From c98364834f9819a2bb25957dbf10456c1d42ce58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Th=C3=A9o=20DELRIEU?= <theo.delrieu@tanker.io>
Date: Tue, 13 Jun 2017 11:11:29 +0200
Subject: [PATCH] remove std::pair support

---
 src/json.hpp                   | 48 +++++-----------------------------
 test/src/unit-constructor1.cpp | 36 -------------------------
 2 files changed, 6 insertions(+), 78 deletions(-)

diff --git a/src/json.hpp b/src/json.hpp
index eb4df22f69..a4ea2c8fc3 100644
--- a/src/json.hpp
+++ b/src/json.hpp
@@ -866,14 +866,6 @@ void to_json(BasicJsonType& j, T (&arr)[N])
     external_constructor<value_t::array>::construct(j, arr);
 }
 
-template <typename BasicJsonType, typename CompatibleString, typename T,
-          enable_if_t<std::is_constructible<typename BasicJsonType::string_t,
-                      CompatibleString>::value, int> = 0>
-void to_json(BasicJsonType& j, std::pair<CompatibleString, T> const& p)
-{
-    j[p.first] = p.second;
-}
-
 ///////////////
 // from_json //
 ///////////////
@@ -1047,23 +1039,16 @@ void from_json(const BasicJsonType& j, CompatibleObjectType& obj)
     using std::begin;
     using std::end;
     using value_type = typename CompatibleObjectType::value_type;
-    std::vector<value_type> v;
-    v.reserve(j.size());
     std::transform(
-        inner_object->begin(), inner_object->end(), std::back_inserter(v),
+        inner_object->begin(), inner_object->end(),
+        std::inserter(obj, obj.begin()),
         [](typename BasicJsonType::object_t::value_type const & p)
     {
-        return value_type
-        {
-            p.first,
-            p.second
-            .template get<typename CompatibleObjectType::mapped_type>()};
+        return value_type(
+                   p.first,
+                   p.second
+                   .template get<typename CompatibleObjectType::mapped_type>());
     });
-    // we could avoid the assignment, but this might require a for loop, which
-    // might be less efficient than the container constructor for some
-    // containers (would it?)
-    obj = CompatibleObjectType(std::make_move_iterator(begin(v)),
-                               std::make_move_iterator(end(v)));
 }
 
 // overload for arithmetic types, not chosen for basic_json template arguments
@@ -1109,27 +1094,6 @@ void from_json(const BasicJsonType& j, ArithmeticType& val)
     }
 }
 
-template <typename BasicJsonType, typename CompatibleString, typename T,
-          enable_if_t<std::is_constructible<typename BasicJsonType::string_t,
-                      CompatibleString>::value, int> = 0>
-void from_json(const BasicJsonType& j, std::pair<CompatibleString, T>& p)
-{
-    if (not j.is_object())
-    {
-        JSON_THROW(type_error::create(302, "type must be object, but is " + j.type_name()));
-    }
-
-    auto const inner_object = j.template get_ptr<const typename BasicJsonType::object_t*>();
-    auto const size = inner_object->size();
-    if (size != 1)
-    {
-        JSON_THROW(other_error::create(502, "conversion to std::pair requires the object to have exactly one field, but it has " + std::to_string(size)));
-    }
-    auto const& obj = *inner_object->begin();
-    // cannot use *inner_object, need to convert both members
-    p = std::make_pair(obj.first, obj.second.template get<T>());
-}
-
 struct to_json_fn
 {
   private:
diff --git a/test/src/unit-constructor1.cpp b/test/src/unit-constructor1.cpp
index db100a6960..0e56db7c59 100644
--- a/test/src/unit-constructor1.cpp
+++ b/test/src/unit-constructor1.cpp
@@ -156,20 +156,6 @@ TEST_CASE("constructors")
             CHECK(j == j_reference);
         }
 
-        SECTION("std::pair<CompatibleString, T>")
-        {
-            std::pair<std::string, std::string> p{"first", "second"};
-            json j(p);
-
-            CHECK((j.get<decltype(p)>() == p));
-
-            std::pair<std::string, int> p2{"first", 1};
-            // use char const*
-            json j2(std::make_pair("first", 1));
-
-            CHECK((j2.get<decltype(p2)>() == p2));
-        }
-
         SECTION("std::map<std::string, std::string> #600")
         {
             std::map<std::string, std::string> m;
@@ -980,28 +966,6 @@ TEST_CASE("constructors")
                 "[json.exception.type_error.301] cannot create object from initializer list");
             }
 
-            SECTION("std::pair<CompatibleString, T> with error")
-            {
-                SECTION("wrong field number")
-                {
-                    json j{{"too", "much"}, {"string", "fields"}};
-                    CHECK_THROWS_AS((j.get<std::pair<std::string, std::string>>()), json::other_error);
-                    CHECK_THROWS_WITH((j.get<std::pair<std::string, std::string>>()),
-                                      "[json.exception.other_error.502] conversion "
-                                      "to std::pair requires the object to have "
-                                      "exactly one field, but it has 2");
-                }
-
-                SECTION("wrong JSON type")
-                {
-                    json j(42);
-                    CHECK_THROWS_AS((j.get<std::pair<std::string, std::string>>()), json::type_error);
-                    CHECK_THROWS_WITH((j.get<std::pair<std::string, std::string>>()),
-                                      "[json.exception.type_error.302] type must be object, but is number");
-                }
-            }
-
-
             SECTION("empty array")
             {
                 json j = json::array();