Initial loading of JSON-based settings

scwx-qt/source/scwx/qt/util/json.cpp

@@ -0,0 +1,193 @@
+#include <scwx/qt/util/json.hpp>
+
+#include <fstream>
+
+#include <boost/log/trivial.hpp>
+
+namespace scwx
+{
+namespace qt
+{
+namespace util
+{
+namespace json
+{
+
+static const std::string logPrefix_ = "[scwx::qt::util::json] ";
+
+/* Adapted from:
+ * https://www.boost.org/doc/libs/1_77_0/libs/json/doc/html/json/examples.html#json.examples.pretty
+ *
+ * Copyright (c) 2019, 2020 Vinnie Falco
+ * Copyright (c) 2020 Krystian Stasiowski
+ * Distributed under the Boost Software License, Version 1.0. (See
+ * http://www.boost.org/LICENSE_1_0.txt)
+ */
+static void PrettyPrintJson(std::ostream&             os,
+                            boost::json::value const& jv,
+                            std::string*              indent = nullptr);
+
+bool FromJsonString(const boost::json::object& json,
+                    const std::string&         key,
+                    std::string&               value,
+                    const std::string&         defaultValue)
+{
+   const boost::json::value* jv    = json.if_contains(key);
+   bool                      found = false;
+
+   if (jv != nullptr)
+   {
+      if (jv->is_string())
+      {
+         value = boost::json::value_to<std::string>(*jv);
+         found = true;
+      }
+      else
+      {
+         BOOST_LOG_TRIVIAL(warning)
+            << logPrefix_ << key
+            << " is not a string, setting to default: " << defaultValue;
+         value = defaultValue;
+      }
+   }
+   else
+   {
+      BOOST_LOG_TRIVIAL(debug)
+         << logPrefix_ << key
+         << " is not present, setting to default: " << defaultValue;
+      value = defaultValue;
+   }
+
+   return found;
+}
+
+boost::json::value ReadJsonFile(const std::string& path)
+{
+   std::ifstream ifs {path};
+   std::string   line;
+
+   boost::json::stream_parser p;
+   boost::json::error_code    ec;
+
+   while (std::getline(ifs, line))
+   {
+      p.write(line, ec);
+      if (ec)
+      {
+         BOOST_LOG_TRIVIAL(warning) << logPrefix_ << ec.message();
+         return nullptr;
+      }
+   }
+
+   p.finish(ec);
+   if (ec)
+   {
+      BOOST_LOG_TRIVIAL(warning) << logPrefix_ << ec.message();
+      return nullptr;
+   }
+
+   return p.release();
+}
+
+void WriteJsonFile(const std::string&        path,
+                   const boost::json::value& json,
+                   bool                      prettyPrint)
+{
+   std::ofstream ofs {path};
+
+   if (prettyPrint)
+   {
+      PrettyPrintJson(ofs, json);
+   }
+   else
+   {
+      ofs << json;
+   }
+   ofs.close();
+}
+
+static void PrettyPrintJson(std::ostream&             os,
+                            boost::json::value const& jv,
+                            std::string*              indent)
+{
+   std::string indent_;
+   if (!indent)
+      indent = &indent_;
+   switch (jv.kind())
+   {
+   case boost::json::kind::object:
+   {
+      os << "{\n";
+      indent->append(4, ' ');
+      auto const& obj = jv.get_object();
+      if (!obj.empty())
+      {
+         auto it = obj.begin();
+         for (;;)
+         {
+            os << *indent << boost::json::serialize(it->key()) << " : ";
+            PrettyPrintJson(os, it->value(), indent);
+            if (++it == obj.end())
+               break;
+            os << ",\n";
+         }
+      }
+      os << "\n";
+      indent->resize(indent->size() - 4);
+      os << *indent << "}";
+      break;
+   }
+
+   case boost::json::kind::array:
+   {
+      os << "[\n";
+      indent->append(4, ' ');
+      auto const& arr = jv.get_array();
+      if (!arr.empty())
+      {
+         auto it = arr.begin();
+         for (;;)
+         {
+            os << *indent;
+            PrettyPrintJson(os, *it, indent);
+            if (++it == arr.end())
+               break;
+            os << ",\n";
+         }
+      }
+      os << "\n";
+      indent->resize(indent->size() - 4);
+      os << *indent << "]";
+      break;
+   }
+
+   case boost::json::kind::string:
+   {
+      os << boost::json::serialize(jv.get_string());
+      break;
+   }
+
+   case boost::json::kind::uint64: os << jv.get_uint64(); break;
+
+   case boost::json::kind::int64: os << jv.get_int64(); break;
+
+   case boost::json::kind::double_: os << jv.get_double(); break;
+
+   case boost::json::kind::bool_:
+      if (jv.get_bool())
+         os << "true";
+      else
+         os << "false";
+      break;
+
+   case boost::json::kind::null: os << "null"; break;
+   }
+
+   if (indent->empty())
+      os << "\n";
+}
+
+} // namespace json
+} // namespace util
+} // namespace qt
+} // namespace scwx