service_locator.hpp

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#pragma once
#include <klib/assert.hpp>
#include <gsl/pointers>
#include <typeindex>
#include <unordered_map>
 
namespace le {
class ServiceLocator {
  public:
    template <typename Type>
    void bind(Type* service) {
        KLIB_ASSERT(service != nullptr);
        m_services.insert_or_assign(typeid(Type), service);
    }
 
    template <typename Type>
    void unbind() {
        m_services.erase(typeid(Type));
    }
 
    template <typename Type>
    [[nodiscard]] auto contains() const -> bool {
        return find<Type>() != nullptr;
    }
 
    template <typename Type>
    [[nodiscard]] auto find() const -> Type* {
        auto const it = m_services.find(typeid(Type));
        if (it == m_services.end()) { return nullptr; }
        return static_cast<Type*>(it->second.get());
    }
 
    template <typename Type>
    [[nodiscard]] auto get() const -> Type& {
        KLIB_ASSERT(contains<Type>());
        return *find<Type>();
    }
 
    [[nodiscard]] auto service_count() const -> std::size_t { return m_services.size(); }
    void clear() { m_services.clear(); }
 
  private:
    std::unordered_map<std::type_index, gsl::not_null<void*>> m_services{};
};
} // namespace le