From 08d781058c118836c9fc8a50b7d4675558ec08d8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= <theo.delrieu@tanker.io>
Date: Mon, 19 Jun 2017 12:03:38 +0200
Subject: [PATCH] add from_json support for std::array

---
 src/json.hpp                   | 11 ++++++++++-
 test/src/unit-constructor1.cpp |  8 ++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/json.hpp b/src/json.hpp
index ccf83d5ee..87c8d21f8 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -1063,6 +1063,15 @@ auto from_json_array_impl(const BasicJsonType& j, CompatibleArrayType& arr, prio
     });
 }
 
+template <typename BasicJsonType, typename T, std::size_t N>
+void from_json_array_impl(const BasicJsonType& j, std::array<T, N>& arr, priority_tag<2>)
+{
+    for (std::size_t i = 0; i < N; ++i)
+    {
+        arr[i] = j.at(i).template get<T>();
+    }
+}
+
 template<typename BasicJsonType, typename CompatibleArrayType,
          enable_if_t<is_compatible_array_type<BasicJsonType, CompatibleArrayType>::value and
                      std::is_convertible<BasicJsonType, typename CompatibleArrayType::value_type>::value and
@@ -1074,7 +1083,7 @@ void from_json(const BasicJsonType& j, CompatibleArrayType& arr)
         JSON_THROW(type_error::create(302, "type must be array, but is " + j.type_name()));
     }
 
-    from_json_array_impl(j, arr, priority_tag<1> {});
+    from_json_array_impl(j, arr, priority_tag<2> {});
 }
 
 template<typename BasicJsonType, typename CompatibleObjectType,
diff --git a/test/src/unit-constructor1.cpp b/test/src/unit-constructor1.cpp
index a74e9a638..9dbf45405 100644
--- a/test/src/unit-constructor1.cpp
+++ b/test/src/unit-constructor1.cpp
@@ -283,12 +283,13 @@ TEST_CASE("constructors")
             CHECK(std::get<2>(t) == j[2]);
         }
 
-        SECTION("std::pair/tuple failures")
+        SECTION("std::pair/tuple/array failures")
         {
             json j{1};
 
             CHECK_THROWS((j.get<std::pair<int, int>>()));
             CHECK_THROWS((j.get<std::tuple<int, int>>()));
+            CHECK_THROWS((j.get<std::array<int, 3>>()));
         }
 
         SECTION("std::forward_list<json>")
@@ -299,12 +300,15 @@ TEST_CASE("constructors")
             CHECK(j == j_reference);
         }
 
-        SECTION("std::array<json, 5>")
+        SECTION("std::array<json, 6>")
         {
             std::array<json, 6> a {{json(1), json(1u), json(2.2), json(false), json("string"), json()}};
             json j(a);
             CHECK(j.type() == json::value_t::array);
             CHECK(j == j_reference);
+
+            const auto a2 = j.get<std::array<json, 6>>();
+            CHECK(a2 == a);
         }
 
         SECTION("std::vector<json>")