Added new example.

example/x3/unpack.cpp

@@ -0,0 +1,43 @@
+// MessagePack for C++ example
+//
+// Copyright (C) 2017 KONDO Takatoshi
+//
+//    Distributed under the Boost Software License, Version 1.0.
+//    (See accompanying file LICENSE_1_0.txt or copy at
+//    http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <sstream>
+#include <cassert>
+
+// MSGPACK_USE_X3_PARSE should be defined before including msgpack.hpp
+// It usually defined as a compiler option as -DMSGPACK_USE_X3_PARSE.
+
+#include <msgpack.hpp>
+
+int main() {
+    std::stringstream ss;
+    std::map<std::string, std::vector<int>> v1 {
+        { "ABC", { 1, 2, 3 } },
+        { "DEFG", { 4, 5 } }
+    };
+    std::vector<std::string> v2 {
+        "HIJ", "KLM", "NOP"
+    };
+    msgpack::pack(ss, v1);
+    msgpack::pack(ss, v2);
+
+    std::string const& buf = ss.str();
+    auto it = buf.begin();
+    auto end = buf.end();
+    {
+        auto oh = msgpack::unpack(it, end);
+        // it is updated here.
+        assert(v1 == (oh.get().as<std::map<std::string, std::vector<int>>>()));
+    }
+    {
+        auto oh = msgpack::unpack(it, end);
+        assert(v2 == oh.get().as<std::vector<std::string>>());
+    }
+}