Struct AnchorSidecar 

pub struct AnchorSidecar {
    pub version: u32,
    pub entities: BTreeMap<String, Vec<Anchor>>,
}

The engine-owned anchors sidecar document persisted at ANCHOR_SIDECAR_PATH on the mem branch: entity id → its anchors.

Written only through engine commits (the crate::backend::MemBackend sidecar seam). Rename rewrites the key atomically in the same commit as the entity move; delete drops the key in the same commit as the entity delete.

Fields

version: u32

Document schema version.

entities: BTreeMap<String, Vec<Anchor>>

Entity id (mem--slug) → its anchors. An entity with no anchors carries no key (an empty vec is pruned on write).

Implementations

impl AnchorSidecar

pub fn from_bytes(bytes: &[u8]) -> Result<Self, Error>

Parse sidecar bytes; an absent/empty payload yields an empty document so callers need not special-case a fresh mem.

pub fn to_bytes(&self) -> Vec<u8>

Serialise to canonical pretty JSON with a trailing newline — diff-friendly on the mem branch.

pub fn get(&self, entity_id: &str) -> &[Anchor]

The anchors recorded for entity_id, or an empty slice.

pub fn set(&mut self, entity_id: &str, anchors: Vec<Anchor>)

Replace entity_id’s anchors. An empty list prunes the key so the sidecar never accumulates empty rows.

pub fn merge( &mut self, entity_id: &str, unsets: &[AnchorUnset], incoming: Vec<Anchor>, )

Merge incoming into entity_id’s anchor row after applying unsets — the write-path set arithmetic.

Unset applies first: each selector removes its matching anchors (a selector matching nothing is a no-op). Then each incoming anchor replaces the surviving anchor with the same (artifact, grain, class) triple in place, and appends otherwise — untouched anchors keep their bytes and their position. Writing anchors never removes an anchor the call did not name in unsets; an empty incoming merges nothing. A row emptied by unsets prunes its key so the sidecar never accumulates empty rows.

pub fn remove(&mut self, entity_id: &str)

Drop entity_id’s anchors entirely (delete leg). Idempotent.

pub fn rename(&mut self, from: &str, to: &str)

Move from’s anchors to to (rename leg), leaving zero rows under the old id. No-op when from has no anchors. When to already has anchors they are overwritten — a rename onto a live id is refused upstream, so this is the residual-stub case only.

pub fn is_empty(&self) -> bool

Whether the document holds no anchors for any entity.

Trait Implementations

impl Clone for AnchorSidecar

fn clone(&self) -> AnchorSidecar

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for AnchorSidecar

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

Formats the value using the given formatter.

impl Default for AnchorSidecar

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for AnchorSidecar

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for AnchorSidecar

impl PartialEq for AnchorSidecar

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for AnchorSidecar

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for AnchorSidecar