CacheRegistry.h

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// SPDX-FileCopyrightText: 2026 Valentin Eloy
// SPDX-License-Identifier: GPL-3.0-or-later
 
#pragma once
 
#include <optional>
#include <string>
#include <unordered_map>
#include <utility>

 
namespace hmi {

template <typename Resource>
class CacheRegistry {
public:
    template <typename Loader>
    [[nodiscard]] const Resource* getOrLoad(const std::string& key, Loader&& loader) {
        const auto found = _entries.find(key);
        if (found != _entries.end()) {
            return found->second ? &*found->second : nullptr;
        }
        const auto inserted = _entries.emplace(key, std::forward<Loader>(loader)()).first;
        return inserted->second ? &*inserted->second : nullptr;
    }

    void invalidate(const std::string& key) {
        _entries.erase(key);
    }

    void invalidateAll() {
        _entries.clear();
    }

    [[nodiscard]] std::size_t size() const noexcept {
        return _entries.size();
    }
 
private:
    std::unordered_map<std::string, std::optional<Resource>> _entries;
};
 
}  // namespace hmi