feat: Add object cache container

include/utils/cache.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <unordered_map>
+
+#include "common.hpp"
+#include "utils/concurrency.hpp"
+
+POLYBAR_NS
+
+template <typename ValueType, typename KeyType>
+class cache {
+ public:
+  using map_type = std::unordered_map<KeyType, std::weak_ptr<ValueType>>;
+  using safe_map_type = mutex_wrapper<map_type>;
+
+  template <typename... MakeArgs>
+  shared_ptr<ValueType> object(const KeyType& key, MakeArgs&&... make_args) {
+    std::lock_guard<safe_map_type> guard(m_cache);
+    auto ptr = m_cache[key].lock();
+    if (!ptr) {
+      m_cache[key] = ptr = make_shared<ValueType>(forward<MakeArgs>(make_args)...);
+    }
+    return ptr;
+  }
+
+ private:
+  safe_map_type m_cache;
+};
+
+namespace cache_util {}
+
+POLYBAR_NS_END