helios::ecs::Entity Class Reference

Unique identifier for entities with generation counter to handle recycling. More...

#include <entity.hpp>

Public Types
using	IndexType = uint32_t
using	GenerationType = uint32_t

Public Member Functions
constexpr	Entity () noexcept=default
	Constructs an invalid entity.
constexpr	Entity (IndexType index, GenerationType generation) noexcept
	Constructs entity with specific index and generation.
constexpr	Entity (const Entity &) noexcept=default
constexpr	Entity (Entity &&) noexcept=default
constexpr	~Entity () noexcept=default
constexpr Entity &	operator= (const Entity &) noexcept=default
constexpr Entity &	operator= (Entity &&) noexcept=default
constexpr bool	operator== (const Entity &) const noexcept=default
constexpr bool	operator!= (const Entity &) const noexcept=default
constexpr bool	operator< (const Entity &other) const noexcept
constexpr bool	Valid () const noexcept
	Checks if the entity is valid.
constexpr size_t	Hash () const noexcept
	Generates a hash value for this entity.
constexpr IndexType	Index () const noexcept
	Gets the index component of the entity.
constexpr GenerationType	Generation () const noexcept
	Gets the generation component of the entity.

Static Public Attributes
static constexpr IndexType	kInvalidIndex = std::numeric_limits<IndexType>::max()
static constexpr GenerationType	kInvalidGeneration = 0

Detailed Description

Unique identifier for entities with generation counter to handle recycling.

Entity uses a combination of index and generation to provide stable references even when entities are destroyed and their indices are recycled. The generation counter ensures that old entity references become invalid when the index is reused.

Memory layout: 32-bit index + 32-bit generation = 64-bit total

Note

This class is thread-safe for all operations.

Definition at line 21 of file entity.hpp.

Member Typedef Documentation

GenerationType

using helios::ecs::Entity::GenerationType = uint32_t

Examples

/home/runner/work/HeliosEngine/HeliosEngine/src/core/include/helios/core/ecs/details/entities_manager.hpp.

Definition at line 24 of file entity.hpp.

IndexType

using helios::ecs::Entity::IndexType = uint32_t

Examples

/home/runner/work/HeliosEngine/HeliosEngine/src/core/include/helios/core/ecs/details/entities_manager.hpp.

Definition at line 23 of file entity.hpp.

Constructor & Destructor Documentation

Entity() [1/4]

constexpr helios::ecs::Entity::Entity ( )

constexprdefaultnoexcept

Constructs an invalid entity.

Creates an entity with invalid index and generation values.

Entity() [2/4]

constexpr helios::ecs::Entity::Entity ( IndexType  index, GenerationType  generation  )

inlineconstexprnoexcept

Constructs entity with specific index and generation.

Private constructor used by entity manager to create valid entities.

Parameters

index	The entity index
generation	The entity generation

Definition at line 41 of file entity.hpp.

: index_(index), generation_(generation) {}

Entity() [3/4]

constexpr helios::ecs::Entity::Entity ( const Entity &  )

constexprdefaultnoexcept

Entity() [4/4]

constexpr helios::ecs::Entity::Entity ( Entity &&  )

constexprdefaultnoexcept

~Entity()

constexpr helios::ecs::Entity::~Entity ( )

constexprdefaultnoexcept

Member Function Documentation

Generation()

constexpr GenerationType helios::ecs::Entity::Generation ( ) const

inlineconstexprnoexcept

Gets the generation component of the entity.

The generation counter prevents use of stale entity references after recycling.

Returns

Entity generation, or kInvalidGeneration if entity is invalid

Definition at line 82 of file entity.hpp.

{ return generation_; }

Hash()

constexpr size_t helios::ecs::Entity::Hash ( ) const

constexprnoexcept

Generates a hash value for this entity.

Combines index and generation into a 64-bit hash value. Invalid entities always return hash value of 0.

Returns

Hash combining generation (high bits) and index (low bits)

Definition at line 96 of file entity.hpp.

                                             {
  if (!Valid()) [[unlikely]] {
    return 0;
  }
 
  return (static_cast<size_t>(generation_) << (sizeof(size_t) / 2)) | static_cast<size_t>(index_);
}

Index()

constexpr IndexType helios::ecs::Entity::Index ( ) const

inlineconstexprnoexcept

Gets the index component of the entity.

The index identifies the entity's storage location in sparse arrays.

Returns

Entity index, or kInvalidIndex if entity is invalid

Definition at line 75 of file entity.hpp.

{ return index_; }

operator!=()

constexpr bool helios::ecs::Entity::operator!= ( const Entity &  ) const

constexprdefaultnoexcept

operator<()

constexpr bool helios::ecs::Entity::operator< ( const Entity &  other ) const

constexprnoexcept

Definition at line 89 of file entity.hpp.

                                                                   {
  if (index_ != other.index_) {
    return index_ < other.index_;
  }
  return generation_ < other.generation_;
}

operator=() [1/2]

constexpr Entity & helios::ecs::Entity::operator= ( const Entity &  )

constexprdefaultnoexcept

operator=() [2/2]

constexpr Entity & helios::ecs::Entity::operator= ( Entity &&  )

constexprdefaultnoexcept

operator==()

constexpr bool helios::ecs::Entity::operator== ( const Entity &  ) const

constexprdefaultnoexcept

Valid()

constexpr bool helios::ecs::Entity::Valid ( ) const

inlineconstexprnoexcept

Checks if the entity is valid.

An entity is valid if both its index and generation are not the reserved invalid values.

Returns

True if entity has valid index and generation, false otherwise

Definition at line 58 of file entity.hpp.

                                                      {
    return index_ != kInvalidIndex && generation_ != kInvalidGeneration;
  }

Member Data Documentation

kInvalidGeneration

constexpr GenerationType helios::ecs::Entity::kInvalidGeneration = 0

staticconstexpr

Examples

/home/runner/work/HeliosEngine/HeliosEngine/src/core/include/helios/core/ecs/details/entities_manager.hpp.

Definition at line 27 of file entity.hpp.

kInvalidIndex

constexpr IndexType helios::ecs::Entity::kInvalidIndex = std::numeric_limits<IndexType>::max()

staticconstexpr

Examples

/home/runner/work/HeliosEngine/HeliosEngine/src/core/include/helios/core/ecs/details/entities_manager.hpp.

Definition at line 26 of file entity.hpp.