Method MergeEnvironmentVariables

FEXCore/Source/Interface/Config/Config.cpp:184–222

void MetaLayer::MergeEnvironmentVariables(const ConfigOption& Option, const DefaultValues::Type::StringArrayType& Value) {
  // Environment variables need a bit of additional work
  // We want to merge the arrays rather than overwrite entirely
  auto MetaEnvironment = OptionMap.find(Option);
  if (MetaEnvironment == OptionMap.end()) {
    // Doesn't exist, just insert
    OptionMap.insert_or_assign(Option, Value);
    return;
  }

  // If an environment variable exists in both current meta and in the incoming layer then the meta layer value is overwritten
  fextl::unordered_map<fextl::string, fextl::string> LookupMap;
  const auto AddToMap = [&LookupMap](const DefaultValues::Type::StringArrayType& Value) {
    for (const auto& EnvVar : Value) {
      const auto ItEq = EnvVar.find_first_of('=');
      if (ItEq == fextl::string::npos) {
        // Broken environment variable
        // Skip
        continue;
      }
      auto Key = fextl::string(EnvVar.begin(), EnvVar.begin() + ItEq);
      auto Value = fextl::string(EnvVar.begin() + ItEq + 1, EnvVar.end());

      // Add the key to the map, overwriting whatever previous value was there
      LookupMap.insert_or_assign(std::move(Key), std::move(Value));
    }
  };

  AddToMap(std::get<DefaultValues::Type::StringArrayType>(MetaEnvironment->second));
  AddToMap(Value);

  // Now with the two layers merged in the map
  // Add all the values to the option
  Erase(Option);
  for (auto& Val : LookupMap) {
    // Set will emplace multiple options in to its list
    AppendStrArrayValue(Option, Val.first + "=" + Val.second);
  }
}

void MetaLayer::MergeConfigMap(const LayerOptions& Options) {
  // Insert this layer's options, overlaying previous options that exist here