From 33de24239a4c119162e78fe9c440f11d706e55e0 Mon Sep 17 00:00:00 2001
From: Takatoshi Kondo <redboltz@gmail.com>
Date: Mon, 31 Aug 2015 09:05:09 +0900
Subject: [PATCH] Fixed #357. Added a conversion member function to
 msgpack::object. If msgpack::object is nil then returns false else returns
 true and sets a value.

---
 include/msgpack/object.hpp     |  9 +++++++++
 include/msgpack/object_fwd.hpp |  3 +++
 test/convert.cpp               | 17 +++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/msgpack/object.hpp b/include/msgpack/object.hpp
index 065adf1d..159f9b8f 100644
--- a/include/msgpack/object.hpp
+++ b/include/msgpack/object.hpp
@@ -511,6 +511,15 @@ inline T* object::convert(T* v) const
     return v;
 }
 
+template <typename T>
+inline bool object::convert_if_not_nil(T& v) const {
+    if (is_nil()) {
+        return false;
+    }
+    convert(v);
+    return true;
+}
+
 #if defined(MSGPACK_USE_CPP03)
 
 template <typename T>
diff --git a/include/msgpack/object_fwd.hpp b/include/msgpack/object_fwd.hpp
index fcbfd030..ac446729 100644
--- a/include/msgpack/object_fwd.hpp
+++ b/include/msgpack/object_fwd.hpp
@@ -149,6 +149,9 @@ struct object {
     template <typename T>
     T* convert(T* v) const;
 
+    template <typename T>
+    bool convert_if_not_nil(T& v) const;
+
     object();
 
     object(const msgpack_object& o);
diff --git a/test/convert.cpp b/test/convert.cpp
index fc4ced0a..b30ecade 100644
--- a/test/convert.cpp
+++ b/test/convert.cpp
@@ -93,3 +93,20 @@ TEST(convert, return_value_ref)
     EXPECT_EQ(&i, &j);
     EXPECT_EQ(i, j);
 }
+
+TEST(convert, if_not_nil_nil)
+{
+    msgpack::object obj;
+    int i;
+    EXPECT_FALSE(obj.convert_if_not_nil(i));
+}
+
+TEST(convert, if_not_nil_not_nil)
+{
+    msgpack::zone z;
+    msgpack::object obj(1, z);
+
+    int i;
+    EXPECT_TRUE(obj.convert_if_not_nil(i));
+    EXPECT_EQ(i, 1);
+}