Implement a way to map entities to their names, which comes up often enough.

demos/calc.cpp

@@ -153,7 +153,9 @@ struct CalculatorUI {
     $gui.set<guecs::Background>($gui.MAIN, {$gui.$parser});
 
     for(auto& [name, cell] : $gui.cells()) {
+      // NOTE: quick test here for the ent->name functionality
       auto id = $gui.entity(name);
+      assert(name == $gui.name_for(id) && "BUG! name and entity don't match");
       auto& label = LABELS.at(name);
 
       $gui.set<guecs::Rectangle>(id, {});

include/guecs/ui.hpp

@@ -47,6 +47,7 @@ namespace guecs {
       std::unordered_map<std::type_index, EntityMap> $components;
       std::unordered_map<std::type_index, std::any> $component_storages;
       std::unordered_map<string, Entity> $name_ents;
+      std::unordered_map<Entity, string> $ents_name;
       shared_ptr<sf::Font> $font = nullptr;
       lel::Parser $parser;
       string $grid = "";
@@ -60,6 +61,7 @@ namespace guecs {
       Entity init_entity(const string& name);
       Entity entity(const string& name);
       Entity entity(const string& name, int id);
+      const std::string& name_for(Entity gui_id);
 
       inline lel::CellMap& cells() {
         return $parser.cells;

src/guecs/ui.cpp

@@ -38,11 +38,19 @@ namespace guecs {
     auto ent = entity();
     // this lets you look up an entity by name
     $name_ents.insert_or_assign(name, ent);
+    // this lets you get a name by entity
+    $ents_name.insert_or_assign(ent, name);
     // this makes it easier to get the name during querying
     set<CellName>(ent, {name});
     return ent;
   }
 
+  const std::string& UI::name_for(Entity gui_id) {
+    assert($ents_name.contains(gui_id) &&
+        "Attempt to get name_for an Entity but that's not a valid ID.");
+    return $ents_name.at(gui_id);
+  }
+
   Entity UI::entity(const string& name) {
     assert($name_ents.contains(name) &&
         "GUECS entity does not exist. Mispelled cell name?");