app: simplify config loading code, handle errors too

Signed-off-by: Marcus Fritzsch <marcus_fritzsch@mentor.com>

diff --git a/src/app.cpp b/src/app.cpp
index 8c929fe..353557e 100644 (file)
--- a/src/app.cpp
+++ b/src/app.cpp
@@ -59,12 +59,24 @@ result<struct layout> layout_from_json(json const &j) {
    return Ok(l);
 }
 
+result<json> file_to_json(char const *filename) {
+   std::ifstream i(filename);
+   if (i.fail()) {
+      return Err<json>("Could not open config file");
+   }
+   json j;
+   i >> j;
+   return Ok(j);
+}
+
 struct result<layouts_type> load_layout(char const *filename) {
    DB("loading layout from " << filename);
 
-   json jlayouts;
-   std::ifstream i(filename);
-   i >> jlayouts;
+   auto j = file_to_json(filename);
+   if (j.is_err()) {
+      return Err<layouts_type>(j.unwrap_err());
+   }
+   json jlayouts = j.unwrap();
 
    auto layouts = layouts_type();
    layouts.reserve(jlayouts.size());
@@ -78,9 +90,11 @@ struct result<surface_id_to_layer_map>
    load_layer_ids(char const *filename) {
    DB("loading IDs from " << filename);
 
-   json jids;
-   std::ifstream i(filename);
-   i >> jids;
+   auto j = file_to_json(filename);
+   if (j.is_err()) {
+      return Err<surface_id_to_layer_map>(j.unwrap_err());
+   }
+   json jids = j.unwrap();
 
    return to_surface_id_to_layer_map(jids);
 }