Struct HeapHeader 

pub struct HeapHeader {
    pub kind: u16,
    pub elem_type: u8,
    pub flags: u8,
    pub len: u32,
    pub cap: u32,
    pub aux: u64,
    /* private fields */
}

Fixed-layout header for heap-allocated objects.

This struct is designed to be readable by JIT-generated code at known offsets. The JIT can load kind at offset 0, len at offset 4, and aux at offset 16 without any Rust ABI knowledge.

Fields

kind: u16

Object type discriminator (matches HeapKind and HEAP_KIND_* constants).

elem_type: u8

Element type hint for homogeneous containers (0 = untyped/mixed). For arrays: 1=f64, 2=i64, 3=string, 4=bool, 5=typed_object. For typed objects: unused (0).

flags: u8

Bitfield flags (FLAG_MARKED, FLAG_PINNED, FLAG_READONLY).

len: u32

Element count (array length, field count, string byte length, etc.).

cap: u32

Allocated capacity (for growable containers). 0 if not applicable.

aux: u64

Auxiliary data interpreted per-kind:

• TypedObject: schema_id (u64)
• Closure: function_id (low u16) | captures_count (next u16)
• TypedTable/RowView/ColumnRef/IndexedTable: schema_id (u64)
• Future: future_id (u64)
• Enum: variant_id (low u32)
• Other: 0

Implementations

impl HeapHeader

pub const OFFSET_KIND: usize = 0

Byte offset of the kind field from the start of the header.

pub const OFFSET_ELEM_TYPE: usize = 2

Byte offset of the elem_type field.

pub const OFFSET_FLAGS: usize = 3

Byte offset of the flags field.

pub const OFFSET_LEN: usize = 4

Byte offset of the len field.

pub const OFFSET_CAP: usize = 8

Byte offset of the cap field.

pub const OFFSET_AUX: usize = 16

Byte offset of the aux field.

pub fn new(kind: HeapKind) -> Self

Create a new HeapHeader with the given kind. All other fields are zeroed.

pub fn with_len_aux(kind: HeapKind, len: u32, aux: u64) -> Self

Create a HeapHeader with kind, length, and auxiliary data.

pub fn from_heap_value(value: &HeapValue) -> Self

Build a HeapHeader from an existing HeapValue.

Extracts kind, length, and auxiliary data from the HeapValue’s contents.

pub fn heap_kind(&self) -> Option<HeapKind>

Get the HeapKind from this header.

pub fn has_flag(&self, flag: u8) -> bool

Check if a flag is set.

pub fn set_flag(&mut self, flag: u8)

Set a flag.

pub fn clear_flag(&mut self, flag: u8)

Clear a flag.

Trait Implementations

impl Clone for HeapHeader

fn clone(&self) -> HeapHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HeapHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for HeapHeader

fn eq(&self, other: &HeapHeader) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for HeapHeader

impl Eq for HeapHeader

impl StructuralPartialEq for HeapHeader