From 69476967aeaa245c452a3b3b92b9ba3c571bb958 Mon Sep 17 00:00:00 2001
From: Glen Fraser <holaglen@gmail.com>
Date: Fri, 18 Jun 2021 16:40:38 +0200
Subject: [PATCH] Reimplement pair_conversion() helper

- resolves issue #563.
---
 .../dispatchkit/type_conversions.hpp          | 18 ++++++++++++++++
 unittests/compiled_tests.cpp                  | 21 +++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/chaiscript/dispatchkit/type_conversions.hpp b/include/chaiscript/dispatchkit/type_conversions.hpp
index e47afbf7..3f89e66b 100644
--- a/include/chaiscript/dispatchkit/type_conversions.hpp
+++ b/include/chaiscript/dispatchkit/type_conversions.hpp
@@ -534,6 +534,24 @@ namespace chaiscript {
     return chaiscript::make_shared<detail::Type_Conversion_Base, detail::Type_Conversion_Impl<decltype(func)>>(
         user_type<std::map<std::string, Boxed_Value>>(), user_type<To>(), func);
   }
+
+  template<typename Left, typename Right>
+  Type_Conversion pair_conversion() {
+    auto func = [](const Boxed_Value &t_bv) -> Boxed_Value {
+      const std::pair<Boxed_Value, Boxed_Value> &from_pair
+          = detail::Cast_Helper<const std::pair<Boxed_Value, Boxed_Value> &>::cast(t_bv, nullptr);
+
+      auto pair = std::make_pair(
+        detail::Cast_Helper<Left>::cast(from_pair.first, nullptr),
+        detail::Cast_Helper<Right>::cast(from_pair.second, nullptr)
+      );
+
+      return Boxed_Value(std::move(pair));
+    };
+
+    return chaiscript::make_shared<detail::Type_Conversion_Base, detail::Type_Conversion_Impl<decltype(func)>>(
+        user_type<std::pair<Boxed_Value, Boxed_Value>>(), user_type<std::pair<Left, Right>>(), func);
+  }
 } // namespace chaiscript
 
 #endif
diff --git a/unittests/compiled_tests.cpp b/unittests/compiled_tests.cpp
index f8873df8..29f49875 100644
--- a/unittests/compiled_tests.cpp
+++ b/unittests/compiled_tests.cpp
@@ -866,6 +866,27 @@ TEST_CASE("Map conversions") {
   CHECK(c == 42);
 }
 
+TEST_CASE("Pair conversions") {
+  chaiscript::ChaiScript_Basic chai(create_chaiscript_stdlib(), create_chaiscript_parser());
+  chai.add(chaiscript::pair_conversion<std::string, std::string>());
+  chai.add(chaiscript::pair_conversion<int, double>());
+
+  {
+    const auto p = chai.eval<std::pair<std::string, std::string>>(R"cs(
+        Pair("chai", "script");
+    )cs");
+    CHECK(p.first == std::string{ "chai" });
+    CHECK(p.second == "script");
+  }
+  {
+    const auto p = chai.eval<std::pair<int, double>>(R"cs(
+        Pair(5, 3.14);
+    )cs");
+    CHECK(p.first == 5);
+    CHECK(p.second == Approx(3.14));
+  }
+}
+
 TEST_CASE("Parse floats with non-posix locale") {
 #ifdef CHAISCRIPT_MSVC
   std::setlocale(LC_ALL, "en-ZA");