From 59e11d3ada55cb68d7ecc6af4bb25b5ec59f1712 Mon Sep 17 00:00:00 2001
From: Scott Sanderson <ssanderson@quantopian.com>
Date: Fri, 14 Jun 2019 12:27:11 -0400
Subject: [PATCH] ENH: Add to and from object support for std::pair.

Delegates to the existing implementation for std::tuple.
---
 include/libpy/from_object.h | 10 ++++++++++
 include/libpy/to_object.h   | 11 +++++++++++
 2 files changed, 21 insertions(+)

diff --git a/include/libpy/from_object.h b/include/libpy/from_object.h
index 34c5e779..c085977f 100644
--- a/include/libpy/from_object.h
+++ b/include/libpy/from_object.h
@@ -11,6 +11,7 @@
 #include <type_traits>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
 #include <vector>
 
 #include <Python.h>
@@ -356,6 +357,15 @@ struct from_object<std::tuple<Ts...>> {
     }
 };
 
+template<typename T, typename U>
+struct from_object<std::pair<T, U>> {
+public:
+    static std::pair<T, U> f(PyObject* tup) {
+        std::tuple<T, U> tmp = from_object<std::tuple<T, U>>(tup);
+        return std::make_pair(std::get<0>(tmp), std::get<1>(tmp));
+    }
+};
+
 template<typename T>
 struct from_object<std::optional<T>> {
     static std::optional<T> f(PyObject* maybe_value) {
diff --git a/include/libpy/to_object.h b/include/libpy/to_object.h
index e7cac1bc..3414b747 100644
--- a/include/libpy/to_object.h
+++ b/include/libpy/to_object.h
@@ -8,6 +8,7 @@
 #include <type_traits>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
 #include <vector>
 
 #include <Python.h>
@@ -296,6 +297,16 @@ struct to_object<std::tuple<Ts...>> {
     }
 };
 
+template<typename T, typename U>
+struct to_object<std::pair<T, U>> {
+public:
+    static PyObject* f(const std::pair<T, U>& p) {
+        // Delegate to std::tuple dispatch.
+        return std::move(py::to_object(std::make_tuple(std::get<0>(p), std::get<1>(p))))
+            .escape();
+    }
+};
+
 template<typename T>
 struct to_object<std::optional<T>> {
     static PyObject* f(const std::optional<T>& maybe_value) {