xiiGenericId< InstanceIndexBits, GenerationBits > Struct Template Reference

#include <Id.h>

Public Types
enum	{ STORAGE_SIZE = ((InstanceIndexBits + GenerationBits - 1) / 8) + 1 }
	Number of bytes requested for the underlying integral storage type.
using	StorageType = typename xiiSizeToType<STORAGE_SIZE>::Type
	Integral type used to store the packed identifier.

Public Member Functions
	XII_DECLARE_ID_TYPE (xiiGenericId, InstanceIndexBits, GenerationBits)
XII_ALWAYS_INLINE	xiiGenericId (StorageType instanceIndex, StorageType generation)

Public Attributes
union {
StorageType   m_Data
	Packed representation containing both identifier components.
struct {
StorageType   m_InstanceIndex: InstanceIndexBits
	Index of the referenced instance.
StorageType   m_Generation: GenerationBits
	Generation associated with the instance.
}
};

Detailed Description

template<xiiUInt32 InstanceIndexBits, xiiUInt32 GenerationBits>
struct xiiGenericId< InstanceIndexBits, GenerationBits >

A compact generational identifier that combines an instance index and a generation counter. A generational identifier uniquely identifies an instance within an indexed collection while providing a mechanism for detecting stale references when instance indices are reused.

The identifier consists of two components:

• Instance Index: Identifies the slot occupied by an instance within a collection.
• Generation: Distinguishes successive instances that occupy the same slot.

When an instance is removed, its index may be reused for a new instance. By incrementing the generation counter associated with that slot, previously issued identifiers can be distinguished from identifiers referring to the newly allocated instance.

Both components are packed into a single integral storage type, allowing the identifier to be stored, copied, and compared efficiently.

Template Parameters

InstanceIndexBits	Number of bits reserved for the instance index.
GenerationBits	Number of bits reserved for the generation counter.

Note

The generation counter provides stale-identifier detection only when the owning collection maintains and validates generation values. Generation counter wraparound may eventually cause an old identifier to become valid again.

The bit-field layout is implementation-defined. The packed representation should not be assumed to have a portable binary layout across different compilers or platforms.

See also

XII_DECLARE_ID_TYPE

Constructor & Destructor Documentation

xiiGenericId()

template<xiiUInt32 InstanceIndexBits, xiiUInt32 GenerationBits>

XII_ALWAYS_INLINE xiiGenericId< InstanceIndexBits, GenerationBits >::xiiGenericId ( StorageType instanceIndex, StorageType generation )

inline

Constructs an identifier from an instance index and generation counter.

Parameters

instanceIndex	The index of the instance within its owning collection.
generation	The generation associated with the instance.

Note

Both values must fit within their respective bit widths. Values exceeding the allocated widths may be truncated when assigned to the bit fields.

---

The documentation for this struct was generated from the following file:

• /home/runner/work/XII/XII/Source/Engine/Foundation/Types/Id.h