ada840b713644acbf84b98 Mon Sep 17 00:00:00 2001
From: Vinnie Falco <vinnie.falco@gmail.com>
Date: Thu, 3 Aug 2017 04:43:38 -0700
Subject: [PATCH] Add variadic min/max

---
 CHANGELOG.md                                  |  1 +
 .../boost/beast/core/detail/type_traits.hpp   | 74 +++++++++++++++++++
 test/beast/core/type_traits.cpp               | 23 ++++++
 3 files changed, 98 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2fc69f61..338248e7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ Version 100:
 * Rename test macros
 * Reorder define test macro params
 * vcxproj workaround for include symlinks
+* Add variadic min/max
 
 WebSocket:
 
diff --git a/include/boost/beast/core/detail/type_traits.hpp b/include/boost/beast/core/detail/type_traits.hpp
index ed03ce66..65c27e8f 100644
--- a/include/boost/beast/core/detail/type_traits.hpp
+++ b/include/boost/beast/core/detail/type_traits.hpp
@@ -180,6 +180,80 @@ struct is_contiguous_container<T, E, void_t<
     >::type>>: std::true_type
 {};
 
+template<class...>
+struct unwidest_unsigned;
+
+template<class U0>
+struct unwidest_unsigned<U0>
+{
+    using type = U0;
+};
+
+template<class U0, class... UN>
+struct unwidest_unsigned<U0, UN...>
+{
+    BOOST_STATIC_ASSERT(std::is_unsigned<U0>::value);
+    using type = typename std::conditional<
+        (sizeof(U0) < sizeof(typename unwidest_unsigned<UN...>::type)),
+        U0, typename unwidest_unsigned<UN...>::type>::type;
+};
+
+template<class...>
+struct widest_unsigned;
+
+template<class U0>
+struct widest_unsigned<U0>
+{
+    using type = U0;
+};
+
+template<class U0, class... UN>
+struct widest_unsigned<U0, UN...>
+{
+    BOOST_STATIC_ASSERT(std::is_unsigned<U0>::value);
+    using type = typename std::conditional<
+        (sizeof(U0) > sizeof(typename widest_unsigned<UN...>::type)),
+        U0, typename widest_unsigned<UN...>::type>::type;
+};
+
+template<class U>
+inline
+constexpr
+U
+min_all(U u)
+{
+    BOOST_STATIC_ASSERT(std::is_unsigned<U>::value);
+    return u;
+}
+
+template<class U0, class U1, class... UN>
+inline
+constexpr
+typename unwidest_unsigned<U0, U1, UN...>::type
+min_all(U0 u0, U1 u1, UN... un)
+{
+    return u0 < u1? min_all(u0, un...) : min_all(u1, un...);
+}
+
+template<class U>
+inline
+constexpr
+U
+max_all(U u)
+{
+    BOOST_STATIC_ASSERT(std::is_unsigned<U>::value);
+    return u;
+}
+
+template<class U0, class U1, class... UN>
+inline
+constexpr
+typename widest_unsigned<U0, U1, UN...>::type
+max_all(U0 u0, U1 u1, UN... un)
+{
+    return u0 > u1? max_all(u0, un...) : max_all(u1, un...);
+}
+
 //------------------------------------------------------------------------------
 
 //
diff --git a/test/beast/core/type_traits.cpp b/test/beast/core/type_traits.cpp
index ea2684bb..e3be630a 100644
--- a/test/beast/core/type_traits.cpp
+++ b/test/beast/core/type_traits.cpp
@@ -94,6 +94,29 @@ BOOST_STATIC_ASSERT(std::is_same<get_lowest_layer<F4<F2>>::type, F2>::value);
 BOOST_STATIC_ASSERT(std::is_same<get_lowest_layer<F4<F3<F1>>>::type, F1>::value);
 BOOST_STATIC_ASSERT(std::is_same<get_lowest_layer<F4<F3<F2>>>::type, F2>::value);
 
+//
+// min_all, max_all
+//
+
+BOOST_STATIC_ASSERT(std::is_same<std::size_t,
+    widest_unsigned<unsigned short, std::size_t>::type>::value);
+BOOST_STATIC_ASSERT(std::is_same<std::uint64_t,
+    widest_unsigned<unsigned short, std::uint32_t, std::uint64_t>::type>::value);
+BOOST_STATIC_ASSERT(! std::is_same<std::uint64_t,
+    widest_unsigned<unsigned short, std::uint32_t>::type>::value);
+BOOST_STATIC_ASSERT(std::is_same<unsigned short,
+    unwidest_unsigned<unsigned short, std::size_t>::type>::value);
+BOOST_STATIC_ASSERT(std::is_same<unsigned short,
+    unwidest_unsigned<unsigned short, std::uint32_t, std::uint64_t>::type>::value);
+BOOST_STATIC_ASSERT(! std::is_same<std::uint32_t,
+    unwidest_unsigned<unsigned short, std::uint32_t>::type>::value);
+BOOST_STATIC_ASSERT(max_all(1u) == 1);
+BOOST_STATIC_ASSERT(max_all(1u, 2u) == 2);
+BOOST_STATIC_ASSERT(max_all(1u, 2u, static_cast<std::uint64_t>(3)) == 3);
+BOOST_STATIC_ASSERT(min_all(1u) == 1);
+BOOST_STATIC_ASSERT(min_all(1u, 2u) == 1);
+BOOST_STATIC_ASSERT(min_all(1u, 2u, static_cast<std::uint64_t>(3)) == 1);
+
 } // (anonymous)
 
 } // detail