ResourceRef.h

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#pragma once
 
#include <cstdint>
#include <functional>
#include <limits>
#include <string>
#include <string_view>
 
namespace z8 {
enum class ResourceTy {
  None,
  Mesh,
  Material,
  ShaderComponent,
  Shader,
  Texture,
  Audio,
};
 
class Resource {
public:
  std::string Id;
  ResourceTy Type = ResourceTy::None;
 
  virtual ~Resource() = default;
  [[nodiscard]] bool IsValid() const { return !Id.empty(); }
};
 
template <typename ResourceTy> class ResourceRef {
private:
  static constexpr uint32_t Invalid = std::numeric_limits<uint32_t>::max();
  std::string Id;
 
public:
  uint32_t Index = Invalid;
 
  ResourceRef() = default;
  explicit ResourceRef(uint32_t index) : Index(index) {}
  explicit ResourceRef(std::string_view id) : Id(id) {}
 
  [[nodiscard]] const std::string &GetId() const { return Id; }
  [[nodiscard]] bool IsResolved() const { return Index != Invalid; }
  [[nodiscard]] bool IsValid() const { return IsResolved() || !Id.empty(); }
 
  bool operator==(const ResourceRef &other) const {
    return Index == other.Index && Id == other.Id;
  }
 
  bool operator!=(const ResourceRef &other) const { return !(*this == other); }
};
 
template <typename ResourceTy> struct ResourceRefHash {
  size_t operator()(const ResourceRef<ResourceTy> &reference) const noexcept {
    const size_t index = std::hash<uint32_t>{}(reference.Index);
    const size_t id = std::hash<std::string>{}(reference.GetId());
    return index ^ (id << 1U);
  }
};
 
} // namespace z8