--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cpp/json_util/json_util.cpp	Tue Mar 20 13:18:44 2018 +0100
@@ -0,0 +1,155 @@
+/*
+ * json_util.cpp -- utilities for JSON
+ *
+ * Copyright (c) 2018 David Demelier <markand@malikania.fr>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "json_util.hpp"
+
+namespace json_util {
+
+boost::optional<nlohmann::json> get(const nlohmann::json& json,
+                                    const nlohmann::json::json_pointer& key) noexcept
+{
+    // Unfortunately, there is no find using pointer yet.
+    try {
+        return json.at(key);
+    } catch (...) {
+        return boost::none;
+    }
+}
+
+boost::optional<bool> get_bool(const nlohmann::json& json,
+                               const nlohmann::json::json_pointer& key) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v || !v->is_boolean())
+        return boost::none;
+
+    return v->get<bool>();
+}
+
+boost::optional<std::uint64_t> get_int(const nlohmann::json& json,
+                                       const nlohmann::json::json_pointer& key) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v || !v->is_number_integer())
+        return boost::none;
+
+    return v->get<std::uint64_t>();
+}
+
+boost::optional<std::uint64_t> get_uint(const nlohmann::json& json,
+                                        const nlohmann::json::json_pointer& key) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v || !v->is_number_unsigned())
+        return boost::none;
+
+    return v->get<std::uint64_t>();
+}
+
+boost::optional<std::string> get_string(const nlohmann::json& json,
+                                        const nlohmann::json::json_pointer& key) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v || !v->is_string())
+        return boost::none;
+
+    return v->get<std::string>();
+}
+
+boost::optional<bool> optional_bool(const nlohmann::json& json,
+                                    const nlohmann::json::json_pointer& key,
+                                    bool def) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v)
+        return def;
+    if (!v->is_boolean())
+        return boost::none;
+
+    return v->get<bool>();
+}
+
+boost::optional<std::int64_t> optional_int(const nlohmann::json& json,
+                                           const nlohmann::json::json_pointer& key,
+                                           std::int64_t def) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v)
+        return def;
+    if (!v->is_number_integer())
+        return boost::none;
+
+    return v->get<std::int64_t>();
+}
+
+boost::optional<std::uint64_t> optional_uint(const nlohmann::json& json,
+                                             const nlohmann::json::json_pointer& key,
+                                             std::uint64_t def) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v)
+        return def;
+    if (!v->is_number_unsigned())
+        return boost::none;
+
+    return v->get<std::uint64_t>();
+}
+
+boost::optional<std::string> optional_string(const nlohmann::json& json,
+                                             const nlohmann::json::json_pointer& key,
+                                             const std::string& def) noexcept
+{
+    const auto v = get(json, key);
+
+    if (!v)
+        return def;
+    if (!v->is_string())
+        return boost::none;
+
+    return v->get<std::string>();
+}
+
+std::string pretty(const nlohmann::json& value)
+{
+    switch (value.type()) {
+    case nlohmann::json::value_t::boolean:
+        return value.get<bool>() ? "true" : "false";
+    case nlohmann::json::value_t::string:
+        return value.get<std::string>();
+    default:
+        return value.dump();
+    }
+}
+
+bool contains(const nlohmann::json& array, const nlohmann::json& value) noexcept
+{
+    for (const auto &v : array)
+        if (v == value)
+            return true;
+
+    return false;
+}
+
+} // !json_util